Background.Although cerebral auto somal dominant arte-riopathy with subcortical infarcts and leukoencephalopathy(CADASIL)is considered a cerebrovascular dis order with almost exclusively neurological sy mptoms,the arteriopathy is generalized and involves choroid al and retinal vascula-ture as demonstrated by fluorescein angiographic and oc-ular electrophysiological abnorma lities.The occurrence of acute visual loss due to nonarteritic anterior ischemic optic neuropathy(NAION)has not previously been reported in CADASIL.Objective:To describe acu te visual loss due to NAION as a possible manifestation of CADASIL.Patients and Methods:The patient was a 60-year-old man with subcortical diffuse leukoencephalopathy,multi-infarct de-mentia,tetraparesis,visual loss,and a family history of stroke.We performed clinical and neuroophthalmological evaluation,electrophysiological assessment,brain mag-netic resonance imaging,and geneti c screening for muta-tions or small deletions of the Notch3gene,(causing CADASIL).Results:The patient ’s first symptom was a-cute visual loss in the right eye due t o NAION at age 27years,in absence of the common cardi ovascular risk fac-tors and before any neurological imp airment.The patient was reevaluated at age 60years,and n eu-ro-ophthalmological examination s howed optic disc atrophy in the right eye with arteriolar narrowing and a reduction in visual acuity in the left eye.Fluorescein angiography ofthe right eye showed evidence of pers istent peripapillary hypofluorescence with a retinal pig ment epithelial windows defect in the inferior temporal area.Pattern reversal visual evoked potentials were abolished in the right eye.The P100latency of the left eye was delay ed and reduced in amplitude.The diagnosis of CADASIL was confirmed by molecular analysis(heterozygotes for the C406T mutatio n on exon 3of the Notch3gene).There was a family history of cerebrovascular disorders and ocular impairment.Con-clusions:Visual loss due to transie nt or stable ischemic events involving the optic nerve hea d should be considered in the CADASIL phenotype.The possib ility of CADASIL should also be evaluated in patients with NAION who do not have cardiovascular risk factors but do have a family history of stroke. Background. Although cerebral auto-somal dominant arte-riopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is considered a cerebrovascular disorder with almost exclusively neurological sy mptoms, the arteriopathy is generalized and involves choroid al and retinal vascula-ture as demonstrated by fluorescein angiographic and oc-ular electrophysiological abnorma lities.The occurrence of acute visual loss due to nonarteritic anterior ischemic optic neuropathy (NAION) has not previously been reported in CADASIL.Objective: To describe acu te visual loss due to NAION as a possible manifestation of CADASIL. Patients and Methods: The patient was a 60-year-old man with subcortical diffuse leukoencephalopathy, multi-infarct de-mentia, tetraparesis, visual loss, and a family history of stroke. We performed clinical and neuroophthalmological evaluation, electrophysiological assessment, brain mag- netic resonance imaging, and geneti c screening for muta- tions or small deletions of the Notch 3 gene, (ca using CADASIL). Results: The patient’s first symptom was a-cute visual loss in the right eye due to NAION at age 27years, in absence of the common cardi ovascular risk fac-tors and before any neurological imp airment. patient was reevaluated at age 60years, and n eu-ro-ophthalmological examination s howed optic disc atrophy in the right eye with arteriolar narrowing and a reduction in visual acuity in the left eye. Fluorescein angiography of the right eye showed evidence of pers istent peripapillary hypofluorescence with a retinal pig ment epithelial windows defect in the inferior temporal area. Patient reversal visual evoked potentials were abolished in the right eye. P100 latency of the left eye was delay ed and reduced in amplitude. The diagnosis of CADASIL was confirmed by molecular analysis (heterozygotes for the C406T mutatio n on exon 3 of the Notch3gene.) There was a family history of cerebrovascular disorders and ocular impairment. Conclusions: Visual loss due to transie nt or st able ischemic events involving the optic nerve hea d should be considered in the CADASIL phenotype. the possibility of CADASIL should also be evaluated in patients with NAION who do not have cardiovascular risk factors but do have a family history of stroke.