Green spaces may have "protective effect" against dry eye disease

The investigators found that greater 10-year green space exposure was associated with a higher tear meniscus area. Image credit: ©Victoriia – stock.adobe.com

A recent study assessed the association between exposure to green space and dry eye disease. According to first co-authors Weijing Cheng, MD, and Hanyou Wu, MD, greater 10-year green space exposure was associated significantly with lower odds of development of dry eye.¹

Cheng and Wu are from the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University; and Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China.

"Dry eye is closely associated with environmental exposure and presents a significant risk to human visual health and quality of life,"² the investigators commented.

Previous results have supported that environmental exposure is a culprit, with studies indicating the impact of air pollution and climatic factors. The air pollutants associated with dry eye primarily include particulate matter, nitrogen dioxide, ozone, sulfur dioxide and carbon monoxide.^3-7 Climatic culprits include temperature, humidity and sunlight exposure.^6-8

They cited a large study that found that the prevalence of dry eye disease is higher among urban residents compared to those in rural areas.⁵

"Urbanisation has resulted in a decrease in green space despite its known positive impact on public health. Studies have demonstrated that green space exposure can mitigate the prevalence of mental health disorders, including anxiety, depression and sleep disturbances, all of which are recognised risk factors for the onset of dry eye.^9-11 Furthermore, studies have also reported that exposure to green spaces has positive effects on eye health, such as reducing the prevalence of myopia and the incidence of allergic conjunctivitis,"^12,13 the investigators explained.

In light of all the previous research, they wanted to determine if there was a relationship between green space and dry eye.

Dry eye study methods

The study under discussion included two parts: a case-control study and a cross-sectional study.

Part one included 450 patients with dry eye and 900 controls recruited from electronic health records database. The data were used to investigate the relationship between green space exposure and the occurrence of dry eye.

The cross-sectional segment included 140 patients with diabetes recruited from the community registry in Guangzhou. The data were analysed to identify an association between green space exposure and quantitative measures of the tear meniscus.

What did the data analysis show?

Part one included a total of 1,350 patients and controls, of whom 59.33% were female. The participants were an average age of 31.07 ± 4.58 years.

The investigators reported that “higher 10-year green space exposure was significantly associated with lower odds of dry eye (odds ratio = 0.96; 95% confidence interval [CI], 0.94, 0.97; P < 0.001)" after adjusting for age, sex, rainfall, temperature, particulate matter and other factors.

Part two was comprised of 140 patients with diabetes, of whom 53.57% were women. The average patient age was 64.48 ± 8.19 years. In this group, the investigators found that “greater 10-year green space exposure was associated with a higher tear meniscus area (β = 0.07, 95 % CI, 0.02, 0.11; P = 0.007)" after adjusting for the same factors as in part one.

Commentary

In commenting on their findings, the authors explained the significant public health implications of their results, specifically that “the potential protective effect of green space exposure on dry eye warrants consideration. Disparities in access to green space between urban residents in developed and developing countries are stark, with the latter having access to only one-third of the green space available to the former.¹⁴ This research underscores the need to enhance urban planning and management, improve urban spatial organisation, and promote the equitable distribution of green space. Furthermore, future research on conditions such as dry eye should account for the potential influence of green space exposure.”

They continued, “Our research identified a negative relationship between green space exposure and dry eye. Urban planning decisions should thoroughly incorporate the design and functionality of green space to offer effective measures for preventing dry eye.”

References

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14. Klohe K, Koudou BG, Fenwick A, et al.A systematic literature review of schistosomiasis in urban and peri-urban settings. PLoS Negl Trop Dis. 2021;15:e0008995