Topical treatment of glaucoma: established and emerging pharmacology

ABSTRACT

Introduction: Glaucoma is a collection of optic neuropathies consisting of retinal ganglion cell death and corresponding visual field loss. Glaucoma is the leading cause of irreversible vision loss worldwide and is forecasted to precipitously increase in prevalence in the coming decades. Current treatment options aim to lower intraocular pressure (IOP) via topical or oral therapy, laser treatment to the trabecular meshwork or ciliary body, and incisional surgery. Despite increasing use of trabecular laser therapy, topical therapy remains first-line in the treatment of most forms of glaucoma.

Areas covered: Novel glaucoma therapies are a long-standing focus of investigational study. More than two decades have passed since the last United States Food and Drug Administration (FDA) approval of a topical glaucoma drug. Here, the authors review established topical glaucoma drops as well as those currently in FDA phase 2 and 3 clinical trial, nearing clinical use.

Expert opinion: Current investigational glaucoma drugs lower IOP, mainly through enhanced trabecular meshwork outflow. Although few emerging therapies show evidence of retinal ganglion cell and optic nerve neuroprotection in animal models, emerging drugs are focused on lowering IOP, similar to established medicines.

KEYWORDS:

• Adenosine receptor
• neuroprotection
• norepinephrine transporter inhibitor
• nitric oxide
• primary open angle glaucoma
• RHO-associated protein kinase inhibitor
• ribonucleic acid interference
• trabecular meshwork
• uveoscleral outflow

Article highlights

• Glaucoma is the most common cause of irreversible vision loss worldwide and is expected to increase in prevalence in the coming decades

• Topical therapy of glaucoma is first-line for treatment in most patients

• Two decades have passed since the FDA last approved a topical drug for the treatment of glaucoma

• Current investigational drugs in phase 2 or phase 3 FDA study show effective intraocular pressure lowering through pathways different than current drugs- namely enhanced trabecular meshwork outflow.

• As emerging drugs are still focused on intraocular pressure control, a paradigm shift in the treatment of glaucoma has not yet been realized.

This box summarizes key points contained in the article.

Declaration of interest

TS Vajaranant has received grants from the NIH, Allergan, Aerie Pharmaceuticals and Bausch & Lomb. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed

Additional information

Funding

T Vajaranant has received an NIH grant from the National Eye Institute (K23EY022949).