Seasonal variation of intra-ocular pressure in glaucoma with and without dry eye

The management of intra-ocular pressure (IOP) is important for glaucoma treatment. IOP is recognized for showing seasonal fluctuation. Glaucoma patients can be at high risk of dry eye disease (DED). We thus evaluated seasonal variation of IOP with and without DED in glaucoma patients. This study enrolled 4,708 patients, with mean age of 55.2 years, who visited our clinics in Japan from Mar 2015 to Feb 2017. We compared the seasonal variation in IOP (mean ± SD) across spring (March-May), summer (June-August), fall (September-November), and winter (December-February). IOP was highest in winter and lowest in summer, at 14.2/13.7 for non-glaucoma without DED group (n = 2,853, P = 0.001), 14.5/13.6 for non-glaucoma with DED group (n = 1,500, P = 0.000), 14.0/13.0 for glaucoma without DED group (n = 240, P = 0.051), and 15.4/12.4 for glaucoma with DED group (n = 115, P = 0.015). Seasonal variation was largest across the seasons in the glaucoma with DED group. IOP was also inversely correlated with corneal staining score (P = 0.000). In conclusion, the seasonal variation was significant in most of study groups and IOP could tend to be low in summer.