What Does the Retina Do?

The retina is a thin layer of specialized, light-sensitive brain tissue located in the back of the eye. Its main function is to transform light rays into electrical signals so you can see. There are several eye conditions that can impact the retina and, hence, affect your vision. In this blog, we will explain the importance of the retina, common retinal disorders and diseases, and how various procedures and surgeries are utilized to treat these conditions.

Retinal Function

Light hits the retina whenever it passes through the eye. From there, cells called photoreceptors in the retina convert light rays into electrical signals that travel through the optic nerve to the brain. The brain translates these signals and interprets them into the images you see.

Because the retina is so crucial to how you interpret images, any disease or damage to that part of the eye can impact how you see images and cause vision changes.

Anatomy of the Retina

The retina measures 32 mm across and the average thickness is about 0.2 mm. The retina contains five types of neurons that each play an important role in its function.

Photoreceptors: Photoreceptors contain photopigments that absorb photons of light to help your brain understand images. There are two types of photoreceptors in the retina: rods and cones. Rods are mainly responsible for peripheral vision and vision at night and in dim light. They help you sense contrast, brightness, and motion. About 95% of the retina’s photoreceptors are made up of rods, which amounts to 120 to 130 million rods. Cones are responsible for central vision in bright light. They specialize in detecting red, green, and blue light. In addition, cones help you sense fine resolution, spatial resolution, and color vision. By comparison, cones account for just 5% of the retina’s photoreceptors – or about 6 to 7 million cones.

Retinal ganglion cells: Ganglion cells serve as the retina’s main output neuron and extend to form the optic nerve, the nerve at the back of the eye that relays messages to your brain to create visual images.

Bipolar cells: Bipolar cells receive information from photoreceptor cells and send them to ganglion cells.

Horizontal cells: Horizontal cells regulate the output of photoreceptors and help adjust your eyes to light – both bright and dim.

Amacrine cells: Amacrine cells are intermediate neurons that make connections with bipolar cells and ganglion cells.

In summary, photoreceptors absorb light once it hits the retina. Rods and cones send signals to bipolar cells, which also communicate with horizontal cells. Bipolar cells send impulses to ganglion cells, which also communicate with amacrine cells. Finally, the messages leave the ganglion cells at the optic nerve and are communicated to the brain.

Further, the retina consists anatomically of the macula (center of the retina) and the peripheral retina (area outside the macula).

Retina Layers

Before light can reach the retina’s photoreceptors, it must first travel through several layers. Here is an overview of the various neurons found in the retina’s layers. The layers are listed in descending order from the vitreous (the clear, gel-like substance that fills up the eyeball) to the choroid (the blood vessels network that is part of the uvea between the sclera and the retina).

Retinal Disorders

Treatment Options for Retinal Disorders

While the main goal of treating retinal disorders is to improve altered vision or restore vision loss, sometimes the only option is to slow down or stop how the disease or disorder progresses.

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Treating Retinal Disorders at DMEI

If you experience any changes to your vision, do not wait to see an ophthalmologist. Delaying an eye exam or treatment can put you at risk of permanent vision loss or, in severe cases, blindness.

For more information on retinal disorders, our experienced team, with newest addition, Dr. Coussa, is here for you. Request an appointment today to receive a personalized treatment plan.