Solid fuels (coal and biomass) are used for cooking and heating by approximately 3 billion people worldwide-- almost all in the developing world. Kerosene is also widely used for cooking and lighting. These fuels emit into the kitchen high concentrations of pollutants, including particulate matter, carbon monoxide and other organic compounds known to affect the eye, such as formaldehyde and naphthalene. Usually, women doing the cooking are the most exposed. There is evidence linking solid fuels to a wide range of health effects, but the impact on eye diseases has not been extensively investigated. Virtually no studies have investigated kerosene use and eye disease. In every part of the world, females are at higher risk of eye disease at all ages. About 90% of visually impaired and blind people lived in developing countries. These two closely related ocular disease studies, which focus on cataract of the lens and age-related macular degeneration (AMD), the first and third most common causes of blindness in the world, and dry eye disease, a major cause of pain and discomfort, take advantage of the established infrastructure, including offices, vehicles and trained field staff, and prior data collection-household cooking, heating and lighting appliance use, and air pollution monitoring data--of an earlier NIH-funded epidemiologic study of TB and indoor fuel use, in Pokhara, Nepal. The ocular disease studies are a cross-sectional study investigating cataract and dry eye disease, and a case-control study investigating AMD. In the cross-sectional study, women, aged 40-70 years, from TB study households, chosen on the basis of their cooking, heating and lighting appliance use, will be transported to the Manipal Teaching Hospital in Pokhara, where they will receive a free and comprehensive eye examination. Slit-lamp photos of the crystalline lens will be taken and tests done for dry eye disease. Separately, a case-control study of AMD diagnosed in women attending the hospital will be carried out. Statistical analysis in both studies will focus on examining associations between household fuel uses, for cooking, heating and lighting, and the ocular outcome measures. Together, these will comprise the most comprehensive investigation ever of these potentially causal relationships. Results will have implications for policy and for health interventions. In particular, if evidence is produced that kerosene is a risk factor for eye diseas, then this will strengthen arguments for not treating kerosene as a clean fuel alternative to biomass, as is currently the policy of some international agencies, including WHO. The studies will provide data for reworking cost-benefit analyses of replacing biomass stoves and fuel-based lighting sources with alternatives, such as LPG stoves or electric lighting.
Use of solid fuels for cooking and heating, and kerosene for cooking and lighting, are common in the developing world, including Nepal. Although these household fuels are known to cause various health effects, little is known about their effects on the eyes. This study, in Nepal, will investigate whether there are associations between using these fuels and cataract of the lens of the eye and macular degeneration, which often cause blindness, and dry eye disease, which causes discomfort and pain.
