To better understand seasonal and weekday intraocular pressure (IOP) variations, researchers assessed long-term daily IOP measurements in patients with glaucoma using an intraocular sensor implanted at the time of cataract surgery. Their study confirmed previously observed seasonal IOP variations; measurements were significantly higher in winter compared with summer months and were highest on Wednesdays and lowest on Fridays.

The study analyzed IOP variation patterns in 22 eyes of 22 patients with primary open-angle glaucoma. The telemetric system combines an implantable IOP sensor with a hand-held reading device. The researchers instructed the patients to self-measure their IOP as often as desired, but at least four times daily. Each enrolled patient recorded daily IOP measurements for an average duration of 721 days. Between mid-winter (December to January) and mid-summer months (June to July, there was a reduction in mean IOP of 8.1% (-1.55mm Hg). In addition to the winter/summer variation, another seasonal pattern emerged as two peaks in March and September.

All patients were pseudophakic, and the researchers believe this may influence the patterns and magnitudes of IOP variations. Also, they note that a considerably larger cohort would allow for an actual comparison between subgroups such as treated patients or those with a positive surgical history. They conclude that a better understanding of the mechanism(s) responsible for these IOP variations may enhance glaucoma management.