Certified Polysomnographic Technician (CPSGT) 2025 – 400 Free Practice Questions to Pass the Exam

The EOG, or electrooculography channel, detects changes in the electrical potential produced by eye movements, specifically focusing on the cornea. The cornea's surface is positively charged compared to the more negatively charged interior of the eye. This difference in charge generates an electrical potential that varies as the eyes move. When a person looks in different directions, the shift in position of the cornea relative to the surrounding tissues produces measurable changes in this potential, which the EOG captures.

While the other parts of the eye listed play important roles in vision—such as the retina being responsible for capturing light images, the optic nerve transmitting visual information to the brain, and the lens focusing light onto the retina—they are not involved in the electrical potential changes detected by EOG. Therefore, the correct answer highlights the role of the cornea in generating the signals monitored by the EOG channel.