By Linda Kaspari
Updated, March 2006
Cigarette smoking reduces levels of plasma antioxidant, a substance in the blood stream, which protects retinal cells. Smoking causes the protective layer between the retina and blood vessels to erode, resulting in poor circulation, irritation and scarring.
Smoking is damaging to the blood supply. Smoking exposes the body to free radicals which causes cellular damage and can cause poor circulation of nutrients to the retina and lens. Carotenoid levels and vitamin C blood concentrations are substantially reduced. Smoking oxidizes cholesterol, causing fat to build up in the arteries. This leads to heart attack, stroke, and probably macular degeneration.
Researchers think smoking contributes to the incidence of some types of cataracts. “What makes us suspect this is the consistency of studies all over the world,” says Robert Sperduto, M.D., chief, epidemiology branch of the National Eye Institute. “If there’s one thing people can do to improve their general health, including the health of their eyes, it is to stop smoking,” says Dr. Sperduto.
Carbon monoxide from cigarette smoke creates a hypoxic effect, it is clear that hypoxia will degrade night vision. (Hypoxia is a state of oxygen deficiency in the body which is sufficient to cause an impairment of function. The inadequate oxygen transport or the inability of the tissues to use oxygen causes hypoxia.)
Smoking produces cyanide, a retinal toxin. Smokers may develop a problem called toxic amblyopia. Amblyopia is reduced or dimness of vision that is not related to visible changes in eye health. Causes include exposure to toxic substances, such as alcohol and tobacco smoke, diabetic, and medication.
Amblyopia, especially of one eye, is also called lazy eye. This condition occurs when one eye is not properly aligned or when the visual correction needed by one eye is significantly worse than in the other. The weaker eye becomes unused and, if not treated, may become “blind.”
Smokers have double the risk of developing macular degeneration, but if their diets were rich in lutein & other carotenoids (esp: spinach, collard greens, and kale), they significantly reduced that risk. Vision Res, 36(18) 1996.
In two major studies published in the “Journal Of The American Medical Association” each report reached the same conclusion that “Smoking Is A Major Cause Of Age Related Macular Degeneration”. According to these reports, individuals 65 years of age and over double their risk of developing Macular Degeneration if they smoke.
Women who smoked a pack of cigarettes per day or more had about two and a half times the risk of developing this serious eye disease, macular degeneration, compared with people who never smoked. Furthermore, those who smoked the most actually had the greatest risk. Men who smoked a pack or more a day were two to three times more vulnerable to developing Macular Degeneration.
Smoking and Hearing Loss
Another study conducted at the University of Wisconsin Medical School in Madison concluded that their findings suggest there may be an association between cigarette smoking and hearing loss. Karen Cruickshanks, associate professor of ophthalmology and visual sciences found that in a study of 4,753 adults age 48 to 97 smokers had a 70 percent higher risk of hearing loss than nonsmokers.
A continuing study is needed to determine if an exact cause-effect relationship exists. Cruickshanks commented that “It’s most likely that there are many factors that play a role in the age-related loss of hearing, and possibly smoking is one of them.”
Smoking and Night Vision
There are several factors that make investigation of the effects of smoking on night vision difficult. Contradictions still exist in the published studies. Night vision is, in itself, a complex physiological process. Visual function at night encompasses many parameters, e.g., scotopic dark adaptation, mesopic vision, contrast sensitivity, visual discrimination of moving targets, peripheral retinal sensitivity, glare recovery, and dark focus.
One well-done study found that temporary abstinence from smoking could sharply improve the night vision of smokers. Several studies found that smokers were more likely to have automobile accidents than nonsmokers were. Another study reported that, among people who had automobile accidents, smokers were more than two times as likely to have their accidents at night.
Finally, the chronic effects of active or passive cigarette smoking must be acknowledged. Smoking is believed to accelerate the overall aging process in humans and, among other things, we can no longer ignore that smoking can affect visual function.
Wiley RW. Dark adaptation and recovery from light adaptation: Smokers versus nonsmokers. Mil Med 154:427-430, August 1989.
Robinson F, Petrig BL, Riva CE. The acute effects of cigarette smoking on macular capillary blood flow in humans. Invest Ophthalmol and Vis Sci 26(5):609-613, 1985.
Calissendorff B. Effects of repeated smoking on dark adaptation. Acta Ophthahnologica 55:261-268, 1977.
Luria SM, McKay CL. Effects of low levels of carbon monoxide on vision of smokers and nonsmokers. Arch Environ Health, pp. 38-44, Jan/Feb 1979.
Ernest J, Krill AE. The effect of hypoxia on visual function: Psycho-physical studies. Investigative Ophthalmol Vis Sci 10(5):323-328, 1971.
Research from Duke and Vanderbilt University Medical Centers (published in the online edition of the American Journal of Human Genetics, March 6, 2006) has discovered that a version of the LOC387715 gene significantly increases the risk of developing ARMD in tobacco smokers. This is an unusual instance wherein genetics and environment can combine to create a disease risk. The other example related to ARMD is the CFH gene and how its effects are related to the body’s immune system. For more information about the CFH gene, see “CFH and CFB Proteins May Lead to AMD” on this site.
By Linda Kaspari