Prevalence and Causes of Corneal Opacity in a Rural Population in Bihar: Need for Promotion of Health Awareness for Prevention of Corneal Blindness.

ABSTRACT

Background: The cornea is the transparent frontal part of the eye that covers the iris, pupil and anterior chamber. Together with the lens, the cornea refracts light accounting for approximately two-thirds of the eye’s total optical power. The cornea has unmyelinated nerve endings that are sensitive to touch, temperature and chemicals. The cornea is devoid of blood vessels as transparency is of prime importance. The cornea receives its nutrients by diffusion from the tear fluid at the outside and from the aqueous humor at the inside. In humans the cornea has a diameter of about 11.5 mm and a thickness of 500-600μm at the centre and 600-800μm at the periphery. Transparency, avascularity, presence of immature resident immune cells and immunologic privilege makes the cornea a very special tissue. Corneal opacity is a disorder of the cornea and it occurs when the cornea becomes scarred. This condition causes disruption of light waves passing through the cornea to the retina thus giving a cloudy or hazy appearance of the cornea. The aim of the study is to evaluate the prevalence and causes of corneal opacity in a rural area in Bihar. Design of the study – A population based retrospective and observational study. Methods: Among all the cases that presented with ocular morbidity between September 2014 and February 2016 to the outdoor clinic of Department of Ophthalmology or any of the primary health centres of Katihar Medical College, those with corneal opacity were enrolled for this study. Participants belonged to rural areas that were medically catered to by the primary health centres under the Department of Community Medicine of Katihar Medical College. Those participants who attended either the primary health centres or the outdoor clinic of the Department of Ophthalmology with corneal disease were included in this study. Results: During the study period a total of 519 cases presented with ocular morbidity and were diagnosed for corneal opacity. Prevalence of corneal opacity was 2.35% among the study population. Corneal opacity was reported to be much higher in the elderly probably due to a weakened immune system and among cases with poor personal hygiene. Common causes of corneal opacity in the study population was corneal degeneration, infective keratitis, ocular trauma and pterygium. Conclusion: Corneal morbidity in rural Bihar is attributed to keratitis, keratopathy, corneal degenerations, lack of hygiene and generalized immunodeficiency. Efforts must be made by health workers for health promotion and health awareness for promotion of corneal blindness.