Incidence of blindness and low vision in a sample population - The Priverno Eye Study, Italy

Purpose: To study the incidence of blindness and low vision over a 7-year period. Design: Population-based cohort study. Participants: The survivors of the original cohort of 860 persons from Priverno, Italy, aged 45 to 69 years, were reexamined. Of the 760 eligible survivors, 619 (81.4%) had a 7-year follow-up visit. Methods: Baseline and follow-up examinations included the collection of anamnestic and ophthalmologic data by the same observers using the same methods and classification criteria to minimize sources of variability. Main Outcome Measures: Best-corrected visual acuity (VA) measured at 4 m by standardized logarithmic chart was expressed as the logarithm of the minimum angle of resolution (logMAR). World Health Organization definitions of blindness and low vision were adopted (respectively, VA > 1.3 logMar and VA > 0.6 to 1.3 logMar in the better eye or in either eye). Participants at risk for visual impairment were those without blindness or low vision in one or both eyes at baseline; participants at risk for one-eye visual impairment were those without blindness or low vision in both eyes at baseline. Results: A total of 33 participants were defined as incident cases of visual impairment. The overall incidence figures for blindness, low vision, one-eye blindness, and one-eye low vision were respectively 0.2% (95% confidence interval [Cl], 0.0-0.9),1.3% (95% Cl, 0.7-2.6), 1.2% (95% Cl, 0.6-2.4), and 2.9% (95% Cl, 1.8-4.6). Conclusions: This study provides population-based estimates of the incidence of visual impairment in an adult, free-living European population. With respect to the younger participants, older subjects at baseline were at higher risk for incident visual impairment, the main causes of which were cataract, myopia, and diabetic retinopathy. The incidence of visual impairment in the subgroup aged 55 to 64 years at baseline was significantly higher than that found in Beaver Dam 5-year study and similar to that found in Beaver Dam 10-year Study, when the same definitions were adopted. This difference may be partially explained by social and cultural habits of the female samples, but many other factors may play a role.