Apoptosis in health and diseases of the eye and brain.

Apoptosis is a form of programmed cell death (PCD) and enables the immunologically silent disposal of senescent or unwanted cells, causing minimal damage to the surrounding environment. Apoptosis can occur via intrinsic or extrinsic pathways that initiate a series of intracellular and extracellular signaling events. This ultimately leads to the clearance of the cell by phagocytes. This normal physiological mechanism may be accelerated in several diseases including those involving the eyes and brain, leading to loss of structure and function. This review presents the role of PCD in the health of the eyes and brain, and the evidence presented for its aberrant role in disease.