|Year : 2021 | Volume
| Issue : 2 | Page : 245-248
Correlation between cigarette smoking and raised intraocular pressure in males
Sushmita Mukherji1, Soumen Karmakar2, Sibaji Dasgupta3
1 Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, West Bengal, India
2 Department of Psychiatry, Rampurhat Medical College, Kolkata, West Bengal, India
3 Department of Neurosurgery, National Neuroscience Centre, Kolkata, West Bengal, India
|Date of Submission||22-Sep-2020|
|Date of Acceptance||03-May-2021|
|Date of Web Publication||31-May-2021|
Dr. Soumen Karmakar
Senior Resident, Department of Psychiatry, Rampurhat Medical College, West Bengal; c/o Sisir Karmakar, Brahmanigram, Sagardighi, Murshidabad, West Bengal
Source of Support: None, Conflict of Interest: None
OBJECTIVE: Smoking is one of the most important risk factors both in systemic as well as ocular diseases. Its role in pathogenesis of ocular hypertension and open-angle glaucoma has been proposed, but there remains a controversy in the study results. Our aim is to find any association between cigarette smoking and raised intraocular pressure (IOP).
METHODS: This was a cross-sectional study. A total of 60 male subjects were selected according to inclusion and exclusion criteria. Thirty-one were selected using simple random sampling, had raised IOP, among which 17 were smokers. Two-nine matched subjects had normal IOP, with 11 smokers among them. Smoking parameters were classified using Smoking Index as well as pack-years. The correlation between different smoking parameters and IOP was studied and analyzed.
RESULTS: There was a positive association between IOP and smoking overall (P value 0.021). In addition, there was a significant correlation between IOP and pack-years (P value 0.036), as well as IOP and duration of smoking (P = 0.044). However, there was no significant association of daily number of cigarettes smoked with IOP, as well as between mild, moderate, and heavy smokers in terms of intraocular pressure.
CONCLUSION: Smoking is found to be an important risk factor in pathogenesis of ocular hypertension, as well as glaucoma. Lifestyle modification in terms of prohibition of smoking may reduce the overall incidence and progression of glaucoma worldwide.
Keywords: Ocular hypertension, open-angle glaucoma, smoking
|How to cite this article:|
Mukherji S, Karmakar S, Dasgupta S. Correlation between cigarette smoking and raised intraocular pressure in males. Indian J Health Sci Biomed Res 2021;14:245-8
|How to cite this URL:|
Mukherji S, Karmakar S, Dasgupta S. Correlation between cigarette smoking and raised intraocular pressure in males. Indian J Health Sci Biomed Res [serial online] 2021 [cited 2022 Aug 13];14:245-8. Available from: https://www.ijournalhs.org/text.asp?2021/14/2/245/317405
| Introduction|| |
Tobacco smoking remains to be a major health hazard, with more than 1.1 billion adult (≥15 years of age) smokers affected globally in 2015. The global prevalence of adult male smokers in 2015 is 34.83%, whereas in India, it is 20.4% (14.5–27.3); female prevalence is significantly low of 1.9% (1.4–2.5). Smoking affects almost every system of the body and is a well-established risk factor for coronary artery diseases, hypertension, chronic obstructive pulmonary disease (COPD), stroke, and many cancers such as cancers of the lung, bladder, cervix, and esophagus. Among ocular complications, there is a significant risk of cataracts, age-related macular degenerations (ARMD), uveitis, dry eye, and diabetic retinopathy among smokers compared to nonsmokers.
Glaucoma is an optic neuropathy, in which tissue damage occurs at the level of the optic nerve head, resulting in a characteristic alteration of its appearance, as well as visual-field disturbances. Most of these conditions are related to elevated intraocular pressure (IOP), which can also damage the optic nerve directly. Studies have reported that relatively high IOP can cause optic nerve damage and visual-field abnormalities, even if it is within the normal range. High IOP can also affect the progression of visual-field defects in patients with open-angle glaucoma (OAG).
