A comparative study of various prism adaptation forms in the surgical management of esophoria

To evaluate the outcome in participants who underwent surgery for esophoria following one of three different methods of preoperative prism adaptation test (PAT).

This prospective, multicentre study was carried out at five eye departments from 2012 to 2019. 116 participants were included and allocated to three groups as per investigator choice: Group 1 (n = 55) had a short prism adaptation period ranging from 1 to 5 hours during their visit at the clinic. Group 2 (n = 36) underwent partial prism correction for at least 4 weeks before surgery. Group 3 (n = 25) underwent full prism correction for at least 4 weeks before surgery. Motoric success was determined by postoperative angle of deviation (AOD), and sensoric success was evaluated with Lang and Bagolini striated lens test.

A significant increase (p < 0.001) in AOD after PAT was observed in all groups, with no significant difference between groups (distance: p = 0.22; near: p = 0.31). Motoric and sensoric success was comparable between groups 3 months (p = 0.52; p = 0.55) and 1 year (p = 0.53; p = 0.29) after surgery. Prolonged prism adaptation (n = 24) for more than 365 days was not associated with better results.

Our study indicates that the postoperative result is independent from the duration and amount (partial or full correction) of prism adaptation before surgery at least up to one year of follow-up. Prolonged prism adaptation (>365 days) before surgery does not improve the results.