UW EYE ELECTROPHYSIOLOGY AND COLOR VISION TESTING
The following tests, with the exception of color vision testing, do not rely on the subjective response of the patient to a stimulus, but rather provide a purely objective evaluation of the functioning of the visual system.
The “Outer Retinal Function Tests” demonstrate the functional integrity of the mid- and outer-retinal layers and retinal pigment layer to light stimuli under conditions of light and dark adaptation. If those tests are normal, then subsequent tests in the “Higher Visual Pathways by VEP” list can be done to evaluate the responses of the more central visual portion of the visual system.
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Outer Retinal Function Tests
ERG: Full Field Electroretinogram (click to open and close)
mfERG: Multifocal Electroretinogram (click to open and close)
EOG – Electro-Oculogram (click to open and close)
Dark Adaptation (click to open and close)
Retinal Ganglion Cell Test
pERG: Pattern ERG
OVERVIEW: This test measures primarily the function of the central retinal ganglion cells and secondarily the function of the macular photoreceptor cells.
HOW DONE: The preparation and set-up are the same as for the multifocal ERG. The difference is in the character of the stimulus which consists of an isoluminant reversing black-and-white checkerboard. The test requires that a fairly accurate refractive correction be in place so that the checkerboard be in good focus on the retina.
USEFUL FOR: This test facilitates the determination of whether an abnormal visually evoked potential (discussed subsequently) is due to macular disease or due to more central CNS disease.
HOW REPORTED: The test is reported as the presence and age-related normal amplitude of a positive wave (P50) followed by a negative wave (N95). The N95 wave is specifically associated with the function of macular retinal ganglion cells. It is reduced in glaucoma, optic neuritis, and other disorders of the optic nerve. It is used primarily as a research tool but on occasion may be useful as an adjunct to clinical testing.
Higher Visual Pathways by Visually Evoked Potential
Single Flash VEP – Basic (click to open and close)
Multifocal VEP – Cortical Aspect of Visual Field Abnormality (click to open and close)
Sweep VEP – Visual Acuity Estimator (click to open and close)
Albinism VEP (click to open and close)
COLOR VISION SPECIAL TESTS
100 Hue and Lantern Test
OVERVIEW: In addition to providing color vision assessment with Ishihara plates, the service provides Farnsworth AO HRR plates, D15, FM 100 hue testing and the “lantern test,” required by some occupations.
The Ishihara plates can be done in a short time and are available in most eye professionals’ offices. They mostly useful for detecting the type of red-green color confusion found in around 6% of males. Ishihara testing can also be abnormal in severe acquired color vision loss.
In addition to the above tests, our service provides the more definitive and sensitive testing with the D 15 panel, the 100 hue test. These tests help determine the character of the color abnormality and whether it is due to photoreceptor or optic nerve disease. AO-HRR plates are also available, which may be useful as a quick screening tool to identify blue-yellow color deficits.
We also provide the “LANTERN TEST,” which is a specific type of test required in some professional job applications typically related to operating aircraft, trains, or boats.
HOW DONE: In the 100 hue test and in its shorter version, the D 15 panel, the patient is asked to put in order of hue change a series of discs with colored inserts. The former takes about an hour and the latter about 15 minutes. Importantly, the test is performed under standard lighting conditions.
USEFUL FOR: The specialized tests help define the character and possible causes of the color abnormality. The sensitive FM-100 hue test is also important in following patients who are taking ethambutol for tuberculosis since acquired color vision loss is an early indicator of ethambutol toxicity.
HOW REPORTED: The D15 panel is reported as the axis along which most color matching errors were made thus distinguishing congenital from acquired defects and is presented in a display of a circle with 15 points along its circumference. The FM-100 hue test is reported in summary form as the score related to the numbers of errors made in matching and in the more detailed form as a page size disc with errors displayed in the axes in which they occurred.
How to Order Special Tests
The request for testing is initiated by filling out the appropriate forms:
Fax or mail the completed form(s) to the address on the form along with the following:
- A copy of the patient’s most recent ocular exam
- Copies of any ancillary tests that have been done of retinal appearance (fundus photos, OCTs) or function (visual field tests)
- Our technician calls patient to explain the tests, answer questions and schedule their testing. A description and a map of our location is then mailed to them
Within a week after the test is done, a panel of retinal specialists reviews the test results along with the ancillary tests provided. Their interpretation and suggested differential diagnoses are reported to the referring professional later that week. Copies of the raw test data along with another copy of the report is sent by surface mail.
Visual Function Form
Please note that no emails will be accepted, due to HIPAA compliance.
Meet the experts
Kimberly E. Stepien, MD
Professor, Co-Vice Chair of Clinical Affairs, John W. and Helen Doolittle Professor