eye disorders
Ischemic Optic Neuropathy
Diagnosis of Ischemic Optic Neuropathy
Erythrocyte sedimentation rate (ESR), C-reactive protein, and complete blood count (CBC) Computed tomography (CT) or magnetic resonance imaging (MRI) of the brain and orbits if vision loss is progressive Diagnosis of optic nerve infarction is based mainly on clinical evaluation, but ancillary testing may be needed. Most important is to exclude the arteritic variety because the other eye is at risk if treatment is not started quickly. Immediate tests include ESR, CBC, and C-reactive protein. ESR is usually dramatically elevated in the arteritic variety, often exceeding 100 mm/hour, and normal in the nonarteritic variety. C-reactive protein is also elevated and is more sensitive than ESR in diagnosing Giant Cell Arteritis . CBC is done to identify thrombocytosis ( If giant cell arteritis is suspected, corticosteroids should be started immediately, and temporal artery biopsy should be done as soon as feasible (at least within 1 to 2 weeks because effects of theprednisonetherapy may reduce the diagnostic yield of histopathology). Changes in C-reactive protein level are useful for monitoring disease activity and the response to treatment. For cases of progressive vision loss, CT or MRI of the brain and orbits should be done to rule out compressive lesions. For nonarteritic ischemic optic neuropathy, additional testing may be indicated based on the suspected cause or risk factor. For example, if patients have excessive daytime sleepiness or snoring or are obese, polysomnography should be considered to diagnose obstructive sleep apnea. If patients have vision loss on awakening, 24-hour blood pressure monitoring can be done. 