Development and initial validation of DESCAQ: A Rasch-based computer-adaptive questionnaire for assessing digital eye strain

Abstract

The purpose of this study was to develop the Digital Eye Strain Computer Adaptive Questionnaire (DESCAQ), a quick, easy-to-administer test for measuring digital eye strain in 8- to 65-year-old Spanish- and English speaking individuals. The Spanish DESCAQ was cross-culturally adapted to English using standardised methods. The English version was administered online to digital device users from the United Kingdom and the United States, and the responses were analysed using the partial credit model. In a simulation study, calibration parameters were employed for the purpose of optimising the configuration of the item bank. Test–retest repeatability was calculated by administering DESCAQ twice within weeks. The first administration's results were compared with Computer Vision Symptom Scale (CVSS)17 scores to assess convergent validity. Thirty-six items fitting the Rasch model were included in the final English version (38 items in the Spanish version). The reliability index was 0.95, sufficient to distinguish statistically up to eight levels of severity along the DES continuum. DESCAQ used 12.20 ± 2.15 items to complete the measure and provided the final score in 120.35 ± 69.18 s. The repeatability limit was 13.35 points and the two-way, single measure Intraclass Correlation Coefficient for test retest reliability was 0.884 (95% CI, 0.852–0.910). Spearman's correlation between DESCAQ and CVSS17 scores was 0.87 (p < 0.001). The DESCAQ is a quick, easy-to-interpret tool developed for researchers and clinicians. This web-based tool provides a valid, precise and reliable Digital Eye Strain score, categorised across eight severity levels.