Effects of smoking on tear film and ocular surface

Indoor air pollution and human ocular diseases: Associated contaminants and underlying pathological mechanisms

People spend a long time indoors, especially young children. The risk of indoor pollution on human health is one of the current hotspots in environmental and public health. The human ocular surface is highly susceptible to indoor environment quality. Epidemiological data have linked human ophthalmological disorders with exposure to indoor pollution. In this review, we summarized the adverse impacts of indoor pollution on the human ocular surface. Several studies demonstrated that indoor contaminants including particulate matter, volatile/semi-volatile organic compounds, heavy metals, and fuel combustion and cigarette smoke exposure were associated with the incidence of human dry eye, conjunctivitis, glaucoma, cataracts, age-related macular degeneration, and keratitis. In addition, toxicological investigations revealed that indoor pollution-induced induced chronic inflammation, oxidative damage, and disruption of tight junctions are the main underlying pathological mechanisms for ocular surface diseases. Taken together, this review may expand the understanding of pollution-induced eye disorder and highlight the importance of reducing associated contaminants to decrease their detrimental effects on human eyes.

The effects of tobacco waterpipe smoking on the ocular surface

CLINICAL RELEVANCE

This study was conducted to determine the effect of tobacco waterpipe smoking on the ocular surface. The findings could be useful in understanding ocular surface changes and associated symptoms in waterpipe smokers.

BACKGROUND

Tobacco smoking has been reported to have many systemic and ocular adverse effects. However, the effect of specific delivery methods of tobacco using a waterpipe on the eye has not been commonly studied.

METHODS

This study enrolled 33 waterpipe smokers (with no history of cigarette smoking) and 31 non-smokers of age-matched control group. Participants were tested in the following sequence: the presence of ocular symptoms using Ocular Surface Disease Index questionnaire, tear osmolarity, tear film break-up time and corneal staining. Statistical analysis using unpaired sample t-tests was performed to study the difference in ocular surface parameters obtained for each group. The prevalence of dry eye disease was also measured in each group.

RESULTS

The mean tear osmolarity values and corneal staining were significantly higher (P < 0.05) in the waterpipe smoking group (314.64 ± 15.24 mOsm/L and 0.73 ± 0.94, respectively) compared to non-smokers (306.42 ± 13.48 mOsm/L and 0.10 ± 0.30, respectively). The mean values obtained from tear film break-up time test were significantly lower (P < 0.05) in the waterpipe smoking group (5.82 ± 3.77 s) compared to non-smokers (8.32 ± 3.46 s). The difference in the average Ocular Surface Disease Index scores in the study groups was not statistically significant (P > 0.05). The prevalence of dry eye disease was significantly higher (p < 0.05) in the waterpipe smoking group (57.6%), compared to the control group (35.5%).

CONCLUSION

Waterpipe smoking could have a significant effect on tear film parameters and be associated with dry eye disease. Dryness also seems to be more prevalent among waterpipe smokers.

Association of dry eye disease with smoking: A systematic review and meta-analysis

There is conflicting evidence for the association between smoking and dry eye disease (DED). We conducted a meta-analysis to determine the true relationship between smoking and DED. A systematic literature search was performed using electronic databases, including PubMed, Embase and Cochrane Library, till August 2021 to identify observational studies with data on smoking as risk factor of DED. Quality assessment of the included studies was conducted using Joanna Briggs Institute (JBI) critical appraisal checklists. The random-effects model was used to calculate the pooled odds ratio (OR). Heterogeneity was evaluated by Cochrane Q and I² index; in addition, subgroup, sensitivity, and meta-regression analyses were performed. Publication bias was assessed using funnel plot and Egger’s regression test. A total of 22 studies (4 cohort and 18 cross-sectional studies) with 160,217 subjects met the inclusion criteria and were included in this meta-analysis. There is no statistically significant relationship between current smokers (OR_adjusted = 1.14; 95% CI: 0.95–1.36; P = 0.15; I² = 84%) and former smokers (OR_adjusted = 1.06; 95% CI: 0.93–1.20; P = 0.38; I² = 26.7%) for the risk of DED. The results remained consistent across various subgroups. No risk of publication bias was detected by funnel plot and Eggers’s test (P > 0.05). No source of heterogeneity was observed in the meta-regression analysis. Our meta-analysis suggest current or former smoking may not be involved in the risk of dry eye disease. Further studies to understand the mechanism of interaction between current smokers and formers smokers with DED are recommended.

