Contributor: Gordon K. Klintworth
The retina degenerates in response to numerous noxious agents. These incude toxins. In certain conditions the degeneration involves a specific part of the retina. In many inherited disorders the photoreceptors degenerate. This degeneration may affect predominantly the rods or the cones. In retinitis pigmentosa the degeneration first affects the rods, but eventually the cones also undergo degeneration. The outer retina also degenerates following retinal detachment, because the outer retina normally obtains oxygen and other nutrients from the choroidal circulation. The outer retina overlying an adajacent choroidal melanoma [melanoma - choroid]  also degenerates.  In retinal occlusovascular disease and glaucoma retinal degeneration effects mainly the inner part of the retina. Under certain circumstances the degeneration splits the retina producing retinoschisis. The peripheral retina commonly undergoes degenerative changes [lattice degeneration - retina].