A questionnaire-based survey of dry eye disease among leather tannery workers in Kanpur, India: a case-control study

Kanpur is a major leather processing center in India, where a large number of tanneries are situated. During tanning process, workers are constantly exposed to heat, leather dust produced in buffering operations and a wide range of chemicals. All these factors are known to cause dry eye. Being ophthalmologists of a tertiary health care center in Kanpur, we used to notice over a period of time that a considerable number of patients with dry eye symptoms, attending our out-patient department, were related to leather tanning industries. But, no published data is available on the prevalence of and risk factors for dry eye disorders among tannery worker.

To estimate the prevalence of dry eye problem and its severity among the workers of leather tanneries in the industrial belt of Kanpur and to evaluate various risk factors related to it.

In this cross-sectional case-control study, Ocular Surface Disease Index (OSDI) Questionnaire was presented to randomly selected tannery workers and control group. OSDI score was calculated based on subjects' response, and was evaluated with OSDI chart to assess the magnitude of dry eye symptoms and to grade its severity. RESULTS were analyzed statistically to evaluate the significance level.

A total of 800 workers were selected by simple random sampling, out of which 72 workers were excluded from the study. Thus the questionnaire was presented to a total of 728 workers, while control group included 260 individuals. All the workers as well as controls were male with age ranging from 20 to 59 years. The mean age for tannery workers was 34.05 ± 8.96 years and that for control group was 32.97 ± 10.59 years (p = 0.14). The tannery workers had mean duration of work at tanneries for 6.99 ± 4.86 years. The prevalence of dry eye symptoms among tannery workers was 33.79% (95% CI: 30.35-37.24), while that in control group was 15.77% (95% CI: 11.31-20.23) (p < 0.0001). Among symptomatic workers, 47.96% (95% CI: 41.68-54.26) workers had mild, 36.99% (95% CI: 30.91-43.07) workers had moderate and 15.04% (95% CI: 10.54-19.54) workers had severe dry eye symptoms. Severe symptoms were more prevalent among symptomatic workers of age ≥ 40 years in comparison to those <40 years (34.72% versus 6.90%, p < 0.0001). With increase in duration of work (1-5, 6-15 and 16-25 years), both prevalence and severity of dry eye symptoms increased significantly (p = 0.036 and <0.0001, respectively).

Dry eye is a significantly prevalent occupational hazard among tannery workers, severity of which increases with the age and the duration of work in tannery. Chemical exposure in hot and dusty working environment of a tannery may have a causative role. Tannery workers should be motivated to use various preventive measures to reduce chemical and dust exposure such as wearing protective glasses, and their ocular health should be monitored periodically for adequate and timely treatment, if required.