Age at onset of esotropia predicts surgical outcomes
medwireNews: The age at onset of acquired nonaccommodative esotropia (ANAET) in children is a crucial determinant of postoperative functional outcomes, Canadian researchers believe.
Accordingly, they suggest that surgery may safely be delayed in children with an age at onset of 30 months or later.
Inas Makar (Ivey Eye Institute, St Joseph's Hospital, London, Ontario) and co-workers reviewed the clinical characteristics of 34 children with ANAET seen at the Ivey Eye Institute.
The children's mean age at the time of surgery was 57.2 months and the mean age at disease onset was 28.7 months. Eleven children had A/V pattern strabismus, five (14.7%) had a recent history of intermittent control of deviation, eight (23.5%) had dense amblyopia, and all had a mild hyperopic refractive error.
The magnitude of esotropia decreased significantly following surgery, report Makar et al in the Canadian Journal of Ophthalmology. Deviation at distance fixation fell from 34.9 to 2.0 prism diopters (PD) while deviation at near fixation fell from 40.4 to 2.5 PD, on average, although 22 children (64.7%) had residual esotropia after surgery.
With regard to functional outcomes, five patients (14.7%) achieved bifoveal fixation, of whom four were orthophoric for distance and near, and one had residual esotropia measuring 2 PD for near. Twenty patients (58.8%) had stereopsis ranging from 80 to 3000 seconds of arc, and nine patients (24.7%) had no evidence of stereopsis.
Ten patients (29.4%) had evidence of fusion both for distance and near on the Worth 4-dot test; all 10 patients were orthophoric or had residual esotropia of 2 PD for distance and near. Twenty-eight patients had fusion for near (82.3%), with a mean residual esotropia of 2.1 PD.
In multivariate analysis, age at disease onset was the only significant independent predictor for stereopsis. Specifically, the adjusted odds ratio for achieving stereo acuity of 100 seconds of arc or better was 1.063 for each 1-month increase in age at onset.
Noting that postoperative stereopsis in childhood esotropia is an important predictor for future stable alignment, the study authors conclude: "Early onset of esotropia carries a poor prognosis for development of stereopsis…
"Parents who are hesitant about surgery for older children with long duration of misalignment might think differently if, despite months to years of delay, there is still reasonable potential for regaining stereopsis, which can promote long-term stability."
By Joanna Lyford, Senior medwireNews Reporter