PURPOSE. To report the baseline risk factors and causes for incident blindness.
METHODS. Six years after the baseline study, 4419 subjects from the cohort underwent a detailed examination at the base hospital. Incident blindness was defined by World Health Organization criteria as visual acuity of less than 6/120 (3/60) and/or a visual field of less than 108 in the better-seeing eye at the 6-year follow-up, provided that the eye had a visual acuity of better than or equal to 6/120 (3/60) and visual field greater than 108 at baseline. For incident monocular blindness, both eyes should have visual acuity of more than 6/120 (3/60) at baseline and developed visual acuity of less than 6/120 (3/60) in one eye at 6-year follow-up.
RESULTS. For incident blindness, 21 participants (0.48%, 95% confidence interval [CI], 0.3–0.7) became blind; significant baseline risk factors were increasing age (P = 0.001), smokeless tobacco use (P < 0.001), and no history of cataract surgery (P = 0.02). Incident monocular blindness was found in 132 participants (3.8%, 95% CI, 3.7–3.8); it was significantly more (P < 0.001) in the rural population (5.4%, 95% CI, 5.4–5.5) than in the urban population (1.9%, 95% CI, 1.8–1.9). Baseline risk factors (P < 0.001) were increasing age and rural residence, and no history of cataract surgery was a protective factor (P = 0.03).
CONCLUSIONS. Increasing age was a significant risk factor for blindness and monocular blindness. No history of cataract surgery was a risk factor for blindness and a protective factor for monocular blindness.
All Science Journal Classification (ASJC) codes
- Sensory Systems
- Cellular and Molecular Neuroscience