Strabismus
Adapted with permission from lectures from
William E. Scott, M.D.

• Introduction to Strabismus
• Basic Examination Techniques
• Amblyopia
• Esotropia
• Exotropia
• Monofixation Syndrome
• Nystagmus
• Patterns
• Vertical Deviations
• Mydriatics & Cycloplegics
  Index of Surgical Tables

• Incidence of Strabismus
• Frequency of Types of Strabismus

• Heterotropias 3.7% (7.1 million)
• Esotropia 1.2%
• Exotropia 2.1%
• Hypertropia 0.6%
• Heterophorias 16.0% (30.7 million) (From National Health Survey)
• Incidence of heterotropia in children
• McNeil (1955) 2.7%
• Frandsen (1960) 4.5%
• Nordlow (1962) 3.86%
• Graham (1974) 4.39%
• Schutte,et al(1976) 4.3%
• Simons K, Reinecke R. Amblyopia screening and stereopsis. In: Symposium on Strabismus: Transactions of the New Orleans Academy of Ophthalmology. St. Louis;CV Mosby Co:1978, pp. 15-50.
• Incidence of strabismus is 2-3% of the general population

• Esodeviations 60%
• Accommodative 50%
• Hypermetropic 40%
• Pure High AC/A 10%
• Non-accommodative 10%
• Exotropia and verticals 40%
  (From private practice of Marshall Parks)

• Basic Examination Techniques for Children and Strabismic Adults
• Examining the Diplopic Patient

• History
• Sensory exam
• Visual Acuity in Children
• Measuring the basic deviation
• Detection of strabismus
• Quantitation of strabismus
• Positioning of prisms
• Variables with prism cover test
• Eye Movement evaluation (ductions/versions)
• Fusional amplitute measurement
• Torsional measurements
• Angles: alpha, gamma, kappa, lambda
• Supranuclear conrol of eye movements

• Ocular motility disorder
• Age and mode of onset?
• Which eye?
• Which direction is misalignment?
• Duration?
• Documented photographically?
• Description of symptoms
• Blurring, asthenopia, diplopia?
• Constant, intermittent, variable?
• Worse in gaze?
• Distance or near?
• Monocular or binocular?
• Known cause associated with onset
• Previous treatment
• Glasses: When first prescribed? How current is prescription? Improvement in condition?
• Prisms.
• Occlusion: Which eye? Period of time?
• Exercises: Description?
• Drugs: What type?
• Surgical: Which eye? How many muscles? How many times?
• Family history
• Birth history
• General health/growth and development? Medications? Diagnosed syndromes?

• Worth 4-Dot
• Central @ distance (6m)
• Peripheral @ near (¹/₃ m)
• Polarized 3-Dot
• * Arthur BW, Keech RV: The polarized three-dot test. J Ped Ophthalmol Strab 1987;24(6):305-308.
• Stereotests
• Titmus
• Randot
• Distance Vectograph.

• Alignment as measured with proper spectacle correction
• Accommodation is controlled with an accommodative target.
• Scott fixation device.
• Finger puppets.
• Wiggle sticks.
• Snellen acuity chart.
• Fusion is suspended.
• * Scott WE, Mash AJ, Redmond MR. Comparison of accommodative and non-accommodative targets for the assessment of ocular deviations. Amer Orthop J 1976;26:83-86.

• Single Cover Test (SCT) and Cover/Uncover Test.
• Fusion is not suspended.
• Detects presence of tropia.
• Alternate Cover Test (ACT)
• Detects presence of phoria.
• Detects basic deviation.

• Corneal Reflection Tests
• Hirschberg - corneal light reflex.
• Modified Krimsky - prism held in front of fixing eye.
• Accommodation is not controlled.
• Fusion is not suspended.
• Prism Cover Tests
• Single prism cover test.
• Simultaneous cover and prism test.
• Alternate cover and prism test.
• Scleral comparison

The deviation that a prism produces or neutralizes is dependent on the position of the prism as it is held before the patient. Remember--when prisms are used to measure a strabismus deviation, the prism displaces the image so that no movement of either eye is needed to fixate on the target.

• Prentice position.
• The line of sight of the deviated eye is perpendicular to the posterior face of the prism. This is the proper way to hold a glass prism.
• Minimum deviation position.
• The visual axis inside the prism is perpendicular to the line bisecting the apex angle of the prism. This is the position in which plastic prisms are calibrated.
• Frontal plane position.
• The posterior face of the prisms is held in the frontal plane of the patient. This is the commonest way of holding plastic prisms.
• Horizontal and vertical prism bars are calibrated for use in the frontal plane position.
• Fresnel press-on prisms are calibrated in the Prentice position.
• Prism held perpendicular to the line of sight anterior to the prism when measuring lateral gaze, vertical gazes, or near.
• Prism held with base parallel to the lateral wall or floor of the orbit when measuring in head tilt
• Never stack two prisms in the same direction as this causes large measurement error. Adding a vertical and a horizontal prism together causes no measurement error.
• Splitting prisms between the two eyes to measure large deviations causes some measurement error but substantially less than stacking.
• *Thompson JT, Guyton DL. Ophthalmic prisms. Measurement errors and how to minimize them. Ophthalmol 1983;90(3):204-210.
• * Helveston EM. Prism placement. Measurements of horizontal and vertical deviations with the head tilted. Arch Ophthalmol 1975;93:483-486.
• * Thompson JT, Guyton DL. Ophthalmic prisms. Deviant behavior at near. Ophthalmol 1985;92(5):684-690.
• * Scattergood KD, Brown MH, Guyton DL. Artifacts introduced by spectacle lenses in the measurement of strabismic deviations. Amer J Ophthalmol 1983;96(4):439-448.

• Prisms
• positioning.
• Stacking.
• Splitting.
• Spectacles
• High plus or minus spectacles (generally = 5 D) create a built in prismatic effect in strabismic patients that must be taken into account when performing a PCT.
• High minus glasses will induce a base in prism effect for esotropes and a base out prism effect in exotropes. In both cases this will have the effect of making the deviation by the PCT appear larger than the true deviation by 2.5 D %. (i.e., a patient wearing -10.00 D glasses with a 40^D esotropia by PCT will have a true deviation of 30^D ).
• High plus glasses will induce a base out prism effect for esotropes and base in effect for exotropes. In both cases this will make the measured deviation smaller than the true deviation by 2.5 D % (i.e., a patient wearing +10.00 D glasses with a 40^D esotropia by PCT will have a true deviation of 50^D ).
• Anisometropic spectacles.
• Prism is induced in the presence of an anisometropic spectacle correction when the visual axis is not aligned with the optical axis of the lenses. This can cause diplopia and account for differences in measurements obtained in secondary and tertiary gaze positions.
• Incomitant deviations
• A & V patterns.
• Paresis.
• Restriction.
• Anomalous innervation.
• Variable deviations
• Cyclic deviations.
• Nystagmus blockage.
• DVD.
• Myasthenia.
• Thyroid.
• CNS disorders.

Examination of ocular movement (ductions & versions)

• Actions of extraocular muscles
• Synergists
• Yoke muscles
• Ductions: movement of a single eye in any direction.
• Versions: movement of both eyes in any direction.
• Tests are based on
• Hering's Law (of equal innervation): when innervation is sent to a muscle causing it to contract, equal innervation goes to its yoke muscle (contralateral synergist) in order to maintain parallelism of the visual axes.
• Sherrington's Law (of reciprocal innervation): when one extraocular muscle receives an impulse to contract, its ipsilateral opposing muscle (direct antagonist) receives an impulse to relax, allowing smooth movement to take place.

• Action of Extraocular muscles from primary position 
• Synergists: Two or three muscles of the same eye that work together to produce a given movement.

• Yoke Muscles: Pairs of extraocular muscles that move both eyes together in a parallel movement in the nine directions of gaze.

• On examining ocular movement, the extent of movement in each direction of gaze, as well as the quality of that movement, should be noted.
• The patient should be asked to fixate a target moving from primary into the limits of the eight positions of gaze. Versions should be tested first, then ductions.
• * Keep patient's head straight throughout the examination.
• * Test depression without holding lids up first to note associated anomalies of lid movement.
• * Test ductions in case of limitation on versions and manifest strabismus.
• Observations
• Abnormalities of ocular movement can be seen by comparing the amount of visible sclera, corneal reflections or the position of the limbus. Variations in palpebral fissure shape and size can give a misleading impression. The following observations should be noted and recorded.
• Underaction and overaction (-4 -> 0 -> +4).
• Differences on duction vs. version.
• End point nystagmus or pathological nystagmus.
• Changes in fissure size.
• Lid changes.

• Normal fusional amplitudes
• Convergence, divergence and vertical fusional amplitudes can be measured with a prism bar at both distance (20 feet) and near (13 inches). The bar is placed in front of one eye and is slowly moved from the smallest prism to prisms of increasing strength while the patient fixates a 20/40 target. The patient is instructed to report when the letter blurs and when he appreciates diplopia. At this point, the power of the prism is decreased until he again is able to fuse the image. The point where fusion broke, the one where it was recovered, as well as the blur point (which may not always be reported) are recorded. The blur point is the point at which the patient can no longer exert fusional convergence to overcome diplopia and tries to use accommodative convergence for this purpose. By accommodating in excess of the requirements for a given distance, the image will be blurred.
• Fusional amplitudes cannot be measured on suppressing or diplopic patients. It is necessary to look for fusional movements while doing this test to ensure that the patient is not suppressing.

• Double Maddox Rod- Orient both red and white lenses vertically, thereby creating two horizontal lines. Ask the patient to make both lines horizontal by turning the knobs at the sides of the frames.
• Bagolini lenses- Less dissociative than Double Maddox rod. Orient both lenses at 90°. Lines will be created at 180°. Measure torsion as in Double Maddox rod.
• Single Maddox Rod- Can only qualitatively assess torsion.
• Maddox Double Prism- Can only qualitatively assess torsion. Consists of two 4^D prisms mounted base to base. The prism is placed before one eye. When looking at a single horizontal line, the patient will thus see three lines. The central line is seen by the eye without the prism while the Maddox double prism causes the other eye to see two lines - one above and one below the central line. The patient then judges whether or not the central line is parallel to the other lines.
• Objective fundus viewing
• With indirect ophthalmoscope.
• With fundus camera.

• Optic axis (BO). The line that passes through the center of curvatures of all the refracting surfaces.
• Pupillary axis (AY). A line perpendicular to the cornea that passes through the center of the pupil. Usually coincides with the optical axis.
• Visual axis (MF). A line from the point of fixation to the fovea passing through the nodal points of the eye.
• Angle alpha (<FNO). Angle between optic axis and visual axis at the anterior nodal point (N).
• Angle gamma (<FCO). Angle between optic axis and visual axis at the center of rotation (C).
• Angle kappa (<FNO[Y]). Angle between pupillary axis and visual axis at the anterior nodal point (N). The angle that is clinically called the angle kappa is actually, the angle lambda.
• Angle lambda (<FDO[Y]). Angle between pupillary axis and visual axis at the center of the pupil (D).

