The prevalence and causes of blindness and vision impairment in Trinidad and Tobago

Abstract

Purpose: To estimate the prevalence and causes of blindness and vision impairment in people aged >40 years in Trinidad and Tobago

Methods: A population-based nationally-representative cross-sectional survey, using randomized multistage cluster sampling with probability-proportionate-to-size methods, identified 120 clusters each of 35 people. The attributable cause of vision loss was determined for each eye with presenting visual acuity worse than 6/18, following comprehensive examination. Retinal images were graded by a Reading Centre to provide independent validation.

Results: Of 4200 people enumerated and invited for comprehenisve examination, 3588 were examined (85.4%). The age and gender-adjusted prevalence of functional blindness (presenting visual acuity worse than 6/60 in the better eye) was 0.32% (95% CI 0.14 to 0.50), and of blindness at 3/60 was 0.22% (95% CI 0.07 to 0.37%). The age and gender-adjusted prevalence of moderate and severe vision impairment (presenting acuity worse than 6/18 but better than or equal to 3/60 in the better seeing eye) was 2.42% (95% CI 1.92 to 2.92%). Cataract was the commonest cause of functional blindness (35.1%), and a leading cause of vision impairment (33.5%). The other main causes of blindness were diabetic retinopathy (18.9%) and glaucoma (16.2%). Uncorrected refractive error was the leading cause of moderate and severe vision impairment (34.3%).

Conclusions: This is one of only two nationally-representative studies of vision loss to be conducted in the Caribbean for the past 20 years, and makes an important contribution to understanding the local and regional vision loss burden. Strategies to make good quality, affordable and accessible cataract, refractive error and diabetic retinopathy screening services available in Trinidad and Tobago will have the greatest impact on reducing the burden of avoidable vision loss.