Measurement of Quality of Life in Keratoconus
Purpose: To identify and assess the quality of questionnaires used to measure quality of life in keratoconus and guide selection of the most appropriate questionnaire for evaluating the impact of keratoconus.
Methods: A literature search was carried out in Scopus, Web of Science, PubMed, MEDLINE, Cochrane, and PsycINFO databases. Articles that described a questionnaire to measure quality of life in keratoconus were included. Information on psychometric properties and validity was extracted and analyzed based on a set of quality criteria. Finally, the impact of keratoconus and its management methods on quality of life was reviewed.
Results: The search yielded 331 publications, of which 45 articles describing 18 (12 ophthalmic including 2 keratoconus-specific and 6 generic) questionnaires were reviewed. Most of the articles (40, 88.9%) described ophthalmic questionnaires not specific to keratoconus. The National Eye Institute Visual Function Questionnaire was the most frequently used questionnaire (n = 26). Only 4 articles provided information on psychometric properties. The Keratoconus Outcomes Research Questionnaire, the only validated keratoconus-specific questionnaire, had the most superior psychometric properties. However, it consists of items on only 2 domains of quality of life (activity limitation and symptoms). Overall, keratoconus management methods (spectacles, contact lenses, and cross-linking in early stages, corneal transplantation in late stages) improved quality of life. The quality of life scores were associated with clinical measures including visual acuity, corneal topography, pachymetry, and keratoconus severity.
Conclusions: There is a need for a comprehensive and high-quality patient-reported outcome measure in keratoconus. A questionnaire should be chosen based on the purpose and the quality of the questionnaire. This review guides selection of an appropriate questionnaire.