Reliability of the scale NEI VFQ-25 in a Colombian population with chronic eye disease

Introduction: The Quality of life related of visual Functioning, is a measure that reflect the subject perception the patient has of his condition and the implications that carries of ocular disease, if consider: objective, expectations and interests. There are instruments designed to measure this construct, as the scale of National Eye Institute Visual Functioning Questionnaire -25 (NEI VFQ-25), that like any other questionnaire, before being used, it requires an analysis of reliability that supports the usefulness of the results. Methods: The reliability of the Scale NEI VFQ-25 was evaluated in terms of internal consistency (Cronbach's Alpha coefficient) and reproducibility (Intraclass Correlation Coefficient-Limits of agreement of Bland and Altman). The questionnaire was applied in 206 people between 40 and 70 years old with diagnostics of bilateral chronic eye disease, who they were treated in the Fundación Oftalmológica de Santander FOSCAL. To assess reproducibility a subsample of 101 people were employed in whom it was applied twice the questionnaire. Results: The participants has an average age of 58.1 years and had glaucoma (21.71%), cataract (36.92%) or some form of retinopathy (35.46%). The Cronbach's Alpha coefficient ranged from α= 0.4761 (social Functioning) and α= 0.8430 (difficulties at work), while the Intraclass correlation coefficient was higher than 0.90. Conclusion: The findings demonstrate adequate reproducibility test fails, but shortcomings in the theoretical conceptualization of some domains of the scale.