Retine

Retine is typically a misspelling or archaic variant of retina, the light-sensitive layer at the back of the vertebrate eye. In modern anatomy, retina is the correct term; retine is not widely recognized as describing a distinct structure. When encountered, retine generally refers to the same tissue, reflecting historical spellings rather than a separate entity.

The retina lines the inside of the posterior eye and contains photoreceptor cells, supporting neurons, and the retinal pigment epithelium. The main neuronal layers include the photoreceptor layer (rods and cones), the outer nuclear layer, the inner nuclear layer, the ganglion cell layer, and the nerve fiber layer, with synaptic connections that process visual information.

Phototransduction begins in the photoreceptors, which convert light into electrical signals that are transmitted through bipolar and amacrine cells to retinal ganglion cells. The ganglion cell axons form the optic nerve, carrying visual information to the brain’s visual cortex for interpretation. The retinal pigment epithelium supports photoreceptor function and participates in the visual cycle.

Developmentally, the retina originates from the neural tube and differentiates into its layered structure through signaling between neuroectoderm-derived tissues and the pigmented epithelium. Blood supply comes from the choroid to the outer retina and from the central retinal artery to the inner retina.

Clinical relevance: retinal disease can impair vision. Common conditions include retinal detachment, age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa, and retinal vascular occlusions. Symptoms may include flashes, floaters, blurred vision, or field loss. Treatments vary and can include laser therapy, intravitreal injections (such as anti-VEGF agents), corticosteroids, and surgical repair.

Etymology: retina derives from Latin retina, meaning net, reflecting its layered, interconnected structure. See also retina, optic nerve, photoreceptors, macula, and visual pathway.