Association of Changes in Visual Acuity With Vision-Specific Functioning in the Singapore Malay Eye Study.

Importance: Longitudinal population-based data on the effect of vision loss on vision-specific functioning (VSF) are scarce, particularly in Asian populations.

Objective: To examine the association between changes in presenting visual acuity (PVA) and VSF.

Design, Setting, and Participants: Vision-specific functioning of 1895 adults was assessed in the baseline (January 20, 2004-July 31, 2006) and follow-up (June 28, 2010-July 31, 2014) phases of the longitudinal population-based Singapore Malay Eye Study. Mean (SD) differences and effect sizes for results of the modified Visual Function Index were calculated for 3 categories of change in PVA in the eye with better vision during the follow-up period (PVA gain of ≥2 lines [+0.2 logMAR], no change [PVA between a loss of 2 lines and a gain of 2 lines], and PVA loss of ≥2 lines [-0.2 logMAR]). The group with PVA loss was further stratified into incident vision impairment (VI) (baseline PVA ≥6/12) and progression of VI (baseline PVA <6/12) that worsened by 2 or more lines at follow-up. Associations between PVA and VSF changes were assessed using multiple linear regression models.

Exposures: Presenting visual acuity was measured using a logMAR chart during an ophthalmic examination at baseline and follow-up.

Main Outcomes and Measures: Vision-specific functioning and associations between PVA and changes in VSF.

Results: Of the 1895 participants (mean [SD] age at baseline, 56.9 [10.1] years; 862 men and 1033 women), at follow-up, 319 (16.8%) had lost 2 or more lines of PVA (mean [SD] PVA loss, 0.34 [0.22] logMAR; P < .001), which was associated with a mean (SD) -0.87 [2.12] logit decrease in VSF (medium effect size, -0.61). Of these 319 participants, 153 (48%) had incident VI and 166 (52%) had progression of VI, which were associated with mean (SD) -1.08 (2.15) (effect size, -0.86) and -0.64 (2.06) (effect size, -0.41) logit reductions in VSF, respectively. In adjusted models, compared with participants with no change in PVA, those who lost 2 or more lines had a significant 117% reduction in VSF (β, -0.39; 95% CI, -0.62 to -0.16). Older age (-0.55 logit decrease in VSF; 95% CI, -0.66 to -0.43) and female sex (-0.25 logit decrease in VSF; 95% CI, -0.45 to -0.06) were also independently associated with poorer VSF at follow-up (P < .01).

Conclusions and Relevance: Approximately 1 in 6 Malay adults lost 2 or more lines of PVA during the 6 years of the study; this loss was associated with a sizable deterioration in VSF. Loss of VSF was greater in participants with new-onset VI compared with those whose existing VI worsened. In older adults, strategies to prevent the onset of new VI may have more relative effect than delaying further progression among those with existing VI.