Key Takeaways

  • Lower ambient temperatures were significantly associated with higher IOP in patients with medically controlled POAG

  • The temperature-IOP association appeared stronger in patients with severe glaucoma or those using multiple medications

  • Environmental temperature may be relevant to IOP monitoring, although further research is needed to establish clinical implications

A retrospective study published in the British Journal of Ophthalmology found that lower ambient temperatures were significantly associated with higher intraocular pressure (IOP) in patients with medically controlled primary open-angle glaucoma (POAG), suggesting that environmental temperature may contribute to IOP fluctuations.1

The study, led by Toru Ikushima, MD, of Kyoto Prefectural University of Medicine in Japan, analyzed 2,655 IOP measurements from 154 eyes of 77 patients treated between 2012 and 2023. Participants had a mean age of 65.8 years and were followed for an average of 5.2 years.

Eligible patients were at least 40 years old, had no history of ophthalmic surgery or changes in glaucoma medications, and attended at least three visits annually for 3 or more years. IOP was measured using Goldmann applanation tonometry.

Researchers used a linear mixed-effects model to assess associations between IOP and environmental factors, including ambient temperature, atmospheric pressure, humidity, wind speed and seasonal conditions. The analysis also accounted for clinical variables such as blood pressure, central corneal thickness, glaucoma severity and medication use.

Ambient temperature was negatively associated with IOP (estimate = −0.029; P = .003), while mean blood pressure showed a positive association (estimate = 0.021; P < .001).

The number of glaucoma medications, glaucoma type and time of day also significantly influenced IOP fluctuations. Additional analyses suggested that the association with temperature was more pronounced among patients with severe glaucoma or those using multiple glaucoma medications.

The investigators noted that the observational design prevents conclusions about causality. Potential confounders, including physical activity and obesity, were not assessed, and patients with poorly controlled IOP were excluded. The findings suggest that ambient temperature may warrant consideration when interpreting IOP measurements and managing patients with stable POAG. Larger studies are needed to determine whether the association extends to patients with milder disease or less intensive medical treatment.

Reference:

1. Ikushima T, et al. Effects of ambient temperature on intraocular pressure in patients with stable primary open-angle glaucoma under medical treatment. British Journal of Ophthalmology. Published online September 29, 2026.