Authors: Alaa AlAli, Sadik T. Sherief, Katelyn MacNeill, Kim Quann, Michael J. Wan, David R. Smith
Author Disclosure Block: A. AlAli: None. S.T. Sherief: None. K. MacNeill: None. K. Quann: None. M.J. Wan: None. D.R. Smith: None.

Abstract Body:

Purpose: To measure the primary strabismic deviation accurately, fixation and accommodation must be controlled and all fusional divergence must be eliminated. The 45- minutes diagnostic occlusion test (DOT) is one of the key test that is used to assess the full degree of deviation in intermittent exotropia. This test is not considered as part of the work-up for patients with acquired esotropia. About 20% of children with acquired esotropia have unstable ocular alignment over time. In this study we aim to assess the change in measured esodeviation after a 45- minutes DOT in patients with acquired esodeviations.

Study Design: Prospective interventional study

Methods: We conducted a prospective interventional study with a total of 67 participants with acquired esotropia. Two orthoptists (KN and KQ) measured the angle of deviation with prism and alternating cover test at far and near target before and after 45 minutes. 37 participants where assigned to patch group (one eye patched for 45 minutes) and 30 participants where assigned to the control group (participants waited for 45 minutes with no patch, and then one eye is patched just before the patient was assessed by one of the blinded orthoptist; KN or KQ). Independent T-test was used to determine the strabismus angle difference between the 2 groups.

Results: Out of the 67 patients enrolled, 42% were males and 58% were females. The average age of the participants was 9 years of age (range 3-17 years old). 37.3% had a diagnosis of accommodative esotropia compared to 62.7% who were diagnosed with partially accommodative esotropia. 33% of patients in the patching group showed a significant change in the amount of measured esotropia after the DOT. On the other hand, none of participants assigned to the control showed a significant change in the amount of measured esotropia.

Conclusions: This study demonstrated that DOT can be applied clinically for acquired esotopia for accurate measurement of angle of deviation. Performing DOT in acquired esodeviations may help to reveal the full deviation and ultimately decrease the risk of surgical undercorrection. On average there  may be 0.5-1.0 mm change in the amount of recti muscle recesssion or resection if a surgical plan is initiated.