Abstract
Abstract: :
Purpose: To validate the Quality of Life Impact of Refractive Correction (QIRC) questionnaire developed using Rasch analysis (ARVO abstract, 2002), and to compare the performance of subjects with refractive correction by spectacles, contact lenses and refractive surgery. Methods: The 20-question QIRC questionnaire was given to 225 people (75 of each correction mode) for validation and to compare performance between each of the three groups. Contact lens and spectacle wearers were drawn from optometric practice and refractive surgery subjects had undergone LASIK at least 3 months prior. Rasch estimation of scores was performed using Winsteps version 3.35 and basic statistical testing using SPSS for Windows version 11.0. Results: Cronbach’s alpha was 0.79 suggesting good internal consistency, without redundancy. This was confirmed by Rasch fit statistics (mean ± SD); person infit 0.97 ± 0.45, outfit 0.99 ± 0.50, item infit 1.00 ± 0.14, outfit 0.99 ± 0.15. Patient separation was 1.38 and item separation was 7.70. The items (mean score 50 ± 6.0) were well targeted to the patients (mean score 46.6 ± 4.8) with a mean difference of 3.4 logits. Overall scores were not significantly different (ANOVA p>0.01) for the groups of spectacle wearers (46.8 ± 5.2), contact lens wearers (47.4 ± 4.0) and those having undergone refractive surgery (45.5 ± 4.8). Breaking down the responses for the 20 questions showed that 16 questions contained significant differences between groups. For example, the refractive surgery group was significantly better than the contact lens group for the symptoms item ("eyes feeling tired or strained"), some convenience items (e.g., "seeing on waking") and some concerns items (e.g., "vision not being as good as it could be") but significantly worse for other concerns items (e.g., "concerned about UV protection"). Spectacle wearers fared poorly on psychosocial well-being items (e.g., "confidence"), but much better for "concerns about medical complications". Conclusions: QIRC provides a valid measure of quality of life in refractive correction. A comparison of quality of life among spectacle, contact lens and refractive surgery patients yielded no significant overall difference. However, major differences were found between groups for individual questions. This suggests that people with refractive correction experience good quality of life irrespective of correction type, but correction preference is probably driven by individual variation in prioritisation of quality of life issues.
Keywords: quality of life • refraction • clinical (human) or epidemiologic studies: bio