Supranuclear control of eye movements

• Saccades
• fast movements, 400-500 degrees/ second
• responsible for refixation or moving eye to another location of visual interest
•  initiated by burst cells in the paramedian pontine reticular formation (PPRF)
• Pause cells must be suppressed in order for the burst cells to generate a saccade
• Pause cells are inhibited by the frontal lobe via the corticobulbar pathway
• Smooth pursuit
• allows the eyes to follow an object
• limited to 30-60 degrees/second
• Striate cortex (occipital lobe) generates impulse to the dorolateral pontine nuclei. The vestibular nuclei receive imput (probably via the cerebellar flocculus and dorsal vermis) and transmit it to the 3^rd, 4^th, and 6^th cranial nerve nuclei.
• Vergence system: control of this system is not fully understood
• Position maintenance: control of gaze maintenance is not understood
• Nonoptic reflex systems: coordinate eye with head and body movements.
• Labrinthine reflex system: semicircular canals and the vestibular nucleus send imput to the 3^rd, 4^th, and 6^th cranial nerve nuclei.
• Utricle and saccule of the inner ear have some imput but are less important
• Cervical receptors also provide imput to this system

• History
• Cover test
• Measure deviation
• Fields of binocular single vision

 Diplopia History- careful history important

• Is diplopia monocular or binocular?
• If the patient claims the diplopia is relieved by covering one eye, make sure that is true for either eye.
• Use a red filter and the distance fixation light to give the patient two different images at distance. Ask how many lights the patient sees and of what color. More than one of each color indicates that the patient has monocular diplopia.
• Is diplopia worse at distance (when driving) or at near (when reading)?
• Is diplopia constant, intermittent or variable?
• Is diplopia horizontal, vertical, oblique or torsional?

Measure patient using the cover test- providing he/she has adequate visual acuity for fixation.

• Does this amount of prism alleviate diplopia?
• If patient has a vertical and horizontal component to his/her deviation, will correcting one direction of the misalignment enable the patient to control the other component?

Measure the deviation with red filter and distance fixation light. Can patient fuse?

• ET - uncrossed (homonymous) diplopia.
• XT - crossed (heteronymous) diplopia.
• HT - object will be viewed as lower or below fixation target.
• HypoT - object will be viewed as higher or above fixation target.
• Torsion - object will be viewed as having a rotation opposite that measured.

• Diagnostic test for diplopic patients. Varies with gaze position and the eye chosen for fixation in incomitant patients.
• Area of least deviation is characteristically diagonally opposite to the field of main action of the paretic muscle.
• Can be performed on any perimeter used for monocular visual field testing. Unlike monocular field testing, the patient must follow the target with his eyes.
• Must have:
• Normal monocular fields.
• Reasonable visual acuity without correction.
• No suppression.

• Definition
• Etiology
• Congenital Esotropias
• Pseudoesotropia
• Congenital (infantile) ET
• Congenital non-comitant ET
• Duane's syndrome
• Moebius syndrome
• Congenital VI nerve palsy
• Acquired Esotropias
• Acquired accommodative
• Hypermetropic ET
• High AC/A ratio
• Combined Hypermetropia, High AC/A ratio
• Acquired Non-accommodative ET
• Monofixation syndrome
• Work-Up
• Prism Adaptation

• Esophoria - a convergent deviation held latent by fusion.
• Intermittent Esotropia - a convergent deviation held latent at times but can be manifest.
• Esotropia - a manifest convergent deviation.

• Mechanical or anatomic
• Secondary contractures
• Adherence syndromes
• Innervational
• Excessive tonic convergence
• High AC/A ratio
• Refractive
• Fusional deficiencies
• Genetic (Multifactorial) 25-50% (Mash, Spivey)
• Nystagmus
• Impaired vision in one eye (Sensory, 4%)
• If visual impairment is from birth, an esodeviation is most likely. If visual impairment is after age 3-4, eye will exodeviate.
• If seeing eye is hyperopic, esodeviation is most likely; if closer to emmetropia, eye will exodeviate.

• Sensory testing
• Visual acuity - diagnosis of amblyopia
• Versions
• Measurements- Determine the Basic Deviation
• Cycloplegic refraction
• Fundus examination

Pseudoesotropia - Accounts for About 50% of All Suspected ET

• Epicanthal folds, most common cause
• Bilateral, usually asymmetrical
• Three types of epicanthus
• Supraciliaris
• Palpebralis
• Tarsalis
• Large negative angle kappa, uncommon
• Abnormally small I.P.D.

• Characteristics
• Management of Congenital Esotropia
• Surgical Tables
• DVD

• Onset before six months of age - generally not present at birth.
• Large angle of deviation.
• 40% incidence of amblyopia
• Crossfixation
• Distance and near deviations are equal
• Low refractive errors
• Latent nystagmus 40-60%
• DVD 60-80%
• Inferior oblique overaction - secondary to superior oblique palsy 40-60%
• V pattern
• Peripheral fusion at best - not bifoveal fusors.
• 40-50% will develop an accommodative component.
• Strong family history.

Dissociated Vertical Deviation (DVD)

• Characteristics
• Explanations
• DVD & IOOA
• Measurement
• Treatment
• Previously used treatments
• "Super Maximum" treatment
• Surgical tables
• aka: Alternating Hyperphoria, Double Hypertropia, Occlusion Hypertropia, Alternating Sursumduction, Dissociated Vertical Divergence
• Occlusion Hyperphoria: a latent vertical deviation becoming manifest only when fusion is suspended.

• A spontaneous manifest vertical deviation.
• Usually bilateral - eye deviates up and out when dissociated.
• Asymmetrical.
• Variable amount and frequency of deviation.
• If a fixation preference exists, a DVD may be present in the non-preferred eye with an occlusion hyper in the fixing eye.
• Head tilt to the side of the DVD to control.
• Usually associated with congenital esotropia or A pattern exotropia.
• Rarely occurs without horizontal strabismus.
• Rarely have bifoveal fusion.

• Bielschowsky (1930)
• Unilateral stimulation to upward gaze (variation, occlusion, and reduced illumination)
• Unequal stimulation of each retina. Abnormal excitability of the subcortical vertical divergence center (there is no evidence for these centers).
• Posner (1944)
• Synthesis of the primitive monocular tonus regulator and the higher binocular innervation. Reflex mechanism - eyes tend toward divergence and elevation, i.e. Bell's Phenomenon.
• Chavasse (1939)- One retina is less dominant; the eye moves up and out.
• Verhoeff (1941)^- Nucleus hypoplasia with overaction of obliques.
• White & Brown (1939)^- Due to paresis of SR, IR, or IO.
• Supranuclear origin evidence
• Coordinated nature of movement.
• Failure of direction of gaze to alter deviation.
• IO overactions may exist - evidence of palsy is lacking.

DVD vs IOOA - differential diagnosis

• DVD - features
• Causes elevation in adduction.
• Usually comitant, i.e. same in adduction, primary and abduction.
• No corresponding hypotropia.
• Variable hyper, at times appears small - moderate, other times large.
• Generally not associated with a pattern.
• Same amount of hyper in up gaze and down gaze.
• Hyperdeviation may be associated with torsion and abduction.
• Inferior Oblique Overaction - features
• Causes elevation in adduction.
• Incomitant - larger deviation in field of action of IO.
• Not variable.
• Commonly associated with a V pattern.
• More hyper in upgaze than in downgaze.
• Hyper deviation not associated with torsion.
• Corresponding hypotropia.
• Measurement
• DVD - measure or estimate deviation in non-fixing eye.
• IOOA - neutralize the hyper or hypotropia.
• Treatment
• IOOA - weaken IO\
• IO weakening corrects at most 15 D of vertical in primary, more in its field of action and none in the opposite field
• IO weakening does little to correct DVD.
• DVD - recess SR.
• SR recession cosmetically improves a DVD
• Previously used surgical procedures for DVD
• 4mm superior rectus recession
• Inferior rectus resection
• Vertical R & R
• Faden or posterior fixation suture
• "Super Maximum" recession of SR is now the treatment of choice for DVD
• Technically easier than the Faden operation
• Effective
• Does not cripple the muscle
• Produces no lid changes
• Amount of SR recession for DVD: See surgical tables

*Baverman DE, Scott WE: Surgical treatment of dissociated vertical deviations. J Ped Ophthalmol Strab 1977; 14:337-342.

*Scott WE, Sutton VJ, Thalacker JA: Superior rectus recession for dissociated vertical deviation. Ophthalmol 1982; 89(4):317-322.

Management of Congenital Esotropia (developed over 16 years)

• Pre-op evaluation
• Surgical tables
• Surgical Plan & Results
• Varibility of medial rectus insertion
• Conjunctival recession to augment rectus recession

• The goal in all strabismus surgery is to get the patient straight with the fewest number of operations.
• Prior to surgery, the patient should be evaluated for amblyopia, refractive error, accommodative component, size of the deviation, and associated features.
• Incidence of amblyopia is 40% treated with full time occlusion of the better seeing eye.
• Refractive status is evaluated after dilation with 1% Cyclogyl.
• ³ +2.00 D is given as a trial to observe its influence on the deviation.
  2) Refractions are repeated until two refractions agree within 0.5 D.
• Stable prism cover test measurements are obtained at distance and at near.
• Two consecutive measurements that agree within 5^D .
• Deviation measured on an accommodative target at distance and near.
• Complete examination includes investigation in the diagnostic positions of gaze.
• Rule out A or V pattern with oblique overaction or underaction.
• Differentiate inferior oblique overaction from DVD. Variable elevation in adduction caused by DVD.

• Selective surgery consists of three or four horizontal muscles where esotropia exceeds 50 PD
• Surgical Tables
• Results of using the selective approach
• Average pre-op deviation in 48 patients who underwent three or four muscle procedures was 70 PD
• Successful alignment was obtained in 65%
• Sensory fusion resulted in 40% of patients

*Kraft SP, Scott WE: Surgery for congenital esotropia- an age comparison study. J Ped Ophthalmolo Strab 1984;21:57-68.

*Scott WE, Reese PD, Hirsh CR, et al.: Surgery for large-angle congenital esotropia. Two versus three and four horizontal muscles. Arch Ophthalmol 1986; 104-:374-377.

• Anatomic Variability- Medial recurs insertion classically referred to as being 5.5mm from the limbus.
• Variability of medical rectus insertion has been reported by Helveston and Kushner
• Helveston measured distance between medial rectus insertion and limbus in 114 eyes; average 4.4mm (range3-6mm)
• Kshner measured distance between medial rectus insertion and limbus in 80 eyes; average 4.3mm (range 3.5-5.5mm)
• Apt describes a change in the distance between medial rectus insertion and limbus with intraoperative manipulation

*Apt L: An anatomical re-evaluation of rectus muscle insertions. Trans Amer Ophthalmol Soc 1980;78-356-375.

• Sugical Variability
• Measurement of insertion in 26 eyes of patients ranging in age between 10 and 30 months with preoperative deviation of 25 PD to 70 PD
• A limbal conjunctival incision was used
• Distance between the surgical limbus and anterior medial rectus insertion was measured
• Average insertion 5.5mm from limbus (5-6mm)
• Measurement of distance between the stump of the disinserted medial rectus and limbus.
• Following disinsertion, a measurement was taken of the distance between the limbus and the stump of the muscle.
• There was an average of 1.2 mm movement of medial rectus muscle stump toward the limbus (range 0.5- 2.0 mm)
• The muscle was re-attached to the globe an appropriate distance from the limbus using a curved ruler.
• Following re-attachment, the distance between the stump of the medial rectus and the limbus was remeasured.
• The distance of the medial rectus stump was an additional 0.5 mm closer to the limbus.
• Significant variability exists in the distance of the medial rectus muscle from the limbus secondary to intraoperative factors.
• More accurate measurements of the amount of recession being performed are obtained by measuring from the limbus.
• The location of the medial rectus muscle should be measured before disinsertion

*Keech RV, Scott WE, Baker JD. The medial rectus muscle insertion site in infantile esotropia. Amer J Ophthalmol 1990;109:79-84

Conjunctival recessions to augment medial rectus recession

• Helveston reported recession of the conjunctiva adds to the effect of the medial rectus recession
• Guidelines:
• Grasp eye with forceps and abduct it
• Use a small muscle hook and palpate the conjunctiva with eye abducted
• If conjunctiva tight: recess it back to the original insertion using a limbal incision
• If conjunctiva loose: recession will not augment the medial rectus recession, use a limbal or fornix incision

• Characteristics
• Alignment
• Classification
• Clinical-Pathologic correlation
• Surgical Treatment

• More common in females than males.
• OS affected more often than OD.
• 10%-30% incidence of anisometropic amblyopia.
• Face turn toward the side of limited movement permits fusion.
• 80% of cases are unilateral, when bilateral it is usually asymmetric.
• Orthophoric, esotropic or exotropic in the primary position.
• Angle of deviation always less than 30^D , usually less than 15^D .
• Narrowing of the fissure and retraction of the globe of the involved eye on attempted adduction.
• Abduction is limited in ortho and ET Duane's.
• XT Duane's show limited adduction.
• The amount of limitation depends on the amount of co-contraction of the medial rectus and lateral rectus.
• Forced ductions are positive.
• Abnormal firing of the lateral rectus is found with EMG testing.
• Saccadic velocities on adduction are slowed secondary to the co-contraction.
• Should be differentiated from a VI nerve palsy.

