Clouding your vision

Smoking has long been known to cause lung cancer and heart disease; however, many people do not realise that smoking can cause vision loss too. Studies show that smoking increases the risk of age-related macular degeneration (ARMD), cataract, glaucoma and dry eyes.

Cigarette smoke is composed of various toxic chemical particles including nicotine, carbon monoxide and formaldehyde. These can adversely affect health – directly by causing diseases and indirectly by decreasing the efficacy of drugs or altering the immune response. Cigarette smoking has also been linked to causing various ocular diseases such as cataract and ARMD, 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. ARMD causes irreversible blindness since it affects the macula, which is the central part of the retina for vision. The vision becomes blurred and distorted when the macula is affected, sometimes leading to darkness in the central vision area. The loss of central vision affects the day-to-day life of an individual. The risk of ARMD is tripled with smokers when compared with nonsmokers. Smokers are likely to develop ARMD a decade earlier than nonsmokers.

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 ultimately lead to blindness.

Anterior ischemic optic neuropathy (AION) is also an eye disease that results in a sudden, painless loss of vision, often leading to permanent blindness.

Smokers have a 16-fold increased risk of developing optic neuropathy, and that too, at a young age. It is a known fact that passive smoking causes dry eyes. 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 newborn 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.

India is home to approximately 275 million tobacco users, including 47.9 per cent of adult males and 20.3 per cent 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. Hence, educating adults with nationwide campaigns and students in schools may result in eliminating an individual’s desire of starting to smoke, or may also help smokers in kicking the butt.

(The author is consultant, Laser
Refractive Surgery Centre, LV Prasad Eye Institute, Hyderabad)