GLAUCOMA IN FOOD-RESTRICTED AND AD LIBITUM-FED DBA 2NNIA MICE/

We allocated 110 DBA/2NNia mice of either sex to one of two feeding re gimens: ad libitum (AL) or food restriction (FR) to 60% of the amount consumed by the AL group. The mice were examined at 3, 6, 9, 12, 18, a nd 24 months (at 3 months, only AL mice were examined). During the rem aining periods approximately equal numbers (n = 10) of mice of both se xes and diet groups were examined. Peripheral anterior synechia was th e first glaucoma-associated lesion observed and was present in 8 of 10 AL female mice, 6 of 10 AL males, and 1 FR male at 6 months. At 9 mon ths peripheral anterior synechia was present in all AL females and was accompanied by depletion of retinal ganglion cells and degeneration o f the optic nerves and optic tracts. Ninety percent of the eyes in the AL males also had peripheral anterior synechia at 9 months, but gangl ion cell depletion and optic nerve degeneration were not observed as f requently. Neovascular membranes in the iridocorneal angle, a componen t of peripheral anterior synechia, were first observed at 9 months in approximately 55% of the globes of the AL mice and 5% of the FR mice. This was a major difference in the microscopic features of synechia be tween the diet groups and resulted in increased severity of synechia i n the AL mice compared with their FR cohorts. Degeneration of the opti c nerves and tracts was characterized by atrophy, astrogliosis, increa se in cellularity, fragmentation of axons, and loss of myelin. Glaucom a in the FR mice of both sexes was less severe than in their AL counte rparts. The most severely affected were AL females, followed by FR fem ales, AL males, and FR males. Food restriction reduced the incidence a nd severity of the ocular lesions in females at all periods. The prima ry benefit of FR in males occurred during the 6- and 9-month periods w hen the incidence and severity of the glaucoma-related lesions were re duced; in the succeeding months the major benefit was minimal reductio n of the severity of the lesions.