Patient Education Information

 

The Retina


The retina has two parts: the peripheral retina and the macula. If you imagine the retina as a circle with a bull’s-eye at the center, the macula is like the bull’s-eye, it is very small. The large area of the retina that surrounds the macula and makes up 95% of the retina is called the peripheral retina. The peripheral retina gives us vision to the side, called “peripheral” vision. It is this part of the retina that is at work when we see something out of the corner of the eye. Because the peripheral retina is not able to see detail clearly, we cannot use this peripheral vision to read, thread a needle, drive, or even recognize a face. If you see someone off to your side, “out of the corner of your eye”, you may be able to tell who it is because you recognize the person’s general shape, but you won’t be able to see the expression on the person’s face. In order to see fine detail, we must look straight ahead, using the macula, the “bull’s-eye” center of the retina. Even though the macula makes up only a small part of the retina, it is one hundred times more sensitive to detail than the peripheral retina. The macula allows you to see tiny detail, read fine print, recognize faces, thread a needle, read the time, see street signs, and drive a car.

HOW THE EYE WORKS

The eye is like a camera. When you take a picture the lens in the front of the camera allows light through and focuses that light on the film that covers the back inside wall of the camera. When the light hits the film, a picture is taken.

Normal Optical Coherence Tomography (OCT) Study

Normal Fluorescein Angiogram

The eye works in much the same way. The front parts of the eye (the cornea, pupil, and lens) are clear and allow light to pass through. The light also passes through the large space in the center of the eye called the vitreous cavity. The vitreous cavity is filled with a clear, jelly-like substance called the vitreous or the vitreous gel. The light is focused onto a thin layer of tissue called the retina by the cornea and the lens. The retina covers the back inside wall of the eye. The retina is like the film in a camera. It is the seeing tissue of the eye. When the focused light hits the retina, a picture is taken. Messages about this picture are sent to the brain through the optic nerve. The brain then interprets these messages and this is how we see.