Rostami Masoud, Kiarudi Mohammad Yaser, Hassanzadeh Samira, Sharifi Mahdi, Ziaei Mohammed
Refractive Error Research Center, Department of Optometry, Mashhad University of Medical Sciences, Mashhad, Iran.
Eye Research Center, Department of Ophthalmology, Mashhad University of Medical Sciences, Mashhad, Iran.
Clin Exp Optom. 2025 Aug;108(6):733-737. doi: 10.1080/08164622.2024.2400317. Epub 2024 Sep 9.
Transient monocular eye closure and photosensitivity under bright light have been reported in people with intermittent exotropia (IXT). The exact mechanism of these symptoms has not been established.
This study examines the effect of sunglass filters on contrast sensitivity (CS), transient monocular eye closure, and blinking rate under bright light in people with IXT.
Forty participants with IXT and complaints of photosensitivity were included in the study. The binocular CS test was performed under mesopic and photopic conditions with and without glare, and with and without two filters with different grades of light transmission (filter 1: 44-80%; filter 2: 20-43% light transmittance). The effect of two filters on transient eye closure, contrast sensitivity, and blinking rate was assessed under bright light. Also, participants were divided into 3 groups based on their degree of control of fusion (good, fair, and poor control).
The mean age of the participants was 12.0 years ± 8.0 (standard deviation) (range: 7-40 years). There was no significant difference between the age ( = 0.139), stereopsis ( = 0.134), as well as the near and far degree of deviation ( = 0.516, and = 0.237) between the three groups of fusion control. Under mesopic conditions with glare, mean binocular CS was significantly higher with filters ( < 0.001). Without filters, 57.5% of the participants exhibited monocular eye closure under a photopic setting with additional glare. No participant showed eye closure using filter 2. People in the poor control group showed exodeviation before monocular eye closure (62.5% without filter and 12.5% with filter 1, = 0.01). The blinking rate decreased from 36.0 ± 4.0 blinks per minute without filter to 21.0 ± 3.0 using filter 1, and 20.0 ± 3.0 with filter 2.
In people with IXT, wearing sunglass filters of different transmittance reduces monocular eye closure and blinking rate under bright light. To improve these symptoms, sunglasses can be considered for IXT.
间歇性外斜视（IXT）患者曾有报道出现瞬目单眼闭合及强光下的光敏现象。这些症状的确切机制尚未明确。
本研究探讨太阳镜滤光片对IXT患者在强光下的对比敏感度（CS）、瞬目单眼闭合及眨眼频率的影响。
40例有光敏症状的IXT患者纳入本研究。在明视和暗视条件下，分别在有无眩光、有无两种不同透光率等级的滤光片（滤光片1：44 - 80%；滤光片2：20 - 43%透光率）的情况下进行双眼CS测试。评估两种滤光片在强光下对瞬目单眼闭合、对比敏感度及眨眼频率的影响。此外，根据融合控制程度将参与者分为3组（良好、中等、差）。
参与者的平均年龄为12.0岁±8.0（标准差）（范围：7 - 40岁）。三组融合控制组之间的年龄（= 0.139）、立体视（= 0.134）以及近、远距离斜视度（= 0.516，= 0.237）无显著差异。在暗视条件下有眩光时，使用滤光片时双眼平均CS显著更高（< 0.001）。不使用滤光片时，57.5%的参与者在有额外眩光的明视环境下出现单眼闭合。使用滤光片2时无参与者出现单眼闭合。融合控制差的组在单眼闭合前出现外斜视（不使用滤光片时为62.5%，使用滤光片1时为12.5%，= 0.01）。眨眼频率从不使用滤光片时的每分钟36.0±4.0次眨眼降至使用滤光片1时的21.0±3.0次，使用滤光片2时为20.0±3.0次。
对于IXT患者，佩戴不同透光率的太阳镜滤光片可减少强光下的单眼闭合及眨眼频率。为改善这些症状，IXT患者可考虑佩戴太阳镜。
