Influence of Distance and Near Visual Impairment on Self-Reported Near Visual Functioning in a Multinational Study

Abstract Purpose To assess the influence of distance and near visual impairment on self-reported near visual functioning (VF) among adults in a multi-country study. Design Population-based cross-sectional study. Participants Participants aged ≥35 years were randomly selected with cluster sampling at seven sites: rural sites in Nepal (Kaski) and India (Madurai), a semi-rural site in China (Shunyi), semi-urban sites in South Africa (Durban) and Niger (Dosso), and urban sites in the United States (Los Angeles) and China (Guangzhou). Methods Binocular presenting distance and near visual acuity (VA) were measured with a LogMAR tumbling E chart at 4 meters and 40 cm, respectively. A 12-item near VF questionnaire interview was administered by trained local interviewers, with responses scored from 100 to 0 as visual “disability” increased. Multiple linear regression was used to investigate the association of age, gender, education and VA with overall eyesight, difficulty with activities and social functioning subscale scores. Main Outcome Measures VF subscale scores. Results The study sample consisted of 6,851 questionnaire respondents. The VF subscale scores decreased significantly with worse distance and near VA, and even mildly impaired VA could result in reduced VF at all sites. In multiple linear regression modeling, lower VF subscale scores were associated with older age in four sites, female gender in three sites, and greater education in two sites. The influence of near VA was greater than that of distance VA in three sites, and in one site distance VA was more influential than near VA. With study site included in the regression modeling, lower scores for the overall eyesight subscale (compared to the Shunyi reference site) were found in Guangzhou, Kaski and Durban; lower difficulty in activities scores were found in Kaski and Durban, but better scores in Guangzhou and Madurai; social functioning scores were lower in Kaski, Durban and Dosso. Conclusions Along the entire VA spectrum, lower levels of distance and near VA led to significant reductions in VF subscale scores, with wide variation both within and between study sites. The impact of near vision on VF should receive greater emphasis with further investigation in various socio-economic and cultural settings.