• 36% orthophoric
• 25% exotropic
• 24% esotropic
• 15% bilateral
• * Isenberg S, Urist MJ. Clinical observations in 101 consecutive patients with Duane's retraction syndrome. Amer J Ophthalmol 1977;84:419-425.

Duane's- Classification

• Type I - poor abduction & normal adduction
• Type II - (ortho to exotropia) poor adduction, normal abduction
• Type III - (esotropia) poor abduction, poor adduction

• For example, in a left Duane's
• The left abducens nucleus - no cell bodies from motor neurons except cell bodies compatible with internuclear neurons.
• The left abducens nerve was absent.
• The left lateral rectus muscle was partially innervated by branches from the inferior division of the IIIrd nerve.
• * Miller NR, Kiel SM, Green WR, Clark AW. Unilateral Duane's retraction syndrome (Type 1). Arch Ophthalmol 1982;100(9):1468-1472.

• Indications.
• Abnormal head position (AHP) - face turn toward limitation of movement.
• Deviation in primary position.
• Upshoot or downshoot on adduction.
• Types
• Type I - commonest of types; usually associated with AHP; esotropia in primary.
• Type II - much less common; AHP.
• Type III - more common than type II; usually not associated with AHP; upshoots or downshoots more common.
• Surgical procedures
• Recess MR - resect LR in involved eye.
• Recess MR, recess LR in involved eye plus recess MR of normal eye with or without posterior fixation suture.
• Transposition procedures temporally on involved eye.
• Posterior fixation of LR.
• Single recession of MR if ET or LR if XT.
• Recession of LR with posterior fixation for upshoots and downshoots.

Moebius syndrome (Congenital facial diplegia)

• No facial expression (VII nerve palsy)
• Esotropia (VI nerve palsy)
• Ptosis
• Deformity of external ear
• Atrophy of tongue
• Club foot, syndactyly, deficiency of pectoralis muscle.

Acquired Esotropia

• Accommodative Esotropia
• AC/A Ratio
• Mydriatics, Cycloplegics and Anticholinesterases
• Prism Adaptation
• Surgery Tables
• Prism Adaptation for Near Angle
• Non-accommodative Acquired Esotropia

• Clinical Features
• Differential Diagnosis
• Congenital or Acquired
• Treatment
• Post-op evaluation

• Large angle esotropia in primary
• Poor or absent abduction
• Normal adduction
• Absent firing or reduced firing of lateral rectus with EMG
• Normal adduction on saccadic velocities

• Infantile esotropia with cross-fixation.
• Duane's syndrome.

• Congenital
• Birth trauma.
• Hypoplasia of VIth nerve nucleus.
• Anomaly of nerve fibers.
• Acquired
• Trauma to cranial floor.
• Increased intracranial pressure.
• Meningeal edema.
• Inflammation in base of skull.
• Displacement of brain stem.
• Sensitivity to toxic substances.
• Demyelinating disease.
• Viral illness.
• Vasculitis.

• Medical
• No treatment - if compensatory head posture.
• Alternate occlusion.
• Fresnel prisms.
• Recover 3-6 mo.
• Surgical
• If lateral rectus function is 40% normal or better by saccadic velocity, R & R (adjustable).
• If lateral rectus function is absent or poor (less than 40% of normal), Jensen transposition procedure.

• Determine etiology
• Exposure - cornea status
• Diplopic field
• Saccadic eye movement studies
• Forced duction
• Forced generations.
• Iris angiography

 Accommodative Esotropia

• History
• Types
• Hypermetropic accomodative esotropia
• Accomodative esotropia with high AC/A ratio
• Combined hypermetopia & high AC/A
• Management
• Indications for surgery

• Donders - 1864
• Duane's classification - 1924
• Convergence excess - near deviation exceeds distance.
• Divergence insufficiency - distance deviation exceeds near.
• Combined - distance = near.
• Costenbader - 1950
• Parks - 1958

• Accounts for 40% of accommodative ET
• Distance and near measurements equal
• Average age of onset 3.5 years
• Average refractive error is +4.75 D
• Incidence of amblyopia is 15%
• Deterioration rate of 15%

Accommodative esotropia with a high AC/A ratio

• 68% of accommodative esotropes will have abnormal AC/A
• Near deviation exceeds distance by 10 ^D
• Grade I - 10^D - 19^D greater at near.
• Grade II - 20^D - 29^D greater at near.
• Grade III - 30^D or more.
• Average refractive error +3.27 D
• 19.8% incidence of amblyopia
• Average age of onset 2 yr, 7 mo.
• Rate of deterioration
• Grade I - 25%
• Grade II - 42.3%
• Grade III - 51.6%
• Deterioration rate 30.3% overall.
• Rate of deterioration increases with the severity of the AC/A and lower refractive error.
• Rate of deterioration is increased in patients with early onset of accommodative ET.
• * Ludwig IH, Parks MM, Getson PR, et al. Rate of deterioration in accommodative esotropia correlated to the AC/A relationship. J Ped Ophthalmol Strab 1988;25(1):8-12.
• Deterioration rate - overall 13%
• AC/A ratio - no influence (only 12/93 > 9:1).
• Delay between onset and spectacle correction.
• Onset before 24 months of age.
• Decreasing hyperopia with > 5:1 AC/A.
• * Dickey CF, Scott WE. The deterioration of accommodative esotropia: Frequency, characteristics, and predictive factors. J Ped Ophthalmol Strab 1988;25(4):172-175.

Combined hypermetropia & High AC/A

• Moderate hyperopia, +3.00 D
• Distance-near disparity (N > D)
• Average age of onset 3 years
• Incidence of amblyopia is 30%
• Commonest type of esotropia

• Occlusion for amblyopia
• Anti-accommodative therapy
• Optical
• Single vision lenses: full hypermetropic correction.
• Bifocal lenses: to elicit fusion at near.
• Medical - miotics. Optical correction is a more permanent solution.
• Surgery for non-accommodative component: surgical tables

• Unable to keep patient aligned with glasses alone
• For fusion.
• For alignment.
• Surgical Tables
• Once deterioration has occurred an attempt should be made to align patients and re-establish fusion pre-operatively with Fresnel prisms ("Prism Adaptation").

• Methods for determining AC/A
• Normal values for AC/A ratio
• Accommodative convergence - measured in meter angles or prism diopters
• Accommodation - measured in diopters

• Heterophoric Method -

• The heterophoric method assumes that convergence is wholly due to accommodation, it does not take into consideration the whole near response, i.e. tonic convergence, proximal convergence.
• Gradient Method - fixation distance is fixed. The deviation is measured with and without a modifying lens. This lens changes the amount of accommodation used to create a clear image and thus changes the resultant deviation. AC/A = change in deviation / change in accomodation
• Measure by stimulating accomodation
  • Measure ocular misalignment while fixating at 6 meters, then remeasure with a -1.00 D lenses in front of both eyes
  • The difference between the two measurement is the AC/A ration
• Measure by relaxing accomodation
  • Measure misalignment with target at 0.33 meters, then remeasure with +3.00 D lenses over both eyes
  • The difference is divided by 3 to get the AC/A ratio
• Slope gradient method- Use series of lenses, i.e. +3.00, +1.00, -1.00, -3.00. Make slope of values.

• By Gradient Method - average is 3.7:1
• Gradient Method range is 0.9 - 9.8
• Low - 0-2.0
• Normal - 2.5 - 5.0
• High - >5.0
• By Heterophoric Method - average is 4.4:1
• Heterophoric Method range is 2.7 - 7.7 (0gle)¹⁵
• Factors that can influence the AC/A ratio
• Glasses/Bifocals
• Anticholinesterases
• Surgery
• Time
• Orthoptics

• Mydriatics & cycloplegics
• Table of commonly used mydriatics
• Anticholinesterases

• Mydriacyl
• Atropine
• Cyclogel
• Homatropine
• Table

Mydriacyl (Tropicamide)

• Peak effect in 20-25 minutes.
• 30-40 minutes duration.
• Produces less than 2.00D of residual accommodation.
• Concentration/Dosage - 2 drops of 1% given 5 minutes apart.
• Minimal toxicity.

Atropine - acts directly on smooth muscle

• Onset - hours.
• Duration - 10-14 days.
• Concentration
• 1% - for darkly pigmented children.
• 1/₂%- for lightly pigmented children over age 4.
• 1/₄% - for lightly pigmented children under age 4.
• Dosage - administered t.i.d. for 3 days prior to appointment; ointment should not be used on day of appointment.
• Toxicity
• Fatal dose for children - 10 mg., 1 drop of 1% atropine = 0.5 mg.
• Systemic absorption is reduced with ointment.
• Reversed with physostigmine.

Cyclogyl (Cyclopentolate) - parasympatholytic

• Peak cycloplegia in 40 minutes.
• Compares favorably with atropine as a cycloplegic.
• Robb and Petersen (1968)¹⁶ found less than 0.50 D more hypermetropia with Atropine than 1% Cyclogyl.
• Endpoint is two refractions that agree within 0.50 D.
• Concentration/Dosage
• 1/₂%-2 drops at a 5 minute interval in children under age 1.
• 1%-2 drops at a 5 minute interval in children over age 1.
• 2% rarely used.
• Toxicity
• Flushing of the skin.
• Fever.
• Dryness of the mouth.
• Increased I.O.P.
• CNS - psychosis, behavior disturbances.
• Tachycardia.

• Onset - 10-30 minutes
• Peak cycloplegia in 3 hours
• Dosage - 6-8 drops given 10-15 minutes apart.
• Duration - 36 hours.
• Residual accommodation averages 1.00 D.

Anticholinesterases in accommodative esotropia- If an anticholinesterase has to be given more than every other day to yield a good result, its use should be reconsidered.

• Mechanism
• Dosages of common agents
• Systemic effects
• Ocular effects

• Inhibit or inactivate acetylcholinesterase.
• Allows acetylcholine to accumulate at cholinergic receptor sites-acts as if cholinergic neurons are being continually stimulated.
• Dosages of commonly used miotics
• D.F.P. (physostigmine)- supplied as .025% ointment.
• Diagnostic dose 1/4 inch ointment every night for 2 weeks.
• Therapeutic dose - every night for two weeks; decrease to every other night for two weeks then once a week for 2 months.
• Phospholine Iodide (P.I.) - stable longer than D.F.P.
• Diagnostic dose-0.125% every night for 2-3 weeks.
• Therapeutic dose-0.125% every other night, 0.06% every night, 0.03% every night.
• Humorsol - not frequently used in strabismus.

Systemic effects of anticholinesterase agents.

