Retina

Retina

The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centers of the brain through the fibers of the optic nerve.

Anatomy

The retina is a complex, layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are types of neurons which are capable of phototransduction. The other neurons present in the retina are interneurons, which interpret signals from the photoreceptor cells and transmit them to a complex network of other neurons for further processing.

Function

The retina translates an optical image into neural impulses starting with the patterned excitation of its light-sensitive cells, the photoreceptors. A layer of photoreceptor cells at the back of the retina contains two types of photoreceptor cells, rods and cones. The retina processes light through a layer of bipolar cells and ganglion cells where it is processed into regular image representation and the information is sent down the optic nerve to the visual cortex in the brain.

Clinical significance

Damage to the retina can cause vision loss, making retinal diseases serious conditions. Some common diseases that affect the retina include retinal detachment, diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and retinoblastoma.

See also

• Eye
• Optic nerve
• Photoreceptor cell
• Visual cortex

References

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