Registered Electroencephalographic Technologist (R. EEG T.) Practice Exam 2025 – Your Comprehensive All-in-One Guide to Achieve Certification Success!

A large lesion at the optic chiasm typically produces complete visual loss because it affects the crossing of the optic nerve fibers from both eyes. The optic chiasm is the point where the optic nerves from both eyes meet and partially cross over. This crossing is critical for binocular vision and depth perception.

When the optic chiasm is compromised, especially by a large lesion, it can disrupt the transmission of visual information from both lateral visual fields to the opposite hemisphere of the brain. Consequently, this can lead to a condition known as bitemporal hemianopsia, where the individual loses peripheral vision in both eyes, but depending on the size and nature of the lesion, it may lead to complete loss of vision in one or both eyes.

Understanding the anatomy and functions of the optic chiasm is essential for recognizing how lesions in this area can have profound effects on vision, resulting in conditions such as complete visual loss.