Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 7  |  Issue : 1  |  Page : 13-18  

Dry eye syndrome: A rising occupational hazard in tropical countries


1 Department of Ophthalmology, Padmshree Dr D Y Patil Medical College, Pimpri, Pune, India
2 Department of Ophthalmology, SBKS Medical Institute and Research Center, Vadodara, Gujarat, India

Date of Web Publication10-Dec-2013

Correspondence Address:
Kavita R Bhatnagar
B 4/21, Brahma Aangan, Off Salunke Road, Kondhwa, Pune - 411 048
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-2870.122755

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  Abstract 

Aim : The aim of this study was to find out the prevalence of dry eye and evaluate personal and environmental risk factors attributable to dry eye in a hospital-based population. Materials and Methods : In this cross-sectional study, 1890 patients above 15 years of age were screened randomly for dry eye. McMonnies Dry Eye Questionnaire, Schirmer's test, tear film breakup time (TBUT), presence of conjunctival injection, punctate epithelial erosions (PEE), and meibomian gland dysfunction (MGD) were used to diagnose dry eye. Patient demographics including age, sex, smoking, and occupation and working environment were also recorded. Correlation of dry eye signs with symptoms and TFBUT and Schirmer's tests was also assessed. Results : The prevalence of dry eye was 10.58%. The prevalence was higher in outdoor workers (17.77%). The male: female ratio was 2.33:1. The number of males was highest in the 56-60 (13%) and 60-65 (14%) years age groups while that of females was highest in the 46-50 (16.67%) years age group. A total of 10% of the patients were smokers, while 8% were tobacco chewers. A 2.15-fold increase was found in the odds for dry eye in those exposed to excessive wind, 1.91-fold to sunlight exposure, and 2.04 for air pollution. Abnormally low TBUT and Schirmer's tests were significantly associated with dry eye signs (P=0.009 and 0.014, respectively). Conclusion : Dry eye is a leading cause of ocular discomfort in OPD patients. Excessive exposure to wind, sunlight, high temperature, and air pollution was significantly related to dry eyes. There was a significant correlation between patient's history, symptoms, dry eye signs and objective tests for tear film. The rural people and those with outdoor occupation are more exposed to extraneous influences of environmental factors in tropical climate. These factors affect the tear film and ocular surface causing the dry eye syndrome.

Keywords: Dry eye, occupation, tropical climate


How to cite this article:
Bhatnagar KR, Sapovadia A, Gupta D, Kumar P, Jasani H. Dry eye syndrome: A rising occupational hazard in tropical countries. Med J DY Patil Univ 2014;7:13-8

How to cite this URL:
Bhatnagar KR, Sapovadia A, Gupta D, Kumar P, Jasani H. Dry eye syndrome: A rising occupational hazard in tropical countries. Med J DY Patil Univ [serial online] 2014 [cited 2019 Apr 21];7:13-8. Available from: http://www.mjdrdypu.org/text.asp?2014/7/1/13/122755


  Introduction Top


Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tears film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. [1]

The prevalence of dry eye ranges from 5% to 35% worldwide, while in India it is 29.25% based on Ocular Surface Disease Index (OSDI) data. [2] Reduction in quality of life is inevitable when symptoms of dry eye occur. [3] Studies utilizing tests of tear function including Schirmer's test, tear film break up time, fluorescein staining, or rose bengal staining for determination of dry eye have found generally lower prevalence rates compared to questionnaire-based surveys of dry eye symptoms which included history of contact lens wear, previous treatment for dry eye, frequency of symptoms, sensitivity to provocative stimuli, use of systemic medications, and comorbidity. Borderline dry eye can become manifest in the presence of cigarette smoke, or in highly air-conditioned or centrally heated environments. Besides there is occupation-based etiology, like prolonged use of computers in IT professionals with exposure to air pollution, low humidity, high temperature, sunlight exposure in outdoor workers. Chlorine used to disinfect swimming pools is another known provocative stimulus, as is dehydration after alcohol consumption. If left untreated, dry eye may result in decreased vision complicated by ulceration and scarring. [4],[5],[6]

Our aim was to determine dry eye prevalence, evaluate personal and environmental risk factors attributable to dry eye and find out the association between subjective complaints and objective tests of dry eye in a hospital-based population in the Indian state of Gujarat.


