The Macula of the Human Eye
The macula, macula lutea, is the small, yellowish central portion of the retina of the human eye. The macula is the most active part of the eye and processes the light signals that allow us to do fine work. It is responsible for sharp, clear central vision and the ability to perceive color.
The Function of the Macula
Like the film in a camera, the retina receives light rays from the front of the eye and transmits those light rays through the optic nerve to the brain where the rays are converted into images. The densely packed photoreceptor (light-sensitive) cells in the macula control all of the eye’s central vision and are responsible for the ability to read, drive a car, watch television, see faces and distinguish detail. The rest of the retina handles peripheral vision that enables your eyes to see objects off to the side while you are looking forward.
There are two types of photoreceptor cells in the cornea – rods and cones. The rods provide vision at low light levels, while the cones provide sharp vision and discrimination. Because the macula contains a high concentration of cones, straight-ahead vision is in sharp focus, particularly in bright light. Most of the rods are located in the periphery of the retina, so faint objects are more visible if you do not look directly at them.
The most common cause of functional blindness in people over the age of 60 is macular degeneration, a deterioration or breakdown of the macula. Damage to the macula results in the loss, either partial or complete, of the ability to see objects clearly in the center of vision. Although not totally blind, the person has difficulty performing tasks that require straight-on vision such as driving a car, reading or watching television. Because peripheral vision is not affected, the person can adapt somewhat to the loss of central vision and continue to pursue some normal daily activities, such as walking, without assistance.
There are two types of macular degeneration. The “dry” form is usually the result of aging and thinning of the macula’s layers and the “wet” form occurs when abnormal blood vessels under the retina leak fluid and blood, causing scarring. Vision loss with dry macular degeneration occurs gradually over a number of years and the affected person may not be aware of any problem. Dry macular degeneration is the less serious of the two forms. With the wet form of this disease, central vision capabilities can be damaged rapidly. Early detection usually results in more successful treatment.
It is important to care for your eyes to maintain healthy vision. In Phoenix, our doctors recommend that you receive a thorough vision exam annually. If you are due for an eye exam or if you have noticed any changes in your vision, contact Associated Retina Consultants at 602-242-4928 or associatedretinaconsultants.com.