A study published in the British Journal of Ophthalmology has found that lower ambient air temperatures are significantly associated with increased intraocular pressure in patients with stable primary open-angle glaucoma receiving medical treatment, with the effect most pronounced in those with severe disease or using multiple eye drops.
Glaucoma is most commonly caused by elevated fluid pressure within the eye, which damages the optic nerve and can lead to irreversible vision loss if not managed effectively. While previous research has explored the relationship between climatic factors and intraocular pressure in the general population, the effect of ambient temperature on treated glaucoma patients had not been clearly established.
The study reviewed medical records from 77 patients with primary open-angle glaucoma treated at a university hospital in Japan between 2012 and 2023. Patients were aged over 40, had no history of ocular surgery, attended at least three clinic appointments per year for a minimum of three years, and maintained a stable antiglaucoma eye drop regimen throughout the study period. A total of 2,655 intraocular pressure measurements from 154 eyes were included in the final analysis, with patients monitored for an average of approximately five years. Climatic data were obtained from the Japan Meteorological Agency.
Statistical analysis showed that a decrease in ambient temperature of 35 degrees Celsius was associated with a 1 mmHg increase in intraocular pressure, an association that remained significant after adjustment for age, sex, blood pressure, and corneal thickness. The temperature effect was statistically significant only in patients with severe glaucoma or those using multiple antiglaucoma medications, suggesting greater susceptibility in more advanced disease.
The authors note that the observational design precludes causal conclusions and that lifestyle factors such as exercise and body weight were not accounted for. They call for larger studies to determine whether the association extends to patients with mild glaucoma or those on monotherapy.
Source: British Medical Journal. Effects of ambient temperature on intraocular pressure in patients with stable primary open-angle glaucoma under medical treatment. British Journal of Ophthalmology (2026). DOI: 10.1136/bjo-2026-330361