  Materials and Methods Top


In this prospective, cross-sectional study, 1890 patients above 15 years and below 65 years of age presenting with various eye problems to outpatient department of a tertiary care teaching hospital during November 2009 to October 2010 were screened for dry eye using a validated 12-point McMonnies Dry Eye Questionnaire [Appendix 1]: [Figure 1]. The patients were randomly selected and informed about the nature of the study. A written informed consent was taken from the study subjects. Institutional Ethical Committee approval was obtained before starting the study.

All patients who visited our outpatient department with various symptoms of dry eye and later diagnosed to have abnormal tests and signs of dry eye were included in this study.{Figure 1}

Patients with acute eye infections, extensive corneal or conjunctival pathology including allergic conjunctivitis, poor lid closure, and contact lens users were excluded from the study. We also excluded patients who had undergone any eye surgery within 6 months of screening. Patients with thyroid eye disease were excluded. Younger patients, <15 years old, were not included in the study, because at their initial trial their cooperation for Schirmer's test and TFBUT was inadequate.

Patient's age, sex, history of smoking, occupational history, and place of residence were recorded. Then the patients were asked to fill a 12-point McMonnies Dry Eye Questionnaire. The dry eye symptoms included itching, redness, burning, watering, discomfort/foreign body sensation, and photophobia. After ascertaining the responses to each of the questions, the symptom score was calculated. Patients who were found to have dry eye on this questionnaire were subjected to objective tests of tear function under room temperature conditions. These tests comprised (in order, each at 10 minute intervals to minimize reflex tearing and ocular surface changes secondary to testing) Schirmer's test and tear film breakup time (TBUT). Precut strips for these tests were obtained from common source to ensure uniformity. The presence of conjunctival injection, punctate epithelial erosions on cornea and  Meibomian gland More Details disease were looked for. McMonnies Dry Eye Questionnaire score of >10, Schirmer's test value of 10 mm in 5 minutes on Whatman's filter paper no. 41, TFBUT value <10 seconds, presence of punctate epithelial erosions on cornea, conjunctival injection, papillary hypertrophy, follicles, and meibomian gland disease were considered as indicators of dry eye. The diagnosis was made when McMonnies dry eye questionnaire scores were >10, TFBUT was <10 seconds, Schirmer's test values were <10 mm in 5 minutes, and at least two of the dry eye signs were present.

The association of these signs with subjective symptoms of the patients and objective tests for tear film was assessed.

Questionnaire: A validated 12-item McMonnies Dry Eye Questionnaire was used [Appendix 1: Figure 1]. Scores were given to each response. A score of <10 was labeled normal, of 10-20 marginal dry eye, and of >20 pathological dry eye.

Statistical analysis

Statistical analysis was performed using standard software. A P value <0.05 was considered statistically significant. The likelihood ratio test was used to calculate the P values. The odds ratio was used to study the strength of the association of environmental risk factors with dry eye.


  Results Top


A total of 1890 patients were screened for dry eye. Mean age of patients was 44.7 ± 14.09 years. The prevalence of dry eye in OPD was 10.58% (100 patients of dry eye in total 1890 outpatients screened for dry eye). The prevalence in outdoor workers was 17.77%. The number of males was highest in the 56-60 (13%) and 60-65 (14%) years age groups while that of females was highest in the 46-50 (16.67%) years age group. The male: female ratio was 2.33:1. A total of 10% patients were smokers, while 8% were tobacco chewers. Majority (77%) were from rural areas and majority of these (47%) were outdoor workers (farmer, laborer, fabrication, carpenter, driver, welding worker, bakery worker, and construction) [Table 1].
Table 1: Baseline characteristics of study subjects*


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We found a good association between subjective symptoms of dry eye and signs of dry eye. Out of a total of 100 patients who had subjective symptoms of dry eye, 86 (86%) were positive for dry eye signs. A total of 14 (14%) patients did not have dry eye signs but were positive for dry eye tests. The common symptoms were redness, burning, watering, and discomfort. The most common sign associated was follicles <5 mm (45.35%), followed by concretions (38.37%), conjunctival injection (30.23%), blepharitis (10.46%), punctate epithelial erosions (10.46%), trachoma (5.8%), and meibominitis (5.8 %) [1] [Table 2].
Table 2: Distribution and correlation of symptoms and signs of dry eye


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[Table 3] shows the strength of the association of various environmental exposure factors with dry eye. All the risk factors had a high propensity for higher risk of dry eye; excessive wind (OR: 2.15, P = 0.004), sunlight/high temperature (OR: 1.91, P = 0.014), and air pollution (OR: 2.04, P = 0.002)

