After years of successful IOP control with a prostaglandin analogue (PGA), some patients may wonder if they still need the monotherapy. As it turns out, the answer is probably, yes. Researchers recently discovered that a six-week washout after long-term monotherapy resulted in a small but statistically significant increase in IOP.

This prospective, randomized, controlled clinical study evaluated 154 eyes of 87 participants who had open-angle glaucoma or were open-angle glaucoma suspects. While the control group continued PGA monotherapy, 85 eyes of 48 participants discontinued PGA monotherapy for 42 days.

In the control group, the researchers noted that the control group’s IOP remained stable at each follow up. In the washout group, on the other hand, mean IOP values at days seven (16.19±3.80mm Hg), 21 (17.28±3.55mm Hg) and 42 (17.84±3.31mm Hg) were significantly greater than those at day zero (14.48±1.94mm Hg) and day-matched control group values. While the majority of washout eyes maintained an IOP lower than 21mm Hg at six weeks, 24.7% had an IOP greater than or equal to 21mm Hg.  None of the control eyes had a six-week IOP higher than 20mm Hg.

Lim CW, Diaconita V, Liu E, et al. Effect of 6-week washout period on intraocular pressure following chronic prostaglandin analogue treatment: a randomized controlled trial. Can J Ophthalmol. November 8, 2019. [Epub ahead of print].