• Salivation.
• Sweating.
• Urinary incontinence.
• Diarrhea.
• Muscle weakness.
• Respiratory difficulties (anticholinesterases are contraindicated in asthmatics).
• Cardiac irregularities.

Ocular effects - miosis, ciliary spasm.

• Pain - brow ache, retro-ocular ache.
• Myopia.
• Retinal detachment - never reported in children.
• Lens changes - begin as mossy anterior subcapsular opacities; Later - nuclear sclerosis. When drug is discontinued, lens opacities seem to reverse but often appear later. - Possible causes of lens opacities: Michon, Kinoshita (1967)¹⁷ -lens epithelium contains cholinesterases Leopold (1975)¹⁸ -anticholinesterases increase serum amino acids which may cause defects in lens metabolism.
• Iris cysts-prevented by compounding with neosynephrine.
• Ocular effects decrease after using the drug for two weeks.
• Existing uveitis is a contraindication to the use of anticholinesterases.

• Clinical features
• Treatment
• Surgical Tables

• Moderate angle of deviation
• Equal vision
• Little or no hypermetropia
• Normal AC/A Ratio
• May show suppression or Anomalous Retinal Correspondance\
• Patients falling into this classification are probably broken-down monofixators.

• Prism adaptation
• Surgery for full amount of deviation: Surgical Tables

• Background
• Technique
• Prism Response
• Prism Non-response
• Mechanisms of adaptation
• Prism Adapted Surgery (Study results)

• Indications for surgery in deteriorated accommodative esotropia: unable to align or keep patient aligned with glasses alone.
• For fusion.
• For alignment.
• Indications for prism adaptation.
• Deteriorated accommodative esotropia, deviation initially controlled by medical treatment.
• Partially accommodative esotropia: glasses correct only part of the deviation.
• Nonaccommodative acquired esotropia.
• Prism adaptation: preoperative test to predict fusional capability and success of surgery in acquired esotropia when surgery is indicated.

• Esotropia is neutralized distance and near with Fresnel press-on prisms; enough prism should be mounted to render patient orthotropic to slightly exotropic.
• Patients are followed weekly and prisms adjusted appropriately until they can be labeled "responder" or "non-responder".
• Responder
• Deviation stabilized at 8^D esotropia or less with peripheral fusion on Worth 4-dot while wearing prisms.
• In these patients surgery is done for amount of esotropia present after prism adaptation.
• Non-responder
• With Fresnel prisms deviation builds to greater than 60^D without fusion.
• Angle of deviation does not build with prisms but fusion is not obtained; with prisms patient is exotropic at distance and esotropic at near without fusion.
• In these patients, surgery is done for original angle of deviation.

• Deviation on simultaneous prism and cover test (SPCT) 0 to 8^D at distance and near plus fusion of Worth 4-Dot at ¹/₃ m, or
• Diplopia on Worth 4-dot at near but also had 2/9 circles and 2/3 animals on Titmus stereo.

• Exotropia on SPCT at distance and near with suppression to Worth 4-Dot, or
• Esotropia 0 to 8^D distance and near with no fusion; held here for 30 days
• Deviation built to >60^D

• Uncovers latent esotropia
• Measures fusion potential

Surgery after prism adaptation- Randomized clinical trial compared overall effectiveness of PA as preoperative test

• Surgical Tables
• Target angle - amount of surgery done for esotropia in distance measured by ACPT at time of randomization
• Used for
• Control group.
• Non-responders.
• Prism responders randomized (level 2) to entry angle.
• Prism adapted surgery done for total amount of prism at time of response to prisms.
• Standardized to amount and technique.
• Success defined as 0 - 8^D by SPCT
• Primary goal
• Overall PA success rate, 83%
• Success of controls, 72%
• Statistically significant Z-statistic of 2.02 (p = 0.04)
• Postoperative alignment
• Total seven overcorrections (>8^D exotropia), five in controls (non-PA, surgery for entry angle).
• Undercorrections (>8^D esotropia)
• 25% controls.
• 21% PA response/ES (surgery for entry angle).
• 10% PA response/PS (surgery for amount of prisms).
• Orthotropic
• 49% PA response/PS.
• 24% PA non-response/ES.
• Once PA response, surgery for entry angle or surgery for prism adapted angle.
• Summary
• Prism adaptation had overall effect of producing better postoperative alignment than controls (p = 0.04).
• Operating for built angle had lower rate of undercorrections (10%) without increasing overcorrections <1%).
• PA identifies group of patients that can safely receive larger amounts of surgery.
• Non-responders had lowest rate of postoperative fusion.
• 55% of prism responders built their angle little with prisms.
• Recommend that PA be done for patients with acquired esotropia to determine target angle for surgery.
• * Prism Adaptation Study Group. Efficacy of prism adaptation in the surgical management of acquired esotropia. Arch Ophthalmol 1990;108(9):1248-1256.

• When near deviation is greater than distance deviation
• Preliminary results
• Group I (n = 10), no fusion response to prisms or exotropia in distance with prisms.
• Group II (n = 17) stabilized with prisms for near angle and fused
• Group III (n = 4) increased esotropia 10^D or more in response to base-out prism; no exotropia in distance
• Summary
• 21 of 31 fused with prisms pre-op when near deviation was offset without any exotropia at distance.
• 20 of 21 maintained fusion at last post-op exam.
• None required bifocals post-op for fusion.
• * Kutschke PJ, Scott WE, Stewart SA. Prism adaptation for esotropia with a distance-near disparity. Submitted for publication, J Ped Ophthalmol Strab.

• General considerations
• Features
• Etiology
• Tests for Monocular Scotoma During Binocular Viewing
• Specific Characteristics
• Treatment
• Prognosis

• Deviation of 0^D - 8^D . An "orthotropic" monofixator has no shift on prism cover test but responds like a tropic patient to sensory testing.
• Central suppression of the deviated eye
• Good fusional vergence amplitudes
• Synonyms for monofixation syndrome
• Esophoria with retinal slip
• Esophoria with fixation disparity
• Fixational disparity
• Subnormal binocular vision
• Small angle esotropia
• Convergent fixation disparity

• Constant features
• Absolute facultative scotoma in the monofixating eye
• Peripheral fusion
• Fusion of Worth 4-Dot lights at near.
• 3000 to 60 seconds of stereoacuity.
• Variable features
• Strabismus history
• Anisometropia
• Unilateral macular lesion
• Amblyopia
• Eccentric fixation
• Orthophoria
• Phoria
• Small tropia
• Alternate cover exceeds cover-uncover

• Treated strabismus
• Anisometropia
• Unilateral macular lesion
• Inherent inability to fuse similar images on each macula (primary monofixation)

• Worth 4-Dot (100%)
• Stereopsis (100%)
• Binocular perimetry (99%)
• Bagolini lenses (93%)
• 4^D Base Out (72%)

• Amblyopia
• Incidence of amblyopia varies with the etiology of monofixation
• Congenital esotropes - 34% incidence of amblyopia.
• Acquired esotropes - 67%.
• Primary monofixators - 73%.
• Strabismus and anisometropia - 88%.
• Anisometropes - 100%.
• Most monofixators have amblyopia.
• Ocular alignment in monofixation
• 63% have a shift on cover-uncover test
• 1^D - 8^D horizontally.
• 2^D - 3^D vertically.
• 37% have no shift on cover-uncover test
• Deviation varied with etiology
• Lack of shift on cover-uncover provides four possibilities
• Monofixational orthophoria.
• Monofixational phoria.
• Bifixational orthophoria.
• Bifixational phoria.
• Orthophoria does not automatically indicate bifixation
• Alternate cover often exceeds cover-uncover
• Fusional divergence amplitudes in monofixation
• Equal to those in bifixators. Approximately 7^D at distance and 10^D - 12^D at near.
• Strabismic patients (exceeding 8^D deviation) have limited or non-existent amplitudes. 

• Motor
• Surgery - rare.
• Prisms - rare.
• Sensory
• Amblyopic therapy.
• Orthoptics - not appropriate.
• Follow every 6 months until age 8.

• Stability of monofixation syndrome (MS)
• Average follow-up 17.5 years.
• 74% remained aligned with MS.
• 45% remained aligned without MS fusion.
• Potential for bifixation - poor
• * Parks MM. The monofixation syndrome. Trans Amer Ophthalmol Soc 1969;67:609-657.
• Stability of alignment in monofixation
• Comparison of 38 patients with monofixation to 42 patients without monofixation. All well aligned (± 8^D) following surgery for congenital esotropia.
• No difference between those with monofixation and those without in terms of:
• Post-operative follow-up time.
• Pre-operative esotropia.
• Alignment immediately post-operatively.
• Monofixators were aligned at a significantly earlier age (mean 2.6 yrs vs. 3.9 yrs)
• Stability of alignment is significantly better in monofixators (estimated mean time at loss of stability 32.2 yrs vs. 9.8 yrs)
• * Arthur BW, Scott WE. Long-term stability of alignment in the monofixation syndrome. J Ped Ophthalmol Strab 1989;26(5):224-231.

• Classification
• Characteristics
• Etiology
• Exophoria
• Intermittent Exotropia
• Specific Exotropias
• Management of Exotropia

• Exophoria - X- Tendency toward divergence of the visual axes held latent by fusion.
• Intermittent Exotropia - X(T)- Tendency toward divergence of the visual axes not always controlled by fusion.
• Constant Exotropia - XT- Constant divergence of the visual axes.

• Monocular
• Alternating
• Natural - 2/3rds of cases spontaneously occur as exotropia
• Secondary - following surgery for esotropia
• Consecutive - spontaneous XT usually following esotropia associated with high hypermetropia.

• Anatomical - position of rest of the eyes; exodeviation may worsen with age.
• Heredity
• Sensory abnormalities
• Rare to find sensory abnormalities in exophoria.
• Intermittent XT's usually have a mild amblyopia; anisometropia is common.
• Suppression or ARC, once established tend to make the exotropia occur more easily. Since these sensorial adaptations develop over time, many XT's don't show up until the age of 6-8 years.
• Innervational factor
• Nerve palsy
• Duane's syndrome
• Decreasing AC/A ratio with age
• Relaxation of the vergence mechanism

• A small exophoria is considered physiologically normal. Up to 4^D at distance and up to 6^D at near.
• Convergence insufficiency type exophoria - 2 types
• "Eye Strain" associated with near work
• X at near greater than distance.
• Poor convergence amplitudes; Normal amplitudes: near = 30^D - 40^D ; distance = 20^D - 30^D .
• Reduced near point of convergence: normal range 4cm - 10cm.
• Normal near point of accommodation.
• This type of convergence insufficiency is treated with orthoptic exercises to teach convergence and build fusional amplitudes.
• Hypo-accommodative convergence insufficiency; premature loss of ability to accommodate - may be related to effort. Treat with plus lenses for near work before attempting orthoptic therapy.

• Progression
• Symptoms
• Signs
• Follow-up
• Treatment
• Onset usually between 0-10 years, peak incidence 5.5 years.

• Congenital exotropia
• Tight lateral rectus syndrome
• Right angle exotropia
• Exotropia associated with ambylopia
• Vertical deviations associated with exotropia
• Duane's classification of exotropia

1. Onset at birth - congenital XT is uncommon.
2. Alternating - if a congenital XT is not alternating, further evaluation of etiology is indicated.
3. Usually large deviation
4. Requires large amounts of surgery for alignment
5. Poor fusional potential

1. Characteristics

2. X patterns usually occur in longstanding exodeviations.
3. Large angle of deviation
4. More common in monocular exotropia

1. In primary position, the cornea of the deviated eye touches the lateral margin of the orbit.
2. Right angle limitation of adduction
3. Right angle limitation in vertical movements
4. Surgery - Urist (1964)¹⁹ was the first to recommend 4 muscle surgery.