Out of 86 patients with signs, 74 (86.04%) had abnormal (low) TFBUT; and 12 (13.95%) had normal TFBUT. It indicates that low TFBUT was associated with dry eye syndrome (P = 0.009) [Table 4].
Table 3: Strength of the association of environmental exposure factors with dry eye


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Table 4: Correlation between dry eye signs and TFBUT


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Abnormally low Schirmer's test values were persistently associated with dry eye syndrome (P = 0.014) [Table 5].
Table 5: Correlation between dry eye signs and Schirmer's test


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Abnormally low TFBUT was more or less consistently associated with advancing age [Table 6].
Table 6: Agewise distribution of TFBUT (N=100)


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  Discussion Top


In this study, out of 1890 patients screened, 100 were found to have dry eye syndrome. The overall prevalence was 10.58 % and among outdoor workers, it was 17.77%. Majority (77%) was from rural background and majority of these were outdoor workers (47%). A total of 10% were smokers and 8% were tobacco chewers. Mean age of patients was 44.7 ± 14.09 years with males more than females. Abnormally low Schirmer's test values (P = 0.014) and low TFBUT (P = 0.009) were associated with dry eye syndrome. 86% symptomatic patients were positive for dry eye signs. Exposure to excessive wind, sunlight/high temperature, and air pollution was significantly related to dry eye causation (P = 0.004, 0.014, and 0.002 respectively).

The prevalence of dry eyes varies from 10.8% to 57.1% [4],[7],[8] depending on the study. The vast disparity in dry eye prevalence stems mainly from different dry eye diagnostic criteria employed and different cut-off values for objective dry eye tests. The high prevalence in some studies is because objective dry eye tests have been performed in patients with rheumatoid arthritis, Sjogren's syndrome, thyroid dysfunction, which have proven dry eye component.

Mean age of patients was 44.7 ± 14.09 years in our study. This may be because most of the diseases namely trach­oma, Sjogren's syndrome, and idiopathic kerato-conjunc­tivitis sicca (KCS), responsible for dry eye, are common in this age group. [9] In our study five (5.8%) patients had trachoma but none had Sjogren's syndrome. This peak also reflects the dry eye state induced by environmental exposure, to which this age group, being most active occupationally, is exceptionally prone. This phenomenon may be more common in tropical countries where sunlight and wind exposure is immense. [9] Much research is required in tropical climates before a final conclusion can be drawn.

The decreased quantity of tears as indicated by decreasing Schirmer's values with advancing age [10] may also explain the age incidence of dry eye in some cases in our study.

Most studies report a higher prevalence of dry eye in females than males. [4],[5],[8],[10] In contrast to their findings in our study males (70%) were more commonly affected then females (30%). The number of male patients was highest in the 56-60 (13%) and 60-65 (14%) years age groups. Senile changes in conjunctiva and cornea due to multiple factors leading to decreased tear production and unstable tear film (lid retraction, entropion, trichiasis, ectropion, drugs, etc.), and longer exposure time to environmental factors may be responsible for dry eye in the older age group. [11] Abnormally low TFBUT was more or less consistently associated with advancing age in our study. More females in the 46-50 (16.67%) years age group may be due to the effect of hormonal changes in perimenoposal period. Menopause causes oestrogen deficiency and a consequent change in the local hormonal milieu of the lacrimal gland. It is thought to decrease tear production and occurrence of dry eye in females. [9]

Trachoma, chronic blepharitis, blepharo-conjunctivitis, and meibomian keratoconjunctivitis are risk factors for dry eye. These factors may render the tear film prone to evaporation at air-tear interphase, air flow over the surface of eye, surface area of the interpalpabral fissure and have been thought to be important in the etiopathogenesis of dry eye syndrome. Irregularities in the corneal surface lead to poor wetting. [1],[12],[13]

In our study, majority were outdoor workers (47%). The prevalence was higher among outdoor workers at 17.77% while the overall prevalence in this study was 10.58%. Out of 27 housewives positive for dry eye, 22 (81.48%) gave history of burning coal and wood for cooking which exposes them to smoke, hence higher prevalence of dry eye. Some of retired people had previous exposure of working outdoors, so they were also candidates for dry eye in their retired life. Exposure to excessive wind, sunlight/high temperature, and air pollution was significantly related to dry eye causation (odds ratio: 2.15, 1.91, and 2.04 respectively). It suggests a definite correlation between dry eye syndrome and outdoor occupation due to various environmental factors like heat, low humidity, sunlight, air pollution, and direct hot air currents. Various other studies have found a strong association between exposure to these environmental risk factors and dry eye syndrome (DES). [6],[11],[12],[13]

