Ocular injury, manual labor, and low education are factors strongly associated with the prevalence of corneal ulcers in urban and peri-urban settings, according to findings published in the British Journal of Ophthalmology.
Researchers conducted a population-based, matched case-control study to examine the risk factors for corneal ulcer in Nepal. The study was part of a cluster randomized trial in 24 village development communities. The researchers used incidence density sampling to match incident corneal opacity cases to participants in a control group.
The trial identified 540 participants with incident opacities, and of these, 433 participated in the substudy and were matched to a control. Cases, compared with participants in the control group, had lower odds of having any education vs no education (95% CI, 0.39-0.94), working in non-manual labor occupations vs manual labor occupations (95% CI, 0.42-0.95), and preferring medical shops for ocular trauma vs eye care system centers (95% CI, 0.37-0.92). Compared with those in the control, case patients had higher odds of protective goggle use vs no protection (95% CI, 1.3 to 11.0) and having experienced at least 1 ocular injury vs none (95% CI, 4.3 to 13.6).
The researchers explained that, since controls were expected to represent the experience of the source population that gave rise to cases of corneal ulcer, the study’s population-based design using incidence density sampling was one of its strengths. The researchers could not definitively show whether the controls had greater access to and awareness of healthcare resources such as medical shops, or whether cases were more likely to indicate the need to present to an eye care center than controls. However, they acknowledge that access to convenient resources is not ubiquitous among the study’s participants.
“Given the continued burden of corneal blindness in this area, prevention efforts could consider increasing awareness of available eye care resources and access to prompt eye care in areas where these factors are particularly common,” the researchers explain.
Study limitations include possible selection bias, recall bias, and over-representation of trauma-related corneal opacities among the cases due to misinterpretation of the corresponding screening question.
Byanju R, Kandel RP, Poudyal B, et al. Risk factors for corneal ulcers: a population-based matched case–control study in Nepal. Br J Ophthalmol. Published online October 20, 2022. doi:10.1136/ bjo-2022-322141