1. Onset usually in adults.
2. Surgery - large recess/resect (8-12 mm).

1. If a vertical is present, there is usually a tendency to undercorrect.
2. If associated with amblyopia, determine if cosmetic.
3. Determine with prisms, whether vertical is significant; if a patient is horizontally aligned with prisms he may be able to control the vertical.

1. Divergence excess - larger deviation at distance then near.
2. Convergence insufficiency - larger deviation at near than distance.
3. Basic - distance and near deviations equal.
4. Pseudodivergence excess - apparent divergence excess, but when fusional convergence is eliminated with 45 minute occlusion and/or accommodative convergence eliminated with +3.00 lenses, near deviation equals distance.
5. Duane's classifications are used to plan the type of surgical correction.

• Non-Surgical Treatment
• Surgical Treatment

• Dominant eye occlusion
• Prisms
• Minus lenses
• Orthoptic therapy
• Botulinum toxin

• Preop evaluation
• Factors to consider
• Surgical Options
• Surgical Goals
• Surgical Tables
• Management of undercorrections

1. Determine basic deviation
2. Determine type of deviation (control), i.e. constant tropia distance and near, XT distance - X(T) near, etc.
3. Look for patterns
4. Lateral gaze measurements - measure in mid-right and mid-left gaze; take note of extreme right and left gaze deviation.
5. Measure at near with +3.00 D lenses to eliminate accommodative convergence
6. Assess versions - real vs. pseudo oblique overactions, limitation of adduction, tight LR's

1. Age of patient
2. Type of deviation
3. Visual acuity
4. Pattern
5. Measurements
6. Versions

1. Recession/resection

2. Bilateral lateral rectus recessions

3. Bimedial rectus resections - rarely done

1. Temporarily overcorrect to break down suppression, leave patients 4^D - 14^D ET
2. Cure = phoria with no evidence of suppression

Exotropia: Management of surgical undercorrections

• Types of Patterns
• Etiology
• Principles of Treatment
• Horizontal Muscle Shifts
• Expected Correction from Oblique Muscle Weakening
• Vertical Transposition of Horizontal Muscles

"V" Patterns - increased esodeviation or decreased exodeviation in down gaze. 15^D difference in up gaze vs. down gaze
"A" Patterns - increased esodeviation or decreased exodeviation in up gaze. 10^D difference in up gaze vs. down gaze
"X" Patterns - more exodeviation in up gaze and down gaze than in primary position
"Y" patterns - marked divergence in up gaze, less in primary and down gaze
"V" Patterns are 5 times as common as "A" patterns

A. Anatomic theory - (Urrets-Zavalia).

• Local variations in muscle attachment and orbital configuration.

B. Innervational theory - theoretical CNS center alters muscle tone.
C. Horizontal muscle tone theory - (Urist).

• MR are adductors, especially in down gaze; LR are abductors especially in up gaze. Patterns are caused by overactions or underactions of these muscles.

D. Theoretical surgical considerations based on the horizontal muscle theory

E. Vertical rectus theory - (Brown)²³

• The SR and IR are both adductors and their underaction or overaction could cause a pattern.

F. Theoretical surgical considerations based on the vertical rectus theory - (Miller)²⁴

G. Horizontal-vertical theory - (Tamler) compromise theory.

H. Oblique muscle theory - (Jampolsky)²⁶

• Patterns are due to the abducting effect of the IO's in up gaze and the SO's in down gaze.
• This is the most popular and widely held theory.

I. Theoretical surgical considerations based on the oblique muscle theory.

J. Objections to obliques being the sole cause of patterns (Burian, Cooper, Costenbader)²⁷

• V pattern esotropia
• V pattern exotropia
• A pattern esotropia
• A pattern exotropia
• Horizontal muscle shifts

1. Collapse "V" pattern

    Procedure                              D of "V" corrected

    IO weakening                                 15 - 25
    Tuck SO OU                                  15 - 25
    Vertical shift of horizontal recti         20 - 25
    Weaken IO OU and vertical shift    25 - 30
    SO tuck and IO weakening              40 - 50

2. Horizontal surgery for deviation in primary
3. Best procedure for "V" pattern ET

• If there is significant IO overaction, weaken IO's with bimedial recessoin or R&R.
• With no significant IO overaction, do bimedial recession with infraplacement.

1.Collapse "V" pattern

    Procedure:                                                 D of "V" corrected

    IO weakening                                                     15 - 25
    Vertical shift of horizontal recti                             15 - 20
    IO disinsertions and vertical shift of horizontals    30

2. Horizontal surgery for deviation in primary
3. Best procedures - "V" pattern XT

• With IO overaction: weaken IO's
• No IOOA: weaken LR, with upward displacement.

Treatment of "A" Pattern Esotropia

1. Collapse "A" pattern

    Procedure:                                      D of "A" corrected

    Intrasheath SO tenotomies                     30 - 40
    Vertical shift of horizontal recti               20 - 25

2. Horizontal sugery for deviation in primary.
3. Best procedure for "A" pattern ET

• "A" pattern > 40D: do SO tenotomies; horizontal sugery for residual.
• "A" pattern < 40D: do bimedial recession with upward displacement; bilateral resection with downward displacement; R&R with appropriate offsets.

1. Collapse "A" pattern
2. Horizontal surgery for deviation in primary
3. Best procedure for "A" pattern XT 

• "A" pattern > 40D: do SO tenotomies; horizontal surgery for residual.
• "A" pattern < 40D: do bilateral recession with downward displacement; R&R with offsets.

4.Surgical alternatives

• If < 20 D of "A" pattern, do nothing
• If 20D to 40D of "A" pattern or deviation in down-gaze, do bilaterals and infraplace mm or do R&R with infraplacement of LR and supraplacement of MR.
• If 40D or greater in downgaze, do bilateral superior oblique tenotomies.

5. Indications for bilateral SO tenotomies.

• Overaction of SO OU
• "A" pattern of at least 40D in downgaze
• No overaction of IO's

6. Complications of SO tenotomy - reported by others

Expected Correction from Oblique Muscle Weakening

A. SO tenotomy

• upgaze: 0
• primary: 10D - 12D
• downgaze: 40D - 45D
• Amount of Eso Shift in Downgaze with Bilateral SO Weakening Procedure
• Author; Average; (Range in D)
• Bedrossian: 20D (5 - 35)
• Jampolsky: 45D (35 - 65)
• Helveston: 33D (5 - 75)
• Harley & Manley: 41D (24 - 50)
• Scott, WE: 43D (30 - 55)

B. IO weakening

• upgaze: 15D - 25D
• primary: 0
• downgaze: 0

C. Summary of results of bilateral SO tenotomies done alone (10 cases)

• Change in IO action:
• 8 of the 20 IO (40%) changed from a pre-op underaction to a post-op overaction with an average of a +2 overaction (range +1 to +3).
• Two V-patterns developed; one of 8D, the other 15D
• Complications: 3 Brown's syndromes, one needing re-op.

Vertical transposition of the horizontal rectus muscles - the preferred opteration in cases of A and V pattern strabismus in which oblique muscle dysfunction is inadequate to merit oblique surgery.

• Blow-Out Fracture
• Brown's Superior Oblique Tendon Sheath Syndrome
• Chronic Progressive External Ophthalmoplegia
• Congenital Fibrosis Syndrome
• Cyclic Third Nerve Palsy
• Dissociated Vertical Deviation
• Double Elevator Palsy
• Grave's Ophthalmopathy
• Inferior Oblique Palsy
• Myasthenia Gravis
• Superior Oblique Palsy
• Third Nerve Palsy

• Etiology
• Clinical Features
• Park's three step test
• Surgical Treatment

• Congenital
• Acquired - usually following closed head trauma

• Hypertropia or hypotropia - determined by fixing eye.
• Abnormal head positions.
• Head tilt to opposite side most common; i.e., left tilt for right superior oblique palsy, etc.
• Patients occasionally adopt a face turn to the same side as the head tilt.
• Amblyopia
• May be unilateral or bilateral
• Excyclotorsion
  • Measured subjectively with the Double Maddox Rod (in primary and reading positions).
  • Measured objectively with indirect ophthalmoscopy, fovea should be adjacent to the lower third of the disc
• Diagnostic Criteria

 Parks' three step test- The diagnosis of a superior oblique palsy is made by the 3-step test and not on the actions of the oblique muscles seen on versions.

Step 1 - hypertropia in primary position; i.e.: RHT - secondary to weak depressors OD or weak elevators OS.

Step 2 - hyper increases in one lateral gaze. RHT increase in left gaze - indicates weak RSO or LSR.

Step 3 - Bielschowsky Head Tilt Test; RHT increases on right tilt - RSO is paretic.

	RSO

• If the right superior oblique is paretic the right superior rectus is acting against decreased opposition to elevation thus RHT increases on right tilt.

* Parks MM. Isolated cyclovertical muscle palsy. Arch Ophthalmol 1958;60:1027-1035.

Surgical treatment of superior oblique palsy - operations of choice

• Management tree, unilateral superior oblique palsy
• Surgical case numbers
• Simplified approach
• Surgical Tables
• When antagonist inferior oblique is overacting and deviation in primary is not greater than 18D, recess the inferior oblique.
• If deviation is > 18D with an overacting antagonist IO, recess IO and contralateral IR..
• If antagonist inferior oblique is not overacting, recess contralateral IR.
• Rule of thumb: 1 mm recession = 3D of correction
• If forced ductions show a tight SR on the side of the deviation, recess it instead of the contralateral IR.
• If deviation is greater than 35D think about doing 3 muscles.

Superior oblique palsy- management tree

1.) Superior oblique traction test:

• Absent Tendon =  Recess ipsilateral superior rectus, recess ipsilateral inferior oblique
• Marked Tendon laxity = Tuck ipsilateral Superior oblique, recess ipsilateral inferior oblique
• Normal = go to step 2

2.) Inferior oblique overaction?

• Yes
  • Hypertropia < 16 PD = Weaken ipsilateral inferior oblique
  • Hypertropia > 16 PD
    • Superior rectus restriction?
      • Yes = Recess ipislateral superior rectus, weaken ipsilateral inferior oblique
      • No = Recess contralateral inferior rectus, weaken ipsilateral inferior oblique
• No
  • Hypertropia < 16 PD = Recess contralateral inferior rectus
  • Hypertropia > 16 PD = Recess contralateral inferior rectus, recess ipsilateral superior rectus

• 118 cases at U Iowa Hospitals, 1972 - 1983.

• 84 (71.1%) unilateral, subdivided into 8 patterns
• 26 (22.1%) bilateral, subdivided into 4 patterns
• 8 (6.8%) "Masked bilateral

• Steps in the management of unilateral superior oblique palsy

• Measure deviation and grade versions - should coincide.
• One muscle surgery - <13^D in primary.
• If oblique done
  • No deviation out of field of action.
  • Amount of deviation is proportional to amount of OA.
  • Do IO if OA.
  • If IO normal, and SO is UA, tuck SO. Deviation > in field of action of SO.
  • If there is a spread of comitance, do vertical rectus.
  • If "fallen eye", relieve restriction - recess IR.
• Two muscle surgery-13^D - 30^D

• Deviation between 13^D - 30^D .
• If significant IOOA - weaken.
• If normal inferior oblique and SO underaction - SO tuck.

• Other procedures for superior oblique palsy

• Deviation greater in upgaze - recess ipsilateral SR.
• Deviation in downgaze - recess yoke IR.
• Spread of comitance - vertical recess/resect.

• Deviation greater than 30^D - refer to someone you don't like

Double Elevator Palsy- More appropriately called Monocular elevation deficiency.

