Impact of topical therapy on visual function

Fundamentally, glaucoma is a neurodegenerative disease and from experimental models we know that alpha2 agonists are neuroprotective agents. As such, the Low-pressure Glaucoma Treatment Study (LoGTS) was conceived to examine the possibility of other therapeutic measures being useful in the management of glaucoma other than a simple intraocular pressure (IOP)-lowering medication.

An important trial

To ensure we had an appropriate study group we set out certain exclusion parameters, which were untreated IOP > 21 mmHg, VF mean deviation worse than –16 decibels, or contraindications to study medications. To allow for a higher patient attrition in the brimonidine group to an expected ocular allergy, both eyes received twice-daily monotherapy in blocks of 7 (4 brimonidine, 3 timolol) by an independent pharmacy in new white bottles.

We determined the efficacy of the treatments mainly on the VF progression in either of the patient's eyes, but it had to be defined as the same three or more points with a negative slope {≥–1 db/year on three consecutive tests, which was assessed by pointwise linear regression. We also examined the level of our study groups' progression on glaucoma change probability maps (GCPM) of pattern deviation and the 3omitting method for pointwise linear regression as a secondary outcome of the treatment efficacy.