Visual Electrophysiology

Visual electrophysiology tests are used to help detect, diagnose and evaluate a variety of visual disorders.

Visual electrophysiology is a collection of advanced techniques used to test the functioning of cells along the full visual pathway – from the retina to the optic nerve to the primary visual cortex in the brain. Visual electrophysiology measures and records electrical signals that occur in these areas in response to visual stimuli. These tests are used to help detect, diagnose and evaluate a variety of visual disorders.

Visual electrophysiology testing

The Henry Ford visual electrophysiology and psychophysics service offers a full complement of testing, including electroretinography, electrooculography, visual evoked potentials, spatial resolution, and color vision and chromatic sensitivity tests. Visual electrophysiology tests are:

• Currently the only objective way to measure visual pathway function
• Noninvasive
• Performed according to the standards of the International Society for Clinical Electrophysiology of Vision (ISCEV)
• Provided to both adults and children

For some tests, electrodes may be attached to your head or eyes. The process is painless. Depending on the test, your eyes may be dilated first using eye drops.

Electroretinography (ERG)

ERG visual electrophysiology tests measure the bioelectrical response of retinal nerve cells, and include:

• Standard (flash) ERG: This test can be useful in the diagnosis of several retinal diseases, including retinitis pigmentosa, Leber congenital amaurosis, congenital stationary night blindness, cone dystrophy, cone-rod dystrophy, suspicion of ocular siderosis, cancer- or melanoma-associated retinopathy, drug toxicity and retinal vascular disease.
• Pattern ERG: This test can be useful for detecting visual dysfunction in patients with glaucoma or other optic nerve disorders.
• Multifocal ERG: These test results can be useful in assessing macular degeneration, drug toxicity (Plaquenil®) and enlarged blindspot syndrome.

Electrooculography (EOG)

The EOG visual electrophysiology test measures bioelectrical responses in the outer retina and retinal pigment epithelium. The EOG is most useful for assessing patients suspecting of having Best’s vitelliform macular dystrophy, Stargardt’s disease or fundus flavimaculatus, and dominant drusen.

Visual evoked potentials (VEPs)

The VEP is a measure of bioelectrical activity in specific areas of the primary visual cortex in response to flash or pattern stimulation. These visual electrophysiology tests can be used to evaluate neurological diseases, such as multiple sclerosis, optic neuritis, amblyopia, and cortical blindness. They also can be used to determine the visual potential and acuity of infants and non-verbal adults. There are several types of VEP tests, including:

• Flash
• Pattern (pathway integrity)
• Pattern (visual acuity)

Spatial resolution

Standard clinical evaluation of visual acuity measures spatial resolution for high contrast (black on white) letters at daylight light levels. However, many aspects of visual functioning are performed at other contrast and light levels. Therefore, alternative tests of spatial resolution have been developed to assess vision under these conditions. These include tests that measure:

• Contrast sensitivity
• Low contrast letter acuity
• Glare sensitivity

Color vision and chromatic sensitivity

These tests are used to detect and quantify congenital color vision defects as well as to detect and monitor the progression of acquired color vision issues. Specific tests include:

• Farnsworth panel D-15
• Desaturated D-15
• F-M 100 Hue

At Henry Ford, patients come first.

The Henry Ford Department of Ophthalmology is committed to providing our patients with compassionate, personalized care. We feature the most advanced treatments in eye care and are dedicated to vision research – always staying at the forefront of innovation. A leader in Michigan, as well as one of the largest ophthalmology practices in the United States, we treat more than 55,000 patients per year at 12 locations throughout southeast Michigan. In addition, our team works closely with Henry Ford Medical Group physicians in other departments, providing multidisciplinary, coordinated care for those patients who need it.