Comparative evaluation of surgical outcomes in acute acquired comitant esotropia managed with and without pre-operative prism adaptation test

<i>Introduction</i>: Acute acquired comitant esotropia (AACE) is a rare type of esotropia for which until now the main treatment modalities prescribed are prism glasses, botulinum toxin injection and surgery. The purpose of our study is to compare the surgical outcomes in patients with AACE managed with and without pre-operative prism adaptation test (PAT). <i>Methods</i>: We have done a prospective, interventional study for the duration of one year. Forty patients with AACE were randomly divided into two groups by computerized randomization - those undergoing surgery after pre- operative PAT and those undergoing surgery without it. In control group (Group C), patients underwent surgery based on the angle of deviation at distance measured by prism bar cover test (PBCT) and wearing full cycloplegic correction, while in test group (Group T), patients underwent surgery based on the preoperative prism-adapted angle at distance wearing prism power determined by PBCT and wearing full cycloplegic correction. The primary outcome was post-operative deviation and secondary outcome was stereopsis. Post-operatively, patients were followed up at week 1, week 4 and final follow-up was done at week 12. <i>Results</i>: The mean age of the 40 patients was 13.95 ± 5.36 years. The age of the youngest and the oldest patients enrolled were 8 years and 35 years, respectively. The mean SD (standard deviation) of the PBCT for distance (measured in prism diopters - PD), PBCT for near (measured in prism diopters - PD) and stereopsis for near (measured in seconds of arc using Titmus Fly Test) at last follow-up visit (week 12) in the test versus control group were as follows: 1.70 ± 1.42 PD versus 4.75 ± 3.39 PD, 2.55 ± 1.82 PD versus 6.95 ± 3.35 PD and 74.90 ± 53.47 sec of arc versus 48.60 ± 31.97 sec of arc, respectively, which were statistically significant (<i>p</i> = <0.01, <i>p</i> = <0.01 and <i>p</i> = .03, respectively). The change in visual acuity and spherical equivalent in each group was insignificant. <i>Discussion</i>: Surgical outcomes in patients of AACE are better when surgical planning is done after performing pre-operative PAT as opposed to when surgery is planned without PAT. Better motor alignment (less under correction and over correction) and better sensory results in terms of improvement in stereopsis were observed. We recommend the use of pre-operative PAT in surgical planning in patients of AACE.