# Validation of Binocular Vision and Ocular Surface Assessment Tools in Digital Eye Strain Syndrome: The DESIROUS Study

## TL;DR

This study tests a protocol to assess digital eye strain by evaluating binocular vision and ocular surface health in students.

## Contribution

The study introduces a validated protocol for assessing digital eye strain with objective binocular vision and ocular surface measures.

## Key findings

- The protocol showed good internal consistency for two of the three questionnaires used.
- Observer A demonstrated the highest agreement with the gold standard in the BUT test.
- The study highlights the need for further validation in diverse populations.

## Abstract

Background: To understand if binocular vision disorders are associated with Digital Eye Strain Syndrome (DESS), a study protocol is needed to ensure consistency across observational studies. This study aims to test the feasibility of a protocol to assess DESS, screen time, binocular vision, and dry eye. Methods: DESIROUS is an observational cross-sectional study among Polytechnic students at the Lisbon School of Health Technology, Portugal. The protocol includes three questionnaires (Computer Vision Syndrome Questionnaire [CVS-Q], Convergence Insufficiency Symptom Survey [CISS], and Dry Eye Questionnaire version 5 [DEQ-5]), an assessment of visual acuity and binocular vision (cover test for near and distance, stereopsis, near point convergence (NPC), near point accommodation (NPA), accommodative facility, vergence), and the ocular surface break-up tear (BUT) test. The questionnaires were validated using Cronbach’s alpha. Interobserver variability for BUT was assessed using Cohen’s Kappa, Intraclass Correlation Coefficient (ICC), and Bland–Altman analysis involving three observers (A, B, and C), compared against an expert as the gold standard. Results: A total of 18 students were included in the validation phase (mean age: 21.50 ± 0.62 years; females: 77.8%). The internal consistency of the CVS-Q (α = 0.773) and the CISS (α = 0.756) was considered good, while the DEQ-5 showed a reasonable internal consistency (α = 0.594). Observer A had the highest agreement with the gold standard (Cohen’s Kappa = 0.710 and p < 0.001; ICC = 0.924, p < 0.001). Conclusions: We provide a protocol to assess binocular vision and the ocular surface, with an emphasis on objective measures while integrating other assessment approaches. Further studies are necessary to validate this protocol, potentially incorporating new measures to enhance its validity across different populations.