A study from the Wilmer Eye Institute has demonstrated a dose-dependent rise in intraocular pressure (IOP) following washout of topical ocular hypotensive eye drops in patients treated for open-angle glaucoma. The researchers’ secondary analysis of data from the COMPASS and HORIZON studies revealed washout of prostaglandin analogs resulted in a greater rise in IOP than washout of alpha-adrenergic agonists, whereas washout of individual medications within the prostaglandin analog class resulted in comparable IOP elevation. The researchers also believe that thicker CCT and a history of selective laser trabeculoplasty (SLT) may predict reduced response to IOP-lowering medications.

The study reviewed 1,400 eyes, 781 from the HORIZON study and 619 from the COMPASS study, with primary open-angle glaucoma who were using zero to four classes of topical IOP-lowering medication.

Post-washout IOP change was similar between the HORIZON and COMPASS cohorts. The change in IOP following washout for patients using zero (n=100), one (n=705), two (n=355), three (n=214) or four (n=26) medications was 0.2mm Hg, 5.7mm Hg, 6.9mm Hg, 8.8mm Hg and 9.5mm Hg, respectively. 

The study’s analysis identified greater number of glaucoma medications, higher unmedicated IOP, thinner CCT, lack of prior SLT and male sex as factors associated with greater IOP rise upon medication washout.

As clinical trials for new glaucoma therapies are ongoing, the researchers believe that understanding the expected IOP elevation following medication washout will increase the efficiency of the trial’s planning and recruitment.