CONCOMITANT ESOTROPIA
In a comitant deviation the angle is the same, or nearly the same, for all positions of gaze; the two types are non-accommodative and accommodative.
Non-accommodative
Early-onset (infantile)
Presentation
- •
Before the age of 6 months.
Signs
- •
Large and stable angle with no significant refractive error.
- •
Fixation may be alternating in the primary position with cross fixation in side-gaze ( Figs 14.1 and 14.2 ).
Fig. 14.1
Fig. 14.2
Look for
- •
Latent and manifest-latent nystagmus.
- •
Inferior oblique overaction may be present initially or develop later.
- •
Dissociated vertical deviation (DVD) which often develops by the age of 3 years.
Differential diagnosis ( Table 14.1 )
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Basic near
Presentation
- •
After the age of 6 months.
Signs
- •
Straight for distance and esotropia for near.
- •
Normal or low AC/A ratio and normal refraction.
Distance
Presentation
- •
Early adult life.
Signs
- •
Intermittent or constant esotropia for distance, and minimal or no deviation for near.
- •
Myopia is common.
Microtropia
Presentation
- •
May be spontaneous or following surgery for a large deviation.
Signs
- •
Very small angle that may not be apparent on cover testing.
- •
Central suppression scotoma of the deviating eye.
- •
Abnormal retinal correspondence (ARC) with reduced stereopsis and variable peripheral fusional amplitudes.
- •
Anisometropia and amblyopia are common.
Acute (late onset)
Presentation
- •
At about 5 years of age with sudden onset of diplopia and esotropia.
Signs
- •
Esotropia for distance and near.
- •
Normal motility.
- •
Normal refraction.
Differential diagnosis
- •
Sixth nerve palsy.
Sensory (secondary)
Pathogenesis
- •
Unilateral congenital or early-onset reduction in visual acuity which interferes with or abolishes fusion.
Look for
- •
Opacity of the media such as cataract.
- •
Optic atrophy or optic nerve hypoplasia.
- •
Colobomatous microphthalmos ( Fig. 14.3 ).
Fig. 14.3
- •
Macular scarring from toxoplasmosis ( Fig. 14.4 ).
Fig. 14.4
- •
Retinoblastoma ( Fig. 14.5 ).
Fig. 14.5
Convergence spasm
Presentation
- •
Usually in adult life as an intermittent phenomenon which is usually hysterical.
Signs
- •
Esotropia and bilateral miosis ( Fig. 14.6 ).
Fig. 14.6
- •
Pseudo-myopia due to accommodative spasm.
Cyclic
Presentation
- •
Alternating manifest esotropia lasting 24 hours followed by normal binocularity for 24 hours.
Signs
- •
Large deviation but diplopia is unusual.
- •
Fusional amplitudes are subnormal or absent.
Consecutive
Cause
- •
Surgical overcorrection of exotropia.
Refractive accommodative
The AC/A ratio is normal and esotropia is a physiological response to excessive hypermetropia. Presentation is usually between 2 and 3 years of age.
Fully accommodative
Signs
- •
Esotropia without correction ( Fig. 14.7A ).
Fig. 14.7A
- •
Straight after correction of hypermetropia ( Fig. 14.7B ).
Fig. 14.7B
Partly accommodative
Signs
- •
Esotropia without correction ( Fig. 14.8A ).
Fig. 14.8A
- •
Angle is reduced but not eliminated after correction of hypermetropia ( Fig. 14.8B ).
Fig. 14.8B
Non-refractive accommodative
Refraction is normal but the AC/A ratio is high so that a unit increase of accommodation is accompanied by a disproportionately large increase in convergence.
Convergence excess
AC/A ratio is high due to increased accommodative convergence.
Signs
- •
Straight for distance ( Fig. 14.9A ).
Fig. 14.9A
- •
Esotropia for near ( Fig. 14.9B ).
Fig. 14.9B
- •
Straight through bifocals ( Fig. 14.9C ).
Fig. 14.9C
Hypoaccommodative convergence excess
AC/A ratio is high due to weak accommodation.
Signs
- •
Remote near point of accommodation.
- •
Straight for distance.
- •
Esotropia for near.
