FEB 09, 2016
Using a non-invasive contact lens sensor (CLS), the authors of this randomized trial assessed the effect of ocular hypotensive medications on a patient’s circadian IOP pattern.
Contact lens sensors were first introduced in 2011 as a non-invasive, continuous method to measure IOP by registering changes in ocular dimension at the corneo-scleral junction. It contains an embedded microprocessor that takes measurements every 5 minutes and sends an output signal to a portable recorder.
In this trial, investigators used the CLS to monitor IOP changes throughout the day. Subjects included 23 patients with open-angle glaucoma were monitored for 1 month without medication to establish baseline values. Patients were then randomized to 1 of 4 classes of glaucoma drops (bimatoprost 0.01%, brimonidine 0.1%, brinzolamide 1% and timolol 0.25%) followed by a prostaglandin analogue (bimatoprost) add-on after 1 month.
After 3 months, the authors found no significant differences in IOP fluctuations throughout the day (wake/sitting to sleep/supine) before and after starting glaucoma medications. Additionally, only prostaglandin analogues reduced the nocturnal IOP rise associated with horizontal sleeping positions (P<0.024). These findings confirmed previous studies that have shown sustained effects of prostaglandin analogues during the night.
The authors conclude that the overall impact of ocular hypotensive medications on circadian IOP-related patterns is small. They acknowledge that CLS measurements are not a direct measure of IOP, but this and other studies have shown that it can be a convenient method to continuously detect IOP changes throughout the day.