Validation of the Ocular Pain Assessment Survey Instrument With Rasch Analysis

Purpose: The Ocular Pain Assessment Survey (OPAS) has been used to quantify chronic ocular pain and quality of life (QOL). We aim to investigate the psychometric properties of individual OPAS items with the Rasch analysis in an Asian population of dry eye disease and neuropathic corneal pain (NCP). Methods: Question responses were obtained from 196 patients; 138 with dry eye disease (DED) and 58 with NCP, at the Singapore National Eye Centre. Item hierarchy, item fit statistics, item separation, reliability indices, and Yen's Q3 values were calculated. Results: Individual dimensions that quantify eye pain levels in the past 24 hours and QOL showed good discriminative ability according to their person separation index values. However, individual dimensions that measured eye pain in the past 2 weeks, non-eye pain, as well as aggravating and associated factors showed suboptimal person separation index values. Significant correlations were found between the individual item pairs of the aggravating factors dimension as well as between some of the items in the QOL and associated factors dimensions. Conclusions: Two dimensions of the OPAS questionnaire were validated with the Rasch analysis. Based on these findings, we shorten the number of questions in some dimensions to improve the performance of the tool in similar Asian populations. Translational Relevance: Our study provides insights to improve the existing OPAS for real-world clinical applications and clinical trials.