Smoking is currently a worldwide epidemic of bad habits, is a variety of cardiovascular and cerebrovascular disease risk factors, in the United States each year, 20% of the deaths in the population died of smoking complications. Similarly, it also produces different degrees of damage to various tissues of the eye, and now briefly describes the effects of smoking on various tissues of the eye for ophthalmology colleagues to refer to. Harmful components of tobacco cigarettes in the combustion of cigarettes, can be released more than 4,000 kinds of components, most of which are harmful to the cardiopulmonary system, and there are more than 40 kinds of carcinogenic components. The main components are nicotine, tar, polycyclic aromatic hydrocarbons and carbon monoxide. Smoke also contains a variety of heavy metals and harmful minerals, such as aluminum, lead, mercury and so on. Nicotine and some vasoactive substances can cause vasoconstriction, leading to ischemia and hypoxia in eye tissues. Nicotine and carbon monoxide can make the blood viscosity change, so that platelet aggregation is elevated, easy to thrombosis, can cause ocular vascular lesions. Cigarettes contain a variety of peroxides, which can cause age-related changes in ocular tissues. Eye diseases: 1, eye surface diseases: conjunctival mucosa is very sensitive to harmful gases, whether active smokers or passive smokers, there are different degrees of eye irritation symptoms, such as conjunctival congestion, tear secretion increased. Prolonged exposure to smoke environment such as cigarette factory, can make the conjunctival epithelium chemotaxis. 2, glaucoma: the relationship between open-angle glaucoma and smoking is still under debate, some surveys indicate that smoking can increase the risk of glaucoma, but there are some surveys did not see this correlation. Wilson et al. in a case-control study found that smokers with a risk of glaucoma is 2.9. Quigley et al. did not see a correlation between the two, and we are in a case-control study did not find that smoking and primary closed glaucoma. We also did not find an association between smoking and primary angle-closure glaucoma in a case-control study. The combined data from the current studies suggests that smoking is not associated with the development of glaucoma and hypertension. Cataract: Cataract is the most important blinding and disabling eye disease in the world today, and about 15 million people around the world are blinded as a result. A number of foreign studies have shown that smoking is mainly associated with nuclear cataract, posterior subcapsular cataract, and not with cortical cataract, with a risk between 1.09 and 2.40. Cumming et al. also found that the risk of pipe smokers was higher than that of cigar and paper cigarette smokers. The possible mechanism by which smoking causes cataracts is damage to the lens by lipid peroxides in smoke; similarly the enrichment of heavy metal substances in smoke in the lens contributes to damage to the lens [1]. As the relationship between smoking and cataract has been confirmed, stop smoking can reduce cataract formation. 4, retinal diseases: blood flow rate: nicotine into the body, can excite the sympathetic ganglia and adrenal glands, so that the blood catecholamine levels rise, which in turn can significantly accelerate the heart rate and vasoconstriction, so that the speed of blood flow. Nicotine can also stimulate angiotensin Ⅱ level rise, so that vasoconstriction, resulting in increased peripheral vascular resistance. In vitro tests have shown that small concentrations of nicotine can excite the sympathetic nerves and stimulate the adrenal glands to secrete catecholamines.Kaiser et al. applied color Doppler technology to determine the systolic blood flow rate, end-diastolic blood flow rate and resistance coefficient of ocular blood vessels of healthy smokers and nonsmokers, and found that smokers’ blood flow rate was significantly faster than that of nonsmokers, and the vascular resistance coefficient did not show any significant difference, and this change was not observed in the ocular artery and the posterior ciliary artery. This change was more pronounced in the ophthalmic artery and the posterior long ciliary artery, and it was also found that the systolic and diastolic blood pressures of smokers were lower than those of nonsmokers.Langhans et al. applied Doppler flowmetry to determine the retinal blood flow of smokers and nonsmokers before and after the inhalation of pure oxygen, and found that the inhalation of pure oxygen could reduce the retinal blood flow of nonsmokers by 33%, and that it could reduce the blood flow of the optic papillae by 37% and could decrease the arterial pressure by 6%. The results showed that inhalation of pure oxygen reduced retinal blood flow by 33%, optic papillary blood flow by 37%, and arterial pressure by 6% in nonsmokers, while in smokers, retinal blood flow was reduced by 10%, optic papillary blood flow was reduced by 13%, and arterial pressure did not change significantly. This suggests that smokers do not respond significantly to changes in oxygen concentration and that smoking causes changes in capillary regulation. Retinal Vascular Changes: Smokers have a significantly higher rate and degree of atherosclerosis than nonsmokers, which is attributed to nicotine-induced arteriolar constriction, elevation of low-density lipoproteins, lowering of high-density lipoproteins, and elevation of plasma free fatty acid levels. Age-Related Macular Degeneration: Age-related macular degeneration (AMD) is one of the world’s leading blinding eye diseases, and its exact cause is unclear. Most studies have shown that smoking increases the prevalence of age-related macular degeneration, with a risk level ranging from 1.20 to 3.29. Vingerling et al. found that the risk of age-related macular degeneration in smokers was 6.6 times higher than that in nonsmokers in a population-based survey in the Netherlands, and found that there was a dose-response relationship between the amount of cigarettes smoked and its risk factors, and that only those who had ceased smoking for 20 years had a risk level close to that of normal smokers. It was found that there was a dose-response relationship between the amount of smoking and its risk factors, with those who had stopped smoking for more than 20 years having a risk that was close to normal. Similarly, Smith et al. found an association between smoking and age-related macular degeneration in an Australian survey, and found that passive smoking also increased the risk