—We would like to address each of Dr Hayreh's concerns. In NAION, is the visual loss due to blockage of the axoplasmic flow? Dr Hayreh states, and we agree, that in papilledema visual dysfunction is secondary to ischemia. Because optic nerve sheath decompression (ONSD) has been demonstrated to reverse severe visual loss in pseudotumor cerebri,1 we considered ONSD for other optic neuropathies in which ischemia may be involved. Dr Hayreh continues that "axoplasmic flow plays no role in the conduction of nerve impulses." While this statement is true in the strict neurophysiologic sense, alteration of axoplasmic flow has produced blockage of impulse conduction in several carefully studied experimental and human conditions. First, giant axonal swellings have been produced in rats by the administration of β-β1-iminodipropionitrile, a toxin that disrupts the cytoskeletal elements of axons.2 In this model, iminodipropionitrile blocks slow axonal transport more than
Sergott RC, Cohen MS, Bosley TM, Savino PJ. The Role of Optic Nerve Sheath Fenestration in Management of Anterior Ischemic Optic Neuropathy-Reply. Arch Ophthalmol. 1990;108(8):1064–1065. doi:10.1001/archopht.1990.01070100019005
Coronavirus Resource Center
Customize your JAMA Network experience by selecting one or more topics from the list below.