Gupta et al. suggested that long-term exposure to air pollution lead to tear film abnormalities. [6] Smoking predisposes the eye to tear film instability by its direct irritant action on the eyes and represents a modifiable risk factor in developing dry eyes. [9]

An adequately formed tear film is essential for the health of the corneal epithelium. A quickly breaking tear film or biochemically defective tear film can cause any amount of discomfort to the patient and may even prove disastrous to the corneal transparency. [13] It is therefore advisable that the TFBUT of the patients in this series be evaluated in relation to the signs of the dry eye. In this study out of 86 patients with signs on slit lamp examination, 74 (86.04%) had abnormal (low) TFBUT; 12 (13.95%) had normal TFBUT (P = 0.009). It indicates that low TFBUT is associated with dry eye syndrome. Abnormally low Schirmer's test values were significantly associated with dry eye syndrome (P = 0.014).

Strengths of the study

Strength of our study lies in the fact that we excluded confounding factors like rheumatoid arthritis, Sjogren's syndrome, thyroid dysfunction, extensive corneal or conjunctival pathology including allergic conjunctivitis, poor lid closure, and contact lens users which have proven dry eye component. Due to the interrelated nature of the tear film components, no single clinical test is sufficiently sensitive or specific to diagnose dry eye and predict the most accurate management strategy. We combined patients' history and subjective symptoms using a prevalidated questionnaire, assessment of lids and meibomian gland disease, assessment of ocular surface, objective tests of tear film quality, and tear film quantity to make a diagnosis of dry eye syndrome. We also studied the association between subjective symptoms and dry eye signs and objective tests and found a good association between them.

Limitations of the study

There were a couple of limitations in this study. We did not have a control group to compare our findings. A prevalidated scale was not used to grade dry eye signs. Ambient levels of environmental factors were not taken into consideration to calculate strength of the association of various environmental exposure factors with dry eye.

Clinical significance of the study

Occupational hygiene measures, such as decreasing the level of particles and gaseous air pollutants at the workplace, as well as optimizing illumination and humidity at the workplace are the major steps in the prevention of eye disease. Prospective longitudinal research in environmental and occupational medicine is needed in order to improve the understanding and diagnostic approach to ocular damage caused by environmental and occupational factors. These studies will help to understand the long-term environmental and occupational effects on the ocular surface, which superimpose on the aging processes in the ever aging working population as a consequence of the evolving demographic shift. Insights into the mechanisms of these events may help us develop preventive measures during the working life, not only in preventing occupational diseases, but also in using occupational surveillance to counteract ocular disability of the advanced age. [14]


  Conclusion Top


Dry eye is a leading cause of ocular discomfort. 1 The prevalence of dry eye was higher among outdoor workers (17.77%) than the overall prevalence (10.58%). We found a good association between subjective symptoms with dry eye signs. We also found a good association between dry eye signs with Schirmer's test (P = 0.014) and TFBUT (P = 0.009). Exposure to excessive wind (OR: 2.15, P = 0.004), sunlight/high temperature (OR: 1.91, P =0.014), and air pollution (OR: 2.04, P = 0.002) was significantly related to dry eyes. Prospective longitudinal research is needed to improve the understanding and diagnostic approach to ocular damage caused by environmental and occupational factors.


  Appendix 1: Figure 1 McMonnies Dry Eye Questionnaire* Top


Please answer the following by underlining the responses most appropriate to you:

Female 1 /Male.

Age: less than 25 years 0/25-45 years (M1/F3)/more than 45 years (M2/F6).

Currently wearing: no contact lenses/hard contact lenses/soft contact lenses.