of the disease, with women having a higher risk than men; it was suggested that widespread publicity about smoking cessation could reduce the prevalence of age-related macular degeneration and the incidence of blindness. The exact relationship between the two is unknown, and the main hypotheses are: (1) smoking decreases plasma levels of anti-peroxidants (e.g., vitamin C, selenium, etc.), which protect the retina from damage caused by peroxides, and smoking also increases plasma levels of peroxides, which aggravates the damage caused by peroxides to ocular tissues; (2) smoking can lead to altered choroidal blood flow and retinal arteriosclerosis, causing ischemic retinal damage; and (3) smoking can lead to ischemia and ischemia of the retina, which can lead to ischemia and ischemia in the retina. which causes ischemic changes in the retina, thus indirectly affecting the development of age-related macular degeneration; (3) Smoking can directly contribute to the growth of subretinal neovascularization. Diabetic retinopathy: Diabetic retinopathy is currently the world’s leading blinding eye disease, which affects a large number of factors, so far there is no effective treatment, studies have shown that smoking is also related to its development. Morgado et al, through the observation of diabetic patients, found that smoking caused a significant reduction in retinal blood flow, as well as a decrease in the ability to self-regulate oxygen uptake, exacerbating ischemia and hypoxia in the retinal tissue. This is due to the fact that carbon monoxide, another major component of tobacco, has a very high affinity for hemoglobin in the blood, which reduces the oxygen-carrying capacity of the blood and thus aggravates the progression of diabetic retinopathy. However, some studies have not shown a positive correlation between the two. Based on the available data, it is not certain that smoking increases the prevalence or exacerbates the progression of diabetic retinopathy, but it may be that smoking leads to an earlier age of death in smokers, depriving them of the opportunity to develop retinopathy. Given that diabetic retinopathy is still an ischemic disease of the retina, and that smoking leads to reduced blood flow to the retina, it is necessary to advise diabetics to stop smoking. 5, optic nerve disease: cigarette toxic amblyopia: cigarette toxic amblyopia manifested as bilateral optic neuropathy, mainly in cigar smoking middle-aged and elderly male patients, often manifested as bilateral symmetric, painless vision loss and the center of the dark spot, after stopping smoking can be partially restored to vision. The exact pathogenesis of smoke-intoxicated amblyopia is not known, and nicotine is not a major factor. This is due to the fact that smoke-intoxicated amblyopia occurs in only a very small number of smokers and does not correlate with the amount of cigarettes smoked, suggesting that its onset is multifactorial. The most common secondary risk factor is alcohol consumption, which has been referred to in the past as tobacco-alcohol toxic amblyopia, but it is not clear who is the primary factor. Other associated factors include malnutrition and impaired vitamin B metabolism, etc. Oku et al. found that cyanide in smoke was a major contributor to optic nerve damage, especially when accompanied by vitamin B deficiency. Anterior ischemic optic neuropathy: Anterior ischemic optic neuropathy is an acute, painless visual disorder caused by obstruction of blood flow to the anterior portion of the optic nerve, which is related to the local anatomy of the eye and a variety of systemic factors, including cigarette smoking.Chung et al. found that cigarette smoking was associated with the development of this condition in 137 cases, and that cessation of cigarette smoking decreased the risk of this condition. However, there have been isolated reports of no correlation. Although the association between smoking and the development of anterior ischemic optic neuropathy has yet to be further determined, most physicians believe that smoking should be discontinued in middle-aged and older adults. Graves’ ophthalmopathy: Graves’ ophthalmopathy is an eye disease in which elevated levels of thyroxine result in hypertrophy of the eye muscles and protrusion of the eyeballs. The exact cause of the disease is unclear and may be related to autoimmunity, genetics and certain environmental factors are also involved in its development. Epidemiologic data show that smoking can also cause or exacerbate the progression of Graves’ ophthalmopathy, with a risk level ranging from 2.10 to 7.70. Tallsteds et al. found that the proportion of smokers who developed Graves’ ophthalmopathy was significantly higher in smokers (19%) than in nonsmokers (8%), and found that blood levels of pro-thyroid hormone receptors were significantly higher in smokers than in nonsmokers. thyroxine receptor levels were found to be significantly higher in smokers. The possible relationship between the two is that smoking inhibits iodine uptake and organicization; it may also be that benzene in smoke damages the sympathetic nervous system, which in turn affects thyroid function. Strabismus: Hakim et al. investigated the risk factors for the development of strabismus in young children and found that maternal smoking during pregnancy increased the odds of having a child with internal strabismus by a factor of 1.8, and when combined with a low birth weight (<2500 g), the risk increased to 8.2. Chew et al. also found that pregnant women who smoked more than two packs of cigarettes per day had children with an increased risk of internal strabismus by a factor of 1.83, and an increased risk of external strabismus by a factor of 2.32. The risk of developing external strabismus increased by 2.32 times. To summarize, smoking is a preventable risk factor that is harmful to human health, and many harmful components contained in tobacco cause damage to the heart, lungs and cerebrovascular system. In the eye, it is mainly closely related to senile cataract and age-related macular degeneration; it is also related to retinal ischemic disease, anterior ischemic optic neuropathy, as well as toxic amblyopia from tobacco and alcohol and Graves' ophthalmopathy. Smoking not only jeopardizes one's own health, but also the health of the surrounding population and the next generation. Therefore, ophthalmologists should take the lead in not smoking and actively promote smoking cessation; and make patients aware of the harmful effects of smoking on ocular tissues in their clinical practice.