Certified Ophthalmic Technician (COT) Test 2025 – 400 Free Practice Questions to Pass the Exam

The electroretinogram (ERG) specifically evaluates the function of the rods and cones, which are photoreceptor cells located in the retina. These cells are crucial for converting light into electrical signals that are sent to the brain, allowing for vision. The ERG measures the electrical responses generated by these photoreceptors when exposed to light stimuli, providing insights into retinal health and function.

In contrast, the other structures mentioned are not tested by the ERG. The macula is part of the retina and is involved in high-acuity vision, but it is not the focus of the ERG. The optic nerve transmits visual information to the brain but does not reflect the direct electrical activity measured by the ERG. The cornea and lens play essential roles in focusing light onto the retina but do not generate electrical signals themselves. The iris and pupil are involved in controlling light entry into the eye but are not related to the electroretinogram’s measurements. Therefore, the testing of the rods and cones provides critical information about retinal function, making it the focal point of the electroretinogram.