Smoking:
a threat to eye health
Cigarette
smoking is an important risk factor for cardiovascular, respiratory, and malignant
diseases. There is also a strong association between smoking and a number of
common eye diseases, which include dysthyroid eye disease, age-related macular
degeneration, glaucoma, and cataract. Despite the multifactorial aetiology of
these ocular syndromes, smoking is an independent risk factor that has dose-response
effects. It causes morphological and functional changes to the lens and retina
due to its atherosclerotic and thrombotic effects on the ocular capillaries.
Smoking also enhances the generation of free radicals and decreases the levels
of antioxidants in the blood circulation, aqueous humour, and ocular tissue.
Thus, the eyes are more at risk of having free-radical and oxidation attacks
in smokers. Smoking, if continued, may perpetuate further ocular damage and
lead to permanent blindness. Cessation of smoking and avoidance of passive smoking
are advised to minimize the harmful effects of smoking on the eyes.
Dysthyroid
eye disease
- Patients
with dysthyroid eye disease who smoke more cigarettes per day have more
serious eye problems.
- Smoking
may cause disturbances in the immune system, resulting in decreased
control of immune cells against thyroidal or orbital antigens.
- It
also enhances the formation of free radicals and inhibits the formation
of antioxidants in the blood circulation, aqueous humour, and ocular
tissue. Thus, the eyes are more at risk of having free-radical and oxidation
attacks in smokers.
|
Dysthyroid
eye disease
|
Age-related macular degeneration (AMD)
- Smoking
may promote the development and progression of new subretinal vessels, which
causes macular degeneration.
- It increases
the carboxyhaemoglobin concentrations. Choroidal blood flow is reduced, thereby
accelerating the degenerative changes in the macula and stimulating neovascular
growth.
- Smoking
reduces the plasma concentration of antioxidants and also the carotenoid concentrations
in the blood and retina. The ability to accommodate oxidative stress and maintain
retinal structures against free radicals formed is thus adversely affected.
|
Dry
AMD
|
Wet
AMD
|
Cataract
- Smoking
increases the risk of developing cataract.
-
Preliminary studies showed that cadmium and isocyanate in cigarette
smoke may cause direct and structural injury to the lens.
|
Cataract
|
Glaucoma
- An
animal study has shown a 5 mm Hg rise in intraocular pressure immediately
after smoking.
- Normal
intraocular pressure should lie between 7 - 21 mm Hg.
|
Glaucoma
|
Age-related
macular degeneration (AMD)
Cataract
Glaucoma
Red Eye
