In a large study of Swedish men, further evidence has emerged of the smoking link to cataract development in the eye, with addiction to 15 cigarettes a day raising the risk of needing a cataract operation by 42%, compared with people who have never smoked.
Introducing their study, the authors point out that smoking was already an established risk factor for cataracts, "which is the leading cause of visual impairment in the world, responsible for more than 50% of world blindness."
The authors did not know, however, what benefit against this higher risk of cataracts would be derived from giving up smoking.
A total of 44,371 men were studied, in the Cohort of Swedish Men, all aged between 45 and 79 years. They had completed a self-administered questionnaire on smoking habits and lifestyle factors in 1997.
The researchers found from an analysis of the prospective data that while the "risk persists for decades" after quitting, succeeding in doing so does seem to decrease the chances of needing extraction surgery for a cataract.
The authors, led by Dr. Birgitta Ejdervik Lindblad of Sweden's Orebro University Hospital, conclude:
"The higher the intensity of smoking, the longer it takes for the increased risk to decline. These findings emphasize the importance of early smoking cessation and preferably the avoidance of smoking."
The authors say the risk of smoking to the eye is not confined to cataracts; it is associated with other common and severe eye diseases, including:
- Age-related macular degeneration (which affects central vision)
- Grave's ophthalmopathy (caused by an autoimmune disorder of the thyroid gland), and
- Ocular inflammation.
How does smoking damage the lens of the eye?
Offering a mechanism by which smoking leads to ocular pathology, the authors explain that oxidative stress is probably the cause, through the "formation of free radicals and lower levels of circulating antioxidants."
The authors add:
"Long-time exposure of oxidative stress leads to accumulation of damaged lens proteins, thus promoting cataract development. Cigarette smoke also contains toxic metal ions, and cadmium can accumulate in cataractous lenses of smokers."
They continue: "Smoking cessation decreased the risk with time, indicating that the lens has some ability to repair protein damage with time, probably by halting oxidative stress, although it takes longer for the lens to recover with higher smoking intensity."
In other health news about smoking this week, Medical News Today reported on Monday, December 30th, that a new public health TV campaign in England shows a graphic representation of how inhaled cigarette smoke generates a "toxic cycle of dirty blood." Harmful chemicals like arsenic and cyanide are circulated around the body, finally ending up in the brain and causing damage to brain cells.
Also on Monday, a study analyzing global cancer rates compiled by the World Health Organization found smoking was one of the lifestyle choices that had most influence in causing cancer.