Photo courtesy of Jeff Gidday, Ph.D.

Scientists have found a way in mice to prevent damage to the optic nerves that normally occurs in glaucoma. Using high-power micrographs like this one of the optic nerve in cross-section, they can quantify glaucoma damage to the axons of the retinal ganglion axons passing through the nerve. In this image, those axons are green, and the branches and nuclei of the astrocytes surrounding them are red and blue, respectively.

Findings: BrightFocus-funded researcher Jeffrey Gidday and co-investigators discovered that temporarily cutting off oxygen in a controlled fashion to “stress” the eyes of mice with glaucoma can prevent further optic nerve injury. This introduction of stress, called “preconditioning,” led to a protective response known as “tolerance,” which makes the nerve cells less vulnerable to future damage.  Normally, the retinal ganglion cells that make up the optic nerve can die as the disease progresses, which may lead to blindness.  Applying a little bit of stress at earlier stages of glaucoma seems to protect them from dying.

The article summarizing this research appeared in the March 2012 issue of the journal Molecular Medicine.

Significance: Gidday and colleagues believe that small episodes of stress to the eyes may actually protect against damage from glaucoma. These studies have only been done in animals, so more research is needed before it is known whether preconditioning could have a protective effect in humans. If so, then perhaps in the future after someone has been diagnosed with glaucoma, he or she could undergo a “stress” treatment with the goal of minimizing additional harm to the optic nerve. So far, the treatments for glaucoma only aim to reduce eye pressure. There are no treatments specifically designed to prevent further direct damage to the optic nerve cells. Currently, Dr. Gidday and colleagues are looking for genes that are turned on (or off) by applying stress. Those genes could be targets for future drugs.

For more information:

• Dr. Gidday's National Glaucoma Research award web page
• Original Scientific Paper (Zhu Y, Zhang L, Schmidt JF, Gidday JM. Glaucoma-induced degeneration of retinal ganglion cells prevented by hypoxic preconditioning: A model of “glaucoma tolerance.” Molecular Medicine)
• Press release from Washington University in St. Louis