Continuous IOP monitoring

Jun 01, 2013

Investigating tolerability of a diagnostic device in healthy and glaucomatous patients

"The role of IOP fluctuation as an independent predictive factor for glaucoma progression is still controversial,"6–10 she added. "Goldmann applanation tonometry (GAT) has been the most widely established indirect method for measuring IOP for many decades and is the gold standard."11–14

"We tested the first model for use in humans for the first time in healthy subjects and in glaucoma patients with the primary objective to investigate tolerability and side effects of the device during and after a 24-hour IOP monitoring period," explained Dr Lorenz. Taking both healthy subjects and glaucoma patients and excluding anyone who had worn contact lenses before, the team placed one sensor in each patient's test eye and performed examinations both before and after the 24 hour wearing period.

"To evaluate the level of discomfort of the device in the study eye at 24 hours, a visual analogue scale (VAS) was presented to the subject. VAS for each subject was scored between 0 and 100 mm, the number corresponding to the distance in millimetres of the subject's mark on the VAS line from the left end. Secondary endpoints included best corrected visual acuity (BCVA), pachymetry, epithelial defects, conjunctival erythema and corneal topography," she said. "Additionally, subjects were asked to fill in a diary which was collected at the end of the study."

A test was also performed initially to ensure that healthy and glaucoma patients could be analysed together, as the device had never been formally tested in healthy subjects before. Dr Lorenz explained that if the glaucoma patients had demonstrated severe discomfort in this trial there would have been some difficulty in proving that it was not significantly associated with ocular surface disease, therefore, healthy subjects were required to be used as controls. "However, contrary to our expectations, no significant differences between the two groups could be demonstrated and both groups were combined for analysis," she asserted.