Uhtoff's phenomenon is most associated with which diagnosis?

• A. NAION
• B. AAION
• C. Papilledema
• D. Optic neuritis

Answer: (D)

Uhtoff's phenomenon reflects how demyelinated nerve fibers struggle more when body temperature rises. Heat slows conduction along exposed axons, so vision or other neurologic functions can transiently worsen in someone with demyelination of the optic nerve. Optic neuritis, which often occurs in multiple sclerosis, features demyelinated optic pathways, making this phenomenon particularly characteristic. Heat, fever, or strenuous exercise can transiently degrade visual acuity or visual symptoms in optic neuritis, with improvement when cooled or after the temperature returns to normal. The other options are vascular or pressure-related optic neuropathies, which do not exhibit this temperature-sensitive conduction block.