BRIEF COMMUNICATION The Turkish version of the National Eye Institute Refractive Error Quality of Life Instrument: translation, validity and reliability Ebru Toker Æ Sumru Onal Æ Muhsin Eraslan Æ Merih Eyriparmak Accepted: 8 October 2008 / Published online: 2 November 2008 Ó Springer Science+Business Media B.V. 2008 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 interna- tional 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 (Cron- bach’s a = 0.83–0.95), with the exception of three subscales (glare, a = 0.65; suboptimal correction, a = 0.66; appear- ance, a = 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 con- structs. The NEI-RQL-42 showed good construct validity in terms of refractive error (myopia, hyperopia and emmetro- pia) 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. Keywords National Eye Institute Refractive Error Quality of Life Instrument (NEI-RQL-42) Á Validity Á Reliability Á Refractive error Abbreviations VRQoL Vision-related quality of life NEI-VFQ-25 National Eye Institute Visual Functioning Questionnaire NEI-RQL-42 National Eye Institute Refractive Error Quality of Life Questionnaire SE Spherical equivalent of refractive error calculated by adding the spherical error and 1/2 of the cylindrical error RSVP Refractive error status and vision profile QIRC Quality-of-life impact of refractive correction Emmetropia The normal refractive function of the eye in which light is focused exactly on the retina with the eye relaxed. An emmetropic eye requires no refractive correction Preliminary results were presented as a poster at the Association for Research in Vision and Ophthalmology (ARVO). Annual Meeting in Fort Lauderdale, FL, 6–10 May 2007. E. Toker Á S. Onal Á M. Eraslan Á M. Eyriparmak Department of Ophthalmology, Marmara University School of Medicine, Istanbul, Turkey S. Onal e-mail: sumruo_md@yahoo.com E. Toker (&) Hamidiye Mah. Barisyolu Cad. Agaoglu My Country Sitesi, G-5 Daire:3 Cekmekoy, Istanbul, Turkey e-mail: aetoker@superonline.com 123 Qual Life Res (2008) 17:1269–1276 DOI 10.1007/s11136-008-9407-5