Prevalence and risk factors associated with corneal opacity in The Gambia

Corneal opacity (CO) is a significant cause of vision impairment and blindness worldwide. The first National Eye Health Survey in The Gambia (1986) and follow-up (1996) showed a decline in the crude prevalence of blindness but an increase in blindness from non-trachomatous CO. This study aimed to provide an update on the prevalence of CO and identify associated risk factors.

Multi-stage stratified cluster random sampling was used to select a nationally representative sample of 10 800 adults aged ≥35 years. Distance best-corrected visual acuity was assessed with Peek Acuity. Ophthalmologists examined participants to identify trachomatous trichiasis, pterygium, CO, corneal ulcers and band keratopathy. CO was graded using a previously described system. Counts and prevalence estimates were based on the weighted sample, corrected for age/sex imbalance. The main outcome was the prevalence of CO. Multivariable logistic regression identified risk factors associated with CO.

9188 participants were examined. CO was found in one or both eyes in 878 participants, giving an age-sex-adjusted prevalence of 9.6% (95% CI 8.7 to 10.5). CO was more likely unilateral (n=673) than bilateral (n=205). Among affected eyes, 41.0% had moderate or severe vision impairment or blindness. Risk factors independently associated with CO included trachomatous trichiasis (OR 5.22 [95% CI 3.46 to 7.86]), older age (OR 4.06 [95% CI 2.54 to 6.47]), male sex (OR 1.58 [95% CI 1.34 to 1.86]) and rural residence (OR 1.62 [95% CI 1.15 to 2.28]).

The prevalence of CO in The Gambia remains high. Focused national efforts to prevent and treat CO are urgently needed.