Background Due to long working time and complex and changeable lighting conditions, greenhouse workers' anisometropia is an issue of concern.
Objective This study is conducted to evaluate the relationship between solar greenhouse working and anisometropia of workers.
Methods Subjects of a solar greenhouse group and a non-greenhouse group in northwest area of China were selected. Questionnaire survey was used to collect general demographicinformation. Standard Logarithmic Visual Acuity Chart (GB 11533—2011) was used to measure naked eye vision before working, the absolute value of binocular visual acuity difference was calculated and converted into classification variables, and both anisometropia absolute value and classification variables of anisometropia were used as indicators to compare the difference of the two groups. A cumulative exposure index that multiplies exposure time and number of greenhouses was further introduced to evaluate cumulative exposure levels of the greenhouse workers and was used to divide them into low, medium, and high cumulative exposure subgroups. Generalized linear model and logistic regression model were used to analyze possible risk factors associated with anisometropia.
Results A total of 1002 subjects were enrolled in this study, including 739 workers in the greenhouse group and 263 workers in the non-greenhouse group. The medians (interquartile intervals) of anisometropia of the greenhouse group and non-greenhouse group were 0.1 (0, 0.2) and 0 (0, 0.1) respectively, and the difference was statistically significant (P<0.05). The proportions of anisometropia=0, ≤0.2, and >0.2 in the greenhouse group were 34.2%, 55.2%, and 10.6%, respectively, and those in the non-greenhouse group were 58.2%, 34.6%, and 7.2%, respectively. The difference of anisometropia distribution between the two groups was statistically significant (P<0.05). According to the cumulative exposure index, the greenhouse group was divided into low, medium, and high cumulative exposure subgroups, with 154 (21.0%), 188 (25.6%), and 392 (53.4%) workers, respectively. There was no statistical significance in anisometropia among workers with different cumulative exposure levels (P>0.05). The results of multiple generalized linear analysis showed that greenhouse working was a risk factor of anisometropia (b=0.053, P<0.05), and the results of multiple logistic regression analysis showed that greenhouse working was associated with an increased risk of anisometropia (OR=2.586, 95%CI: 1.473-4.539). The results of multiple generalized linear analysis showed that medium exposure level increased the degree of anisometropia after adjusting age, gender, and other factors (b=0.054, P<0.05).
Conclusion Solar greenhouse working may be a risk factor for increasing anisometropia in workers.
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