- Member of the Ingenix Normative Health Informatics (NHI) Database during 01/01/2003
through 12/31/2007
- 18 years of age or older
- Had at least 183 days of continuous enrollment in the database
- No doctor visits associated with a diagnosis of ischemic optic neuropathy during the
183 days prior to cohort entry
- Less than 18 years of age
- Less than 183 days of continuous enrollment in the database
- At least one doctor visit associated with a diagnosis of ischemic optic neuropathy
during the 183 days prior to cohort entry