Retina

The retina is a light-sensitive tissue layer that lines the inner surface of the eye. It is part of the central nervous system and converts light into neural signals that are processed by the brain to produce vision. The retina contains photoreceptors, consisting of rods (sensitive in low light) and cones (color and high-acuity vision). Cones are densely packed in the fovea, the central area of the macula, while rods predominate in the peripheral retina. The retina’s multilayer structure includes photoreceptors, bipolar and horizontal cells, amacrine and ganglion cells, and supporting Müller glia. The axons of ganglion cells form the optic nerve, which transmits visual information to the brain. Horizontal and amacrine cells provide lateral processing that enhances contrast and motion detection. The outer retina is closely associated with the retinal pigment epithelium (RPE) and Bruch’s membrane, with the choroid supplying the outer layers; the inner retina is nourished by retinal blood vessels.

Clinically, retinal function depends on intact metabolic support from the RPE and choroid. Disorders include age-related macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, and glaucoma, which affects the optic nerve. Diagnosis relies on ophthalmoscopy, optical coherence tomography (OCT), and fluorescein angiography. The retina has limited regenerative capacity in humans, making early detection and treatment crucial for preserving vision.