The present study was carried out to investigate the ocular and visual status as well as knowledge, attitude and practice (KAP) of safety practices among industrial welders in Nepal. A high prevalence of corneal opacities and lid disorders were identified. There was a lack of widely accepted safety practices although a majority of them reported knowledge about the potential hazards.
Anterior segment disorders
Although, eyes are exposed to harmful radiations and ambient light levels on a daily basis, the inherent protective mechanism is actively in play. The corneal epithelium absorbs short wavelength ultraviolet (UV > 310nm) and lens absorbs long wavelength ultraviolet (UV < 310nm), thereby allowing only the visible and infrared wavelength to reach the retina.9 However, higher doses of ultraviolet radiation (UVR) absorption in the anterior segment leads to several pathological and physiological alterations including impaired corneal epithelial barrier function, susceptibility to infection, and development of the corneal opacity.10 The higher proportions of corneal opacities in the present study probably indicate DNA damages in the cornea.11 It is well established that high doses of ultraviolet radiation (UVR) can induce DNA damages in the form of pyrimidine dimers, single-stranded DNA chain breaks, and DNA-protein cross-links.12 The pyrimidine dimers are molecular lesions of DNA induced by photochemical reactions and manifest, clinically, as corneal opacification or neovascularization.11 Pyrimidine dimers could lead to DNA mutations if not repaired by cells equipped with DNA repair mechanisms.11 These changes affect DNA transcription and replication and can cause cell death, which may manifest as opacities. Gendron and Rochette13 have recently reported the adverse effects of high doses of ultraviolet radiation (UVR) on the extracellular matrix composition of the cornea. They reported that a cumulative high dose of ultraviolet A (UVA) catalyzes the corneal aging that manifests as loss of corneal transparency and increase in turbidity.13
Animal, as well as human studies have shown that cumulative high doses of ultraviolet radiation (UVR) are carcinogenic.14, 15 in an animal study, Ley15 showed that high dose of ultraviolet A (UVA) and ultraviolet B (UVB) radiation induce tumors.15 Therefore, a welding arc containing a mixture of ultraviolet (UV) radiation could be expected to be carcinogenic. Interestingly, the study did not find any case of melanoma in and around the eye, although most of our participants reported working in this profession for several years. However, melanomas may occur decades after a sufficient exposure to the welding arcs.14
Higher proportions of pinguecula were observed in the present study, which is similar to the reports from somewhere else.3, 16 In welders pinguecula occurs more commonly than pterigium, though It is probably because of the susceptibility differences within ethnicities and climates.16 Prevalence of pterigium in welders ranges from 2% to 17∙5%2, 3, 16 and fits well with finding of the results. A weak association of pterigium with welding flashes is not clear because it occurs equally in non-welders.16 However, it is established that a cumulative dose of ultraviolet B (UVB) leads to development of pterigium.17 Interestingly, pterigium is linked with corneal endothelial changes but welding does not alter this corneal feature.16
Although, a comparable number of participants had cataract as that of Nigerian welders (11∙6%), 3 it may not link with welding flashes because 88.2% participants with cataract were over 40 who might have had age-related lenticular changes. However, welding might have had a contributory role since all those welders were in this profession for over 10 years. Literature supports the fact that an unprotected ultraviolet radiation (UVR) exposure from ambient solar radiation leads to cataract.18 However, development of cataract from an unprotected exposure to welding flashes is still controversial.19 A case-control study with an adequate control of cataractogenic factors including age, smoking, radiation exposure and systemic conditions, may help explain this gap in the literature.
Posterior segment disorders
Macular pathologies are common in welders using unprotected arc welding20 and higher proportions of macular pigmentation were observed in the study compared to the literature (7∙7%).3Several factors account for this discrepancy including levels of retinal pigmentation, severity of cataract, use of protective devices, radiation wavelength, energy level and duration of exposure.21 Young welders who have clear ocular media are at higher risks of the blue light retinal hazards.22 In the present study, 9.4% participants below the age of 40 had macular pigmentary changes. Macular damage in welders is due to the oxidative photo stress driven by irradiation.23 Although, some retinopathies may persist as retinal lesion and lead to atrophy, majority are reversible and recover within few months.24
Visual functions
In the present study, the burden of refractive errors was high as compared to literature (25∙2%).3 Factors such as unavailability of health services and non-willingness to wear the refractive corrections explain this variation. The specific symptoms of watery eyes, sore eyes, aching eyes, double vision and after images can be avoided with the use of appropriate shade number.22 Indeed, in the present study more than half of the participants used sunglasses without recommended shade number. Proper education and training may help address this issue.
Knowledge, attitude and practice (KAP) assessment and healthcare policies
There was a significant gap on knowledge, attitude and practice (KAP) about occupational health hazards. The majority of the participants were aware of potential health hazards but only about 63% reported using the personal protective equipment (PPE). A similar finding has been reported from rural Nepal where 90∙7% were aware of the health hazards but only half of them used the personal protective equipment (PPE).24 These findings contrast from developed countries, such as Australia,22 where welders commonly use eye protection with adequate shade number. Governmental law enforcements, 4 as well as education, 22 may help to fulfill these gaps. The concept of occupational safety and health is in its initial stages in Nepal. Lack of proper medical facilities and emergency medical backups at the industrial and workplace make occupational health and safety a difficult task, especially in industries. As Nepal is in the verge of transition through industrialization, addressing these issues may help achieve expected economic growth.
The conclusions of this study must be considered in the context of methodological limitations. The study cannot exclude the possibility that participants had pre-existing ocular disorders such as lid disorders and refractive errors, which may not relate to the unprotected welding. It must be noted that it was a cross-sectional descriptive study and therefore, may not accurately explain the true prevalence of cataract and retinal disorders in this group of occupational workers. A case-control study can accurately identify the incidence of such conditions; however, the ethical considerations may limit the test of such research questions. Nonetheless, two main conclusions can be drawn from this study. First, Nepalese welders are at high risk of ocular morbidities due to unprotected welding and they suffer from several ocular and visual morbidities including corneal opacities, dry eyes, pterygium and retinal conditions. Second, these groups of professionals in Nepal have limited knowledge on the protective devices and safety practices of their occupation. These are the issues addressable by appropriate law enforcements, development of health insurance policies and education.