The retina is a thin membrane made up of nerve cells that lines the back 60% of your eyeball. The nerve cells in the retina detect light and send signals to the brain about what your eye sees. The central area of the retina (the macula) provides the clear, sharp central vision that you use for focusing on what is in front of you. The rest of the retina provides side (peripheral) vision.

The retina consists of two layers that line the back portion of the eye. The sensory retina contains nerve cells that process visual information and send it to the brain. The retinal pigment epithelium (RPE) lies between the sensory retina and the wall of the eye. The sensory retina cannot function without the support of the RPE.

In a normal retina, the two layers lie in contact with each other. Retinal detachment occurs when the sensory retina becomes separated (detached) from the RPE and the wall of the eye. Fluid from the eye flows into the space between the two layers, further separating them.

Once the retina becomes detached, it stops working properly because the eye cannot process what it sees if the sensory retina and the RPE lose contact with each other. This causes vision loss in the affected area of the retina. Detachment always results in some vision loss.

There are three main types of retinal detachment. The most common type is called rhegmatogenous retinal detachment. The retinal detachment results from a tear or hole in the retina, also called a retinal break. A retinal break allows fluid from the middle of the eye to flow into the space under the retina and push the retina away from the wall of the eye. Other types of retinal detachment are less common.

See an illustration of a detached retina.
 

Retinal detachment affects peripheral vision first. Vision loss tends to get worse over time, as more of the retina becomes detached. Once the detachment spreads to the center of the retina (macula), vision loss will become severe or even total. If a person does not have surgery to repair the detached retina, the vision loss will become permanent.

Although retinal detachment can occur at any age, it is most common in older adults.