Question

A female presents with loss of vision in the right halves of both eyes. Where is the lesion located in the optic pathway?

• A. Left optic tract
• B. Optic radiation
• C. Optic chiasma
• D. Right optic tract

Answer 1

The Correct Option is A

The symptom described is a visual field defect known as right homonymous hemianopia, where there is loss of vision in the right half of the visual field in both eyes. To understand where the lesion is located within the optic pathway, it is necessary to trace the pathway of visual signals from the eyes to the brain:

• The retina in each eye receives visual information, and the optic nerve transmits this signal.
• The optic nerves from both eyes meet at the optic chiasma, where fibers partially cross. The fibers from the nasal (medial) side of each retina cross to the opposite side, while the fibers from the temporal (lateral) side remain on the same side.
• After the optic chiasma, the fibers are rearranged into the optic tracts. Each optic tract carries signals from the opposite visual field, meaning the left optic tract carries signals from the right visual field of both eyes.
• Considering the visual defect presented, where the right halves of both eyes are affected, this leads to a defect in processing signals from the right visual field.

Conclusively, the lesion is most likely located in the left optic tract, as it is responsible for carrying visual information from the right half of the visual fields in both eyes.