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Nakul Singh, Rohit Chandramohan Khanna, Srinivasa Reddy, Shiva Shankar Eeda, Bala Krishna Gudapati, Asha Latha Mettla, Subhabrata Chakrabarti, Pushkar Kanade, Ghanshyam Palamaner Subash Shantha; Prevalences, Causes and Risk Factors of Blindness and Visual Impairment in Three Tribal Areas of Andhra Pradesh, India. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1669.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the prevalence of blindness and visual impairment (VI), along with its causes and underlying risk factors, in three tribal areas of Andhra Pradesh (AP), India.
Using the Rapid Assessment of Avoidable Blindness (RAAB) methodology, a two stage sampling survey was performed. In the first stage, clusters (villages) were selected through probability proportionate to size sampling, and in the second stage, households within the clusters were selected through compact segment sampling. Blindness, VI and severe visual impairment (SVI) were defined as per the World Health Organization (WHO) guidelines.
Based on a prior enumeration (n=7500) in these three areas, 7281(97.1%) subjects participated. Subjects had a mean age of 61.0+7.9 years. Based on the presenting visual acuity (PVA), the prevalence of VI was 16.9% (95% CI; 15.7-18.1), SVI was 2.9% (95% CI; 2.5-3.4), and blindness was 2.3% (95% CI 1.9-2.7). However, based on the best corrected visual acuity (BCVA), the prevalences were slightly lower in VI (6.2%, 95% CI; 5.4-6.9), SVI (1.5%, 95% CI; 1.2-1.9)and blindness (2.1%, 95% CI; 1.7-2.5). Refractive error was the major cause of VI (71.4%), whereas cataract was major cause of SVI and blindness (70.3%). Based on the PVA, the odds ratio (OR) of blindness increased with age as evident in the age groups of 50-59 (OR= 3.8, 95% CI 2.8, 5.1) 60-69 years(OR=10.6, 95% CI 7.2, 15.5), 70-79 years and 80 years and above (OR=30.7, 95% CI 19.2, 49). The ORs were relatively higher in females (OR=1.3, 95% CI 1.0, 1.6) and illiterate subjects (OR=4.3, 95% CI 2.2, 8.5), while it was lower in those wearing glasses (OR=0.2, 95% CI, 0.1, 0.4).
To best of our knowledge, this is the first study to assess prevalence of blindness and VI in the tribal populations in AP. The majority of causes of blindness and SVI were avoidable (88.5%); the findings from this study will be useful for planning eye care services in the underserved tribal regions of AP.
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