By Dr. Mark S. Siegel
Primary Open Angle Glaucoma is the most common type of glaucoma. An increase in eye pressure, intraocular pressure (IOP), occurs slowly over time, leading to vision loss. Higher IOP is thought to be the result of changes in the eye that lead to an obstruction in the outflow of fluid, called aqueous humor.
Large clinical studies have shown that, with reduction in IOP, optic nerve damage and progressive visual loss can be slowed or minimized.
Current drug treatments are directed towards lowering IOP. Treatments to reduce IOP rely on topical eye drop medications, laser and or conventional surgery.
Many patients require more than one drug to control IOP, and despite effective current therapies, they don’t work for all patients.
Current glaucoma medications reduce IOP by either reducing the production of fluid in the eye, or by increasing its outflow. Prostaglandins, which increase outflow, are now the most prescribed glaucoma treatment worldwide.
A new class of glaucoma drugs promises to act specifically on the eye’s drainage canals, called the trabecular meshwork, a main outflow and blockage site in glaucoma.
Rho kinase (ROCK) inhibitors target cells in the trabecular meshwork to enhance aqueous humor outflow. Aqueous humor is a clear fluid that maintains the intraocular pressure.
In research models of glaucoma, ROCK inhibitors have been shown to reduce cellular “stiffness” and enhance outflow through the trabecular meshwork, thereby reducing IOP. No drugs currently on the market enhance the eye’s fluid outflow in this way. Therefore this is a novel and unique target and approach to lowering IOP.
ROCK inhibitors are not yet approved and available for glaucoma patients.
Two U.S. companies, Aerie and Altheos, are currently in clinical research development with topical ROCK inhibitors to lower IOP.
Research data has shown that ROCK inhibition has the potential to offer neuroprotective and anti-inflammatory effects as well as enhance blood flow to the optic nerve, all of which could benefit glaucoma patients.
The ophthalmic community looks forward to and awaits the clinical research data as it becomes available for this potentially exciting class of drug compounds.