Medical Management of Glaucoma in the 21st Century from a Canadian Perspective

Abstract

Glaucoma is a medical term describing a group of progressive optic neuropathies characterized by degeneration of retinal ganglion cells and retinal nerve fibre layer and resulting in changes in the optic nerve head. Glaucoma is a leading cause of irreversible vision loss worldwide. With the aging population it is expected that the prevalence of glaucoma will continue to increase. Despite recent advances in imaging and visual field testing techniques that allow establishment of earlier diagnosis and treatment initiation, significant numbers of glaucoma patients are undiagnosed and present late in the course of their disease. This can lead to irreversible vision loss, reduced quality of life, and a higher socioeconomic burden. Selection of therapeutic approaches for glaucoma should be based on careful ocular examination, patient medical history, presence of comorbidities, and awareness of concomitant systemic therapies. Therapy should also be individualized to patients' needs and preferences. Recent developments in this therapeutic field require revisiting treatment algorithms and integration of traditional and novel approaches in order to ensure optimal visual outcomes. This article provides an overview of recent developments and practice trends in the medical management of glaucoma in Canada. A discussion of the surgical management is beyond the scope of this paper.

Figure 1

Glaucoma classification and subtypes.

Figure 2

Secondary open-angle glaucoma classification chart.

Figure 3

Suggested range for initial target IOP for each eye (a) with ≥ 30% reduction from baseline; (b) with 30% to 35% reduction from baseline; (c) with ≥ 25% reduction from baseline; (d) with ≥ 20% reduction from baseline. In patients with severe optic nerve damage, those with rapidly progressing disease or with other risk factors (i.e., family history, advanced age, pseudoexfoliation, pigment dispersion syndrome, uveitis, steroid use, or disc hemorrhage), selecting target IOP lower than 25% of the pretreatment IOP is justified. Other factors such as the rapidity of progression and the severity of disease in the other eye should be taken into consideration. Conversely, choosing a less aggressive IOP range may be reasonable if the risks of aggressive treatment outweigh the benefits (i.e., comorbidities and older age).

Figure 4

The chronology of the introduction of topical IOP-lowering medications. Systemic carbonic anhydrase inhibitors have been available since 1955.

Figure 5

Glaucoma pharmaceutical management algorithm (SLT, MIGS, or other surgeries may be performed at any step of the algorithm). FC, fixed combination; BID single agent, dorzolamide, brinzolamide, and brimonidine; PG, prostaglandin analogue (latanoprost, travoprost, and bimatoprost); PG-βB FC, prostaglandin + timolol (latanoprost + timolol, travoprost + timolol); BID-βB FC, BID-dosed combination with timolol (dorzolamide + timolol, brinzolamide + timolol, brimonidine + timolol); AA-CAI F, α agonist + CIA (brimonidine + brinzolamide); SLT, selective laser trabeculoplasty; MIGS, microinvasive glaucoma surgery. Patient and disease characteristics should be considered at all stages of algorithm and the therapy should be individualized according to patient needs (i.e., ability to tolerate any component of the therapy). In addition, at all stages of the treatment algorithm it is imperative to monitor for adverse effects as well as disease progression (RNFL/VF/disc).