Pathology of retinitis pigmentosa

Eyes from patients with retinitis pigmentosa were obtained at autopsy. They were processed in celloidin and examined by light microscopy. The earliest evidence of retinal degeneration occurred in the equatorial zone and then extended peripherally and centrally. In the eyes with the earliest involvement, a sequence could be demonstrated in the zone of transition from the less involved macula to the more degenerated retina at the equator. The probable order for the development of degenerative changes in our material appeared to be as follows: (1) migration of nuclei from the outer nuclear layer to the rod and cone layer and the outer plexiform layer; (2) degeneration and loss of photoreceptors and their nuclei in the outer nuclear layer; (3) loss of connecting fibers in the outer plexiform layer; (4) migration of the retinal pigment epithelium (RPE) into the retina, mainly around the blood vessels, but also as isolated balls and spots (this prominent feature, which characterizes the disease, is secondary and only follows the loss of the photoreceptors and their nuclei); (5) adhesion of the retinal to the retinal pigment epithelium or Bruch's membrane in spots or broad areas and; (6) possible transneuronal degeneration of some cells in the inner nuclear and ganglion cell layers. Gliosis of the disc was universal as was the presence of glial membranes from the disc extending over the posterior retina, especially prominent in the macular region. As the material was obtained from 16 to 35 years ago, we lack electrophysiologic and familial data and electron microscopy was not possible.