Smoking: The sniper in our island of vision

Sankhajyoti Saha, M.Optometry

Clinical Optometrist, I for Eye-Care, Falakata, India

The doctor of the future will give no medicine but will instruct his patients in care of the human frame, in diet, and in the cause and prevention of disease.” – Thomas Edison

Tobacco consumption is the leading cause of preventable cancers. Tobacco alone accounts for nearly 5.4 million deaths per year; enough to abolish one billion people in this century at this rate. ⁽¹⁾ Owing to increase exposure to environmental tobacco smoke or vapor, health risks are not limited to smokers only, but extend to nonsmokers (especially children) who are exposed to secondhand smoke. Immediately the consequence may seem very minimal, but the ripple effects of small things are precarious.

Cigarette tobacco is a complex physicochemical mixture containing around 7,357 chemical compounds from different classes. Tobacco smoke from cigarette or e-cigarettes is concentrated aerosol consisting mainly of nitrogen, oxygen, carbon dioxide, carbon monoxide, acetaldehyde, methane, hydrogen cyanide, acetone, ammonia, methanol, hydrogen sulfide, hydrocarbons, nitrosamines, and carbonyl compounds, which are suspended in an atmosphere from particles like carboxylic acids, phenols, humectants, nicotine, paraffin, tobacco-specific nitrosamines etc. The tobacco leaf contains many alkaloid chemicals (nicotine is the most copious) which often possess a natural pharmacologic defense against many insects. Nicotine is addictive in humans because a portion of the nicotine molecule is like acetylcholine, which is an important brain neurotransmitter. ⁽²⁾

Adverse outcomes:

• Several chemical components present in cigarette tobacco adversely affect the heart, reproductive system, respiratory tissues, kidney, skin, liver, and bladder. ⁽²⁾
• Nicotine triggers coronary vessels to narrow; and due to restricted oxygen delivery, there is reduced cardiac work, increase in heart rate, blood pressure, and cardiac contractility. Furthermore, it stimulates vagal reflex and parasympathetic ganglia, which eventually increases airway resistance. ⁽²⁾
• Cigarette smoking is one of the main causes of oxidative stress development in the human body, which promotes oxidation of cell components (generation of free radicals) and decreases the levels of antioxidants in the blood circulation, leading to cell and tissue damages. ⁽³⁾
• If you need more reason to quit smoking, add constipation, dry mouth, damages the skin elasticity to the list. ⁽²⁾
• Despite the multifactorial etiology, there is also a strong alliance between smoking and a few common eye diseases like Graves’ ophthalmopathy, retinal neovascularization, age-related macular degeneration, pathologic angiogenesis, glaucoma, dry eye, and tobacco amblyopia. ^{(2, 4, 5, 7)} The synergistic relationship between nicotine and glucose metabolism increases the risk of diabetes mellitus, which eventually accelerates the risk of cataract formation. ⁽²⁾
• Smoking during pregnancy increases the risk to get retinopathy of prematurity, bacterial meningitis as a child, which eventually leads to several vision problems. ⁽⁶⁾

The takeaway:

There is a proverb saying, “Healthy citizens are the greatest asset a country can have.” A potential next step is to initiate clinical guidelines on which eye care practitioners can address their patients about the collision of smoking on eye health, including suitable referral and prevention strategies, to improve quit rates and help discourage people from starting to smoke.

References:

1. WHO Data. Tobacco Fact Sheet; No. 339. Retrieved from:  http://www.who.int/mediacentre/factsheets/fs339/en . (Last accessed: January 30, 2021, 22:00 IST)
2. Centers for Disease Control and Prevention (US); National Center for Chronic Disease Prevention and Health Promotion (US); Office on Smoking and Health (US). How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. Atlanta (GA): Centers for Disease Control and Prevention (US); 2010. 3, Chemistry and Toxicology of Cigarette Smoke and Biomarkers of Exposure and Harm. Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK53014/ (Last accessed: January 31, 2021, 01:00 IST)
3. Lohan, S. B., Bühring, K., Lauer, A. C., Friedrich, A., Lademann, J., Buss, A., Sabat, R., Wolk, K., & Meinke, M. C. (2020). Analysis of the Status of the Cutaneous Endogenous and Exogenous Antioxidative System of Smokers and the Short-Term Effect of Defined Smoking Thereon. Antioxidants (Basel, Switzerland), 9(6), 537. https://doi.org/10.3390/antiox9060537