Prism adaptation test in acquired non-accommodative esotropia
Reviewed by Fiona Rowe

This study investigated factors related to the increase in prism adapted angle in patients with acquired non-accommodative comitant esotropia (ANAET) who had strabismus surgery based on the results of a short prism adaptation test (PAT) and evaluated their outcomes. Short PAT involved a Fresnel prism trial to neutralise the deviation and worn for 15-20 minutes. If a residual esotropia was seen with the prism, the prism strength was increased, and the process repeated until the deviation was neutralised or stable. Binocular vision was confirmed with Bagolini glasses. Patients were grouped into prism builders if showing a >10PD increase or prism non-builder if <10PD. The study included 41 patients (23 male) with median age of 15 years (range 3-54). This was a retrospective study. Ten patients had typical acute esotropia with a clear onset time. Refractive error was -3.03D (SD 3.33) for right eyes and -3.05D (SD 3.23) for left eyes. Myopia of ≥-2D was recorded for 66%. Pre PAT the median angle of deviation was 30PD (range 25-40) at distance and 35PD (22.5-45) for near. This increased to 45PD (40-50) at distance and 45PD (40-55) for near after PAT. Postoperative follow-up was 23 months (9.3-31.8). Prism builders accounted for 27 of 41 patients and esotropia increased from 30 to 45PD at distance. Overall surgical success rate was 83% and was not significantly different between the two groups. The prism builder group had smaller entry deviation at near, more with intermittent strabismus and more with myopic refractive errors. They tended to be older at time of surgery. An average increase of 15PD occurred with prism builders and they were more likely to have preoperative diplopia. The authors conclude that short PAT can help to determine surgical correction dose.

Prism adaptation response and surgical outcomes of acquired nonaccommodative comitant esotropia.
Nishikawa N, Kawaguchi Y, Fushitsu R.
STRABISMUS
2023;31(1):9-16.