Dietary Deficiency of Vitamin E Aggravates Retinal Ganglion Cell Death in Experimental Glaucoma of Rats

Purpose: Investigate the effect of dietary vitamin E (Vit E) on the retinas of a rat model of induced glaucoma, in which surgically induced elevation of intraocular pressure (IOP) is associated with an increase in reactive oxygen species. Methods: Rats were fed a standard chow, Vit E-supplemented diet, or Vit E-deficient diet and subjected to surgically induced IOP elevation (or sham surgery) for five weeks. The retinal ganglion cells (RGCs) were subjected to retrograde fluorescent tracer labeling. Results: The mean number of RGCs of rats on the standard chow, Vit E-supplemented diet, and Vit E-deficient diet were 79.6%, 78.6%, and 71.3% of controls, respectively. Lipid peroxidation of the retinas of rats given a Vit E-deficient diet were significantly higher after IOP elevation for three days (14.42 +/- 0.25 mu M, P=0.016) and five weeks (10.46 +/- 0.11 mu M, p=0.042), compared to rats given standard chow (11.37 +/- 0.31 mu M; 8.95 +/- 0.16 mu M). Compared with rats given standard chow, rats given a Vit E-deficient diet had significantly elevated concentrations of glutathione (p=0.032), but no significant differences in the levels of total superoxide dismutase (SOD), Cu/Zn SOD, or catalase activities three days after IOP elevation. Conclusions: Rats fed a Vit E-deficient diet with surgically induced IOP elevation experience significantly more RGC death than rats fed a normal diet. This phenomenon may be related to the increased level of lipid peroxidation in Vit E-deficient rats.