Mouse model examines age-related susceptibility of retina and optic nerve to IOP injury

May 6, 2009

Data from a mouse model suggest that aging increases retina and optic nerve vulnerability to IOP evaluation and associated oxidative stress. These experiments suggest a possible mechanism through which aging predisposes the eye to glaucoma, said Yu Xiang Kong, PhD, of the glaucoma research unit, Centre for Eye Research Australia, University of Melbourne.

Fort Lauderdale, FL-Data from a mouse model suggest that aging increases retina and optic nerve vulnerability to IOP evaluation and associated oxidative stress. These experiments suggest a possible mechanism through which aging predisposes the eye to glaucoma, said Yu Xiang Kong, PhD, of the glaucoma research unit, Centre for Eye Research Australia, University of Melbourne.

Aging is a primary risk factor for glaucoma, Dr. Kong said, but the pathophysiology underlying this relationship is poorly understood. He and his colleagues developed a mouse model to investigate whether aging increases retinal ganglion cell vulnerability to IOP-induced oxidative stress in vivo.

The researchers induced an acute spike in IOP (50 mm Hg for 30 minutes) in anesthetized wild-type C57/BL6 mice from three age cohorts: 3, 12, and 18 months. Dark-adapted scotopic electroretinogram measurements were taken before, during, and after the IOP challenge. In addition, signals were collected at dim and bright intensities and analyzed to gather data on ganglion cell and ON-bipolar cell responses. Researchers than analyzed ERG responses across time and collected the retina and optic nerve to study for markers of oxidative stress.

They found that increasing age was associated with increased susceptibility to the IOP challenge. The 18-month-old mice displayed greater ganglion cell dysfunction and recovered more slowly than the 3-month- old mice; the older mice also showed significantly greater ON-bipolar cell impairment and slower recovery. The oxidative stress markers HO-1 and HNE in the retinal and optic nerve tissues of the 18-month-old mice were significantly higher than those of the 3-month old-mice.

Dr. Kong suggested that this mouse model could be useful in further studies of IOP insult.