Investigation of Transient Eye Closure associated with Bright light in the Patients with Intermittent Exotropia

Abstract Background: To present a simple method to evaluate transient eye closure (TEC) under bright light using binocular pupillometry in children with intermittent exotropia (IXT). Methods: Sixty-one children with IXT were studied using binocular pupillometry. Each patient was exposed to each phase as follows: scotopic phase (darkness) for 3,300 ms, mesopic phase for 200 ms, scotopic phase for 3,300 ms, low-intensity white light phase (10 cd/m2) for 200 ms, scotopic phase for 3,300 ms, and high-intensity white light phase (100 cd/m2) for 200 ms. TEC was present if the subject closed eyes immediately more than half in response to light, compared with the one in the scotopic phase. We assessed the agreement between TEC and self-reporting photosensitivity, and also evaluated the associated factors for the presence of TEC in IXT patients.Results: With the new method to evaluate TEC under different light intensities, 27 (44.3%) of the 61 IXT patients showed TEC, and 34 (55.7%) did not demonstrate TEC. TEC under high-intensity white light had a strong correlation with photosensitivity (r = 0.77). The smaller angle of deviation at near was associated with the presence of TEC, with statistical significance (p = 0.04). Normal sensory status at distance was significantly associated with TEC (p < 0.01). Multivariate analysis using multiple logistic regression analysis showed that normal sensory status was significantly associated with TEC (p = 0.02).Conclusions: The test using binocular pupillometry is useful in identifying TEC related to bright light, and the presence of TEC was strongly correlated with photosensitivity in patients with IXT.