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C CLINICAL RESEARCH

To properly assess the effectiveness of each drug in an individual treatment regimen, single medications are nor-
mally added one at a time. Having said that, however, the algorithm does note the addition of FC medications. The
clinician should be aware that while some granularity will be lost with respect to the effect of individual medications
in the FC, the IOP response is expected to be fast and significant. This is perhaps a more important consideration in
severe disease and when encountering very high eye pressures. Not apparent in the algorithm is the fact that SLT,
minimally invasive glaucoma surgeries (MIGS) and other surgical interventions may be pursued at any time during
the management continuum. Certainly, those patients for whom progression continues to be documented despite
maximum tolerated medical therapy (MTMT), should be referred for surgical consultation. MTMT is defined as
the largest number of medications that the patient can tolerate and consistently administer.

Currently, the first-line treatment for glaucoma is a prostaglandin analogue (PGA; see STEP 1). Given that these medi-
cations allow for the largest reduction in IOP with a single drop per day, are well-tolerated, lower IOP over 24 hours,
and have relatively few systemic adverse effects, this is the starting point for the treatment algorithm. If progression
is suspected or targets not achieved despite a reasonable follow-up period, it is recommended to switch within the
prostaglandin analogue class prior to moving to STEP 2. Clinicians begin to differ after this point, but STEP 2 may be
one of three options. Adding a beta-blocker in the morning allows the clinician to tailor this treatment to some extent
with choice of agent, concentration and dosing frequency as well as assess for adverse effects. This is also a relatively
inexpensive option to consider. The second option is to switch the prostaglandin analogue to a FC agent with that
medication and timolol. This provides a number of advantages including fewer bottles and fewer drops (one per day
rather than two), thereby reducing the exposure of the ocular surface to preservatives. The third and fourth options
include leaving the PGA in place but adding either a single agent CAI or alpha agonist, or proceeding directly to a FC
of one of these agents with timolol. Progress through STEPS 3 and 4 are dependent on this choice as per Figure 16. If it
is determined that a beta-blocker is not an option at STEP 2, a single agent CAI or alpha agonist may be added. In some
circumstances, the fixed combination without beta-blocker (brimonidine / brinzolamide) may be started right away.
Regardless of what treatment is employed, a thoughtful, evidence-based approach must be taken and all compo-
nents discussed with the individual and informed consent obtained. The consideration of preexisting and iatrogenic
ocular surface disease must also remain an ongoing focus.

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Figure 16: General approach to medical management

54 CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 1, 2017