Almost each one of us is aware of the harmful effects of cigarette smoking on the health of a person, but still millions of people smoke a large number of cigarettes every day. Although people are aware that cigarette smoking is deteriorating their health, many smokers are unaware of the link between cigarette smoking and blindness.
Multiple studies have shown that the eyes are particularly vulnerable to the effects of smoking and there are various mechanisms that can explain the association between the two. Cigarette smoking is an important factor in the pathogenesis and progression of several eye disorders. Some of the ways cigarette smoking is affecting the eyes are as follows:
Cigarette smoking consists of thousands of chemicals that have a harmful effect on the health of a person. Some chemicals combine with haemoglobin more efficiently than oxygen and reduce the availability of oxygen.
Cornea and retina are the two important parts of the eye which make it possible for a person to see. The hot end of the burning cigarette smoking or flying ash significantly affects cornea. Smoking also induces inflammation and vasoconstriction which can have a direct impact on the retina.
Smoking reduces the synthesis of nitric oxide by the vascular endothelium which lowers vasodilation and restricts blood flow.
One of the most harmful and addictive components of cigarette smoking is nicotine, which has a direct impact on the nervous system. Nicotine has an impact on various parts in the body, including the retina.
Burning cigarette or high-temperature tobacco generates free radicals that cause chronic inflammation and multiple malfunctions. Chronic inflammation to different parts of the eyes results in the damage caused to it.
Smoking has many harmful effects on the health of an individual. The severity of the health effects of smoking differs from person to person. It is largely dependent on the duration a person is smoking and the number of cigarettes smoked per day. There are many eye disorders that can occur due to cigarette smoking and some of them are as follows:
1. Diabetic retinopathy
Diabetic retinopathy is one of the serious complications of diabetes mellitus and it occurs when the tiny blood vessels in the retina are damaged. Diabetes mellitus is a disease which is characterized by a high glucose level in the blood and it occurs due to problems associated with insulin, a hormone that regulates the level of glucose in the blood. Diabetes mellitus results from lack of production of insulin in the body, the inability of the body to use insulin effectively or both.
Cigarette smoking has been known to be one of the risk factors of diabetes mellitus. Smoking is closely associated with inflammation and oxidative stress and both of these are related to the increased risk of diabetes mellitus. It increases the level of glucose in the blood. Uncontrolled glucose level is associated with the occurrence of complications, including diabetic retinopathy. Diabetes retinopathy is one of the common causes of vision loss.
2. Age related macular degeneration
Age related macular degeneration is a common eye disorder which can lead to the loss of vision in one or both eyes. It occurs when the macula, a small spot near the centre of the retina is damaged. Macula plays an important role in sharp and central vision. Research has shown that although there are many risk factors for the development of this disease, smoking can double the risk of its development. This eye disorder by itself does not lead to complete blindness. The loss of central vision interferes with the ability to do simple activities such as driving, reading, and writing.
The non-oxidative chemical damage caused to the retina due to cigarette smoking is one of the mechanisms through which smoking causes age-related macular degeneration. Also, cigarette smoking is also associated with restricted or reduced flow of blood which can also be the cause of macular damage.
Cataract is a common disorder of the eyes and is characterized by the clouding of the lens in the eyes, resulting in a direct impact on vision. The clear part of the lens is important to focus light or an image on the retina. Normally, the light passes from the transparent lens to the retina, which is then converted into the nerve signals and sent it to the brain. It is important to have a clear lens as if the lens would be cloudy the image would be blurred.
Smoking and diabetes mellitus are the two most common causes of cataracts. Smoking leads to the build-up of damaged proteins in the lens by eliminating the enzymes that help to clear lens. Diabetes mellitus is also a cause of the occurrence of cataract and smoking is one of the risk factors for the development of diabetes mellitus.
4. Graves’ ophthalmopathy
Graves’ ophthalmopathy, also known as thyroid ophthalmopathy which is characterized by the wide range of symptoms such as redness, conjunctivitis, blurred vision and in some cases, serious and permanent vision damage. This disease occurs due to the swelling of the retrobulbar muscles that are located behind the eyeballs and surrounding fatty tissues within the orbit. Autoimmune disease said to be the main cause of the development of this disease.
Cigarette smoking is often known to be associated with the development and progression of this disease and also autoimmune diseases. The exact mechanism by which smoking causes this disorder is not known but it has been proposed that the formation of superoxide radicals and tissue hypoxia may be involved in it.