Response to “Vision-Related Quality of Life Among Diabetic Retinopathy Patients” [Response to Letter]

Dear editor

We are grateful to Heru Santoso Wahito Nugroho et al for their insightful feedback, which allowed us to elucidate our research. We have thoroughly read your feedback on our article titled “Vision-Related Quality of Life Among Diabetic Retinopathy Patients in a Hospital-Based Population in the Sultanate of Oman”¹ In response to your suggestion to analyze the impact of the stages of diabetic retinopathy on the patient’s quality of life through confirmatory factor analysis (CFA).²

The study adopted the validated NEI-VFQ-25 questionnaire, which contains questions about general health and vision, activities, and responses to vision problems, and was administered to the participants in this study. A previous study assessing the “psychometric properties of the NEI VFQ-25” indicated its robustness in terms of validity and data reproducibility. The NEI-VFQ-25 questionnaire is observed to have internal consistency, supported by a significant correlation with the 51-list-item NEI VFQ, an established, comprehensive survey for measuring the health-related quality of life, among populations with different diseases and their severity.³

For our study on “Vision-Related Quality of Life Among Diabetic Retinopathy Patients in a Hospital-Based Population in the Sultanate of Oman”¹ the original English version of the NEI-VFQ-25 questionnaire was further translated into Arabic and assessed for its validity. The Arabic version of the questionnaire was used in this study.

The factor analysis ensures the relevance of the questionnaire items, especially when developing a questionnaire, and a confirmatory factor analysis was preferred in testing specific hypothesis^4. Our study adopted a validated NEI-VFQ-25 questionnaire with a reduced version of the subscales incorporated in the 51-list-item NEI-VFQ. To determine the total composite score for the VFQ-25, we used the mean subscale scores of the components related to vision and visual functions. This analysis evaluated the mean subscale scores instead of the individual items to provide a more comprehensive evaluation. A larger study population constitutes similar responses. Therefore, like other studies^5,6 conducted in this field, we performed a One-way ANOVA to conduct multiple comparisons, while Pearson’s correlation coefficient was determined for all QoL domains of the questionnaire.