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

To assess the influence of distance and near visual impairment on self-reported near visual functioning (VF) in a multinational study.

Population-based cross-sectional study.

Participants aged 35 years or older were selected randomly with cluster sampling at 7 sites: rural sites in Nepal (Kaski) and India (Madurai), a semirural site in China (Shunyi), semiurban sites in South Africa (Durban) and Niger (Dosso), and urban sites in the United States (Los Angeles) and China (Guangzhou).

Binocular presenting distance and near visual acuity (VA) were measured with a logarithm of the minimum angle of resolution tumbling E chart at 4 m 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.

Visual functioning subscale scores.

The study sample consisted of 6851 questionnaire respondents. The VF subscale scores decreased significantly with worse distance and near VA, and even mildly impaired VA could result in reduced VF. Lower VF subscale scores were associated with older age at 4 sites, female gender at 3 sites, and greater education at 2 sites. The influence of near VA was greater than distance VA at 3 sites, and at 1 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 with 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 were found in Guangzhou and Madurai; and social functioning scores were lower in Kaski, Durban, and Dosso.

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 socioeconomic and cultural settings.