Smoking is thought to be a risk factor for increased IOP, which ranges normally between 10 and 21 mmHg. Ocular hypertension, which is usually defined as IOP higher than normal (IOP >21 mmHg) in the absence of optic nerve damage or visual-field loss, is one of the major risk factors for the development of OAG.
Although several epidemiological studies have reported the association of smoking with glaucoma and elevated IOP, there are some studies which found no association of cigarette smoking with glaucoma or ocular hypertension., Hence, the role of smoking as a risk factor for these remains controversial.
Our aim was to find whether any association existed between smoking and raised IOP.
| Materials and Methods|| |
After receiving due permission from the Institutional Ethics Committee, this cross-sectional study was undertaken from March 2019 to December 2019. Simple random sampling was done, and 31 male patients who have attended the ophthalmology outpatient department of this tertiary care hospital with various ophthalmological symptoms, without any previous history of ophthalmological problems, or ocular surgery (except for corrected refractive error) were selected after obtaining valid consent, and here referred to as Group A. Subsequently, 31 healthy male subjects were selected after age matching from the group of people accompanying the patients, who themselves had no ophthalmological complaints, and fulfilled the inclusion criteria, and referred to here as Group B. However, 2 healthy subjects dropped out of our study, and the total number became 29. Ethical clearance was obtained from Institutional ethical committee, R.G. Kar Medical College, on 16.12.2015, memo no. WB/RGK/1069/2015.
Group A: Patients presenting with various ophthalmological complaints, for example, diminished vision, headache, pain in the eye, redness of the eye and lacrimation, glares etc., who on ophthalmological examination were found to have IOP ≥21 mm of Hg, irrespective of visual-field defects, or optic neuropathy were included. Any abnormality not corroborative with glaucoma/ocular hypertension was excluded.
Group B: Healthy subjects, with no ophthalmological complaints, and without any obvious abnormality found during ophthalmological examination.
After obtaining informed consents from both the groups, demographic data and vital statistics were obtained. All the patients as well as the healthy subjects were subjected to general examination and thorough ophthalmological examinations that include visual acuity testing using Snellen's Chart, direct and indirect ophthalmoscopy, slit-lamp biomicroscopy, 4 mirror gonioscopy, central corneal thickness corrected Goldmann applanation tonometry, and automated perimetry (HFA 24-2).
As IOP of both eyes greatly correlate with one another, mean IOP, instead of IOP of individual eye, has been used, and generally referred to as IOP everywhere in this study.
Detailed information about smoking habits of the subjects was also obtained. Standard pack-years of smoking (defined as the number of packs of cigarettes containing 20 sticks each smoked per day multiplied by the number of years of smoking) was also calculated.
Raw data were tabulated and analyzed using standard statistical software.
| Results|| |
A total of 60 adult male subjects participated in our study, 31 of them (Group A) had raised IOP (≥21mmHg) among other clinical features and 29 healthy subjects (Group B) had normal IOP (10–21 mmHg). The mean age of participants in Group A was found to be 58.11 ± 4.56 years (range: 41–69) and that in Group B was 56.28 ± 4.32 years (range: 41–69). Overall, of all the participants, 28 were found to be smokers (47%). The distribution of all the participants as per IOP and smoking habits is shown in [Figure 1].
|Figure 1: Distribution of overall cases as per intraocular pressure and smoking habits|
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[Table 1] shows the mean IOP of the participants. The mean IOP of smokers in Group A was found to be 24.71 ± 1.86 mmHg and that of nonsmokers to be 23.43 ± 1.45mmHg. In Group B, mean IOP was found to be 16.73 ± 1.85 mmHg and 15.44 ± 1.34 mmHg among smokers and nonsmokers, respectively. Comparison of mean IOPs using unpaired t-test between smokers and nonsmokers was found to be significant both in cases of Group A (P = 0.045) and Group B (P = 0.039).
|Table 1: Comparison of mean intraocular pressure between smokers and nonsmokers (unpaired t-test)|
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Our study also found a significant correlation between duration of smoking in years and IOP (P = 0.044) but not between number of packs of cigarettes smoked daily and IOP (P = 0.309), as shown by Pearson correlation in [Table 2].
