Adults and unborn babies’ vision at risk from compounds in cigarette smoke says Dr. Shabbir Saifuddinan ophthalmologist based in Dubai.
The deleterious effects of smoking on health are well-established and need no further introduction, with the vast majority of people in an educated population being fully aware of the damage that tobacco products cause to the body. With tobacco smoke containing as many as 4,000 active compounds that are linked to over 60 different health conditions, the negative impact of cigarette consumption has been trumpeted loudly by health authorities and institutions since 1950, when five studies were published that showed that smoking was powerfully implicated in the cause of lung cancer. These reports included the now classic paper ‘Smoking and Carcinoma of the Lung,’ which appeared in the British Medical Journal.
What is commonly known by the general public is that tobacco consumption is linked to carcinoma and other diseases of the respiratory and circulatory systems. What is less known, however, is the strong association between tobacco consumption and eye disease. In fact, around 8% of global eye disorders are directly attributable to tobacco consumption; a statistic that has not received a great amount of publicity. The paucity of public information about this situation means that at present, there exists a distinct lack of awareness of the negative effects of smoking on eyesight.
Recently, several multi-centered studies have proved that smoking is a contributory factor for both visual impairment and blindness, with one particular study revealing that smoking may harm unborn babies’ eyes as well. The latter piece of research suggested that for each cigarette a pregnant woman lights up each day, she raises her baby’s risk of strabismus (squint) by 5%. This condition, colloquially known as ‘cross-eyes,’ is a common one affecting some 2 to 3% of children and is a collective term for about 30 different conditions in which the eyes are unable to line-up in the same direction when focusing on an image.
Exposure in the womb to the toxic compounds in cigarette smoke may be one major cause of strabismus; a conclusion drawn from the study when it was found that women who smoked during pregnancy were at a 25% greater risk of having a child with the condition compared to mothers who had not. The report, which was published in the American Journal of Epidemiology, revealed that the effects of smoking in relation to debilitating eye disorders may become more potent later in pregnancy. The effects of smoking were not that significant when it was limited to the first trimester only, but were observed to increase to 43 and 35% for those who smoked during the first two or all three trimesters respectively. The researchers also noted that women who smoked between five and nine cigarettes a day had a 38% greater risk of their baby developing strabismus compared to non-smoking mothers, with smoking 10 or more cigarettes a day being associated with a 90% greater risk.
It has already been established that tobacco consumption during pregnancy can cause more harm to the foetus than it does to the mother. The act of smoking involves inhalation and exhalation, with some of the toxic and stimulant products being removed during the latter action. The foetus is exposed to the harmful compounds that the mother has absorbed into the blood from inhaling; both from the smoke that comes from the mother actively puffing on a cigarette and the second-hand environmental smoke that the mother breathes in passively. These substances subsequently pass into the foetus through the placenta and affect its development and activity in the womb. The nicotine found in cigarette smoke, combined with the high levels of carbon monoxide, causes the baby’s movements to slow down in order for it to conserve oxygen. Its heart will be beating faster in an attempt to attempt to take in more oxygen and the resulting stress will cause it to develop at a decreased rate than the baby in the womb of a non-smoking mother. Besides a slower foetal development, a mother who smokes has a 30% more of a chance of having a child born with too many, too few, or webbed fingers and toes.
Smoking has been observed to harm every phase of reproduction. Despite having greater increased knowledge of the adverse health effects of smoking during pregnancy, many pregnant women and girls continue to smoke (estimates range from 12% to 22%, with only 18% to 25% quitting once they become pregnant). Smoking in the recent past has increased by 12% in Asian countries, especially among the higher income groups of China, India and the countries of the Far East. If a mother (or indeed other family members) continues to smoke after childbirth, the baby will no longer be exposed to harmful compounds via the placenta, but he or she will still be at risk of harm from the second-hand environmental smoke which it is now inhaling involuntarily through its own lungs.
The effects of smoking on eyesight continue throughout a person’s lifetime. It can worsen or even be the cause of several eye disorders, including optic neuropathy. Smoking more than doubles the risk of developing cataracts and increases the risk of Age-related Macular Degeneration (AMD) by up to 600%. Ultimately, it may lead to blindness. Diabetic patients who continue to light up can accelerate diabetic retinopathy, an eye complication that can also lead to complete loss of vision.
Steps to prevent the eye diseases and blindness
The single most important change a person can make to protect their eyesight and the eyesight of their children — whether born or expected — is to stop smoking. Ceasing smoking will also help prevent a myriad of other health conditions associated with tobacco consumption, both for adults and for babies in the womb. Expectant mums who don’t use cigarettes themselves need to be in a smoke-free environment to avoid passing on the harmful compounds found in second-hand smoke to their baby, so fathers-to-be and other relatives sharing the family home should quit as soon as possible.
Other helpful lifestyle changes for adults to protect their own eyes include taking regular exercise and increasing consumption of antioxidants, with epidemiological studies of thousands of people showing that antioxidants are just the starting point for a preventive approach to eye health. Phytonutrients derived from plants are the most under-rated sources of healthful nutrients for our body, with recent research proving that dark, green, leafy vegetables contain compounds that protect sensitive retinal microcirculation and which can prevent — and in some cases improve — macular degeneration and retinopathy. Ginkgo biloba in particular has been shown to promote better circulation in the eyes and brain.
Awareness and greater publicity
Various governmental bodies are taking actions to reduce smoking, which include ending tobacco advertising and sponsorship, promoting media campaigns and investing in smoking cessation initiatives. Cigarette packets in most countries already carry severe health warnings about the dangers of smoking, but addicted consumers say they generally ignore these warnings. However, there is room for improvement here. Pack warnings that are novel and targeted at the concerns of specific population subgroups are likely to have a greater impact than blander and more generic health warnings. For example, the Thai government warning “Smoking causes impotence” helped cut down smoking among Thai teenagers by 20%. Likewise, the information that smoking can lead to being over-weight has helped women in cutting down on the habit. The Australian government has been in the news this month, with its plans to force tobacco companies to strip all logos and colour from their packaging, leaving cigarette packs adorned with only a few words and graphic warning images of shrivelled, diseased lungs or gangrenous toes. Similarly, if “Smoking is a major cause of blindness” were added to the current set of health warnings, some smokers might reconsider their continued tobacco use. After all, the eyes are popularly venerated as being the ‘mirror to the soul’ and blindness is greatly feared. Such warnings may help reduce the levels of tobacco consumption, if introduced.