ERG / VEP

Our practice offers advanced electrophysiological testing to obtain important information on the functional health of the retina. These tests are commonly ordered for patients with suspected inherited retina disease, and they are also helpful in assessing other retinal problems including optic nerve disorders and retinal changes associated with toxic exposures. A combination of tests is often ordered to provide additional information on your retina. Depending on the number and types of testing required, the total time necessary to complete all tests ordered for a given patient may be several hours.

Farnsworth D15 Color Test

This test is used to examine color vision defects. It is often done in conjunction with other tests. The patient will be shown 15 colors scrambled at random and the patient will have to rearrange the colors by hue. Dilation is not required for this exam.

Visual Evoked Potential (VEP)

The VEP test evaluates the functional integrity of the visual pathways that relay information from the retina to the brain, including the optic nerve. After the patient has electrodes applied to their forehead and scalp, the patient will look at a target point on a monitor for about 30 seconds. This will be repeated 4-6 times per eye. Dilation is not required for this exam.

Multi-Focal Electroretinogram (mfERG)

The multi-focal ERG is an objective assessment of the central retinal function. During this test, electrodes are applied to the corners of the eyes and the forehead. The patient then looks at a target point on a monitor for 30 seconds while the screen flashes. Usually, this is repeated 10-15 times per eye with 30 second breaks in between. Dilation is required for this exam.

Full-Field Electroretinogram (ffERG)

The full field ERG test measures the functional integrity of the rod and con photoreceptors in the eye. Rods are responsible for our night vision, and cones help us with our day and color vision. During this test, electrodes are applied to the corners of the patient’s eyes, as well as the forehead. The patient will then look at a target as light flashes stimulate the retina. There will be a dark adaptation period of 20 minutes where the patient and technician will sit in complete darkness. Dilation is required for this exam.

Electrooculogram (EOG)

The EOG test measures the function of the retinal pigment epithelium (RPE). The RPE is an essential layer of cells that provides many important functions to maintain retina health. This test is conducted after the full-field ERG exam. Four additional skin electrodes will be applied, and the patient will be asked to look inside a testing cone and follow a white light back and forth with their eyes. Dilation is required for this exam.