Diagnostic Equipment


Diagnostic Equipment

Glossary of Terms



Electroretinography (ERG)

Electroretinography (ERG) is a test used to measure electrical responses of the eye's light-sensitive cells, the rods and cones. The test is performed twice, once in dim light and again in a well lit room. Your eye will be numb by numbing dropps, and your eyes will be helped open. Electrical sensors, called electrodes, will be placed on each eye. A light flashes and the sensors measure electrical activity of the retina in response to the light. The electrical response then travels from the sensors to a screen, where it can be viewed and recorded.

Fluorescein Angiography (FA)

Fluorescein Angiography is a test using a special camera to look at the blood vessels in the retina. The word Fluorescein is actually the type of dye used to allow the blood vessels to show up under special filters in the camera. Angiography means to study the blood vessels.

The test takes about 15 minutes to complete. The pupils should be fully dilated in order to achieve the best results. First, the technician will position the camera very close to the eye to take pictures of the retina. Then, the technician will inject Fluorescein dye into the vessels of the arm. It only takes a few seconds for the dye to travel through the blood vessels and into the retina. Again, the technician will position the camera close to the eye while taking a series of photos using a special filter that allows the dye to become visible. This will allow the physician to observe how the blood circulates in the retina.

Common complaints:
Flash of the camera while taking photos is bright.
Some patients have slight nausea immediately after the fluorescein is injected but it soon subsides.

On a rare occasion, people have had an allergic response to the dye.

The physician will review the photos and talk with you about the result.

Optical coherence tomography (OCT)

The OCT is a diagnostic test using a special camera that takes a series of images of the retinal layers (located in the back of the eye). The camera is able to produce an image with many different colors to represent the different layers within the retina. The test generally takes about 10 minutes. Although the pupils are not required to be dilated, the images are significantly better when they are. After the series of pictures are taken, the physician will review the photos and talk with you about the result.

This noninvasive diagnostic test is well tolerated by most people.

Integrated Clinical Research, LLC
dba Retina Research Institute of Texas

Sunil S. Patel, M.D., Ph.D.
S. Young Lee, M.D.
5441 Health Center Dr.
Abilene, Texas 79606
Phone: 325-690-4414
Toll free: 800-810-7411
Fax: 325-690-4452