Outcomes for symptomatic esophoria with or without prism adaptation test
Reviewed by Fiona Rowe

The authors aimed to compare the frequency of repeated interventions between patients who had prism adaptation test (PAT) and conventional orthoptic measurements, and those that did not, in order to measure changes in angle after PAT and surgical outcome. This was a retrospective case review of patients with symptomatic esotropia. PAT was undertaken for 30–120 minutes. The study included 105 patients; 61 non-PAT and 44 PAT. There was a ratio of 2:1 for females to males. The median age was 35 years for the non-PAT group and 28 years for the PAT group. The amount of prism within glasses was a median 20PD for non-PAT and 11PD for the PAT group. Preoperatively, the median angle of deviation was 18PD near and distance (non-PAT) and 14PD near/16PD distance (PAT). Results showed a reduced need for repeat surgery in the PAT group; reoperations were more common in the non-PAT group (34% vs 11%). There were no serious complications. Non-PAT reoperations were due to persistent esophoria and, for the PAT group, persistent esophoria or consecutive exodeviation. The total number of operations was higher for the non-PAT group (48% vs 23%). The non-PAT group had more one-muscle surgery than the PAT group; likely due to the lower median deviation angle and thus, lower surgical target. The authors propose that PAT is an important additional assessment with the objective to ensure the entire latent deviation is uncovered. Surgery then aims to undercorrect due to better tolerance of minor residual esophoria than overcorrected exo. It is also better for those with no or poor binocular potential to help prevent drift to consecutive exotropia over time.

Prism adaptation vs conventional orthoptic measurement for symptomatic esophoria: a retrospective study.
Hofsli M, Topr-Pedersen T, Saunte JP, et al.
STRABISMUS
2025;33(4):221–8.