To the Editor.
—In the August Archives Guyer et al1 instructed us to perform "tests of carotid artery patency" on patients with nonarteritic ischemic optic neuropathy (ION). I presume they recommend these tests to detect a carotid atheroma, the excision of which would reduce the patient's risk of stroke. The evidence does not support this recommendation.During their follow-up period, 19 of 200 patients with nonarteritic ION had "cerebrovascular events" (either "cerebrovascular accidents" or "transient ischemic attacks") in undisclosed proportion. Thus, the exact risk of cerebral infarction among these patients cannot be determined, but is possibly about 3% per year. Although this risk is greater than the risk in the general population, it is close to or lower than the combined risk of angiography and endarterectomy in many institutions.2 Furthermore, many of the "cerebrovascular events" were probably caused by a variety of mechanisms not treatable by endarterectomy: lacunar
Ellenberger C. The Role of Carotid Endarterectomy in Ischemic Optic Neuropathy. Arch Ophthalmol. 1985;103(11):1633. doi:10.1001/archopht.1985.01050110027010