Current Concepts in the Diagnosis and Management of NAION
Current Concepts in the Diagnosis and Management of NAION
Just as there is no proven treatment for NAION, there is no proven prophylactic to prevent second-eye involvement. Although some authors have found evidence that aspirin can reduce the incidence of fellow-eye involvement after NAION, a large retrospective review by Beck et al studied 431 patients with NAION for second-eye involvement with and without aspirin use. The 5-year risk for fellow-eye involvement was calculated at 12–19%, depending on the analysis method, and no long-term benefit for aspirin use was found. The 5-year cumulative probability risk for fellow-eye NAION after the initial episode was 17% among treated patients vs 20% among untreated patients. A proposed prospective multicenter trial of aspirin to prevent second-eye involvement in patients with NAION was abandoned when it became clear that the number of subjects who would need to be recruited would be huge (about 2000) and would have to be followed for at least 5 years. In addition, there was concern that it would be impossible to keep subjects randomized to no treatment from being exposed to aspirin products. Nevertheless, although beneficial long-term effects remain unproven for NAION, many experts recommend the use of aspirin after an initial episode, if only for its role in decreasing risk for stroke and myocardial infarction in this vasculopathic population group.
In summary, we have learned much about the clinical manifestations, structural and vascular risk factors, and natural history of NAION; however, much remains to be learned about its pathogenesis, and a consistently effective therapy has yet to be identified.
Prevention
Just as there is no proven treatment for NAION, there is no proven prophylactic to prevent second-eye involvement. Although some authors have found evidence that aspirin can reduce the incidence of fellow-eye involvement after NAION, a large retrospective review by Beck et al studied 431 patients with NAION for second-eye involvement with and without aspirin use. The 5-year risk for fellow-eye involvement was calculated at 12–19%, depending on the analysis method, and no long-term benefit for aspirin use was found. The 5-year cumulative probability risk for fellow-eye NAION after the initial episode was 17% among treated patients vs 20% among untreated patients. A proposed prospective multicenter trial of aspirin to prevent second-eye involvement in patients with NAION was abandoned when it became clear that the number of subjects who would need to be recruited would be huge (about 2000) and would have to be followed for at least 5 years. In addition, there was concern that it would be impossible to keep subjects randomized to no treatment from being exposed to aspirin products. Nevertheless, although beneficial long-term effects remain unproven for NAION, many experts recommend the use of aspirin after an initial episode, if only for its role in decreasing risk for stroke and myocardial infarction in this vasculopathic population group.
In summary, we have learned much about the clinical manifestations, structural and vascular risk factors, and natural history of NAION; however, much remains to be learned about its pathogenesis, and a consistently effective therapy has yet to be identified.
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