Normal Human Electro-Oculogram

Overview

This study will measure the normal range of the human electro-oculogram (EOG) in people of various age groups. EOGs are recordings of electrical signals generated by the retina (the light-sensitive tissue in the back of the eye) when going from a dark to a bright environment. They provide valuable information about the function of the eye in health and disease. A knowledge of what results are to be expected in tests of normal, healthy eyes will be valuable in assessing EOG results in patients with known or suspected retinal diseases. Normal volunteers from ages 6 to 65 who have healthy eyes and normal eyesight will participate in this study. Candidates will undergo tests to check vision and the health of the eye. Study participants will then have an electro-oculogram. In this test, eye drops are placed in the eye to enlarge the pupils. Two electrodes (small disks that picks up electrical signals) are attached to the left and right of each eye and one to the forehead. (These are similar to electrodes placed on the body during an electrocardiogram (ECG), which measures electrical signals from the heart.) During the EOG recording, the volunteer looks at the inside of a hollow sphere, following with their eyes small red lights that turn on and off. The background light is also turned on or off during the test. Some volunteers may be asked to repeat the EOG at another time. Study participants may also be asked to provide a blood sample for tests to study how the immune cells in the blood respond to proteins found in the retina. The response from normal volunteers will be compared with that of patients with eye diseases like retinitis pigmentosa.

Electro-oculograms (EOGs) will be recorded in volunteers of different age groups with normal visual function. The fast and slow oscillations of the EOG will be studied. For the analysis of fast EOG oscillations, peak-to-peak amplitude (micro V), peak-to-trough ratio, and phase (degrees) will be measured. The analysis of slow EOG oscillations will include measurements of the ratio of light peak to dark trough (Arden ratio), implicit time (latency) of the light peak (ms), and amplitude of the dark trough (micro V).

Conditions