Population Prevalence, Pattern and Associated Factors for Retinal Diseases at High Altitude in Nepal

Raba Thapa,1 Sanduk Ruit,2 Manish Prasad Poudel,3 Pratibha Neupane,3 Pradeep Banjara,3 Sushma Duwal,4 Elena Gurung,4 Geoffrey Tabin5 1Department of Vitreo-Retina and Research, Tilganga Institute of Ophthalmology, Kathmandu, Nepal; 2Department of Cataract and Cornea, Tilganga Institute of Ophthalmology, Kathmandu, Nepal; 3Department of Research, Tilganga Institute of Ophthalmology, Kathmandu, Nepal; 4Department of Vitreo-Retina, Tilganga Institute of Ophthalmology, Kathmandu, Nepal; 5Department of Cornea, Byers Eye Institute, Stanford University, Palo Alto, CA, USACorrespondence: Raba Thapa, Department of vitreo-retina and Research, Tilganga Institute of Ophthalmology, Kathmandu, Nepal, Email [email protected]: Retinal diseases are common at high altitudes due to a cascade of changes caused by hypoxia. The aim of this study is to assess the population prevalence, pattern and associated factors of retinal disorders at high altitude in Nepal.Methodology: A cross-sectional study was conducted at three selected high-altitude districts (over 2500 meters) of Nepal. Subjects were at least 40 years old, and the target sample size was 309. A detailed history was taken. Visual acuity, blood sugar, blood pressure, and oxygen saturation were measured. Anterior and posterior ocular evaluations were conducted by retina specialists using slit lamp and indirect ophthalmoscopy.Results: A total of 338 participants were recruited, with nearly equal numbers from the three districts with mean age of 57.0 (S.D 11.1) years. Two-thirds (63.9%) were females; 38.2% were illiterate, and 46.7% were farmers. Average blood oxygen saturation was 87.2% (S.D 4.1%). Systemic hypertension and diabetes mellitus were found in 58% and 11%, respectively. Retinal diseases were found in 176 (52.5%), with bilateral involvement in 157 (46.9%). The major retinal diseases were hypertensive retinopathy (32.2%), high-altitude retinopathy (10.4%), age-related macular degeneration (AMD) (8.1%), branch vein occlusion (BRVO) (2.1%), and diabetic retinopathy (DR) (1.8%). The multivariate analysis showed significant association of retinal diseases with age and hypertension. Best corrected visual acuity better than 6/18 was present in 96.7%.Conclusion: Over half of the study participants had retinal diseases, with hypertensive retinopathy, AMD, and high-altitude retinopathy as the most common retinal problems. A significant association of retinal diseases was found with ageing, and hypertension. Access to eye care services and control of systemic hypertension along with patient education should be emphasized among people living at high-altitude.Keywords: prevalence, pattern, risk factors, high-altitude retinopathy, Nepal