Electrooculography

Diagram showing eye movements during REM sleep

Electrooculography (EOG) is a technique for measuring the cornea-retina standing potential that exists between the front and the back of the human eye. The resulting signal is called the electrooculogram. EOG is used to assess the function of the retina and the ocular system, and it is also employed in the study of eye movements.

Principle

The principle of electrooculography is based on the fact that the eye acts as a dipole in which the anterior pole (cornea) is positive and the posterior pole (retina) is negative. When the eyes move, the potential between electrodes placed around the eyes changes, allowing the measurement of eye movement.

Applications

Clinical Applications

Electrooculography is used clinically to assess the function of the retina, particularly in conditions such as retinitis pigmentosa and Best's disease. It is also used to evaluate the vestibulo-ocular reflex and in the diagnosis of nystagmus.

Research Applications

In research, EOG is used to study saccades, smooth pursuit, and other types of eye movements. It is also used in sleep studies to monitor REM sleep, as shown in the diagram.

Procedure

The procedure involves placing electrodes around the eyes. Typically, electrodes are placed on the skin at the outer canthi of the eyes and above and below the eyes. The patient is asked to perform specific eye movements, and the resulting changes in potential are recorded.

Advantages and Limitations

Advantages

• Non-invasive and relatively easy to perform.
• Can be used to monitor eye movements in various settings, including sleep studies.

Limitations

• Less precise than other methods such as infrared oculography or video-based eye tracking.
• Susceptible to noise from muscle activity and electrical interference.

Related pages

• Electroencephalography
• Electromyography
• Polysomnography
• Eye movement