Visual impairment in non-arteritic anterior ischemic optic neuropathy (NA-AION) is usually acute and then remains relatively stable; spontaneous improvement in visual function is also seen in 42.7% of patients. In nearly 25% of patients, the visual impairment deteriorates gradually over several weeks. If the visual impairment progressively worsens, further testing is needed to rule out the possibility of an infiltrative optic neuropathy, such as an optic nerve sheath meningioma. Anterior ischemic optic neuropathy does not require imaging if typical clinical signs are present, such as acute onset, unilateral visual impairment, ipsilateral optic papillary edema, and in the elderly. However, it is necessary to exclude whether it is due to giant cell arteritis. In those older than 50 years, erythrocyte sedimentation rate and C-reactive protein need to be examined to rule out giant cell arteritis. If the signs are atypical, an etiologic diagnosis is required. NA-AION with atypical clinical signs, or in the elderly, or in combination with diabetes mellitus or hypertension, or in young people with bilateral onset, or recurrent NA-AION, requires laboratory tests to clarify the presence or absence of hypercoagulable state. Circumstances in which laboratory testing for hypercoagulability should be recommended for NA-AION include: 1) age less than 45 years; 2) absence of a high-risk optic disc in the contralateral eye, i.e., small cup-to-disc ratio; 3) simultaneous onset in both eyes; 4) recurrence in the same eye; and 5) previous or family history of recurrent thrombophilia.