Effectiveness of the long-term prism adaptation test over 1 month or more in strabismus surgery for esotropia

Prism adaptation test (PAT) was shown to be an effective assessment for esotropia (ET) surgeries. However, the effectiveness of long-term PAT for ET remains uncertain. This study aimed to evaluate the effectiveness of the long-term PAT for patients with ET by comparing the preoperative deviations before PAT (simple PACT), after short-time PAT (15-30 min/set), and after long-term PAT (1-6 months). This prospective, longitudinal study enrolled 24 consecutive patients who underwent strabismus surgery for ET after long-term PAT. Ocular deviation was measured by prism and alternate cover test (PACT) at pre-PAT, post-short‑time PAT, and post-long‑term PAT. We analyzed the correlation between the effect of long-term PAT and preoperative parameters. The pre-PAT, post-short-time-PAT, and post-long-term-PAT deviations were 13.0 ± 5.2° (23.0 ± 9.0 Δ), 14.4 ± 5.9° (25.7 ± 10.4 Δ), and 15.8 ± 6.3° (28.2 ± 11.0 Δ), respectively. The post-long-term-PAT deviation was larger than that at pre-PAT (p = 0.001). Multivariable analysis revealed that the long-term PAT effect was correlated with PAT duration and short-time PAT effect. Our findings suggest that long-term PAT reveals latent deviation and is associated with surgical success in patients with ET. Future comparative studies with control groups are needed to validate these findings.