Pituitary tumor is an orthograde degeneration etiology?

• A. True
• B. False
• C. Sometimes
• D. Cannot determine

Answer: (B)

The pituitary tumor compresses the optic chiasm, which is located away from the retinal cell bodies. When the axons are disrupted at the chiasm, the degenerative process travels backward toward the neurons’ cell bodies in the retina, causing retrograde degeneration of retinal ganglion cells. Orthograde (anterograde) degeneration, on the other hand, would involve degeneration moving away from the cell body along the axon toward its downstream targets, which is not what happens with a chiasmal mass. Therefore, a pituitary tumor is not an orthograde degeneration etiology; it produces retrograde degeneration of the retinal neurons.