Four-year incidence of visual impairment: Barbados Incidence Study of Eye Diseases.
OBJECTIVE
To describe the 4-year incidence of visual impairment and causes of blindness among black participants of the Barbados Eye Studies.


METHODS
Population-based incidence study.


METHODS
The Barbados Incidence Study of Eye Diseases (BISED) followed the cohort of the Barbados Eye Study (BES), a prevalence study based on a simple random sample of Barbadians 40 to 84 years of age. BISED included 3193 black participants from the original cohort (85% of those eligible).


METHODS
Best-corrected visual acuity (Ferris-Bailey chart) at baseline and follow-up was measured according to a modified Early Treatment of Diabetic Retinopathy Study protocol. By use of World Health Organization (WHO) criteria, low vision and blindness for an individual were defined as visual acuity (VA) <6/18 to 6/120 and <6/120, respectively, in the better eye. By commonly used US criteria, low vision and blindness were defined as VA < or = 20/40 and < or = 20/200, respectively. Vision loss was defined as a doubling of the visual angle (i.e., decrease of 15 letters or more read correctly between baseline and follow-up examinations). Progression was defined as vision loss among those with low vision at baseline.


RESULTS
On the basis of WHO criteria, the overall 4-year incidence was 3.6% (95% confidence interval [CI], 3.0%-4.4%) for low vision and 0.6% (95% CI, 0.4%-1.0%) for blindness. Incidence rates were higher using US criteria: 5.3% (95 % CI, 4.5%-6.2%) and 1.5% (95% CI, 1.1%-2.0%), respectively, reaching 21.5% and 7.3% for persons aged 70 years or older at baseline. One tenth of the cohort had vision loss, and 28.6% of those with low vision progressed. About one half of incident blindness was due to age-related cataract. Nearly one fifth was caused by open-angle glaucoma (OAG) alone or combined with cataract, and approximately 10% was caused by diabetic retinopathy (DR).


CONCLUSIONS
The incidence of visual impairment was high in this Afro-Caribbean population, particularly in older age groups, indicating the public health significance of visual loss for this and similar black populations. Cataract, OAG, and DR were among the leading causes of incident blindness, paralleling their high prevalence in this population.
Leske
M Cristina
MC
Department of Preventive Medicine, School of Medicine, Stony Brook University, Stony Brook, New York 11794-8036, USA. cleske@notes.cc.sunysb.edu
Wu
Suh-Yuh
SY
Hyman
Leslie
L
Nemesure
Barbara
B
Hennis
Anselm
A
Schachat
Andrew P
AP
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001460:Barbados / Q000453:epidemiology; D044383:Black People; D001766:Blindness / Q000208:ethnology* / Q000209:etiology; D005128:Eye Diseases / Q000150:complications; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D015354:Vision, Low / Q000208:ethnology* / Q000209:etiology; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*; D014944:World Health Organization