The effect of active smoking, passive smoking, and e-cigarettes on the tear film: An updated comprehensive review

Active tobacco smoking, passive smoking, and e-cigarette smoking have been associated with different systemic and ocular diseases. The precorneal tear film plays an important role in eye health and its analysis can provide useful information on ocular status. This review investigates the effects of different types of smoking on the precorneal tear film, by analyzing the peer-reviewed literature on this topic. Specifically, tear evaporation rate, stability, volume, ferning, osmolarity, and physical composition (lipids and proteins) of tear film are detailed. Most of the reported works show that cigarette smoking reduces tear film stability and quality by affecting its components. This review highlights that smoking severely affects the tear film, but a single test is not sufficient to determine these effects because smoking can impact different parts of the eye.

Dry eye disease and retinal nerve fiber layer changes in chronic smokers

Purpose:

To study the effect of smoking on tear film parameters and retinal nerve fiber layer thickness (RNFL) in chronic smokers.

Methods:

This was a cross-sectional study, which included 60 (120 eyes) smokers who have smoked at least 10 pack-year and an equal number of healthy subjects as a control for comparison. In addition to history, a detailed slit-lamp examination was done to evaluate the anterior and posterior segments. All patients underwent Schirmer’s I test (SIT) with Whatman-41 filter paper, tear meniscus height (TMH), and RNFL with a Fourier-domain optical coherence tomography (OCT) and tear film breakup time (TBUT) with 2% fluorescein and cobalt blue filter using slit-lamp biomicroscopy.

Results:

The (mean ± SD) age of the participants was 56.48 ± 10.38 years. There was a statistically significant reduction in tear film parameters in smokers compared to nonsmokers (P = 0.000). The incidence of MGD was found to be higher in smokers when compared to nonsmokers with a P value of 0.000. RNFL in all four quadrants was also significantly reduced in smokers compared to nonsmokers (P = 0.00).

Conclusion:

This study shows that chronic smoking leads to an increased incidence of dry eye disease and is associated with RNFL thinning. Smoking can result in cumulative RNFL loss in patients with ocular neurodegenerative disorder and OCT of these patients may have to be interpreted keeping this in mind.

The Effect of Hemodialysis on Axial Length, Ocular Surface, and Intraocular Pressure in Patients with End-Stage Renal Failure

Purpose

To evaluate the changes in intraocular pressure (IOP), central corneal thickness (CCT), axial length, and ocular surface in patients with end-stage renal failure after single-session hemodialysis treatment and to examine the correlation of these findings with systemic hemodynamic parameters.

Patients and Methods

A total of 112 eyes of 112 patients enrolled in a hemodialysis treatment program for three times a week (approximately four hours per session) for at least three months in our hospital between December 2019 and March 2020 were included in the study. Approximately 30 minutes before and after hemodialysis, the best-corrected visual acuity measurement, slit-lamp examination, IOP measurement, and dilated fundus examination with the Goldmann applanation tonometer were performed in all patients. The axial length measurement was undertaken by ultrasonic biometry, and the CCT measurement by ultrasonic pachymetry. The ocular surface evaluation was performed based on the tear breakup time (BUT), basal secretion time (BST) and keratoepitheliopathy score. Blood pressure, serum osmolarity, and body weight were measured before and after hemodialysis.

