Reliability and validity of refractive error-specific quality-of-life instruments

Abstract

Objective: To evaluate the reliability and validity of the National Eye Institute Refractive Error Quality of Life Instrument (NEI-RQL-42) and the Refractive Status and Vision Profile survey (RSVP).

Methods: Eighty-one participants with good visual acuity (better than 20/30 best-corrected acuity in each eye) completed the NEI-RQL-42 and RSVP on 2 occasions. Noncycloplegic, subjective refractions and high-contrast visual acuity assessments were also performed. Statistical analyses addressed internal consistency, test-retest reliability, and validity (ie, concurrent and construct validity) of the 2 instruments.

Outcome measures: The NEI-RQL-42, RSVP survey, subjective refraction, and visual acuity.

Results: The internal consistency for the overall NEI-RQL-42 was excellent (Cronbach alpha = 0.91); and for the overall RSVP, good (Cronbach alpha = 0.81). Likewise, the test-retest reliability for the overall NEI-RQL-42 was excellent (intraclass correlation coefficient [ICC], 0.91; 95% limits of agreement, -9.1 to 10.1); and for the RSVP, fair (ICC, 0.76; 95% limits of agreement, -12.1 to 12.5). The NEI-RQL-42 overall score showed good concurrent validity as it correlated significantly with subjective refraction, whereas the RSVP overall score did not. The NEI-RQL-42 and RSVP showed similar construct validity in terms of refractive error discrimination, but the NEI-RQL-42 showed better construct validity when discriminating by the type of refractive correction used by patients. Between-instrument convergent and divergent validity was good.

Conclusions: The NEI-RQL-42 and RSVP generally have good reliability and validity in this sample of patients with refractive error. However, other factors such as content should be considered in choosing 1 of these instruments for studies of refractive error correction.