The electrooculogram is a diagnostic instrument used in ophthalmology to study the movement of the eye muscles.
This test records the difference in power between the cornea and retina, in addition to measuring the electrical variations that occur in the eye when performing a saccadic movement.
As a curious fact, thanks to the electrooculogram, we can obtain a diagnosis of sleep-related illnesses like narcolepsy.
En Área Oftalmológica Avanzada We explain what an electrooculogram consists of, what it measures and what pathologies it detects.
What is?
The electrooculogram consists of place small electrodes in areas near the eye muscles in order to measure their movements.
You should know that the electrooculogram takes the reference value power difference between the retina and the cornea.
Usually there is a difference 0,4 to 5 mV between the power of the cornea and the Bruch membrane, which is in the posterior segment of the eye.
This originates from the pigmentary epithelium of the retina and allows finding a dipole, where the cornea is considered the positive side and the retina the negative side.
The potential produced by the dipole is susceptible to unipolar and bipolar recording systems, and can be identified by placement of the electrodes on the skin near the eyes.
What does the electrooculogram measure?
There are four types of eye movements, each controlled by a different neural system. However, they all share the same goal: that the motor neurons reach the eye muscles.
These movements are:
- Saccades. Sudden, energetic and jerky movements that occur when we change our gaze from one place to another. These movements place the object of interest in the fovea of the eye.
- soft of chase. They are tracking movements that occur when the gaze searches for an object.
- Vestibular. They are the response to stimuli initiated in the semicircular canals to maintain the visual fixation while the head is in motion.
- of convergence. They approach the visual axes when the gaze is focused on very close objects.
The retina has a electronegative resting bioelectric power regarding the cornea. This means that the turns of the eyeball generate changes in the direction of the dipole vector.
Thanks to them, the electrooculogram allows measure electrical variations that occur in the eye when a saccadic movement is performed.
What pathologies does the EOG detect?
The results of the electrooculogram should be interpreted on the whole with the results of an electroretinogram, since in most cases they are associated with the same alterations.
Many times, the EOG is performed to support the diagnosis of any pathology that has detected an electroretinogram.
Now, what is the electrooculogram for? The EOG is an indispensable test for the diagnosis of the following diseases:
- Dystrophies of the retinal pigment epithelium like Best's disease and Stargardt's disease.
- retinal toxicity for the consumption of certain drugs.
- Diseases associated with sleep disturbance such as narcolepsy, obstructive apnea syndrome, or sleep behavior disorder during the REM phase.
En Área Oftalmológica Avanzada we have the best doctors in all of Barcelona to perform and analyze an electrooculogram.
If it has been a long time since you examined your visual health, contact us and make an appointment to do a review. We are happy to help you!