Results

The mean IOP decreased from 12.2 ± 3.5 to 10.8 ± 2.2 mmHg, and the mean decrease was 1.4 ± 2 mmHg, indicating statistical significance (p<0.001). The mean CCT dropped from 502 ± 41.2 to 494.1 ± 35.4 μm, and the mean decrease was 8.1 ± 7.7 μm, which also indicated a statistically significant change (p<0.001). The mean axial length was reduced from 23.1 ± 0.8 to 22.9 ± 0.8 mm. The reduction in the axial length was significant with an average value of 0.26 ± 0.15 mm (p<0.001). When the ocular surface changes were examined, BUT decreased from 7.4 ± 3.1 to 6.3 ± 2.5 s, BST from 8.6 ± 1.7 to 6.6 ± 1.3 mm, and the keratoepitheliopathy score increased from 0.36 ± 0.61 to 1.59 ± 0.93, and all these changes were statistically significant (p<0.001). There was a significant correlation between the axial length change and the IOP change (r=0.202, p=0.03). A significant correlation was also observed between BST and plasma colloid osmotic pressure (r=−0.268, p=0.004). In addition, there was a strong correlation between serum osmolarity and the keratoepitheliopathy score (r=−0.437, p<0.001).

Conclusion

Hemodialysis causes significant changes in IOP, CCT, axial length, and ocular surface. These changes should be considered in the ophthalmological examination of patients after the hemodialysis session.

Effect of Smoking on Tear Stability and Corneal Surface

Purpose

To determine the effect of smoking on tear stability and ocular surface of the cornea among students aged between 19 and 25 years. This study also aimed to find a correlation between tear film stability with a score of McMonnies Dry Eye Questionnaire (MDEQ) and Ocular Surface Disease Index Questionnaire (OSDI).

Methods

This is a prospective, non-interventional, comparative study of 59 male (27 smokers and 32 non-smokers) undergraduates of a public university. Tear film stability was evaluated using non-invasive tear break-up time and fluorescein tear break-up time. Corneal staining was determined using Efron grading scale. MDEQ and OSDI Questionnaires were used to assess dry eye symptoms. Data were obtained from the right eye only and analyzed using descriptive and correlation analysis.

Results

The age range of the participants was between 19 and 25 years. The mean age for smokers and non-smokers was 22.19 ± 2.20 and 21.22 ± 1.83 years, respectively (P = 0.07). The smoker group had statistically significant lower tear film stability than the non-smoker group (P < 0.0001). Corneal staining was statistically significant higher at the nasal and temporal parts of the cornea in smokers (P < 0.05). There was a moderate correlation between tear film stability and scores of MDEQ and OSDI.

Conclusions

Tobacco smoke has a significant effect on the tear film stability, seen in reduced tear stability values among smokers. Corneal staining was found to be more extensive in the smokers. These findings would be useful to eye-care providers in the management of their dry eye patients related to smoking.

Illicit drugs: Effects on eye

There is a myriad of changes that can be produced in the eye by toxic drugs ranging from mild/no symptoms to severe loss of vision from endophthalmitis. The routes of administration include oral ingestion, smoking, nasal inhalation, intravenous injection, topical application or application to other mucosal surfaces. It is important to recognize certain clinical signs and symptoms in the eye produced by these toxins. This article describes in brief some of the ocular effects of commonly abused drugs. For identification of a particular poisoning, in addition to the clinical presentation, pulse, blood pressure, respiration and body temperature, pupillary size, pupillary reaction to light, ocular convergence and nystagmus can be useful indicators of the type of drug the patient is exposed to. Unmasking these features help the clinician in an early and accurate diagnosis of the offending drug as well as timely management.

