[Digital eye strain. Functional symptoms and binocular balance analysis in intensive digital users].

Introduction: In almost 50 % of cases, acute or chronic screen exposure is accompanied by symptoms of dry eye or binocular imbalance, known as digital eye strain. This phenomenon is described relatively little in the literature. The goal of this study is to determinate the effects of screen exposure on subjective comfort and binocular balance.

Patients And Methods: This is a cross-sectional, prospective, monocentric pilot study conducted from August to October 2019. The first part of the study focused on disturbances induced by short-term screen exposure (comparison between morning and evening examinations) between a control group (less than 5hours a day) and an exposed group (more than 5hours a day). The second part investigates the consequences of chronic exposure (screen exposure greater than 5hours a day, 5 days a week for one year) excluding pre-presbyopic and presbyopic patients (over 35 years of age). The study parameters consisted of an ocular discomfort questionnaire and binocular function tests (refraction, phoria, near point of accommodation and convergence, fusional vergence (FV), and binocular amplitude facility (BAF)).

Results: Short exposure : 52 participants were included. No significant difference was found between the control group (n=24, mean exposure=2.6 hr) and the exposed group (n=28, mean exposure=6.1 hr) for any of the objective parameters. The ocular discomfort score was highest in the exposed group for the following parameters: near (p=0.04) and intermediate (p=0.02) blurred vision and light sensitivity (p=0.04). Chronic exposure: 35 participants were included. The exposed group (n=12, mean exposure=6.7 hr) showed a decrease in FV (p=0.045) and BAF (p=0.038) compared to the control group (n=23, mean exposure=2.1 hr).

Discussion: Binocular balance is disturbed by intensive and chronic use of screens. Special attention must therefore be paid to these patients.