Binocular vision parameters in handloom silk weavers

Abstract

Background: Focusing the gaze for prolonged periods on a fixed distance demands high visual efficiency in handloom silk weavers and might result in various accommodative and vergence dysfunctions. The aim of the present study was to assess accommodative and vergence parameters and determine the frequency of non-strabismic binocular vision anomalies (NSBVAs) among handloom silk weavers.
 Methods: In this cross-sectional study, we recruited voluntary handloom silk weavers from the Government-aided Society of Arignar Anna Silk Co-op Society K.H.-1, Kanchipuram, aged 20–39 years. All participants underwent preliminary visual examinations and comprehensive binocular vision testing of accommodative and vergence parameters. Sensory evaluation was performed using stereopsis testing and the Worth 4 Dot test. Motor evaluation included the ocular motility assessment, heterophoria checks for distance and near, near point of convergence, negative and positive fusional vergences for distance and near, vergence facility, negative and positive relative accommodations, both monocular and binocular near points of accommodation, and accommodative facility. The monocular estimate method was used to determine the accommodative response. Quantitative data are expressed as mean (standard deviation [SD]), and qualitative data are expressed as frequency (percentage).
 Results: We recruited a total of 72 weavers, including 41 (56.9%) men and, 31 (43.1%) women with mean (SD) age, working hours, and work experience of 34.15 (4.12) years, 9 (2.5) h/day, and 17.5 (6.9) years, respectively. Of the 29 (40.3%) weavers with a refractive error, 18 (25%) had astigmatism; seven (9.7%) had myopia; and four (5.6%) had hyperopia. Of the 72 weavers, 38 (52.8%) presented with NSBVAs, including 13 (18.1%) with accommodative dysfunctions, 11 (15.3%) with vergence dysfunctions, and 14 (19.4%) with combined accommodative and vergence dysfunctions. Accommodative insufficiency was the most prevalent dysfunction among all NSBVAs. Overall, 57 (79.2%) patients reported vision-related symptoms during their weaving hours, all with NSBVAs (n = 38), 19 with normal parameters in the binocular vision test, and 15 with no symptoms.
 Conclusions: The frequency of NSBVAs was high among handloom silk weavers compared to the literature. This implies a need for comprehensive binocular vision examination for people in this occupation to rule out NSBVAs for improving their quality of life and occupational productivity. Future large-scale studies are required to determine the exact NSBVAs prevalence among workers of this near vision-related occupation.