2020–2021 BCSC Basic and Clinical Science Course™
8 External Disease and Cornea
Chapter 6: Clinical Approach to Depositions and Degenerations of the Conjunctiva, Cornea, and Sclera
Degenerations of the Sclera
The sclera becomes less elastic with age, and there is a relative decrease in scleral hydration and the amount of mucopolysaccharide. These changes are accompanied by subconjunctival deposition of fat, which gives the sclera a yellowish appearance. Calcium may also be deposited either diffusely among the scleral collagen fibers in granular or crystalline form or focally in a plaque anterior to the horizontal rectus muscle insertions. This senile plaque (Cogan plaque) is visible as an ovoid or rectangular zone of grayish translucency (Fig 6-17) and is sometimes mistaken for a pigmented tumor. Histologically, the mid-portion of the involved sclera contains a focal calcified plaque surrounded by relatively acellular collagen. These plaques do not elicit inflammation and rarely extrude. If sufficiently dense, they may be visualized on a computed tomography scan.
Figure 6-17 Senile scleral plaque (Cogan plaque) anterior to the horizontal rectus muscle insertions.
(Courtesy of Cornea Service, Paulista School of Medicine, Federal University of São Paulo.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.