Ocular conditions and dry eye due to traditional and new forms of smoking: A review

Addiction to cigarette smoking has high prevalence rates recorded worldwide. Smoking has been linked to several life-threatening systemic conditions such as cancer, heart attack and stroke, in addition to a range of ocular pathologies. In recent years, electronic cigarettes (EC) have emerged as alternatives to smoking. ECs are nicotine delivery devices which produce an aerosol by heating, rather than combusting, a liquid which contains nicotine, flavours and preservatives. This review focuses on the association of traditional and new forms of smoking with dry eye disease, contact lens wear and four other common ocular diseases: cataract, age-related macular degeneration, glaucoma and Graves' ophthalmopathy. It is concluded that smoking and vaping appear as a risk factor for the aforementioned ocular conditions. An evidence-based, clear link between cigarette smoking, or EC vaping and ocular problems is yet to be discovered.

Ocular Surface, Meibomian Gland Alterations, and In Vivo Confocal Microscopy Characteristics of Corneas in Chronic Cigarette Smokers

PURPOSE

To evaluate the ocular surface, meibomian gland alterations, and in vivo confocal microscopy (IVCM) parameters through correlation with nicotine dependency level (NDL) and duration of smoking (DS) in chronic smokers.

METHODS

This cross-sectional study included 50 eyes of 50 chronic smokers, and 50 eyes of 50 age- and gender-matched healthy nonsmokers. To examine the ocular surface and tear film, corneal sensitivity (CS) measurement with Cochet-Bonnet esthesiometer, tear film break-up time (TBUT), lissamine green (LG) staining, Schirmer I test with anesthesia, and Ocular Surface Disease Index (OSDI) questionnaire were performed consecutively. Basal epithelial cell, keratocyte, and endothelial cell density, the percentage of endothelial polymegethism/pleomorphism, and subbasal nerve plexus were evaluated using IVCM. Meibomian gland density was evaluated with a meibography unit. The Fagerström test was used to measure NDL, and DS was recorded.

RESULTS

In the chronic smokers group, the basal epithelial cell density, anterior and posterior keratocytes, endothelial cell density, and long and total subbasal nerve numbers were lower, and LG staining, meiboscore, and OSDI scores were higher, compared with the control group, whereas other parameters were similar. The percentage of polymegethism was higher and the percentage of pleomorphism was lower in the chronic smokers group. In the correlation analysis, no significant relationship was found between the DS, NDL and ocular surface, and IVCM findings.

CONCLUSION

Decreased corneal basal epithelium, anterior and posterior keratocytes, endothelial cell density, meibomian gland density, and subbasal nerve numbers were found in chronic smokers. The results of the study show that smoking has an adverse effect on ocular surface parameters.

Associations with Corneal Hysteresis in a Population Cohort: Results from 96 010 UK Biobank Participants

PURPOSE

To describe the distribution of corneal hysteresis (CH) in a large cohort and explore its associated factors and possible clinical applications.

DESIGN

Cross-sectional study within the UK Biobank, a large cohort study in the United Kingdom.

PARTICIPANTS

We analyzed CH data from 93 345 eligible participants in the UK Biobank cohort, aged 40 to 69 years.

METHODS

All analyses were performed using left eye data. Linear regression models were used to evaluate associations between CH and demographic, lifestyle, ocular, and systemic variables. Piecewise logistic regression models were used to explore the relationship between self-reported glaucoma and CH.

MAIN OUTCOME MEASURES

Corneal hysteresis (mmHg).

RESULTS

The mean CH was 10.6 mmHg (10.4 mmHg in male and 10.8 mmHg in female participants). After adjusting for covariables, CH was significantly negatively associated with male sex, age, black ethnicity, self-reported glaucoma, diastolic blood pressure, and height. Corneal hysteresis was significantly positively associated with smoking, hyperopia, diabetes, systemic lupus erythematosus (SLE), greater deprivation (Townsend index), and Goldmann-correlated intraocular pressure (IOPg). Self-reported glaucoma and CH were significantly associated when CH was less than 10.1 mmHg (odds ratio, 0.86; 95% confidence interval, 0.79-0.94 per mmHg CH increase) after adjusting for covariables. When CH exceeded 10.1 mmHg, there was no significant association between CH and self-reported glaucoma.