• Types
• Clinical features
• Indications for treatment
• Surgical Treatment

Monocular elevation deficiency- Three types:

• Inferior rectus restriction.
• Positive forced ductions.
• Normal forced generations.
• Normal saccades of superior rectus.
• Elevation weakness
• Etiology - palsy of the superior rectus and inferior oblique secondary to a supranuclear disturbance.
• Free forced ductions.
• Reduced forced generations.
• Reduced saccadic velocities.
• Combination
• Positive forced ductions.
• Reduced forced generations.
• Reduced saccadic velocities.

Monocular Elevation Deficiency- Clinical features

• Hypotropia
• Amblyopia
• Ptosis - true and pseudo
• Chin up head position - if abnormal head position is not present amblyopia is likely.
• May have restriction of inferior rectus.
• Look for lower lid crease - the crease becomes more pronounced on attempted upgaze if IR restriction is present.
• Bell's phenomenon should be normal unless the IR is restricted.
• Duction = version, if IR restriction is present.
• Forced ductions are positive to elevation.

Monocular Elevation Deficiency- Indications for treatment

• Large vertical deviation with ptosis
• Abnormal head position

Monocular Elevation Deficiency- Surgical treatment

• Relieve restriction if present
• Transposition procedure
• If there is no restriction of IR.
• If there is a residual hypotropia after inferior rectus recession
• Type I - recess inferior rectus
• Type II - transpose medial rectus and lateral rectus superiorly (Knapp procedure)
• Type III - recess inferior rectus and transpose medial and lateral rectus
• A Knapp procedure will correct approximately 35 ^D of deviation in patients without inferior rectus restriction.

* Scott WE, Jackson OB: Double elevator palsy: The significance of inferior rectus restriction. Amer Orthop J 1977;27:5-10.

• Clinical features

• Hypertropia or hypotropia - determined by fixing eye
• Positive 3-Step test
• Overaction of ipsilateral superior oblique
• Duction better than version
• Free forced ductions
• Abnormal head position
• Pupils are normal
• Usually due to direct orbital trauma or viral illness

• Indications for treatment

• Large vertical deviation
• Abnormal head position
• Diplopia

• Treatment: Superior oblique tenotomy - normalizes the action of the superior oblique.
  * Scott WE, Nankin SJ: Isolated inferior oblique paresis. Arch Ophthalmol 1977;95:1586-1593.

• Initially described by Dr. Harold Whaley Brown in 1944; for many years known as the "superior oblique tendon sheath syndrome", a misnomer.
• Clinical Features
• Classification
• Heredity
• Etiology
• Treatment

Brown’s Syndrome-Clinical features

• Must have:
• Deficient elevation in adduction.
• Less elevation deficiency in midline.
• Minimal or no elevation deficit in abduction.
• Minimal or no superior oblique overaction.
• Divergence in upgaze producing a "V" pattern.
• Positive forced duction testing (accentuated by retroplacement of the globe).
• May also have
• Downshoot in adduction.
• Widened palpebral fissure on adduction.
• Anomalous head posture (chin up or face turn away from the affected eye).
• Primary position hypotropia.
• Tenderness to palpation over the trochlea.
• "Click" or snapping sensation in attempted elevation in adduction.
• Palpable nodule.

Brown’s Syndrome-Classification

• Brown initially divided cases into "true" and "simulated" - not useful, since the etiology upon which the subdivisions were based is incorrect.
• Essentially there are two major forms:
• Congenital.
• Acquired.
• Either form can be intermittent.

Brown’s Syndrome- Heredity

• Autosomal dominant with incomplete penetrance and variable expressivity
• Most cases are sporadic

Brown’s Syndrome- Etiology

• Anatomic considerations

• The tendon and Tenon's capsule, through which it passes, create a sleeve arrangement, permitting easy movement of the tendon.
• The intermuscular septum envelops the superior oblique tendon and maintains connections with the superior rectus.
• Each fiber of the superior oblique tendon acts independently as a cord from the muscle fibers to the insertion thus producing a telescoping or slide-by fashion of movement.
• A bursa-like structure is found between the tendon and the trochlear saddle.
• The intratrochlear superior oblique tendon has a highly vascular sheath.
• Probable final common pathway: defect in the trochlea/tendon complex

• Any interference with the normal telescoping movement of the tendon
• Excess fluid accumulation or concretions in the bursa
• Distension of the vascular sheath
• Stenosing tenosynovitis
• Movement of the tendon in the trochlea creates a metabolic requirement for repairing "wear and tear", which is normally performed by the vascular intratrochlear sheath.
• If the wear and tear is excessive, thickening and stenosis of the sheath occurs with secondary enlargement of the tendon at the point of restricted gliding.
• This may be very similar to trigger finger (digital tenosynovitis stenosans) and congenital trigger thumb.
• Inflammation around the trochlea

• Associated with juvenile and adult rheumatoid arthritis.
• Digital pressure over the trochlea can produce pain, but helps to relieve the restriction.
• Sudden release (spontaneous resolution) or attempt to move the superior oblique tendon is often accompanied by discomfort localized to the trochlear area.
• Can occasionally see thickening and edema by CT.
• Improvement with injection of steroids (even in nonrheumatoid cases).
• Trauma: direct non-surgical trauma to the superomedial orbit can result in superior oblique muscle palsy, Brown's syndrome, or both
• Postoperatively: after superior oblique, orbital, retinal, or sinus surgery.
• Conclusions:
• Idiopathic cases of Brown's syndrome may be the result of inflammation caused by wear and tear, in the setting of a congenital anomaly or predisposition.
• Inflammation may subside, leaving persistent adhesions; therefore, absence of trochlear tenderness or swelling does not exclude active stenosing tenosynovitis.
• Intermittent "click" variety may represent an intermediate stage in the resolution of the constant variety.
• Congenital and acquired Brown's syndrome may be a continuum.

Brown’s Syndrome- Treatment

• Non-surgical treatment
• Observation: spontaneous regression is common in acquired and intermittent cases, but less common in congenital and constant cases.
• Elevation in adduction exercises.
• Steroid injections into the superonasal quadrant (paratrochlear) - 40 mg Depo-Medrol, may need to be repeated at monthly intervals.
• Treat the underlying condition, e.g. JRA
• Surgical treatment
• Indications:
• Primary position hypotropia and/or abnormal head position.
• Occasionally, cosmetically unacceptable downshoot of the eye in adduction.
• Tenotomy is the current procedure of choice
• Does not typically lead to torsional difficulties or complete SO paralysis.
• The intermuscular septum serves as an insertion for the proximal end of the cut tendon, transmitting the SO force to the distal severed tendon.
• Some advocate IO recession to decrease the incidence of post-op SO palsy - this is still controversial
• Surgery at the trochlea (the supposed site of abnormality) is fraught with complications
• Silicone tendon expanders.

Blow-out Fractures

• Types
  • Isolated floor fractures
  • Tripod fracture (dislocation fracture of the zygoma)
  • Complex facial fracture with orbital floor fracture
  • Infra-orbital rim fracture with orbital floor fracture
  • Medial wall involvement with orbital floor fracture
• Etiology
  • Auto accidents
  • Fist injury
  • Sports
  • Blunt hurled objects
  • Falls
• Signs and symptoms
  • Ecchymosis
  • Diplopia
  • Other ocular damage
  • Paresthesia of infra-orbital area
  • Enophthalmos
• Diagnosis
  • Motility exam - measurements in all positions
  • Forced ductions
  • Measure intraocular pressure in upgaze and primary
  • Saccadic velocities
  • Radiographs  Plain films or Tomographs.
  • Complete examination
  • ENT consultation
• Motility problems to consider
  • Entrapment of inferior rectus or inferior oblique
    • Hypotropia in primary.
    • Hypotropia increases in upgaze.
    • Positive forced ductions.
    • Once edema has subsided, operate to free entrapped muscle.
  • Paresis of inferior rectus
    • Etiology - trauma to nerve to IR either at the time of injury or at the time or repair of floor.
    • If paresis exists without entrapment, hyper in primary.
    • If paresis exists with entrapment, ortho to slightly hypotropic or hypertropic in primary.
    • May recover with time.
    • Important to recognize.
  • Entrapment of medial rectus
  • Paresis of medial rectus
• Other ocular damage
  • Corneal problems
  • Hyphema
  • IR palsy
  • Pupil injury
  • Cataracts
  • Vitreous hemorrhage
  • Choroidal rupture
  • Optic nerve damage
  • Retinal problems - hemorrhage, edema

* Leibsohn J, Burton TC, Scott WE: Orbital floor fractures: A retrospective study. Ann Ophthalmol 1976;8:1057-1062.

 

Third Nerve Palsy

• Congenital
• Acquired
• Treatment

Congenital Third Nerve Palsy

1.Etiology

2. Differential diagnosis - Congenital Horner's syndrome (because of aberrant reinnervation with pupillary miosis; ptosis).

3. Characteristics

4. Management (See C.)

Acquired Third Nerve Palsy

1. Etiology

2. Differential diagnosis - Myasthenia gravis (can mimic pupil-sparing IIIrd nerve palsy).

3. Characteristics

Treatment of Third Nerve Palsy

• SO tenotomy; maximal LR recession & MR resection
• Combined recess/resect procedure with transposition to improve the weakest ocular rotation.
• Transposition of insertion of SO tendon to 2-3 mm anterior to medial side of SR insertion; large LR recession +/- MR resection.
• For ptosis:
  • frontalis suspension
  • if aberrant regeneration with lid retraction on adduction, try horizontal R&R on unaffected eye

   

Congenital Fibrosis Syndrome (Crawford, JL; Apt L, Axelrod RN)

• Synonyms: General Fibrosis syndrome, Congenital Ophthalmoplegia, Strabismus Fixus.
• Autosomal dominant or sporadic - 60% have positive family history
• Characteristics
  • Head tilt - chin up 16/16.
  • Inability to elevate or depress eye 16/16.
  • Severe blepharoptosis 16/16.
  • Convergent jerky movements on attempted elevation.
  • Horizontal movements severely restricted 16/16, exotropic 8/16, esotropic 1/16.
  • Hyperopic astigmatism 11/14.
  • Bilateral decreased visual acuity 16/16.
  • Present at birth.
  • Reported associations: Coloboma, Retinitis Pigmentosa.
• Pathology
  • Posterior membranous insertion of recti and anterior and medial insertion of obliques.
  • Fibrosis of muscle and Tenon's.
  • Adhesions between muscles, Tenon's & globe.
  • Inelastic & fragile conjunctiva.
• Require multiple procedures for horizontal, vertical strabismus and later ptosis repair

A. Incidence of Graves' at the University of Iowa - approximately 175 patients seen in an 8 year period.
B. Eye changes in Graves' disease

C. Patient characteristics of 25 patients studied with Graves'

D. Thyroid Function - 25 patients

E. Thyroid state at time of eye muscle surgery - 25 patients

F. Pre-op evaluation

G. Muscle involvement - 25 patients

H. Pre-op treatment - 25 patients

I. Treatment - 25 patients

J. Surgical technique

K. Surgical procedures - 22 patients

L. Surgical amounts

M. Post-op results - 22 patients

N. Post-op motility - 22 patients

O. Post-op complications

P. Secondary procedures

*Scott WE, Thalacker JA. Diagnosis and treatment of thyroid myopathy. Ophthalmol 1981; 88:493-498.

* Lueder GT, Scott WE, Kutschke PJ, Keech RV. Long-term results of adjustable suture surgery for strabismus secondary to thyroid ophthalmopathy. Ophthalmol 1992; 99(6): 993-997.