|Table 2: Correlation of different smoking parameters with intraocular pressure|
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| Discussion|| |
Smoking till date remains one of the major health problems worldwide. It has harmful effects on almost every organ of our body. Cigarette smoke contains apart from nicotine around 4000 active chemicals such as polycyclic aromatic hydrocarbons, tar, carbon monoxide, and heavy metals, most of them are toxic on chronic exposure. The ocular effects of smoking are thought to be due to its vasospastic and oxidative effect. Cigarette smoke activates mechanism that causes atherosclerotic changes such as vascular inflammation, disruption of endothelial homeostatic functions, and thrombus formation. The polycyclic aromatic hydrocarbons are particularly responsible for atherogenesis. Nicotine causes a rise in catecholamines leading to a rise in heart rate and blood pressure. The carbon monoxide in cigarette smoke, especially in chronic smokers, causes structurally irreversible damage to vessels also leading to a rise in blood pressure. Increased white blood cells, platelet aggregation and adhesiveness, fibrinogen level, and changes in serum lipids characterize the response to smoking. This effect increases thrombus formation and release of growth factors that lead to vascular smooth muscle cell proliferation.
Ocular complications of smoking include cataract, ARMD, uveitis, and dry eye. Macular degeneration is promoted by interfering with blood flow to the retina causing deterioration of the macula leading to disturbed central vision.
Some previous studies have found a positive association between cigarette smoking and increased IOP., It is thought that increased outflow resistance to aqueous humor by episcleral veins and peripheral ocular circulation due to an increase in blood viscosity accompanied by an increase in hematocrit and fibrinogen might elevate IOP., Another mechanism suggested that high blood pressure (BP), especially elevated systolic BP, might elevate IOP by increasing ultrafiltration of the aqueous humor through the elevation of ciliary artery pressure. Researchers using laser Doppler velocimetry and retinal photography, and the blue-field simulation technique, respectively, reported that retinal blood flow rate decreased by 10%–12% in habitual smokers. Also reported, in rabbits, a 20% reduction in choroidal blood flow was caused by a single inhalation of cigarette smoke.,,
Our study found that there exists a statistically significant difference in IOP between smokers and nonsmokers (P = 0.021) which is corroborative to the previous studies.,
This study also found a significant correlation between pack-years of smoking and raised IOP (P = 0.036). Another observation was that it was the duration of smoking which was more important in the pathogenesis of increased IOP (P = 0.044) than the number of cigarettes smoked daily (P = 0.309).
Furthermore, the odds ratio for high IOP between smokers and nonsmokers was 1.98, which signifies that smokers twice susceptible to raised IOP.
There are some shortfalls of our study. The sample size was small, hence not truly reflective of the entire population. We did not include women in our study, as the prevalence of smoking is low in them. Other forms of tobacco like chewable are more common practice among them. Even among males, we excluded Gutka, Khaini, and Zarda which are other forms of tobacco not used for smoking. In addition, we have not taken into account in our analysis the presence of other comorbidities such as diabetes, hypertension, and COPD, which correlates both with glaucoma and smoking. Also, alcohol consumption and other addictive substances may add a synergistic effect to the raised IOP. We did not study the effect of passive smoking on IOP. Also, we did not differentiate between different types of preparations available, for example, bidis, cigars, hand-rolled cigarettes, and pipes. These may vary according to their tobacco content and other active ingredients.
Despite these drawbacks, our study was clearly able to demonstrate a significant association between smoking and ocular hypertension.
| Conclusion|| |
Smoking is a modifiable and known risk factor for many serious ailments. However, its risk association with ocular morbidities is somewhat lesser known. Estimated 11.2 million persons with glaucoma, among which 6.48 million were primary open-angle type, were prevalent in India in 2010. Glaucoma is the second leading cause of blindness in the world and estimates put the total number of suspected cases of glaucoma at over 60 million worldwide.
Since high IOP is not only a risk factor for glaucoma but also accelerates its progression, and smoking seems to be one of the important and modifiable risk factors associated, the prohibition of smoking may halt the overall burden of glaucoma, and thus blindness associated with it.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]