CONCLUSIONS

In our analyses, CH was significantly associated with factors including age, sex, and ethnicity, which should be taken into account when interpreting CH values. In our cohort, lower CH was significantly associated with a higher prevalence of self-reported glaucoma when CH was less than 10.1 mmHg. Corneal hysteresis may serve as a biomarker aiding glaucoma case detection.

Acute tobacco smoke exposure exacerbates the inflammatory response to corneal wounds in mice via the sympathetic nervous system

Exposure to tobacco smoke is a major public health concern that can also affect ophthalmic health. Based on previous work demonstrating the important role of the sympathetic nervous system (SNS) in corneal wound repair, we postulated that acute tobacco smoke exposure (ATSE) may act through the SNS in the impairment of corneal wound repair. Here we find that ATSE rapidly increases the markers of inflammatory response in normal corneal limbi. After an abrasion injury, ATSE exaggerates inflammation, impairs wound repair, and enhances the expression of nuclear factor-κB (NF-κB) and inflammatory molecules such as interleukin-6 (IL-6) and IL-17. We find that chemical SNS sympathectomy, local adrenergic receptor antagonism, NF-κB1 inactivation, and IL-6/IL-17A neutralization can all independently attenuate ATSE-induced excessive inflammatory responses and alleviate their impairment of the healing process. These findings highlight that the SNS may represent a major molecular sensor and mediator of ATSE-induced inflammation.

Impact of Smoking on the Ocular Surface, Tear Function, and Tear Osmolarity

PURPOSE

This study evaluated the effects of cigarette smoking on the ocular surface, tear function, and tear osmolarity.

MATERIALS AND METHODS

A total of 50 smokers with at least 5 years of heavy smoking (defined as 1 pack/day) and 51 nonsmoking, healthy individuals were enrolled. Tear osmolarity was measured with an osmometer (TearLab^™ Osmolarity System). Ocular surface examinations involved corneal fluorescein staining, measurement of the tear film breakup time (TBUT), the Schirmer 1 test, measurement of corneal sensitivity with a Cochet-Bonnet esthesiometer, and conjunctival impression cytology. Dry eye symptoms were scored using the Ocular Surface Disease Index (OSDI) questionnaire. The results were compared with those from an age and sex-matched control group. The Chi-squared and independent sample t-tests were used for statistical analyses.

RESULTS

The smokers had significantly higher tear osmolarity values (305.38 ± 9.81 vs. 301.14 ± 7.04 mOsm/L; p = 0.014) and OSDI scores (34.13 ± 16.58 vs. 18.09 ± 9.61; p < 0.001) than the healthy controls. However, the TBUT, corneal sensitivity, and goblet cell density were significantly lower in smokers compared to healthy controls, but the fluorescein staining and Schirmer 1 test results were not statistically different between the smokers and controls.

CONCLUSION

Smoking results in increased osmolarity of the tear film, which can damage the ocular surface and tear function.

External eye symptoms in indoor environments

Eye irritation, for example dry or irritated eyes, is generally among top three reported symptoms in office-like environments, in particular among workplaces with cognitive demanding visual display unit (VDU) work. The symptoms are especially among middle and advanced ages and particularly among women more than men. The symptoms are also among the most commonly reported complaints in the eye clinic. To be in a position to interpret the high prevalence of eye symptoms, a multidisciplinary and integrated approach is necessary that involves the external eye physiology (separate from internal eye effects), eye diseases (evaporative dry eye (DE), aqueous-deficient DE, and gland dysfunctions), and risk factors that aggravate the stability of precorneal tear film (PTF) resulting in hyperosmolarity and initiation of inflammatory reactions. Indoor environmental, occupational and personal risk factors may aggravate the PTF stability; factors such as age, contact lenses, cosmetics, diet, draft, gender, low humidity and high temperature, medication, outdoor and combustion pollutants, and VDU work. Psychological stressors may further influence the reporting behavior of eye symptoms. The impact of the risk factors may occur in a combined and exacerbating manner.

