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The chemicals in cigarette smoke (around 4000 of them) get into the bloodstream of smokers and may induce the damage to the eye.

•The chemicals in tobacco smoke can cause inflammation of the conjunctiva (the thin membrane covering the eye), resulting in bloodshot, irritated eyes.

•In a study of nearly 21,000 U.S. male physicians, spanning an average of 13.6 years, researchers found a direct link between smoking and the development of cataracts. The study, known as Physicians Health Study I, evaluated physicians between the ages of 40 and 84 who had no prior history of cataracts before 1982.

Participants were asked to complete questionnaires that included information such as: number of cigarettes smoked daily, age when they started smoking, and their age if they stopped smoking. Each participant received annual eye exams and were required to report the results to the study investigators. The participants' ophthalmologists and optometrists confirmed the results.

•Smoking has also been linked to eye diseases such as age-related macular degeneration. The causes of macular degeneration are not completely understood, but smoking is believed to be the main preventable risk factor. Evidence indicates that more than a quarter of all cases of AMD are linked to current or past exposure to smoking.

•Study results appear mixed about a direct association between smoking and diabetic retinopathy, but most experts agree that smoking should be avoided to help help stop progression of the disease.

•Smoking causes shrinkage or constriction of blood vessels, shown to be directly linked to rising inner eye pressure (intraocular pressure) that can lead to glaucoma and accompanying optic nerve damage.

•Optic neuritis : A landmark study found a strong association between factors such as poor nutrition and smoking linked to a 1992-1993 epidemic of optic nerve damage among Cuban citizens.

Although smoking is associated with several eye diseases, including nuclear cataract and thyroid eye disease, the most common cause of smoking related blindness is age related macular degeneration, which results in severe irreversible loss of central vision.

How does smoking damage the eyes?

When you inhale cigarette smoke thousands of chemicals get into your bloodstream and can travel throughout your body. These chemicals cause damage to the macula (the most sensitive part of the retina, at the back of your eye). Tiny blood vessels can burst through the macula, leading to irreversible damage, or alternatively, the cells of the macula slowly die. Both ultimately lead to loss of vision.

Can this damage be reversed?

No. Laser treatment can sometimes kill the new blood vessels before they hit the macula. However, most people are not able to be helped this way because the blood vessel has already involved the very centre of the macula, and even after treatment, the condition recurs in half the cases and in almost all those who continue to smoke. A new treatment, photodynamic therapy (PDT) may be able to help some to reduce the severity of vision loss, but the majority of people with macular degeneration will still not be able to be treated.

If I quit smoking will my eyes recover?

Your risk of macular degeneration will be reduced if you quit smoking, however existing damage to the eyes cannot be repaired, particularly once vision is affected.

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