What is the Retina? 

Frequently Asked Questions – Vitreoretinal Basics:

1. What is the retina?
2. What is the vitreous?
3. What is the macula?
4. Watch a video of retina and vitreous anatomy made simple

What is the retina?

The retina is a very thin layer of highly specialized tissue that lines the inside of the eye. It is only slightly thicker than a human hair. The retina is analogous to the film in a camera. Light is focused on the retina by the natural lens of the eye (or by an artificial lens in the case of one who has undergone cataract surgery). The image that is focused on to the retina is converted to a chemical and electrical signal. This signal is preprocessed by specialized cells within the retina itself, and is then transmitted to the brain for interpretation. This process is so complex and energy intensive that the retina is the most metabolically active tissue in the body. The retina is similar to brain tissue in that it does not heal or regenerate spontaneously if it suffers injury.

What is the vitreous?

The vitreous is a transparent, gelatinous tissue that fills the inside of the eye. It is quite similar to the texture of an egg white. Before we are born, the vitreous contains the blood vessels that the eye needs for development. Then, prior to birth, these vessels disappear and the vitreous becomes transparent. During childhood, the vitreous is firmly attached to several areas of the retina. Once we reach adulthood, the vitreous begins to liquefy. This may be observed as floaters in the vision. In many older adults, at some point the vitreous suddenly separates from its attachment points on the retina, causing an increase in floaters. This is termed a ‘posterior vitreous detachment,’ and is usually not associated with any serious problem. However, in some people, the vitreous pulls on the retina during this process and causes a retinaL tear, hemorrhage, or retinal detachment, all of which can be serious and lead to permaent vision loss.

What is the macula?

The macula is the very central area of the retina and is important because it is the area we use for most of our visual function. The anatomy of the macula is different from the rest of the retina, and certain diseases affect this area preferentially (such as age-related macular degeneration and diabetic macular edema). The very center of the macula is called the fovea, which is visible as a slight depression in the retina. This area is what we use for reading and seeing fine details.