Prevalence of ocular surface disease symptoms and risk factors in group of university students in Monterrey, Mexico

Background

The objective of this study was to determine the prevalence of symptoms of ocular surface disease and its relationship with associated risk factors in students from the University of Monterrey using Ocular Surface Disease (OSDI) questionnaire.

Methods

A cross-sectional survey was conducted between October and December 2014 to assess the prevalence and risk factors for ocular surface disease in a group of students from Universidad de Monterrey in Monterrey, Mexico. The severity of the disease was measured via the Ocular Surface Disease Index (OSDI) questionnaire.

Results

The OSDI average value was 26.85 ± 20.79 points, with 70.4% of students (579) had OSDI score higher than 12 points. Women had ocular surface disease 1.63 times more than men (OR 1.29, 95% CI 1.13,1.48). Students who used ophthalmic drops have an OR 2.00 (95% CI 1.65,2.40), and students who smoke have an OR 1.24 (95% CI 1.06,1.46). Use of contact lenses, hours in front of computer or history of refractive surgery has low-estimated effect on the probability of presenting an ocular disease.

Conclusions

University students have a prevalence of 70.4% of ocular surface disease (OSD). OSD was associated with gender (women have a higher prevalence), smoking and the use of eye drops. A program to modify these risk factors to reduce the prevalence is needed.

Impact of Cigarette Smoking on Tear Function and Correlation between Conjunctival Goblet Cells and Tear MUC5AC Concentration in Office Workers

The first aim of this study was to clarify whether cigarette smoking affects tear secretion, goblet cell density, and tear MUC5AC concentration. The second purpose was to evaluate the correlations of conjunctival goblet cell density with tear MUC5AC concentration and other ocular surface evaluation factors. This cross-sectional study included 88 office workers. All subjects were required to fill in dry eye and smoking questionnaires, in addition to ocular surface evaluation. Tear wash fluid was collected from inferior fornix, and conjunctival epithelium was obtained by impression cytology. Tear MUC5AC concentration was quantified using enzyme-linked immunoassay, and conjunctival goblet cell density was counted after Periodic-acid Schiff staining. Tear MUC5AC concentration had significant positive correlation with conjunctival goblet cell density (r = 0.181, P = 0.03). In current smokers, Schirmer I test value, goblet cell density and tear MUC5AC concentration were significantly lower than non-smokers. Pack-years of smoking have significant negative correlation with goblet cell density (r = −0.174, P = 0.036) and tear MUC5AC concentration (r = −0.183, P = 0.028). We concluded that smoking might decrease tear secretion, goblet cell density and tear MUC5AC concentration. In addition, MUC5AC concentration in tears depends on goblet cell density in the conjunctiva among office workers.

Prevalence of and risk factors associated with dry eye: the Korea National Health and Nutrition Examination Survey 2010-2011

PURPOSE

To investigate the prevalence of and risk factors associated with dry eye syndrome (DES) in South Korea.

DESIGN

Cross-sectional study.

METHODS

In 2010 and 2011, 11,666 subjects, ranging in age from 19 to 95, were randomly selected as nationally representative participants in the Korea National Health and Nutrition Examination Survey (KNHANES). Subjects were divided into 2 groups: 1 with clinically diagnosed DES and 1 with symptoms of dry eye. We determined the prevalence of and risk factors for dry eyes in a Korean population. Health-related quality of life (HRQoL), measured by the EuroQoL-5 dimension (EQ-5D), was evaluated in patients with dry eyes.

