Comparison of Quality-of-Life Instruments in Adults with Strabismus

Purpose: To compare two health-related quality-of-life (HRQOL) questionnaires in adults with strabismus: the new 20-item Adult Strabismus (AS-20) questionnaire (developed specifically for Adult Strabismus) and the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25). Design: Cross-sectional study. Methods: Eighty-four adult patients with strabismus (median age, 53 years; range, 18 to 81 years) completed the AS-20 and VFQ-25 HRQOL questionnaires. Patients were categorized as diplopic (n = 65) or nondiplopic (n = 19). Subnormal HRQOL was defined as less than the fifth percentile for adults with no visual impairment. The proportion of patients below normal was compared overall and by diplopia status. Results: Overall, more patients scored below normal with the AS-20 than with the VFQ-25 (90% vs 29%; P < .0001). Nondiplopic patients more often were below normal on the AS-20 psychosocial subscale than on the function subscale (95% vs 42%; P = .002), whereas diplopic patients were more often below normal on the function subscale (85% vs 68%; P = .01). On the psychosocial subscale, more nondiplopic than diplopic patients scored below normal (95% vs 68%; P = .01); on the function subscale, more diplopic than nondiplopic patients scored below normal (85% vs 42%; P = .0005). The VFQ-25 seemed to be insensitive to nondiplopic strabismus: no patients scored below normal on composite score and no more than 11% scored below normal on VFQ-25 subscales. Of diplopic patients, 37% scored below normal on VFQ-25 composite score. No more than 38% scored below normal on VFQ-25 subscales. Conclusions: The new AS-20 seems to be more sensitive than the VFQ-25 for detecting reduced HRQOL in Adult Strabismus, and therefore may be a more useful tool for clinical assessment and clinical trials.