Highlights

• The retina has the highest rate of oxygen consumption of any tissue in the human body because of its high metabolic activity.

• Retinal neurons (photoreceptor, bipolar, horizontal, amacrine, and ganglion cells), glial cells (Müller cells, astrocytes, and microglia), and vascular cells (endothelial cells and pericytes) together form a functional neurovascular unit that converts light into a neural signal.

• Light induces hyperpolarization, leading to a cascade of reactions in the photoreceptor outer segments called phototransduction, which converts light energy into an electrical impulse.

• Rods are highly sensitive and can be stimulated by a single photon, whereas cone photoreceptors can adapt to a wider range of light intensities.

• Gene mutations affecting components of the phototransduction pathway lead to inherited retinal dystrophies with varying clinical phenotypes.

Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.