The prevalence and types of strabismus, and average of stereopsis in Japanese adults

Abstract

Purpose: Few studies report the prevalence and types of strabismus, or average of stereopsis in Japanese adults. We performed ophthalmological evaluation including motility and stereopsis during medical examinations at cooperative companies.

Methods: We studies 1214 volunteers. The average age was 41.2 ± 12.6 (range 20-86) years. Examinations were carried out using their customary eyewear, evaluating alternate prism cover test (APCT), and Titmus stereo test (TST).

Results: The mean horizontal angle at near distance (1/3 m) was 8.1 ± 6.0 Prism Diopter (PD), and vertical angle was 0.09 ± 1.0 PD. The total number of cases who had intermittent or constant tropia was 44 (3.6%), and the ratio of exotopia to esotropia (XT:ET ratio) was 18.5:1. The mean horizontal angle at far distance (5 m) was 3.9 ± 3.7 PD, and vertical angle was 0.09 ± 1.7 PD. The total number of cases who had intermittent or constant tropia was 21 (1.7%), and the XT:ET ratio was 7:1. The average TST was 50.1 ± 1.6 arcsec. 7.3% (n = 89) of the cases did not reach 100 arcsec.

Conclusions: We report detailed strabismus and stereopsis in Japanese adults. The XT:ET ratio was 18.5:1 in near distance, 7:1 in far distance. In our study, more than 60% of the cases of exotropia were convergence insufficiency type, and this may be a characteristic in Japanese adults.

Keywords: Average stereopsis; Japanese adults; Prevalence of strabismus; Types of strabismus; XT:ET ratio.