Purpose: To validate the Iris Glare, Appearance, and Photophobia (Iris GAP) questionnaire, a new symptom-based and appearance-based quality-of-life measure for patients with iris defects.
Setting: Single tertiary glaucoma clinic in Toronto, Ontario, Canada.
Design: Prospective cohort study.
Methods: Patients with varying degrees of iris defects were enrolled. Patients completed the Iris GAP questionnaire and the glare and driving subscales of the Refractive Status and Vision Profile (RSVP) questionnaire. Test-retest reliability, defined by Cronbach α and intraclass correlation coefficients (ICCs), was evaluated with repeat testing 2 weeks later.
Results: The study included 73 patients with iris defects, 68 controls with no iris defects, 77 patients with peripheral iridotomies (PIs) or transillumination defects (TIDs), and 22 patientswith surgically repaired irides (n = 22). Iris GAP scores ranged from 0 to 32 with a 97% completion rate. Iris GAP had high test-retest reliability (Cronbach α = 0.866, ICC = 0.953, P < .0005). Iris GAP scores were reliably distinguishable between patients with iris defects, repaired iris defects, and PIs and TIDs and controls (1-way analysis of variance, P < .0005). In pairwise comparisons, the major defect group had statistically significant higher scores than any of the other groups ( P < .005 for each). The control and repaired groups had the lowest scores, whereas the PI/TID group had intermediate scores. 9 patients underwent iris repair between tests and had a mean difference of 8.2 ± 6.2 points between their preoperative and postoperative scores ( P = .004). Iris GAP scores positively correlated with RSVP scores ( R2 = 0.73).
Conclusions: Iris GAP can reliably evaluate symptomatology and patient-reported appearance in patients with iris defects.
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