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Validation of the symptom questionnaire for visual dysfunctions (SQVD): a psychometric analysis within the Nepalese
Umesh Belbase1, Santosh Chhetri2, Anup Subedi1
1Department of Optometry, Himalaya Eye Institute, Pokhara, Nepal.
Clinical Relevance:
Patient-reported visual symptoms provide important information that may not be captured by clinical tests alone. Standardised symptom questionnaires can support the assessment of visual complaints associated with refractive, accommodative, and binocular vision dysfunctions in routine optometric practice.
Background:
Patient-reported symptom questionnaires are valuable instruments for assessing visual symptoms associated with visual dysfunctions; however, cultural and linguistic adaptation is essential to ensure measurement validity. The Symptom Questionnaire for Visual Dysfunctions (SQVD) has demonstrated strong psychometric properties in previous validations but has not yet been validated in the Nepalese population.
Methods:
A multicentre, cross-sectional validation study was conducted in six eye hospitals in Nepal. Adults aged 18-65 years completed the Nepali version of the SQVD and underwent comprehensive clinical examination to establish visual function status. Psychometric evaluation was performed using Rasch analysis. Diagnostic accuracy was assessed using receiver operating characteristic analysis.
Results:
The study included 305 participants (mean age 32.9 ± 11.2 years; 60.7% male). Rasch analysis demonstrated good item fit, ordered response categories, unidimensionality, and adequate person (0.81) and item (0.84) reliability. No meaningful differential item functioning by gender was detected. Item-total correlations ranged from 0.326 to 0.613 (p < 0.001). The SQVD showed good diagnostic accuracy (area under the curve = 0.834), with an optimal cut-off score of ≥6, yielding sensitivity of 0.714 and specificity of 0.775.
Conclusions:
The Nepali version of SQVD demonstrates robust psychometric properties and good diagnostic performance, supporting its use as a standardised instrument for assessing visual symptoms associated with visual dysfunctions in adult clinical populations in Nepal.