RESULTS

The mean age was 49.9 years. The overall prevalence of diagnosed DES was 8.0% (95% confidence interval [CI], 7.3% to 8.7%), and of dry eye symptoms the prevalence was 14.4% (95% CI, 13.1 to 15.7). Age (adjusted odds ratio [aOR] = 1.8, 1.6), female (aOR = 2.8, 1.9); history of eye surgery (aOR = 2.6, 2.2); stress (aOR = 1.7, 1.6); thyroid disease (aOR = 1.7, 1.5); and high education level (aOR = 1.6, 1.5) were common risk factors in the groups. Subjects who had undergone ptosis, cataract or refractive surgery were more likely to have dry eye than subjects with no history of eye surgery. Means of pain and anxiety dimensions in the EQ-5D and the Euro Quality of Life Visual Analog Scale (EQ-VAS) were significantly higher in the group with diagnosed DES than in the normal group.

CONCLUSIONS

The risk factors were mostly similar in both groups. It is thought there are more patients with DES who have not been diagnosed by doctors. Doctors should identify whether a patient has any risk factors for dry eye. Patients need to be educated about the modifiable factors of DES.

Is household air pollution a risk factor for eye disease?

In developing countries, household air pollution (HAP) resulting from the inefficient burning of coal and biomass (wood, charcoal, animal dung and crop residues) for cooking and heating has been linked to a number of negative health outcomes, mostly notably respiratory diseases and cancers. While ocular irritation has been associated with HAP, there are sparse data on adverse ocular outcomes that may result from acute and chronic exposures. We consider that there is suggestive evidence, and biological plausibility, to hypothesize that HAP is associated with some of the major blinding, and painful, eye conditions seen worldwide. Further research on this environmental risk factor for eye diseases is warranted.

Passive smoking as a risk factor of dry eye in children

Purpose. Adult active smoking is a risk factor for dry eye. We hypothesize that passive smoking in children can also produce the same effects. Methods. We included 112 school children presenting with eye discomfort. Assessment of eye dryness and its severity levels depending on symptoms of dry eye, visual symptoms, tear breakup time (TBUT), Schirmer-1 test, and corneal fluorescein staining were done for all of them. Exposure to cigarette smoking was assessed by history-taking and urinary cotinine levels. Results. Dry eye was found in 80/112 children. Passive smoking was documented in 76/112 children. Number of cigarettes to which the child was exposed per day and the duration of exposure to passive smoking were significantly higher in children with dry eye compared to those without. Urinary cotinine, and cotinine/creatinine ratio (CCR) was significantly higher in children with dry eye compared to those without dry eye. Multiregression analysis showed that the most important determinants of dry eye were CCR and number of cigarettes/day. Conclusion. Passive smoking represents a significant risk factor of dry eye in children comparable to that shown with active adult smoking. Male children are more prone to this effect.

Goblet cells of the normal human bulbar conjunctiva and their assessment by impression cytology sampling

Goblet cells of the conjunctiva are the main source of mucus for the ocular surface. The objectives of this review are to consider the goblet cells as assessed by various histological, cytological and electron microscopy methods, and to assess the consistency of published reports (over more than 25 years) of goblet cell density (GCD) from impression cytology specimens from nominally healthy human subjects. Reported GCD values have been notably variable, with a range from 24 to 2226 cells/mm² for average values. Data analysis suggests that a high density of goblet cells should be expected for the healthy human conjunctiva, with a tendency toward higher values in samples taken from normally covered locations (inferior and superior bulbar conjunctiva) of the open eye (at 973 +/- 789 cells/ mm²) than in samples taken from exposed (interpalpebral) locations (at 427 +/- 376 cells/mm²). No obvious change in GCD was found with respect to age, perhaps because the variability of the data did not allow detection of any age-related decline in GCD. Analyses of published data from 33 other sources indicated a trend for GCD to be lower than normal across a spectrum of ocular surface diseases.

The effect of smoking on the ocular surface and the precorneal tear film

BACKGROUND

Smoking, both active and passive, creates a plethora of health-related problems, which primarily affect the cardiovascular and respiratory systems. There is very little evidence on the effects of tobacco smoke on the eye, especially regarding anterior ocular surface related pathology. This study was undertaken to determine the effects of smoking on the ocular surface and the tear film in smokers.

