What does the word Electrooculogram mean?
: a record of the difference in electrical charge between the front and back of the eye that is correlated with eyeball movement (as in REM sleep) and obtained by electrodes placed on the skin near the eye.
What does an Electrooculogram measure?
The electrooculogram (EOG) measures the cornea-positive standing potential relative to the back of the eye. By attaching skin electrodes outside the eye near the lateral and medial canthus, the potential can be measured by having the patient move the eyes horizontally a set distance.
What is the use of Electrooculogram?
Electrooculography (EOG) is a technique for measuring the corneo-retinal standing potential that exists between the front and the back of the human eye. The resulting signal is called the electrooculogram. Primary applications are in ophthalmological diagnosis and in recording eye movements.
What is the difference between ERG and EOG?
The EOG had advantages over the ERG in that electrodes did not touch the surface of the eye. The changes in the standing potential across the eyeball were recorded by skin electrodes during simple eye movements and after exposure to periods of light and dark.
What is an EEG signal?
The electroencephalogram (EEG) is a dynamic noninvasive and relatively inexpensive technique used to monitor the state of the brain. An EEG signal recorded with electrodes placed on the scalp consists of many waves with different characteristics. Arrays of electrodes are distributed over the entire scalp.
How long does an ERG test take?
The standard ERG typically takes about an hour. For the dark-adapted portion of the test, the patient sits in the dark for 20 minutes. Dim light flashes that gradually increase in brightness then appear and the retinal responses recorded. This part takes another 10 to 15 minutes.
What is normal Arden ratio in EOG?
The Arden ratio, the ratio of the Light peak (Lp) to dark trough (Dt) is used to determine the normalcy of the results. An Arden ratio of 1.80 or greater is normal, 1.65 to 1.80 is subnormal, and < 1.65 is significantly subnormal.
What can EOG diagnose?
The electro-oculogram (EOG) investigates abnormalities of the outermost layer of the retina, the retinal pigment epithelium, allowing the early diagnosis of some inherited macular diseases such as Best disease. The EOG is used to assess the function of the pigment epithelium.
How long does an EOG take?
How long does each test take? Students are given 180 minutes to complete the Reading test and 120 minutes to complete the Math test. Students who do not finish within that timeframe will be offered an additional hour. The tests are multiple choice with approximately 40-50 questions, depending on the grade-level.
How are eye movements recorded in an electrooculogram?
Recording of eye movements and eye position provided by the difference in electrical potential between two electrodes placed on the skin on either side of the eye.
What do you mean by Electrooculography in medical terms?
(ē-lek’trō-ok’yū-lō-gram), A record of electric currents in electro-oculography. A record of electric currents in electrooculography. Recording of eye movements and eye position provided by the difference in electrical potential between two electrodes placed on the skin on either side of the eye.
What are the two potentials of an electrooculogram?
The EOG consists of two potentials: the standing potential ( resting potential, dark phase, dark current) which is evoked by moving the eyes in the dark and originates from the retinal pigment epithelium and the light potential ( light rise) which is evoked by moving the eyes in a lighted environment and originates from the photoreceptors.
Where are the electrodes in the electrooculogram?
Four recording skin electrodes (silver-silver chloride or gold-disk) are placed at the medial and lateral canthi of both eyes, and the grounding electrode is placed on the forehead. The difference of electrical potential of the anterior and posterior part of the eyeball is called the standing potential.