6 Strabismus
6.5 Accommodative Esotropia
- Esotropia (ET) linked to accommodation
- Onset 6 months - 7 years (average 2.5 years)
- May be intermittent at onset, (sometimes precipitated by trauma or illness) becoming constant
- Diplopia may occur but usually disappears as the patient develops suppression scotoma
- Approximately 75% have a family history
- Amblyopia common (50%)
- No associated IOOA or DVDs
Accommodative
High AC / A
Mixed (most common)
Definition
Accommodative
Hypermetropia means that a high amount of accommodation (with a proportionate amount of convergence) is required to focus even on a distant target
High AC / A
Accommodation is associated with a dis-proportionately high amount of convergence
Mixed (most common)
Hypermetropia
High AC / A
Accommodative
1.Fully accommodative
Esotropia (ET) fully corrected by full cycloplegic refraction
2. Partially / (Non)
accommodative
ET only partially corrected by full cycloplegic refraction (i.e. still ET for D&N)
Mixed (most common)
Distance prescription corrects distance deviation but a deviation remains at near
CTD / N
Accommodative
ET Distance= ET Near (within 8Δ)
High AC / A
Straight Distance (after correction), ET Near.
ET for near may be reduced or eliminated by a +3.0 add
Mixed (most common)
ET Distance < ET Near (by >8Δ)
i.e. When straight for distance with full cycloplegic correction will still have ET for near.
ET for near may be reduced or eliminated by a +3.0 add
Refraction
Accommodative
Hypermetropia (e.g. +3 to +10D)
High AC / A
Emmetropia (ranges from myopic to high hyperope)
Mixed (most common)
Hypermetropia
AC / A ratio
Accommodative
Normal (e.g. 3-5)
High AC / A
High
Mixed (most common)
High
- Amblyopia is common (50%, especially partially accommodative)
- Abnormal Head Position (AHP)?
- Hirschberg (pupil margin=30Δ, limbus=90Δ) - Esotropia
- (Lids normal)
- (Pupils normal)
- Comitant ET (Measure distance & near as an estimation of AC / A. An ET that is greater for near than distance suggests a high AC / A, but this can only be proven by formal testing- see below)
- A) Without glasses: CTD, CTN
- B) With glasses: CTD, CTN
- (NB: Attempts may also be made to measure the AC / A ratio by the lens gradient method by cover-testing at near with and without +3D lenses)
- Full ductions (Exclude CNVI palsy) ± IOOA
- DVD is uncommon
Often Hypermetropic. Use:
- Cyclopentolate 1%, (Phenylephrine 2.5%) or
- Atropine 1% bd for 3 days prior if dark irides, amblyopic, unsure, unco-operative
Summary
- Fully / Partially / Non-Accommodative ET with presumed Normal / High AC / A
Most accommodative esotropias do not require further investigations. However, neuroimaging (MRI brain) should be considered when the presentation is atypical:
- Acute onset
- Older (>7yrs)
- Incomitant i.e. abduction deficit
- Diplopia, other neurological signs (e.g. CN VI, papilloedema, nystagmus)
- No hypermetropia
Aims:
- Maintain vision (Treat amblyopia / refraction)
- Realign the visual axes (straighten eyes for distance with spectacles)
- Maintain or restore good binocular function (predict fusion potential given age, duration, vision) - most get monofixation syndrome
- Alleviate symptoms (asthenopia, diplopia)
Accommodative Component
High AC / A Component
Fully
Partially / (Non)
Patching
Spectacles
Accommodative Component
Correct refraction (Cycloplegic refraction- Full time spectacle wear)
High AC / A Component
Correct refraction (get straight for distance first before any bifocals)
Spectacles
Accommodative Component
If ET for distance persists:
- Check spectacle prescription
- Repeat cycloplegic refraction (consider atropine) and prescribe any residual latent hyperopia.
If only ET for near persists (i.e. mixed), consider bifocals.
High AC / A Component
Options include:
- Observation if asymptomatic, cosmetically acceptable (advocates argue there is little functional disadvantage if straight for distance but ET for near).
- Bifocals if can correct to ET for near <10Δ with improvement in near stereopsis. Prescribe the minimum plus for close work e.g. +3D for 1 / 3m executive flat-top through pupil or short corridor wide reading-zone multifocal lens.
- Spectacles are the mainstay of management of most accommodative esotropia
- Prescribe spectacles prior to amblyopia patching (patch when vision plateaus)
- Warn parents “ET will be worse without glasses” and that glasses are for alignment not vision. (If not tolerated, try g. cyclopentolate 1% or g. atropine ou daily until they can)
- Try to wean script from 6yrs or when child complains of blurred vision (reduce in + 0.5D increments). Most patients will require spectacles until their teenage years (especially if refraction > +3D)
Accommodative Component
High AC / A Component
Fully
Partially / (Non)
Surgery
Surgery can only be considered once:
1. Refraction has been corrected for distance
2. Amblyopia has been treated (or attempted)
3. There is a stable angle of deviation
Consider surgery (only ~20% will require) if
1. There is potential for maintaining / improving binocular single vision
2. Patient or family is concerned by cosmesis and reassure them the surgery is reconstructive, not cosmetic
Accommodative Component
Only operate on non-accommodative component (make eyes straight with glasses)
- Bilateral MR recession (BMRR)
- MR recession / LR resection (if amblyopic eye)
High AC / A Component
Only operate on non-accommodative component
Options include:
- BMRR (operate for distance)- tends to under correct
- BMRR ± Augmented surgery: operate for average of D and N with bifocals e.g. 10ΔD, 30ΔN: operate for 20)
- BMRR (operate for near) - risks overcorrecting
- BMRR + Faden operation- posterior fixation suture can be used if straight for distance, ET for near i.e. high AC / A. This is often performed as a second operation → If develops consecutive XT after surgery, reduce the strength of the spectacles.
- Follow-up at least 6-monthly (at least annual refraction)
- Monitor for amblyopia, under-correction
Summary Management Algorithm [ii]
Courtesy of Dr Ross Fitzsimmons
Normal AC / A
(ET Distance = ET Near)
High AC / A
(ET Distance < ET Near)
Fully Accommodative
Normal AC / A
(ET Distance = ET Near)
Spectacles
High AC / A
(ET Distance < ET Near)
Bifocals
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