Selective loss of retinal ganglion cells in albino avian glaucoma.

Retinal ganglion cell loss was investigated in the retinae of albino quails before and after the development of glaucoma. The isodensity maps of ganglion cells, the total number of ganglion cells, and the histograms of the cell size in the central region of the retina were similar between albino quails without glaucoma and pigmented quails. However, ganglion cells in the intermediate and peripheral regions of the albino quails retina without glaucoma were significantly smaller than those of the pigmented quail retina. In albino quails with moderate glaucoma in 3 months of age, 11% to 55% of all the retinal ganglion cells had disappeared, with the loss of medium-sized cells (30-60 micron2 occurring earlier than that of small and large cells. In albino quails with advanced glaucoma, there was marked cupping around the optic nerve head, and only small ganglion cells remained in the ganglion cell layer.