Retina

Abstract

The retina is an important part of the eye, playing an integral role in vision by capturing light and relaying visual information to the brain for interpretation. Continue reading below for a brief overview of the role and function of the retina, including anatomical and cellular components.

 by Evan Martow

Main Article

The retina is the part of the eye that captures light, converting it into a cellular signal that is transmitted to the brain for organization and interpretation.
Anatomically, the retina is located at the back of the eye. Light enters the eye through the pupil and is then focused by the lens on to the retina. The retina has several notable anatomical regions. The macula is near the center of the retina, and can be identified by its yellow colour (as compared to the orange-red of the rest of the retina; this is why people often appear to have ‘red eye’ in photos- we are seeing light reflected off of their retina!). At the center of the macula is the fovea, which is responsible for the most central portion of vision and provides the sharpest visual acuity. Another landmark is the optic disk, which represents the area where all of the nerves carrying signals from the retina gather to form the optic nerve, responsible for carrying visual information back to the brain.
The retina has a complicated, multilayered structure, but it is the photoreceptors that are responsible for converting photons of light in to cellular signals, which are ultimately transmitted to the brain via the optic nerve. There are two primary types of photoreceptors: rods and cones. Rods are more sensitive to light (allowing us in maintaining vision in low-light environments), whereas cones require a greater light stimulus but can discriminate between colours. Rods and cones differ not only in their functionality, but also in their distribution throughout the retina: the highest concentration of cones is centrally (with the epicenter being at the fovea, explaining why our sharpest vision is associated with this region), whereas a greater proportion of rods are found as one travels more peripherally.

There are many diseases and conditions that can affect the retina. Considering the integral role the retina plays in our vision, it is important to identify and treat them quickly in order to preserve eyesight. Classic symptoms of damage (or impending damage) to the retina include flashing lights, multiple new floaters, and, of course, loss of vision. Although loss of vision can be sudden, as with the occlusion of a blood vessel supplying an area of retina, vision loss can also be more gradual and insidious. For this reason it is important to regularly be seen by an ophthalmologist, especially if you are at risk. For more details regarding retinal pathologies, please see the other sections under the “Learn More” tab.