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 Table of Contents  
Year : 2022  |  Volume : 60  |  Issue : 3  |  Page : 250-253

Prevalence of aqueous deficient dry eye and common ocular surface changes among salt workers

1 Department of Ophthalmology, Jothi Eye Care Centre, Puducherry, India
2 Department of Ophthalmology, JIPMER-Karaikal, Puducherry, India
3 Department of Ophthalmology, Sri Lakshmi Narayana Institute Medical Science, Puducherry, India

Date of Submission22-Sep-2021
Date of Decision07-Apr-2022
Date of Acceptance11-Apr-2022
Date of Web Publication26-Sep-2022

Correspondence Address:
Sharanyaa Krishnamoorthy
1B, TSC Meridian Heights Apartment, (Opp. DAT Office), Kumaragurupallam, Puducherry - 605 011
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/tjosr.tjosr_145_21

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Background: India is the third-largest salt-producing country in the world and Tamil Nadu is the second largest salt-producing state in India. Salt production is one of the most hazardous occupations, which affects the eye and skin primarily. This study was done for assessing the common ocular surface changes among salt workers in Marakkanam, which is a block of Villupuram district in Tamil Nadu. Methodology: It is a cross-sectional study for 2 months among 253 salt workers with minimum exposure of 6 months after taking informed consent. Those with systemic diseases and other ocular surface disorders were excluded from this study. After performing Schirmer's test, an ophthalmic evaluation was done for ocular surface disorders. Results: The prevalence of aqueous deficient dry eye (ADDE) in salt workers is 38.30%. The prevalence of pterygium is 39.50%. The prevalence of pinguecula is 29.64%. Males (46%) are affected more than females (28%) because males are held in the salt pan where sandy and outdoor environments increase the risk of the development of pterygium. Salt pan workers (47%) who work amidst salt crystals and a sandy environment have an increased risk of developing pterygium, than the dry salt workers (24%). Conclusion: ADDE and pterygium are highly prevalent among salt workers. It will also guide the salt workers to know their ocular conditions and the need for a regular ocular check-up to safeguard their eyes.

Keywords: Aqueous deficient dry eye, pinguecula, pterygium, Schirmer's test

How to cite this article:
Krishnamoorthy S, Selvaraj R, Soubramanianae U, Vaithianathan V, Tipandjan A. Prevalence of aqueous deficient dry eye and common ocular surface changes among salt workers. TNOA J Ophthalmic Sci Res 2022;60:250-3

How to cite this URL:
Krishnamoorthy S, Selvaraj R, Soubramanianae U, Vaithianathan V, Tipandjan A. Prevalence of aqueous deficient dry eye and common ocular surface changes among salt workers. TNOA J Ophthalmic Sci Res [serial online] 2022 [cited 2022 Nov 30];60:250-3. Available from: https://www.tnoajosr.com/text.asp?2022/60/3/250/357104

  Introduction Top

There are several occupations, which have hazardous chemical, physical and biological effects on the eye, which may lead to ocular symptoms such as eye pain, burning sensation, photophobia, eye irritation, foreign body sensation and defective vision. Salt production is one such hazardous occupation. India is the third-largest salt-producing country in the world in which the second largest salt-producing state is Tamil Nadu. This study was done for assessing the common ocular surface disorders among salt workers in Marakkanam, a block of Villupuram district in Tamil Nadu. In the process of salt manufacturing, the workers are engaged in sweeping the salt crystals with a wooden spade, heaping the salt crystals at the edge of the pans, weighing, filling up, grinding and packing the salt.[1] These workers are more frequently affected by dermatological and ophthalmological-related problems.[2] The complete procedure of salt manufacturing is done outdoors in extreme hot weather conditions which makes them vulnerable to more exposure to sunlight and hence more ultraviolet radiation hazard, exposure to salt dust and hence more glaring effect, due to sunlight getting reflected from the concentrated salt brine and the salt crystals, which leads to the ocular surface changes.[3] Many studies have shown that spending long periods outdoor leads to an increased risk of ocular surface problems, which range from minimal to no symptoms, chronic discomfort, eye irritation, reduction of vision and increased light sensitivity. The most common ocular surface problems due to air pollution are described in the literature, to be dry eye syndrome (DES), pinguecula and pterygium.[4],[5] Evaluation of the health status of salt workers has been one of the suggested research priorities and in spite of this, there are only a few studies, assessing the health status of salt workers. This study was done to assess the common ocular surface problems and treatment needs of the salt workers of Marakkanam. This also provides baseline data for improving the ocular health status in the community.

