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Treatment

 

While terminology and theories of origin may be debated, it is the nearly universal belief of strabismologists that surgery is the treatment of choice after refractive/ accommodative components have either been ruled out or treated and after any amblyopia (if present) has been treated. Ideally these patients should alternate fixation before surgery, but surgery is often carried out before this is accomplished. Amblyopia therapy in such cases can be continued after surgery. The age chosen for surgery depends on the surgeon’s preference and varies from as early as 4 months to 3 years of age or more. The trend, however, is for surgery to be done at a younger age. Chemodenervation of both medial recti with Botox has been done, but has not achieved a prominent role. (see chapter 14).

Surgery for infantile esotropia consists of bimedial rectus recession, medial rectus resection, and lateral rectus resection of one eye, a three-muscle procedure combining a bimedial rectus recession with a resection of one lateral rectus or in a very few cases a four-muscle procedure consisting of a bilateral recession-resection. In cases with inferior oblique overaction and V pattern, both inferior oblique muscles may also be weakened at the initial surgical procedure. These patients often have lax superior oblique tendons that could be treated either with bilateral superior oblique tuck or bilateral inferior oblique weakening. Most cases of infantile esotropia, particularly those done at less than 1 year, have only horizontal rectus muscle surgery done at the initial procedure. Inferior oblique overaction may occur months to years after initial horizontal muscle surgery in which case inferior oblique weakening is done as a second procedure.

The best attainable result from treatment for congenital esotropia in my experience is subnormal binocular vision (Table 1). However, Kenneth W. Wright has reported a patient aligned at 2 months and 28 days who obtained alignment and stereo acuity of 40 seconds arc disparity. An acceptable but less desirable result is microtropia, and a still less desirable result is ‘small-angle’ eso- or exotropia. Large-angle eso- or exotropia, a still less desirable result, requires further surgery. We have found that 80%+ of patients treated surgically in our clinic for congenital esotropia have good initial results; that is, small-angle esotropia or exotropia of less than 10 prism diopters, microtropia, or subnormal binocular vision. With continuing treatment nearly 100% of congenital esotropia patients are aligned in the primary position by their teen years. von Noorden confirmed the earlier findings of Ing, Parks, and Costenbader that surgery done before 2 years of age produces better sensory results compared with surgery done between 2 and 4 years of age and surgery done after 4 years of age. In my experience, the best result from surgery for congenital esotropia falls short of normal binocular vision with perfect stereo acuity. That is, eyes may be aligned with equal vision but stereo vision is not normal. Anecdotal reports of infantile esotropia treatment resulting in normal stereopsis of 40 seconds of arc disparity beg the question, “Was this infantile esotropia?” I believe these patients could represent either early acquired esotropia in a child born with normal sensory potential or a ‘rescue’ of sensory function in an infant who could capitalize on being given a second chance by having the eyes straightened early. Of the two, I believe the former alternative to be the most likely.

 

 

 

 

 

Subnormal binocular vision*

Orthotropia or heterophoria
Normal visual acuity in both eyes
Fusional amplitudes
Normal retinal correspondence
Foveal suppression in one eye in binocular vision
Reduced or absent stereopsis
Stability of alignment
Optimal treatment result for congenital esotropia
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*We have examined ‘normal’ parents of children with congenital esotropia and found that they have reduced stereo acuity indicating ‘subnormal binocular vision’.

Microtropia†

Inconspicuous shift or no shift on cover test
Mild amblyopia frequent
Fixation central or parafoveolar in one eye
Fusional amplitudes
Anomalous retinal correspondence (if small shift on cover test)
Reduced or absent stereopsis
Fairly stable alignment
No further treatment except amblyopia prevention
Desirable treatment result
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† Microtropia with identity has harmonious anomalous correspondence between the eccentric fixation of the amblyopic eye and the fovea of the sound eye.

Monofixation (Parks)

Esotropia (XT) < 10 prism diopters
HARC‡
Alternation or amblyopia
Fusional amplitudes
Stable angle
Good result
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‡According to Parks peripheral NRC.

Small-angle esotropia/exotropia
(<20 prism diopters)

Cosmetically acceptable?
80% have anomalous retinal correspondence§
Less stability of angle
Further surgery based on appearance; amblyopia treatment as needed; may benefit from correction of hyperopia
May be acceptable result
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§I believe that all strabismus patients have harmonious anomalous retinal correspondence if tested with tests which disassociate eyes less such as Bagolini

Large-angle esotropia/exotropia
(>20 prism diopters)

Usually cosmetically unacceptable
Less chance for anomalous retinal
correspondence, suppression prevails
Unstable angle
Unacceptable result
Further surgery indicated
Large-angle esotropia/exotropia
(>20 prism diopters)
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HARC can be found.

From von Noorden GK: A reassessment of infantile esotropia, XLIV Edward Jackson Memorial Lecture, Am J Ophthalmol 105:1-10, 1988

Table 1 Results of treatment

 

 

 

 

 


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