Aging, glaucomatous eyes may differ in rate of axon loss

San Diego—The rate of change in axon loss, not the location of the damage, most likely differentiates an aging eye from a glaucomatous eye, according to recent research, said Claude F. Burgoyne, MD, holder of the Van Buskirk Chair for Ophthalmic Research, Devers Eye Institute, Portland, OR.

Such a differentiation could help ophthalmologists determine whether axon loss in an eye with glaucoma is due to aging or due to the disease and whether an IOP-lowering intervention might slow the rate of change.

“Whether it’s glaucoma or aging, the rate of change is essential to determine,” however, he said. “There’s a growing movement to do rate-of-change characterization for both structure and visual field.”

A growing body of literature is examining the overlap of disc and field change in patients with glaucoma and “age-matched normal” patients followed over time for progression, he said.

“Increasingly, the [glaucoma-related] data will be overlaid onto age-matched normals over time so that you can estimate the rate of change in your parameters relative to age-matched normals,” Dr. Burgoyne predicted,

When deciding whether to treat IOP in an aged patient with slowly progressing disease, he said, “all of our current parameters will pertain,” including life expectancy, the risks of lowering IOP, and whether an age-related rate of axon loss affects central vision.

“However, if the pathophysiology of aging and glaucoma can be shown to be linked…it’s reasonable to consider that lowering IOP can influence the rate of [progression previously attributed to aging],” Dr. Burgoyne concluded.