Open AccessObjective evaluation of visual fatigue in patients with intermittent exotropia
Author(s) -
Masakazu Hirota,
K. Yada,
Takeshi Morimoto,
Tamio Endo,
Tomomitsu Miyoshi,
Suguru Miyagawa,
Yoko Hirohara,
Tatsuo Yamaguchi,
Makoto Saika,
Takashi Fujikado
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0230788
Subject(s) - exotropia , intermittent exotropia , medicine , physical medicine and rehabilitation , strabismus , ophthalmology
Purpose The purpose of this study was to evaluate the degree of visual fatigue in patients with intermittent exotropia (IXT) using the binocular fusion maintenance (BFM) test. Methods Fourteen patients with IXT (32.1 ± 16.4 years) and 15 age-matched healthy volunteers (31.2 ± 9.3 years) participated in the study. BFM was assessed by measuring the transmittance of liquid crystals placed in front of the subject's nondominant eye at the instance when binocular fusion was broken and vergence eye movement was induced. A questionnaire on subjective symptoms was administered to the subjects before and after the visual task. The visual task consisted of a reciprocal movement between 67 and 40 cm. Results The change [post–pre] of BFM was significantly lower in the IXT group (−0.185 ± 0.187) than in the control group (−0.030 ± 0.070) ( P = 0.010). The change of total subjective eye symptom score was significantly greater in the IXT group (2.28 ± 1.43) than in the control group (0.93 ± 1.27) ( P = 0.018). The reduction in BFM rate with increasing total subjective eye symptom score was significantly greater in the IXT group (−0.106 ± 0.017) than in the control group (−0.030 ± 0.013) ( P = 0.006). Conclusion The present findings objectively showed that patients with IXT are at a greater risk of visual fatigue in comparison with healthy individuals.