Pseudo-esotropia
Epicanthic folds and broad nasal bridge
This may simulate or accentuate an esotropia.
Signs
- •
Symmetric corneal light reflexes are central or slightly displaced nasally ( Fig. 14.10 ).
Fig. 14.10
- •
No deviation on cover-uncover test.
Negative angle kappa
Signs
- •
The corneal light reflexes are displaced temporally as may occur in high myopia.
Narrow interpupillary distance
This may occur in hypotelorism in which there is narrow separation of the orbits as a result of skull malformation or failure of brain development.
CONCOMITANT EXOTROPIA
Constant (early onset)
Presentation
- •
Often at birth.
Signs
- •
Normal refraction.
- •
Large and constant angle.
- •
DVD may be present.
Look for
- •
Neurological anomalies.
Intermittent (basic)
Presentation
- •
Around 2 years of age with exophoria breaking down to exotropia.
Signs
- •
Straight with BSV at times ( Fig. 14.11A ).
Fig. 14.11A
- •
Divergent with suppression at other times ( Fig. 14.11B ).
Fig. 14.11B
Classification
- a.
Distance (divergence excess) – angle is greater for distance.
- b.
Near (convergence insufficiency) – angle is greater for near.
- c.
Non-specific – angle is the same for distance and near.
Sensory (secondary)
Pathogenesis
- •
Monocular visual impairment by acquired lesions such as cataract ( Fig. 14.12 ) or other opacities of the media.
Fig. 14.12
Consecutive
Presentation
- •
In adult life either in an amblyopic eye or following surgery for esotropia.
Signs
- •
Large and constant deviation ( Fig. 14.13 ).
Fig. 14.13
Microexotropia
Presentation
- •
In isolation or in association with a primary intermittent or constant exotropia.
Look for
- •
Amblyopia and anisometropia.
Hypertelorism
Signs
- •
Congenital anomaly in which there is wide separation of the orbits often associated with shallow orbits as in Crouzon syndrome.
- •
Gross exotropia ( Fig. 14.14 ).
Fig. 14.14
Pseudo-exotropia
- a.
Positive angle kappa without ocular anomalies in which the corneal light reflexes are displaced nasally giving a false impression of an exotropia.
- b.
Positive angle kappa is caused by macular heterotopia (e.g. dragged macula in retinopathy of prematurity – Fig. 14.15 ) with temporal displacement of the fovea and consequent nasal displacement of the corneal light reflexes.
Fig. 14.15
CONGENITAL SYNDROMES
Duane retraction syndrome type 1
Signs (left eye)
- •
Primary position – straight or slight esotropia ( Fig. 14.16A ).
Fig. 14.16A
- •
Abduction is absent or limited and is accompanied by widening of the palpebral fissure ( Fig. 14.16B ).
Fig. 14.16B
- •
Adduction is normal or mildly limited and is accompanied by retraction of the globe and narrowing of the palpebral fissure ( Fig. 14.16C ).
Fig. 14.16C
Duane retraction syndrome type 2
Signs
- •
Primary position – straight or slight exotropia.
- •
Abduction is normal or slightly limited.
- •
Adduction is limited.
Duane retraction syndrome type 3
Signs (left eye)
- •
Primary position – straight or slight esotropia ( Fig. 14.17A ).
Fig. 14.17A
- •
Abduction ( Fig. 14.17B ) and adduction ( Fig. 14.17C ) are both limited.
Fig. 14.17B
Fig. 14.17C
- •
All three types of Duane syndrome may be associated with up-shoot of the affected eye on adduction and occasionally a down-shoot.
Brown syndrome
Signs (left eye)
- •
Primary position – straight ( Fig. 14.18A ).
Fig. 14.18A
- •
Limited elevation in adduction ( Fig. 14.18B ).
Fig. 14.18B
- •
Limited elevation on upgaze ( Fig. 14.18C ).
Fig. 14.18C
- •
Normal left elevation in abduction ( Fig. 14.18D ).
Fig. 14.18D
- •
Absence of left superior oblique overaction.
Causes ( Table 14.2 )
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Monocular elevator deficit
Signs (right eye)
- •
Primary position – usually straight.
- •
Profound limited elevation in all positions of upgaze ( Fig. 14.19A–C ).
