Is 15 minutes of monocular occlusion test as effective as 45 minutes of monocular occlusion test when evaluating divergence excess intermittent exotropes?

Theme: Paediatric ophthalmology and strabismus
What: Paediatric ophthalmology and strabismus
Part of: Paediatrics II: Strabismus- Innovations and Challenging Cases / Pédiatrie II: Ophtalmologie pédiatrique et strabisme - Dépistage du rétinoblastome
When: 6/2/2024, 11:15 AM - 12:45 PM
Where: Room | Salle 714 A

Abstract

Purpose  

This investigation was carried out to determine if 15-minutes of prolonged monocular occlusion (PMO) test would be clinically and statistically equivalent to 45-minutes of prolonged monocular occlusion test when evaluating patients with divergence Excess intermittent Exotropia. 

Study Design 

randomized, prospective, non-interventional study 

Methods  

A total of 22 patients diagnosed with divergence excess intermittent exotropia (DE-IXT) were prospectively reviewed. After a routine orthoptic examination, participants were randomly assigned to start with either a 15-min or 45-min PMO test, with each occlusion test separated by 10-min of recovery time to re-establish the baseline fusional status. The mean near and distance exodeviations obtained following each occlusion test were compared. The mean near-distance disparity obtained following each occlusion test was also compared. The data were statistically analyzed by the non-parametric Wilcoxon Signed Rank test.  

Results  

The mean initial exodeviation before occlusion was 9.64 ± 4.35, and 25.84 ± 5.22 at near and distance fixation points respectively. The mean near-distance disparity before occlusion was also measured to be 16.20 ± 3.94 prism diopters. 

The mean exodeviation at near was found to be 21.07 ± 7.45 and 22.32 ± 8.24 following 15-min and 45-min PMO respectively, with no clinical or statistically significant difference (P-value >0.05) in the size of the near deviation following each occlusion tests. The mean exodeviation at distance was 25.80 ± 5.61, and 26.68 ± 5.95 following the 15-min and 45-min PMO respectively, with no clinical or statistically significant difference notable between the two occlusion tests (P-value > 0.05).  

The initial near-distance disparity before occlusion was 16.20 ± 3.94 prism diopters. The near-distance disparity decreased to 4.95 ± 4.53 after 15-min PMO, and 5.73 ± 4.01 after 45-min PMO with no clinical or statistically significant difference between the two occlusion groups (P-value> 0.05). 

Conclusions  

The change in near and distance exodeviation noted following a 15-min of PMO and 45-min PMO are clinically equivalent and within 5 prism diopters of each other. The near-distance disparity noted in divergence excess exotropia patients can effectively be reduced to basic type with a 15-min of PMO. Therefore, reducing the costs and the time required in evaluating divergence excess intermittent exotropia patients in ophthalmology clinics.  

Presenter(s)

Presenting Author: Sajedeh Uzbak

Additional Author(s):

Michael Wan, Hospital for Sick Children

David Smith, Hospital for Sick Children

Leah Walsh, IWK Health Centre

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