Rapid assessment of avoidable blindness in Iran.

PURPOSE

To determine the extent and causes of blindness and visual impairment (VI) in the Varamin district, Iran, in 2009.

DESIGN

Cross-sectional population-based survey.

PARTICIPANTS

A total of 3000 noninstitutional inhabitants aged ≥50 years from February to August 2009.

METHODS

A standard protocol was used according to the rapid assessment of avoidable blindness (RAAB) method after an initial 4-day workshop. The clusters were selected through probability-proportionate-to-size sampling. In each cluster, people were selected by a "cluster compact sampling" method. Visual acuity (VA) was measured using a standard tumbling "E" chart without and with pinhole. Ophthalmologists examined participants with VA <6/18 in either eye. Blindness was verified by the World Health Organization definition (best-corrected VA in the better eye <3/60). Severe VI (SVI) was defined as VA ≥3/60 and <6/60 and VI was defined as VA ≥6/60 and <6/18 at presentation. The primary cause of VI was defined according to the cause in the participant's better eye.

MAIN OUTCOME MEASURES

Prevalence of blindness, SVI, and VI, and their avoidable causes.

RESULTS

Among 3000 persons, 2819 (94% response rate), including 1289 men (45.1%) and 1530 women (54.9%), were examined. The standardized prevalence rates of blindness, SVI, and VI were 1.33 (95% confidence interval [CI], 0.91-1.75), 1.39 (95% CI, 0.81-1.97), and 6.91 (95% CI, 5.96-7.86), respectively, and the prevalence rates of avoidable causes (cataract, surgical complication, refractive error, and corneal scar) of blindness, SVI, and VI were 56.1%, 65.0%, and 85.6%, respectively. The principal cause of blindness and SVI was cataract, and the principal cause of VI was refractive error.

CONCLUSIONS

Most blindness, SVI, and VI is due to avoidable causes. Cataract and refractive errors were the leading causes in our context.