  1. Have you ever had drops prescribed or other treatment for dry eyes? Yes 6/No 0/Uncertain 0
  2. Do you ever experience any of the following eye symptoms? (Please underline those that apply to you.) 1. Soreness 2. Scratchiness 3. Dryness 4. Grittiness 5. Burning
  3. How often do your eyes have these symptoms? (underline) Never 0/Sometimes 1/Often 4/Constantly 8
  4. Are your eyes unusually sensitive to cigarette smoke, smog, air conditioning, or central heating? Yes 4/No 0/Sometimes 2
  5. Do your eyes become very red and irritated when swimming? Not applicable 0/Yes 2/No 0/Sometimes 1
  6. Are your eyes dry and irritated the day after drinking alcohol? Not applicable 0/Yes 4/No 0/Sometimes 2
  7. Do you take (please underline) antihistamine tablets 2 or use antihistamine eye drops 2, diuretics 2 (fluid tablets), sleeping tablets 1, tranquillisers 1, oral contraceptives 1, medication for duodenal ulcer 1, digestive problems 1, high blood pressure 1, antidepressants 1 or ...? (Write in any medication you are taking that is not listed.)
  8. Do you suffer from arthritis? Yes 2/No 0/Uncertain 0
  9. Do you experience dryness of the nose, mouth, throat, chest or vagina? Never 0/Sometimes 1/Often 2/Constantly 4
  10. Do you suffer from thyroid abnormality? Yes 2/No 0/Uncertain 0
  11. Are you known to sleep with your eyes partly open? Yes 2/No 0/Sometimes 1
  12. Do you have eye irritation as you wake from sleep? Yes 2/No 0/Sometimes 1

    • Based on the scores obtained on the Questionnaire subject will be labeled as-
    • Scores: Normal (< 10) Marginal dry eye (10-20) Pathological dry eye (>20)
    • This questionnaire was adapted from "Bausch and Lomb Academy of Vision Care 2009" available at " www.academyofvisioncare.com"


 
  References Top

1.Michael AL, Christophe B, Jules B, Murat D, Gary NF, Schigeru K, et al. The definition and classification of dry eye disease: Report of the definition and classification subcommittee of the international dry eye workshop (2007). Ocul Surf 2007;5:75-92.  Back to cited text no. 1
    
2.Asbell PA, Lemp MA. Dry Eye disease, The clinician's Guide to Diagnosis and Treatment. New York: Thieme; 2007;2:1-23.  Back to cited text no. 2
    
3.Rozanova E, Heilig P, Godniæ-Cvar J. The eye - a neglected organ in Environmental and occupational Medicine: an overview of known Environmental and occupational Non-traumatic effects on the eyes. Environment and occupational non-traumatic effects on the eyes. Arh Hig Rada Toksikol 2009;60:205-15.   Back to cited text no. 3
    
4.Hikichi T, Yoshida A, Fukui Y, Hamano T, Ri M, Araki K, et al. Prevalence of dry eye in Japanese eye centers. Graefes Arch Clin Exp Ophthalmol 1995;233:555-8.  Back to cited text no. 4
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5.Moss SE, Klein R, Klein BE. Prevalence of and risk factors for dry eye syndrome. Arch Ophthalmol 2000;118:1264-8.  Back to cited text no. 5
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6.Gupta SK, Gupta V, Joshi S, Tandon R. Subclinically dry eyes in urban Delhi: An impact of air pollution? Ophthalmologica 2002;216:368-71.  Back to cited text no. 6
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7.Albietz JM. Prevalence of dry eye subtypes in clinical optometry practice. Optom Vis Sci 2000;77:357-63.  Back to cited text no. 7
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8.Versura P, Cellini M, Torreggiani A, Profazio V, Bernabini B, Caramazza R. Dryness symptoms, diagnostic protocol and therapeutic management: A report on 1,200 patients. Ophthalmic Res 2001;33:221-7.  Back to cited text no. 8
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9.Sahai A, Malik P. Dry eye: Prevalence and attributable risk factors in a hospital-based population. Indian J Ophthalmol 2005;53:87-91.  Back to cited text no. 9
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10.Milder B. The lacrimal apparatus. In: Moses RA, editor. Adler's physiology of the eye - Clinical application. St. Louis: CV Mosby Co.; 1931. p. 24-6.   Back to cited text no. 10
    
11.Versura P, Profazio V, Cellini M, Torreggiani A, Caramazza R. Eye discomfort and air pollution. Ophthalmologica 1999;213:103-9.  Back to cited text no. 11
    
12.Klopfer J. Effects of environmental air pollution on the eye. J Am Optom Assoc 1989;60:773-8.  Back to cited text no. 12
    
13.Novaes P, do Nascimento Saldiva PH, Kara-Jose N, Macchione M, Matsuda M, Racca L, et al. Ambient levels of air pollution induce goblet-cell hyperplasia in human conjunctival epithelium. Environ Health Perspect 2007;115:1753-6.  Back to cited text no. 13
    
14.Khurana AK, Choudhary R, Ahluwalia BK, Gupta S. Hospital epidemiology of dry eye. Indian J Ophthalmol 1991;39:55-8.  Back to cited text no. 14
[PUBMED]  Medknow Journal  



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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