The Turkish version of the National Eye Institute Refractive Error Quality of Life Instrument: translation, validity and reliability

Abstract

Purpose: To translate the original 42-item National Eye Institute Refractive Error Quality of Life Questionnaire (NEI-RQL-42) into Turkish and to investigate its validity and reliability.

Methods: The linguistic translation followed the international guidelines of forward and backward translation. Ninety-five consecutive subjects (37 myopes, 18 hyperopes and 40 emmetropes) who had a visual acuity of 0.8 or better in the worse eye completed the NEI-RQL-42 and the Turkish version of the 25-item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25). Eighty patients completed the NEI-RQL-42 for a second time within 2 weeks. Psychometric evaluation of the Turkish NEI-RQL-42 involved the assessment of internal consistency, test-retest reliability, convergent and known-groups validity.

Results: Internal consistency was generally high (Cronbach's alpha = 0.83-0.95), with the exception of three subscales (glare, alpha = 0.65; suboptimal correction, alpha = 0.66; appearance, alpha = 0.62). Test-retest reliability, assessed by the intraclass correlation coefficient was good (ICC = 0.74-0.95) except for the subscale suboptimal correction (ICC = 0.61). Almost all subscales and the overall score showed significant inter-correlations. Low to moderate correlations were found between the subscales of the NEI-RQL-42 and the NEI-VFQ-25, which measure similar constructs. The NEI-RQL-42 showed good construct validity in terms of refractive error (myopia, hyperopia and emmetropia) and mode of refractive correction (spectacles, contact lens and no correction) discrimination.

Conclusion: The Turkish version of the NEI-RQL-42 is a reliable and valid measure of vision-related quality of life in patients with refractive error.