All Evaluations
On this page:
- Genetic counseling
- Blood draw for genetic studies
- Eye examination
- Electroretinogram (ERG) to test the function of visual cells
- Fluorescein angiography, only if considered necessary, to evaluate the eye's blood vessels
- Hearing tests
- Videonystagmography (VNG)
- Rotary chair test
- Vestibular evoked potential
- Computerized dynamic platform posturography (CDPP)
Genetic Counseling
An NIDCD researcher provides a genetic counseling session.
Blood Draw for Genetic Studies
A blood sample equivalent to 4 teaspoonfuls for participants 10 years and older and 1 teaspoonful for children will be drawn. Genetic test results will be discussed with you when they become available, and a written report will be mailed to you.
Eye examination
The researcher will conduct an eye examination to test your visual acuity; your eye movements, pupils, and eye pressure; the front part of your eyes (A); and your peripheral vision (B).
In addition, your eyes will be dilated and your lenses and retinae will be examined (C).
Electroretinogram (ERG) to test the function of visual cells
During the ERG test, you will wear eye patches and sit in a dark room for 30 minutes. Then the researcher will tape electrodes to your forehead (this is painless, as are all uses of electrodes in these tests) and remove the eye patches. The surfaces of your eyes will be numbed with eye drops, and contact lenses will be placed on your eyes. You will look inside a hollow, dark globe and see a series of light flashes. Then a light will be turned on inside the globe, and more flashes will appear. The contact lenses sense small electrical signals generated by the retina when the light flashes.
Fluorescein angiography
In this test, the researcher will inject a dye into one of your arm veins, and the dye will travel throughout your body, including to the blood vessels in the eyes. Pictures of your retina will then be taken using a camera that flashes a blue light into the eye. The pictures will show if any dye has leaked from the blood vessels into the retina, indicating possible blood vessel abnormality.
Hearing tests
The researcher will conduct tests to evaluate your hearing, including examination of both ears with an otoscope, evaluation of the middle ear and inner ear, and hearing tests using earphones that deliver tones and words that you will listen and respond to.
Videonystagmography (VNG)
The VNG test records eye movements with little cameras. First, you will follow the movements of some small lights. Next, you will wear goggles, lie on an exam table, and turn to the right and left. A soft stream of air will be blown into your ears four times, once in each ear with cool air and once in each ear with warm air.
Rotary chair test
With electrodes placed on your forehead, you will sit in a dark room in a rotary chair—a special chair that moves slowly and in a full circle. Several red lights will appear on the wall of the room, and you will follow the lights as they move back and forth. Then the chair will turn at several speeds, all slower than a merry-go-round.
Vestibular evoked potential
Electrodes will be placed behind your ear and at the base of your neck. Seated in a reclining chair and wearing earphones, you will hear a brief series of loud clicking sounds. When the sounds are on, you will be asked to lift your head up a few inches from the chair. The electrodes record information from the muscles in the neck as the sounds enter the ear.
Computerized dynamic platform posturography (CDPP)
In the CDPP test, you will stand on a platform and remain as still as possible while testing conditions are changed. For example, you will be asked to have your eyes closed or open, and the platform will be stable or moving. A safety harness will prevent you from falling if you lose your balance during the test.
