How Smoking Can Affect Vision
Dr Varsha Rathi, Consultant, Laser Refractive Surgery Centre, L V Prasad Eye Institute, Hyderabad
Smoking has long been known to cause lung cancer and heart disease; however many people do not realize that smoking can cause vision loss. Studies show that smoking increases the risk of Age Related Macular Degeneration (ARMD), Cataract, Glaucoma, Diabetic Retinopathy and Dry eye.
Cigarette smoke is composed of various toxic chemical particles including nicotine, carbon monoxide and formaldehyde. These can adversely affect health – directly by causing disease,and indirectly by decreasing the efficacy of drugs or altering the immune response.Cigarette smoking has been linked withcausing various ocular diseases such as cataract and age related macular degeneration, which are leading causes of visual impairment and blindness worldwide.
Various studies have proven that smoking causes cataract, and that the risk of cataract is high among smokers, when compared with non-smokers. L V Prasad Eye Institute has conducted the “Andhra Pradesh eye disease study”; a cross-sectional population based study, and showed that cigarette smokers have a significantly higher prevalence of cataract compared with people who never smoke. It was also found that heavy smokers (>14 ‘pack-years’ of smoking) have a higher risk of having cataract, compared with light smokers.
Age related macular degeneration (ARMD) causes irreversible blindness since it affects the macula, which is the central seeing part of the retina. The vision becomes blurred and distorted when macula is affected, sometimes leading to darkness in the central vision. The loss of central vision affects the day to day life of an individual and the risk of ARMD is tripled with smokers as compared with nonsmokers. Smokers are more likely to develop ARMD ten years earlier than nonsmokers. In UK, 52000 people are visually impaired or blind, secondary to smoking‐related ARMD.
Besides visual impairments, cigarette smoking is also associated with other diseases such as Thyroid eye disease, Diabetic Retinopathy, Glaucoma and dry eyes. The risk of developing severe Diabetic Retinopathy is doubled or tripled with smoking. Smoking may increase or worsen blood pressure and blood sugar, making them difficult to control, thereby increasing the risk of retinopathy which can further lead to blindness. Anterior ischemic optic neuropathy (AION) is an eye disease that results in a sudden, painless loss of vision, often leading to permanent blindness. Smokers have a16- fold increased risk of developing optic neuropathy, and that too, at young age. It is a known fact that passive smoking causes Dry Eye. Passive smokers are also at a risk for developing thyroid eye disease and have doubled risk of developing ARMD.
Smoking during pregnancy may result in premature birth. It could also cause Retinopathy of Prematurity (ROP), a potential blinding disease in new born babies. Most cigarette smokers start young. Though awareness about causal relationship between blindness and smoking is low among people, the fear of blindness is more than any other disease associated with smoking.
UK, Netherlands and Australia, with their nationwide campaign of “Smoking Causes Blindness”, have helped people quit smoking. An aggressive national tobacco awareness programin Australia has been successful at increasing knowledge among smokers about the link between smoking and blindness with 47% of Australian smokers reporting awareness that smoking causes blindness. India is home to approximately 275 million tobacco users, including 47.9% of adult males and 20.3% of females in 2010, and the World Health Organization (WHO) projects that tobacco-related deaths in India will surpass 1.5 million each year by 2020. India Tobacco Control Policy Evaluation Project TCP India Survey clearly shows that tobacco users are supportive of having more health information on packages of smoked tobacco. International Tobacco Control (ITC) Policy Evaluation Project states that smokers in India are less knowledgeable about important tobacco-related health effects compared to smokers in other countries. Hence, educating adults with nationwide campaigns and students in schools may result in eliminating an individual’s desire of starting to smoke, or in quitting smoking.