  Methodology Top

This study aims to assess the ocular surface changes among salt workers, their level of awareness, attitude and practice to prevent the same. It is a community-based cross-sectional study, which includes 253 participants, done for a period of 2 months at Marakkanam. All the procedures of the study were explained and written informed consent was obtained. Salt workers with a minimum of 6 months of experience were included and the workers, who are diagnosed to have systemic diseases like diabetes mellitus, hypertension, and patients using drugs (mainly diuretics, beta-blockers), with any previous history of ocular surface disorders, a disorder of lid aperture, chronic allergic conjunctivitis and any other ocular surgeries within the past six months were excluded. Socio-demographic details like their age, gender, hours of working per day, years of experience, type of work (salt pan or dry pan), common morbidities were also included in the proforma. The purpose of the study was explained and informed written consent was taken. The data collection was done using a pre-designed questionnaire. The workers involved in the study were examined in the room with maximum illumination and the ocular examination was carried out by torch as it was a field study, then they were shifted to a dark room for Schirmer's tests 1 and 2 (reflex and basal tearing, respectively). For Schirmer's test 1, a tear test strip (a pre-cut strip of Whatman filter paper (Contacare Ophthalmics & Diagnostics- CARE Group) measuring 5 × 35 mm) was placed in the inferior conjunctival cul-de-sac and the patient was made to sit in the dark room. The amount of wetting on the tear test strip was measured, followed by Schirmer's test 2, where, after instillation of topical anaesthetic eye drop (4% Xylocaine), the test strip paper was placed for 5 min and the amount of wetting was measured. The data was compiled, analysed and tabulated using SPSS version 24 (IBM Corporation Business Analytics Software). The correlation was done using the Chi-square test and a P value less than 0.05 was considered statistically significant.

  Results Top

Two hundred and fifty-three salt workers were involved in the study, the mean age enrolled in the study was 45.7, the minimum age being 20 years and the maximum was 70 years. The prevalence of aqueous deficient dry eye (ADDE) among salt workers is 38.3%. Male workers 67 (41%) and female workers 30 (34%) were affected by dry eyes. Out of 253 workers, 167 (66%) were salt pan workers and 86 (34%) were working as dry salt workers. Among them, 69 (41%) of salt pan workers and 28 (33%) of dry salt workers had a dry eye. In this study, with years of experience, workers are divided into two groups, 10 years or less and more than 10 years. Twenty-one (30%) workers with less than 10 years and 76 (41%) with more than 10 years of experience were affected by dry eyes. With hours of working per day, they were divided into two groups: less than 6 h and more than 6 h. In this, 25 (33%) with less than 6 h and 72 (41%) with more than 6 h of working duration were affected with dry eyes [Table 1]. The prevalence of pterygium among salt workers was 39.5%. Seventy-five (46%) of male workers and 25 (28%) of female workers had pterygium. Among salt pan workers and dry pan workers, 79 (47%) and 21 (24%) were found to have pterygium, respectively. With respect to the years of experience, among less than 10 years and more than 10 years, 18 (26%) and 82 (45%) workers had pterygium, respectively. With less than 6 h and more than 6 h of working, 20 (26%) and 80 (45%) workers had pterygium, respectively [Table 2]. The prevalence of pinguecula was 29.60% [Table 3].
Table 1: Dry eye prevalence

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Table 2: Pterygium

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Table 3: Pinguecula

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  Discussion Top

Ocular surface disorders in salt workers have been studied in North India. Studies from Rajasthan and Gujarat observed that 17–85% of salt workers suffer from musculoskeletal, ophthalmic and dermatological problems, as the most common occupational hazards.[2],[6] A similar study from Tamil Nadu in 2015 documented 42% ocular co-morbidities in salt pan workers.[3] However, the prevalence was as low as 7.7% among fishermen, who also have the same risk factors of exposure to sea and sunlight.[7]

The present study found that the commonest ocular symptoms were irritation, discomfort and foreign body sensation because of their longer exposure to sunlight, direct contact with the salt dust and concentrated brine. Out of 253 workers, males were 164 (65%) and females were 89 (35%). The authors have documented three significant gross findings on the ocular surface as the study was conducted on fields with the minimum availability of only torch light. The prevalence of ADDE was 38.30%, pterygium was 39.50% and pinguecula was 29.60%. Out of these three conditions, one of the most common conditions due to dust pollution and sunlight exposure, described in the literature is the DES. The National Eye Institute/Industry Workshop on Clinical Trials in Dry Eyes defined dry eye as 'a disorder of the tear film due to tear deficiency or excessive tear evaporation, which causes damage to the inter-palpebral ocular surface and is associated with symptoms of ocular discomfort'.[8]

The prevalence of ADDE in this study was 38.30%. In a study by Bhatnagar et al.[9] on DES in tropical countries, the prevalence of dry eye was more in males compared to females, as the majority of males were outdoor workers. It correlates with the present study as among those with ADDE, males were 41% and females were 34%. It was observed that out of 164 males, the majority (145) work under the salt pan division, where the exposure to the sun and salt dust is more, compared to the dry salt workers. Hence, 41% of salt pan workers were affected with dry eyes compared to the dry salt worker (33%). Gupta et al.[10] observed that a long period of exposure to outdoor works will lead to tear film instability. Even in our study, the percentage of ADDE was found to be higher among the workers with exposure of more than 10 years and those working more than 6 h per day. However, the correlation of ADDE with gender, years of exposure, hours of work and the type of work (salt pan and dry pan), was not significant statistically.