METHODS

A total of 51 (102 eyes) smokers and 50 (100 eyes) age-and gender-matched healthy non-smokers were included in this study. The ocular surface was evaluated by measuring tear film break-up time, surface staining with fluorescein, and corneal and conjunctival sensitivities, and by completing the Schirmer's II test. Data was analysed using Statistical Package for Social Sciences (SPSS) version 11.5. A p value less than 0.05 was considered statistically significant.

RESULTS

The smoker group had significantly lower tear film break-up time, and corneal and conjunctival sensitivity than the nonsmoker group. Punctate staining was significantly higher in the smoker group than the non-smoker group. There was no statistically significant difference in Schirmer's II test results between the smoker and non-smoker group.

CONCLUSION

Smoking caused adverse effects on the precorneal tear film and there was strong association between smoking and tear film instability. Although a causative relationship could not be determined, there is a need for further longitudinal studies.

"Healthy" eye in office-like environments

Eye irritation symptoms, e.g. dry eyes, are common and abundant symptoms reported in office-like environments, e.g. aircraft cabins. To improve the understanding of indoor related eye symptomatology, relevant knowledge from the ophthalmological and indoor environmental science literature has been merged. A number of environmental (relative humidity, temperature, draft), occupational (e.g. visual display unit work), and individual (e.g. gender, use of cosmetics, and medication) risk factors have been identified, which are associated with alteration of the precorneal tear film (PTF); these factors may subsequently exacerbate development of eye irritation symptoms by desiccation. Low relative humidity including reduced atmospheric pressure further increases the water evaporation from an altered PTF; in addition, work with visual display units may destabilize the PTF by lower eye blink frequency and larger ocular surface. Results from epidemiological and clinical studies support that relative humidity >40% is beneficial for the PTF. Only few pollutants reach high enough indoor concentrations to cause sensory irritation of the eyes, while an altered PTF may exacerbate their sensory effect. Sustained low relative humidity causes impairment of the PTF, while its stability, including work performance, is retained by low gaze and intermittent breaks.

Smoking associated with damage to the lipid layer of the ocular surface

PURPOSE

To evaluate the effects of smoking on ocular surface.

DESIGN

Prospective, comparative, interventional case series.

METHODS

setting: Institutional. study population: Sixty smokers (33 men, 27 women) and 34 healthy subjects (18 men, 16 women) were enrolled into this study. Patients with associated ophthalmic or systemic diseases, and history of contact lens use and ocular surgery were excluded. The duration of average smoking was 13.1 years (range 5 to 35 years).

INTERVENTION

Ocular surface was evaluated by measuring corneal and conjunctival sensitivity, surface staining with fluorescein, tear film breakup time, Schirmer 1 test, and conjunctival impression cytology. Dry eye symptoms were scored by questionnaire. Kinetic analysis of sequential tear interference images obtained by a DR-1 tear lipid layer interferometry was used to investigate the precorneal lipid layer spread. Results were compared with a control group.

MAIN OUTCOME MEASURES

Comparison of subjective complaints with objective parameters in cigarette smokers and normal subjects.

RESULTS

In the smoker group, the mean Schirmer 1 test value was 10.8 mm (range 8 to 14 mm). The mean breakup time was 5.3 seconds (range 1 to 10 seconds), the average conjunctival sensitivity was 26.2 mm (range 0 to 45 mm), and the average central corneal sensitivity was 37.6 mm (range 5 to 60 mm). There was no statistically significant difference in goblet cell densities or in Schirmer 1 test values between smokers and controls (P > .05). Higher grades of lipid layer changes were observed in smokers by DR-1 interferometry kinetic analysis.

CONCLUSIONS

Smoking has deteriorating effects on the lipid layer of precorneal tear film.