Causes of visual loss and their risk factors: an incidence summary from the Barbados Eye Studies.
M. Cristina Leske, Suh-Yuh Wu, Barbara Nemesure, Anselm Hennis and Barbados Eye Studies Group
Objectives. To summarize incidence and risk factors for each main cause of visual loss in an African-Caribbean population and discuss the implications of these data from a public health perspective.
Methods. A nationally representative cohort (n = 4 709; ages 40–84 years at baseline) had ophthalmic and other examinations over 9 years. Incidence rates were estimated by the product-limit approach. Risk factors were evaluated from Cox regression models.
Results. Average incidence was ~ 0.1% per year for blindness (< 6/120) and 0.7% per year for low vision (< 6/18 to 6/120), increasing steeply with age (P < 0.05) and affecting related quality of life (P < 0.05). Age-related cataract and open-angle glaucoma (OAG) accounted for 73.2% of blindness and diabetic retinopathy (DR) for 8.9%; cataract caused two-thirds of low vision. Average incidence was 5.1% per year for all lens changes (gradable/ungradable opacities or aphakia) and 0.4% per year for cataract surgery. Incidence of definite OAG was 0.5% per year (0.9% for suspect or probable); 53% of the affected were unaware. Persons with diabetes mellitus (DM) had a DR incidence of 4.4% per year. Age-related macular degeneration was rare (0.08% per year). Main cataract risk factors were age and DM. OAG incidence increased with age, intraocular pressure, family history, low ocular perfusion pressures, and thinner corneas. DR risk increased with early DM onset, DM duration, oral/insulin treatment, increased systolic and diastolic blood pressures, and hyperglycemia. Antihypertensive treatment halved DR risk.
Conclusions. Incidence of visual impairment was high and significantly affected quality of life. Age-related cataract and OAG caused ~ 75% of blindness, indicating the need for public health action to increase appropriate cataract surgery and early OAG detection and treatment. Controlling DM and hypertension would help prevent DR-related complications and could lower cataract risk, further decreasing visual loss.