Q. 55 patients

R. Average followup 41 months (range 6 - 168 months)

S. 47 surgical patients

T. Surgery

U. Results after initial surgery

V. 24 patients initially given prisms

1. Characteristics
       1.50% autosomal dominant
       2. Average age of onset - 23 years
       3. Usually commences with ptosis
       4. Slowly progressive palsy of all extraocular muscles
       5. Gaze function primarily involved rather than individual extraocular muscle
       6. Upward gaze and convergence involved first, then lateral gaze
       7. Diplopia unusual
       8. Systemic muscular involvement, primarily head, neck and upper limbs
2. Etiology
       1. Prior to 1951 - nuclear atrophy
       2. 1951 (Kiloh and Nevin)³⁵ - myopathy
       3. 1969 (Daroff)³⁶ - myopathy vs. CNS brain stem disease

Myasthenia Gravis

1. Signs and symptoms
       1. Ptosis and diplopia are the most common presenting symptoms. Diplopia may be present without ptosis
           a. Chacteristically signs and symptoms fluctuate, often ptosis is unilateral or bilateral and asymmetric.
           b. One lid may retract on attempted elevation of other lid.
           c. Cogan's lid twitch (temporary lid elevation in redirection of gaze from downward to primary).
           d. Ptosis may worsen with prolonged upgaze or sidegaze and improves after rest.
           e. Extraocular muscle involvement: the medial rectus and elevators are commonly involved but involvement may mimic any isolated nerve or muscle palsy, inter- nuclear ophthalmoplegia, gaze palsy, or double elevator palsy.
2. Diagnostic tests
       1. Tensilon: must have a good endpoint.
       2. Prostigmine: especially useful for
           a. Children who won't cooperate for IV placement.
           b. Adults in whom one wishes to measure prism diopters of deviation before and after drug given.
           c. Adults with equivocal Tensilon tests.
       3. Harvey-Maslan Repetitive Supramaximal motor stimulation.
       4. Acetylcholine receptor antibody
3. Prognosis and treatment of diplopia
       1. 50%-80% of ocular myasthenia will go on to develop generalized myasthenia, usually within two years
       2. Diplopia often responds poorly to anticholinesterase therapy and may do better with prednisone
       3. Diplopia fluctuates, so prisms or surgery are limited to use after the disease has stabilized in the patients with residual deviation

A. Characteristics - 60 cases reported in world literature
    1. Paralysis of the third nerve with alternating paretic and spastic phases
    2. Usually congenital or onset in first few months of life
    3. Usually no history of trauma
    4. Negative family history
    5. Remains throughout life
B. Clinical Findings
    1. Paralysis is usually complete
    2. Degree of involvement
        a. Pupillary musculature uniformly involved.
        b. Ciliary body most likely involved in all.
        c. Levator and medial rectus are the most common extra-ocular muscles showing cycling.
    3. Pupils
        a. During the paretic phase, no direct or consensual light reaction.
        b. Atropine dilates the pupil and interrupts cycling phenomenon.
        c. Pilocarpine produces miosis and abolishes cycling.
        d. Cocaine dilates the pupil but does not interrupt the cycling.
C. Cycling phenomenon - constant time intervals for a given patient.
    1. Paretic phase
        a. Complete ptosis.
        b. Pupil dilated and fixed.
        c. Eye exotropic and hypotropic.
        d. Accommodation relaxed.
    2. Spastic phase
        a. Lid elevates.
        b. Pupil constricts.
        c. Eye returns to midline.
    3. Each phase lasts 30-60 seconds
D. Convergence or adduction of the involved eye tends to prolong the spastic phase while abduction tends to shorten it
E. Cycles usually continue during sleep, but intervals are lengthened, with shortening of the spastic phase
F. Cycles are abolished under anesthesia
G. Etiology - all speculative, no autopsy material
    1. Fuchs³⁷ and Bielschowsky³⁸ - rhythmic variations in blood supply to the third nerve nucleus
    2. Axenfeld and Schurenberg³⁹ - lesion peripheral in third nerve; cycling due to intermittent pressure on the nerve
    3. Behr⁴⁰ and Bielschowsky³⁸ - partial degeneration of third nerve nucleus; remaining ganglion cells of the nucleus respond to rhythmic impulses, which reach the partially destroyed nucleus from higher, presumably vegetative, centers.
    4. Stevens⁴¹ - reported a 25 year old female
        - developed a cyclic third nerve palsy which later became complete.
        - 14 months later papilledema was noted.
        - Dx - brain stem glioma.
        - Rx - radiation
        - Only known case of acquired cyclic palsy.

* Clarke WN, Scott WE: Cyclic third nerve palsy. A report of two cases. J Ped Ophthalmol Strab 1975;12(2):94-99.

* Loewenfeld IE, Thompson HS. Oculomotor paresis with cyclic spasms. A critical review of the literature and a new case. Surv Ophthalmol 1975;20(2):81-124.

• Spasmus Nutans
• Pendular Nystagmus
• Latent Nystagmus
• Congenital Jerk Nystagmus

¨ A clinical entity consisting of the triad of nystagmus associated with head nodding and abnormal head positions
¨ Nystagmus and head nodding are usually present together but either may occur alone

¨ Raudnitz (1897) ⁴²- in a series of 47 cases found

• head nodding 87%
• nystagmus 80%
• abnormal head position 38%

¨ Most often nystagmus is very fine rapid pendular, but may be rotary or vertical

• Asymmetric in the two eyes
• Often varies in different positions of gaze
• May be monocular, spasmus nutans is the most common cause of unilateral nystagmus in infancy
• EOG studies confirm rapid frequency (3-10 HZ), pendular waveform, marked asymmetry between eyes, highly variable frequency (changing from sec. to sec.) subclinical nystagmus may be diagnosed by EOG

¨ Head nodding

• Inconstant and irregular; may be horizontal, vertical or both
• Head movements are not compensatory for nystagmus
• Disappears during sleep or when eyes are closed

¨ Abnormal head position

• Turning or tilting of the head
• Disappears during sleep
• Never the only sign of spasmus nutans

¨ Age of onset usually 4-12 months but ranges from 6 weeks to 3 years

¨ Variable duration, weeks - months. In Hermann's⁴³ study of 20 cases all recovered within 12 months, but Norton and Cogan⁴⁴ report 2 cases which lasted for 8 years.

¨ Pathogenesis - unknown. Get CT
¨ No treatment
¨ Prognosis is good, seems to be a self-limiting entity
¨ Associated conditions

• Strabismus - 7 of 20 cases reported by Norton and Cogan had a tropia
• Refractive errors
• No consistently associated neurological conditions

¨ May mimic life threatening intracerebral tumor

• Lavey et. al. reported on 20 cases of early acquired nystagmus which was the first sign of intracerebral glioma
• 16/20 onset of nystagmus prior to 1 year
• 10/20 originally diagnosed at spasmus nutans. Delay in correct diagnosis of average 14.5 months
• 16/20 originally unilateral nystagmus and 11/20 had head nodding and/or torticollis
• Associated signs which necessitate CT scan but which did not present initially
• optic nerve atrophy developed eventually 18/20.
• diencephalic syndrome - emaciation despite food intake, hyperactivity and euphoria, skin pallor, hypotension, hypoglycemia, neuroendocrine disturbances 7/20.
• papilledema and/or increased head circumference due to obstructive hydrocephalus 9/20.
• afferent pupillary defect or loss of fixation ability.
• Onset of nystagmus after 1 year should have CT
• Tumor is low grade astrocytoma involving chiasm, hypothalamus and optic nerve
• R/4500-5000 rads. Good prognosis for life but optic atrophy progresses in most.
• There is no definite sign to differentiate the acquired nystagmus of spasmus nutans from intracerebral glioma in some reported cases. Therefore, careful consideration of enhanced CT scan in all cases of acquired nystagmus of undetermined etiology is warranted.

• Oscillations that in some positions of gaze are approximately equal in rate in both directions.
• Almost always horizontal.
• Absence of central vision causes loss of fixation reflex.
• 2-4-6 Rule:

• If visual loss happens before 2 years of age nystagmus results.
• 2-6 years - irregular and unsustained movements of fixation but not a true nystagmus.
• Older than 6 years - no abnormal eye movements.

• Patients may attempt to compensate with synchronous, contraversive head-eye movements.
• Nystagmus disappears in sleep and with barbiturates.
• Etiology - any process causing loss of central vision early in life.
• Associated findings:

• Strabismus 6%
• Refractive errors - often CHA.
• OKN response (Cogan)
• Type I - good OKN.
• Type II - No OKN, poorer prognosis, repeat ocular exam.

• Characteristics
• Etiology
• Acuity assessment
• Helpful hints- AHP
• Ambylopia

• Bilateral jerk nystagmus
• Fast phase towards the fixing eye
• Occurs when light stimulus to one eye is diminished or when one eye covered
• Usually congenital
• May occur in conjunction with manifest nystagmus
• i.e., nystagmus amplitude increases with occlusion of one eye

Thought to be the result of the difference in the quality of retinal images.

• Monocular
• High plus lens occluder
• Vectograph
• Duochrome slide
• Vertical Prism
• Binocular

• High plus lens occluder

• Blurs VA of one eye without diminishing light stimulation to decrease the intensity of the latent nystagmus.
• Problems:
• * Patients may peek around the lens.
• * May have such a strong eye dominance that they continue to fixate with the occluded eye, thus the VA of the non-dominant eye cannot be assessed.

• Vectograph

• Patient wears polarized lenses (not as dissociative as an occluder or patch).
• Slides:
• 2 polarized to test OD
• 2 polarized to test OS
• Polarized to test binocularly
• Problems: * May suppress one eye and therefore cannot see letters when attempting to assess VA of the suppressing eye.

• Duochrome slide with green filter occluder

• Duochrome superimposed over Snellen letters or numbers (less dissociative than occluder or patch).
• Patient instructed to read letters/numbers on the red background with the unoccluded eye.
• Problems:
• * Wavelength of the green filter must be the same as the duochrome slide to render letters on the red background invisible
• * May suppress one eye, making VA assessment of that eye impossible

• Vertical prism

• Significantly separates distance between chart viewed with each eye while at the same time blurring the image of the eye under the prism
• Problems: * May prefer to fix with eye occluded with vertical prism

• Always assess for best vision.

1. Abnormal head positions (AHP)

• always allow the use of an AHP.
• may adopt an AHP for null point.
• may adopt a face turn to place the fixing eye in adduction to dampen nystagmus.

2. Near vs. distance visual acuity

• near VA is often better than distance VA as nystagmus is dampened with accommodative convergence

• should be treated in the traditional fashion. see: Occlusion treatment
• Patients will often adopt a face turn to fix in adduction and dampen nystagmus.

• Characteristics
• Medical Treatment
• Surgical Treatment

• Pendular nystagmus which converts to a jerk type on gaze to either side
• Usually horizontal
• Always bilateral.
• Head movements opposite to direction of nystagmus
• Etiology - unknown
• Visual acuity
• Usually in 20/40 to 20/80 range
• Reported as good as 20/30
• Better when measured binocularly due to a latent nystagmus which is often superimposed
• Convergence has a dampening effect on the nystagmus
• Near vision often much better
• 80% can read normal print books and attend normal schools
• "Quiet Zone"
• Position of eyes where amplitude of oscillation is decreased
• Often at extremes of lateral gaze
• Child uses head turn to facilitate gaze straight ahead while maintaining eyes in quiet zone
• May show accompanying chin elevation or depression

1. Quiet the nystagmus

• Minus lenses.
• Cycloplegic drugs.
• Base out prism.

2. Prism realignment

• Stimulates a vergence movement.
• Cosmetically poor.
• Prism distortion.

• Retrospective Review of surgical outcome

1. Objective - to mechanically move the quiet zone to a cosmetically more acceptable position and relieve head turn
2. Parks' "Straight Flush" technique - Works well for head positions of 30° or less.

