The Impact of Vision Impairment (IVI) Questionnaire; Validation of the Thai-Version and the Implementation on Vision-Related Quality of Life in Thai Rural Community

The objective of this study is to validate the Thai-version of the impact of vision impairment (IVI) questionnaire and to evaluate its impact on vision-related quality of life (VRQoL) in southern Thailand. The IVI questionnaire was translated into Thai according to WHO translation guidelines. In addition to the routine ophthalmological examinations, a Thai version of the IVI questionnaire was administered to all participants. A total of 120 patients with visual impairment who presented at Songklanagarind hospital, Songkhla province, were enrolled in the study; 30 had age-related macular degeneration (AMD), 30 had cataract, 30 had diabetic retinopathy, 30 had glaucoma, and 30 non-visually impaired individuals comprised the control group. Statistical analysis demonstrated the Thai-version IVI questionnaire is valid and reliable to evaluate the VRQoL of the Thai patients through three subscales: (i) mobility and independence, (ii) reading and accessing information, and (iii) emotional well-being. The results demonstrated high consistency in all subscales with Cronbach’s alpha ranging from 0.787 to 0.849. Rasch analysis revealed the validity of the Thai-version IVI to assess VRQoL through all three subscales. Test-retest reliability was also high (intraclass correlation coefficient = 0.96). The composite score of the IVI was significantly higher in participants with visual impairment compared with healthy participants. Moreover, the subscale scores of reading and accessing information, and emotional well-being were highest in participants with AMD. While the subscale scores of mobility and independence were highest among those with either cataracts or diabetic retinopathy. The symptoms of the common vision impairment diseases are associated with an adverse impact on VRQoL in a clinic-based population as demonstrated in this study.