Background. The Vision 2020 Philippines program of the Department of Health (DOH) is part of the World Health Organization (WHO) global initiative to eliminate avoidable blindness. Through this program, identification and intervention activities have been in place in many areas of this country to reduce the prevalence of blindness. The Survey of Blindness conducted by the Philippine Eye Research Institute in collaboration with the Department of Health serves as an evaluation tool to measure the impact of the Vision 2020 Philippines Program.
Objectives. This survey of blindness was primarily aimed to determine the prevalence and causes of bilateral blindness at the national level, and, to determine the prevalence of the causes of bilateral low vision at the national level.
Methodology. Survey population from the different administrative regions of the Philippines were enumerated though a multi-stage cluster random sampling using probability proportional to size. A mobile clinic was set up at the barangay health center for each of the study site. A standard survey form was filled up for each patient with patient demographics, patient information and medical information after an informed consent form was obtained. This was followed by a clinical examination composed of: visual acuity testing, gross examination, pupillary reaction, ocular movement examination, Amsler test, color vision test, auto refraction, and a biomicroscopy (slit-lamp) examination for external eye, anterior segment, and lens assessment using a slit lamp. Tonometry and Fundus assessment, using indirect ophthalmoscopy, were done when needed. Optical coherence tomography and random blood sugar measurement were also done for patients 40 years old and above.
Results. The prevalence of visual impairment (presenting visual acuity [VA] worse than 6/18 in the better eye) in the Philippines is 1.98% (confidence interval of 0.98% - 1.98% at 80 percent confidence level and response rate of 84%). The major causes of visual impairment include cataract at 1.06% (1.112M affected population; the estimated number of cataract requiring surgery [VA less than or equal to 6/60] is 333,639), uncorrected error of refraction at 0.38% (398,688), glaucoma at 0.27% (283,287), and maculopathy at 0.2% (209,836). Among those examined with no visual impairment (VA at 6/18 or better), 3.26% (3.4M) have error of refraction, 0.69% (0.7M) have glaucoma, and 0.59% (0.6M) have diabetic retinopathy.
Conclusion. The 2018 Philippine Eye Disease study showed that cataract remains the main cause of visual impairment in the Philippines accounting for around one million affected population with around three hundred thousand people requiring cataract surgery. When compared to the 2002 Philippine National Survey of Blindness, the prevalence has been reduced by 11%. This could be the result of the implementation of the blindness prevention and sight preservation programs of DOH and other government and non-government organizations. In this study however, glaucoma and diabetic retinopathy were seen in patients with no visual impairment. It is recommended that vision screening and treatment programs can be enhanced to detect these conditions among patients with no visual impairment to prevent the development of blindness from these eye diseases.
1University Researcher IV and Principal Investigator, University of the Philippines Manila
2National Institutes of Health, University of the Philippines Manila