• R & R 5, 6, 7, 8 mm.
• ET eye 5 & 8 mm (total 13).
• XT eye 6 & 7 mm (total 13).

• Patient demographics
• Indications for surgery
• Group divisions
• Pre-op evaluation
• Post-op evaluation
• Categorization of Results
• Surgical results: Group I, Group II, Group III
• Summary

Demographics: 32 patients with congenital jerk nystagmus

• Age range 4-20 years
• 2. 22 males, 10 females
• 3. Follow-up 6 months to 7 years. Average follow-up 30 months

• Abnormal head position (20° -50° )
• Abnormal head position and strabismus

• Group 1 n = 18
• Head turn without strabismus.
• Bilateral surgery.
• Group 2 n = 7
• Head turn.
• Strabismus
• Amblyopia
• Bilateral surgery
• Group 3 n = 7
• Head turn
• Strabismus
• Amblyopia
• Unilateral surgery

• Estimate degree of head turn at distance while patient is binocularly viewing an accommodative target.
• Visual acuity OD, OS, OU
• Deviation (when present)
• Versions
• Worth 4-Dot
• Titmus stereoacuity

• Dosage of surgery
• Degree of head turn
• Visual acuity
• Deviation
• Versions
• Worth 4-Dots
• Stereoacuity

• Excellent = Residual head turn £ 5°
• Good = Residual head turn >5° but £ 15°
• Poor = Residual head turn >15°

Dosage of surgery - Group 1

• Parks' "Straight Flush" technique
• ET eye - 5mm MR recession, 8 mm LR resection
• XT eye - 7mm LR recession, 6 mm MR resection
• Augmented technique (Calhoun & Harley - "Classic Plus")
• Increase amount of surgery depending on degree of head turn.
• Head turns 25° or less - 5, 6, 7, 8
• 25° - 45° - 10-40% more surgery
• 45° or more - 40%+ more surgery

Surgical results - Group 1

1. Classic - 9 patients

• 67% = Good/Excellent

2. Augmented - 9 patients

• 89% = Good/Excellent

3. Pre-op vs. post-op visual acuities - Group I

• Improvement in binocular acuity 1-2 lines 11/18 (61%)
• All patients had same or better postoperative stereoacuity

• Surgery for head turn
• Amounts modified to correct strabismus at same time

• Augmented surgery 5/7
• Good/Excellent post-op head position 3/7
• Strabismus corrected ± 10^D 6/7
• Improved binocular visual acuity 3/7
• Limited versions 6/7

• Head turn and strabismus
• Correction by doing R & R on one eye. i.e., R head turn, adducting eye fixing, esotropia present-R & R on fixing eye for both head turn and ET

Surgical results - Group 3

• Good/Excellent post-op head positions 6/7
• Strabismus corrected ± 10^D 5/7
• Limited versions 4/7

• Head turns ³ 25° need augmented surgery
• If strabismus is also present, plan to correct both
• Some patients with head turn and strabismus can be corrected with unilateral surgery
• Expect some improvement in visual acuity
• Expect limitations of versions postoperatively when doing augmented surgery
• Stability is based on limitations of versions - if present more stable

Definition
Classification
Incidence
Acuity Assessment in Children
Diagnosis
Occlusion therapy

Ambylopia Definition: a difference in visual acuity of two or more lines between the eyes.

Ambylopia Classification:

• Functional amblyopia
• Strabismic - secondary to disuse; most common
• Deprivation - cataract, cloudy media; interferes with development of the fixation reflex
• Ametropic - bilateral high refractive error
• Anisometropic - a difference of greater than +1.00 D or -2.00 D
• Organic amblyopia- A structural abnormality that is not treatable; i.e., optic nerve hypoplasia, posterior pole coloboma.

Ambylopia Incidence: unilateral amblyopia in children is 2-4%

• McNeil (1955)                 2.7%
• Vereecken (1966)           4.4%
• Gansner (1968)                2.39%
• Kohler & Stigmar (1973) 2.2%

Visual Acuity Assessment in Children

• Subjective tests
• Snellen chart
• Illiterate E
• Stycar - no verbal response is needed, involves matching letters.
• Allen Pre-School Pictures - may not always pick up a two line difference, 20/30 limit.
• Isolated letters - amblyopes will show a better visual acuity secondary to the crowding phenomenon.   
• Objective tests:
• CSM
• Binocular fixation
• 16 diopter prism
• Forced preferential looking

• a difference in acuity is determined according to how well a patient maintains fixation on a particular target.  Cross fixation - does not necessarily imply equal visual acuity.- a cross fixator must switch at the midline or amblyopia should be suspected.
• See table

• Use cover/uncover test - observe uncovered eye.

• If the uncovered eye fixates and holds when the covered eye is uncovered for a measured time but not to a blink - visual acuity is usually within one line of the other eye.
• If the uncovered eye holds fixation to a blink - there is usually less than one line difference.
• If the uncovered eye holds fixation through a blink - visual acuity is equal.
• If the uncovered eye deviates immediately upon removal of cover - there is usually a 2 or more line difference and amblyopia should be treated.
• * Zipf RF. Binocular fixation pattern. Arch Ophthalmol 1976;94:401-405.

16^D prism induced deviation

• Base down or base in, if base down can't be done.

• Used in patients who don't have manifest strabismus.
• Place 16 ^D BD in front of eye. Eye with the ^D spontaneously shifts upward to pick up fixation = MAINTAINED. Eye with the ^D does not spontaneously pick up fixation: then need to cover eye without prism to force prism covered eye to fixate. Then remove cover. Observe eye under prism. Eye with the ^D maintains fixation through a blink = MAINTAINED. Eye with the prism does not maintain fixation through a blink = UNMAINTAINED
• If patient holds:
• to but not through a blink: mild amblyopia of two lines exists
• briefly: a significant amblyopia is present of more than two lines.
• not at all: dense amblyopia.
• The prism is then placed over the opposite eye and the same steps are followed. If the response to this test is the same with each eye, both eyes are considered to have equal visual acuity.
• * Wright KW, Walonker F, Edelman P: 10-Diopter fixation test for amblyopia. Arch Ophthalmol 1981;99:1242-1246.

• This test consists of a series of cards which contain a pattern stimulus and a homogeneous, non-pattern stimulus. The cards are held at a given distance from the subject. The examiner, who cannot see which side of the card is the patterned side, observes the direction that the baby looks and records this.

• If the stimulus is large enough to be visible to him/her, a young baby will look at the pattern rather than the homogeneous stimulus. The stimuli are presented in decreasing size until no preference is elicited by the baby. At this stage, it is assumed that the baby can no longer see the stimulus and the level is recorded.
• When a child becomes distracted by background objects, noises, etc., they are becoming too old for the test.

Amblyopia Diagnosis

• Observe more than once during exam
• Fixation pattern is dependent on target size
• Always check near vision
• If patient comes in wearing patch check fixation at least 30 minutes after patch has been removed
• Small angle ET's (monofixators) usually have a fixation preference without significant amblyopia
• Cross fixators should switch at midline
• Latent nystagmus is not a contraindication for amblyopia treatment
• Amblyopia is uncommon in exo and vertical deviations.

Occlusion Treatment:

• Strabismic ambylopia
• Anisometropic Ambylopia
• Deprivation Ambylopia
• Organic Amblyopia

• Full-time occlusion (FTO) = patching 24 hours/day
• Little risk of occlusion amblyopia, but if it does occur it is easily reversed
• Follow-up at intervals of 1 week per year of age of the child
• End-point: visual acuity is equal or 3 consecutive episodes of compliant FTO render no improvement
• FTO should be followed by part-time occlusion (PTO) 6-8 hours/day
• PTO may be tapered and discontinued when visual acuity remains stable without patching, with follow-up every 3-4 months
• Patients who slip should be kept on PTO until visual maturity

• Age of patient at the time treatment is started is usually related to duration of treatment; i.e., the older a patient, the longer it will take to achieve equal visual acuity
• The age of the patient at the time treatment is started usually does not affect the final visual result
• Of 78 patients in various age groups 49 did not slip after patching was discontinued
• Patients in whom equal vision is obtained before age six are no more likely to slip when patching is discontinued than those achieving equal visual acuity after age six
• Final visual acuity generally is not influenced by initial visual acuity. *Exception if initial 20/100 or worse, less likely to have final visual acuity of 20/20.
• Results of full time occlusion:
• Excellent (20/20):            76%
• Good (20/25 - 20/40)     16%
• Fair (20/50 - 20/100)        5%
• Poor (<20/100)                 3%
• Complications of patching
• Social pressure.
• Skin irritation.
• Occlusion amblyopia.

• Definition - anisometropia
• Hyperopia (H) - >/= +1.00 D
• Myopia (M) - >/= -2.00 D
• Astigmatism (A) - >/= +1.00 cyl.
• Compound (C) - >/= +0.75 cyl. & sph
• Hyperopic Astigmatism (CHA)
• Myopic Astigmatism (CMA)
• Patient population
• Hyperopic differences in refractive error (mean +2.46 D) more amblyogenic than myopic differences (mean -8.05 D)
• The results of treatment were influenced by
• Initial visual acuity.
• Type of anisometropia - myopes and CMA had poorer visual outcomes.
• The final visual acuity was not influenced by
• 1. Patient age at the time of treatment onset.
• 2. Presence or absence of strabismus.
• 3. Type of initial treatment - glasses with or without patching.
• Overall, 83% obtained 20/40 or better visual acuity

Results of deprivation amblyopia therapy

• Visual acuity of monocular cataracts and persistent hyperplastic primary vitreous (PHPV)
          VA Results
• Patching program
• First 2mos of life:                    50% PTO
• 2mos - 7mos:                         75% PTO
• 7mos - Subjective V/A:          100% FTO
• Stable V/A-Visual Maturity:   50% PTO/FTO
• Monitor:
• Binocular Fixation Pattern
• Reverse Patch 50% for Fixation Switch
• Resume PTO/FTO when phakic eye preferred
• Successful visual development depends on:
• Surgical removal of PHPV or MCC early (before 3 months of age)
• Placement of optical correction (high plus powered contact lens)
• Early onset of occlusion therapy with good compliance.

Results of Organic Amblyopia Therapy

• 51 patients studied
• 14 - optic nerve anomalies.
• 25 - media opacities.
• 12 - macular lesions.
• Results
• Of all patients, 39% had visual acuity 20/40 or better following treatment.
• Earlier age at presentation associated with better results in patients with media opacities and macular lesions, but not in patients with optic nerve abnormalities.
• No significant differences found between those whose vision increased to better than 20/200 and those whose vision did not increase in the areas of:
• Presence or absence of strabismus.
• Presence or absence of anisometropia.
• Presence of absence of RAPD (ON group only).
• No patients with posterior lenticonus improved vision with treatment.
• No patient with optic nerve hypoplasia increased visual acuity to better than 20/200 with treatment.

Index of Surgical Tables

• Congenital Esotropia- Scott
• Dissociated Vertical Deviation -Scott
• Esotropia: Recess/Resect -Scott
• Esotropia: Bimedial recessions  -Scott
• Esotropia: Binocular surgery - Wright
• Esotropia: Monocular surgery -Wright
• Exotropia: 15-35^D -Scott
• Exotropia: 40-50^D -Scott
• Exotropia: 55-80^D -Scott
• Exotropia: Binocular surgery- Wright
• Exotropia: Monocular surgery- Wright
• Exotropia: Ambylopia -Scott
• Kestenbaum
• Prisms- adding horizontal prisms
• Superior Oblique Palsy- Unilateral -Scott
• Superior Oblique Palsy- Bilateral -Scott