|
|
onset before age 6 months (infantile esotropia) |
CONGENITAL ESOTROPIA
onset before age 6 months
(infantile esotropia)
* family history
* etiology
o absence of sensory fusiono abnormality of motor fusion (vergence)
o extraocular muscle development
o "accommodative"
o unknown
* clinical features
o large angle, 30-70 prism diopters+ a few with smaller, variable angleso alternate or "cross" fixation
this means that the right eye is used for fixation in the left visual field and the left eye is used for objects in the right visual field. In this way, both eyes remain in adduction and have little opportunity for abduction.o refractive error
+ higher amounts of moderate hyperopia (2-4D) than expectedo amblyopia
+ more than you think (~50%) but not frequently severe because of cross fixation patterno limitation in abduction
this may be secondary to the limited abduction from the cross fixation pattern frequently observed.o associated motor anomalies
+ inferior oblique overaction (IOO)this can be unilateral or more frequently bilateral+ dissociated vertical deviation (DVD)
each eye elevates under the occluder when doing a cover test. HAs been called double hypertropia in the past.+ latent nystagmus (LN)
- becomes apparent in the first year. This occurs when one eye is occluded (or interocular luminance differences)- one or in any combination (IOO, DVD, LN). These tend to appear after the strabismus and may not be fully expressed until near the end of the first year of life.
+ persistent smooth pursuit abnormality
+ asymmetric OKN
- temporal-to-nasal is much better than nasal-to-temporal. this is consistent with the pattern observed in infancy. Because of the esotropia, the normal maturation and the subsequent development of bidirectional equality of OKN doesn't happen.+ motion detection anomaly
* MANAGEMENT
o correct for significant hyperopiao treat amblyopia
o prism correction
o surgery
+ bilateral medial rectus recession+ timing of surgery (management goals)
o Is normal binocular fusion possible?
+ with stereopsis?+ critical period issue
- 2 schools of thought for timing of surgery* as early as possible* before 2 years of age
+ prognosis for establishment of binocular fusion with stereopsis is "poor"
+ multiple surgeries may be required
+ monofixation syndrome may be the result after surgery and a smaller angle of strabismus remains
+ peripheral fusion with central suppression
+ some stereopsis - usually peripheral, large disparities
o post-operative care
+ monitor for amblyopia+ prism
+ lenses
+ VT
+ occlusion
o sequelae
+ horror fusionis+ intractable diplopia
+ simultaneous perception without superimposition+ lack of retinal correspondence
+ breakdown of "binocular" vision
- consecutive exotropia- intermittent esotropia (convergence excess)
Differential Diagnosis
o infantile accommodative esotropiao congenital fibrosis syndrome
+ fibrous replacement of orbital striated muscle+ general fibrosis syndrome
- all the extraocular muscle- strabismus fixus
- horizontal recti (MR > LR)
o FORCED DUCTION TEST
Differentiates muscle paresis from ocular restriction caused by muscle contractures, fibrosis, etc.
|
|
The eye is anesthetized and forcibly moved with forceps as indicated in this drawing. If the eye moves freely to forced movement, then this indicates that any restriction in eye movement in that direction is caused by a muscle paresis. If the eye cannot be moved, even with this forced duction in a particular gaze direction, then it suggests that the eye must be restricted in its movement and there is no muscle paresis. |
o SACCADIC VELOCITY
In the absence of a forced duction test, the clinicians can use saccadic velocity to differentiate muscle paresis from restriction. If saccadic velocity in the effected field of gaze seems slow, this indicates a probable muscle paresis; i.e. the effected muscle cannot generate the necessary muscle force to generate a fast saccade. If restrictions are present, saccade velocity may be normal up until the restriction comes into play.
o Ciancia syndrome
+ large angle deviation+ limited abduction bilaterally
+ fixing eye in adduction
+ small nystagmus on fixing eye abduction
- fast phase in direction of fixing eye+ face turn toward fixing eye
+ tight MR
o Duane's Retraction syndrome
o Bilateral VI nerve paresis
MONOCULAR ELEVATOR PALSY (MEP)
DOUBLE ELEVATOR PALSY
+ inferior rectus restriction
- hypotropia from secondary contracture of ipsilateral inferior rectus+ >60% of cases, >=35 pd
+ concurrent horizontal strabismus in 50%
+ 33-50% prevalence of strabismic or anisometropic amblyopia
+ pseudoptosis from hypotropia
+ ptosis with paretic variety
+ no ptosis, hypotropia with restrictive variety
+ elevation deficit nearly equal in all fields of gaze
+ chin-up presentation
CYCLIC ESOTROPIA
* age of onset 2-6 years
* 24-48 hour cycle
o esotropia then orthotropia then esotropia
* progressive
o esotropia becomes constant
* may require surgery
