Other degenerative and related disorders of the retina and choroid

Peter J. Francis, David J. Wilson, Alec Garner

Research output: Chapter in Book/Report/Conference proceedingChapter


The morphological changes that accompany degenerative processes in the neural retina tend ultimately to assume a common pattern irrespective of their cause. Loss of neurons is followed by a net loss of tissue volume with replacement by a minor reactive proliferation of astrocytes or by cystoid changes within a network formed by the supporting Müller cells. With age there is a gradual nonpathological dropout of retinal ganglion cells at an approximate rate of 5000 per year resulting in a decrease in the fovea of about 16% from the second to the sixth decade (10). Photoreceptors, particularly the rods, are also vulnerable to loss during aging, but the ratio of photoreceptors to retinal pigment epithelium (RPE) cells remains the same, suggesting parallel loss of these closely apposed cells (10). The human macula comprises a cone-dense fovea encircled by a roddense parafovea. Throughout adult life, the cone density is maintained in the fovea however in the same time period the rod parafoveal density reduces by 30% (5). Loss of neurons in this way is accompanied by loss of the foveal reflex, due to shallowing of the foveal depression and enlargement of the capillary-free zone at the fovea.

Original languageEnglish (US)
Title of host publicationGarner and Klintworth's Pathobiology of Ocular Disease, Third Edition
PublisherCRC Press
Number of pages16
ISBN (Electronic)9781420020977
ISBN (Print)0849398169, 9780849398162
StatePublished - Jan 1 2008
Externally publishedYes

ASJC Scopus subject areas

  • General Medicine


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