Cigarette smoking
The cigarette smoke è between the causes of many preventable diseases such as cancer, stroke and ischaemic heart disease. Smoking is also strongly associated with ophthalmological disorders such as age-related macular degeneration, dry eye, cataracts, retinal vein occlusion, anterior ischaemic optic neuropathy, primary open-angle glaucoma and Graves' ophthalmopathy.
A cigarette contains about 4000 active substancesmost of which have harmful effects on the pulmonary, cardiovascular and neurovascular systems. Tobacco smoke is, in fact, the main source of nicotine intake and heavy metals, toxic elements and carbon monoxide, which induce vasospasm and platelet aggregation resulting in oxidative damage to cellular DNA, lipids and proteins. Smoking, by increasing free oxygen radicals in the aqueous humour and decreasing the level of ascorbic acid (an important antioxidant), has strong effects on the eyes and can cause tear film instability which results in dry eye symptoms (foreign body sensation, burning eyes, granularity and tearing). The Beaver Dam study showed that subjects who were active smokers or had a history of smoking had disturbances of the ocular surface and related symptoms, more frequent than in non-smokers.
Studies on smoking-related corneal changes
A recent study, published in Graefe's Archive for Clinical and Experimental Ophthalmology, evaluated the microstructural corneal changes related to smoking, while considering the effects on the ocular surface and the Meibomian glands. This cross-sectional study was conducted on 50 eyes of 50 chronic smokers and 50 eyes of 50 healthy non-smokers; the two groups were similar in age and gender.
In the group of chronic smokers, the density of basal epithelial cells, anterior and posterior keratocytes, the density of endothelial cells and Meibomian glands, and the number of sub-basal nerves (long and total) was lower in comparison to the non-smokers. Whereas, the lissamine green staining (to assess tear dysfunction) and ocular surface disease index scores were higher, compared to the control group.
Test Results
The results of this study show that smoking has harmful effects on all parameters associated with the health conditions of the ocular surface and meibomian glands, regardless of the level of nicotine addiction and how long you have been a smoker. It would, therefore, be advisable for individuals with dry eye symptoms to be informed that cigarette smoking is one of the most important environmental risk factors for the onset of diseases affecting the ocular surface.
Source
Dr. Carmelo Chines
Direttore responsabile
English 
Italian