The prevalence of pterygium in our study is 39.50%. Few epidemiological studies done around the world have shown that the prevalence of pterygium ranges between 0.3% and 37.46%.[11] Nangis et al.[12] had studied the prevalence and associated risk factors of pterygium, in which they observed that the prevalence was 13% in their whole study population and they also found a preponderance of males to acquire pterygium. Even in our study, male workers (46%) were found to be affected more by pterygium than the females (28%), which is statistically significant (p = 0.006). But in contrast to our study, Andhra Pradesh Eye Disease Study and another study from Tamil Nadu show that females were predominantly affected by pterygium.[13],[14] In a study on pterygium among salt workers by Mathur et al.,[15] they observed that the prevalence of pterygium is more significant among brine workers than the dry salt workers. In our study also, we observed that the pterygium is more prevalent and significantly higher among the salt pan workers (47%) compared to the dry pan workers (24%); as discussed earlier, the salt pan workers are more exposed to sunlight and salt dust than dry pan workers (p < 0.000). Moran and Hollows[16] studied the positive correlation of pterygium and ultraviolet radiation and they mentioned that pterygium is an environmental disease wherein ultraviolet (UV) radiation plays a major role in its development. Exposure to ultraviolet radiation for around 10 to 20 years may result in the formation of pterygium.[17] The fact, that the aetiopathogenesis for the predominant occurrence of pterygium among the people, who are engaged outdoors being ultraviolet radiation, appears to be indubitable.[18] In this study, among the workers with more than 10 years of exposure, 45% had pterygium and with less than 10 years of exposure, 26% had pterygium which was statistically significant. Even with regards to the hours of exposure, pterygium was found to be more prevalent among the salt workers who worked for more than 6 h (45%) than those who worked less than 6 h (20%), which is statistically significant (p = 0.005).

The prevalence of pinguecula among salt workers in this study was 29.60%. In a study by Viso et al.,[19] on the prevalence of pinguecula and pterygium in a general population in Spain, it was observed that occupation related to outdoor environment had a significant association with both pinguecula and pterygium. In a study by Rezvan et al.,[20] it was found that there was a significant association between the prevalence of pinguecula and outdoor working and also the underlying cause was the effect of UV exposure.


As it was a field study, and the examination was carried out with a torch, only basic dry eye parameters could be looked into and it was Schirmer's test.

  Conclusion Top

ADDE, pterygium and pinguecula are the most prevalent ocular surface disorders among salt workers. Salt pan workers exhibit more ocular surface changes compared to dry salt workers due to excessive exposure to sun and salt dust. Among the identified ocular surface changes, pterygium was found to be the most predominant. Salt dust has been observed as a major aetiological factor for pterygium along with ultraviolet radiation, which is a well-known cause. Hence, it is recommended that salt workers should wear a hat and protective goggles not only to protect from UV-rays but also salt dust and also advised to have regular ocular check-ups.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Haldiya KR, Mathur ML, Sachdeva R, Beniwal VK, Singh MB, Yadav SP, et al. Morbidity pattern of desert population engaged in salt manufacture in Rajasthan. J Indian Med assoc 1995;93:95-7.  Back to cited text no. 2
Cherian J, Singh Z, Bazroy J, Purty AJ, Natesan M, Chavada VK. The study of morbidity pattern among salt workers in Marakkanam, Tamil Nadu, India. J Clin Diagn Res 2015;9:LC01-3.  Back to cited text no. 3
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Bhatnagar KR, Sapovada A, Guptha D, Kumar P, Jasani H. Dry eye syndrome: A rising occupational hazard in tropical countries. Med J D Y Patil Univ 2014;7:13-8.  Back to cited text no. 9
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Nangia V, Jonas JB, Nair D, Nangia P, Saini N, Nangia P, Panda-Jonas S. Prevalence and associated factors for pterygium in rural agrarian central India. The central India eye and medical study. PLoS One 2013;8:e82439. doi: 10.1371/journal.pone. 0082439.  Back to cited text no. 12
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Asokan R, Venkatasubbu RS, Velumuri L, Lingam V, George R. Prevalence and associated factors for pterygium and pinguecula in a South Indian population. Ophthalmic Physiol Opt 2012;32:39-44.  Back to cited text no. 14
Mathur ML, Haldiya KR, Sachdev R, Saiyed HN. The risk of pterygium in salt workers. Int Ophthalmol 2005;26:43-7.  Back to cited text no. 15
Moran DJ, Hollows FC. Pterygium and ultraviolet radiation: A positive correlation. Br J Ophthalmol 1984;68:343-6.  Back to cited text no. 16
Saw S-M, Banerjee K, Tan D. Risk factors for the development of pterygium in Singapore: A hospital-based case-control study. Acta Ophthalmol Scand 2000;78:216-20.  Back to cited text no. 17
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Viso E, Gude F, Rodríguez-Ares M. Prevalence of pinguecula and pterygium in a general population in Spain. Eye 2011;25:350-7.  Back to cited text no. 19
Rezvan F, Hashemi H, Emamian MH, Kheirkhah A, Shariati M, Khabazkhoob M, et al. The prevalence and determinants of pterygium and pinguecula in an urban population in Shahroud, Iran. Acta Med Iran 2012;50:689-96.  Back to cited text no. 20


  [Table 1], [Table 2], [Table 3]


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