Ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy

Pathogenesis

Nonarteritic anterior ischemic optic neuropathy is a partial or total optic disc infarction caused by occlusion of the short posterior ciliary arteries. It usually occurs in patients aged 45–65 years with dense optic disc structure and little or no physiologic cupping. Predisposing systemic conditions include hypertension, diabetes mellitus, hypercholesterolemia, collagen vascular disease, antiphospholipid syndrome, sudden hypotension, and cataract surgery.

Symptoms

It presents as sudden, painless, monocular loss of vision without prodromal visual disturbances. Visual impairment is often detected on awakening, suggesting an important role for nocturnal hypotension.

• Visual acuity is normal or slightly reduced in 30% of patients. In the rest, the reduction ranges from moderate to significant;
• visual field defects are usually inferior altitudinal, but central, paracentral, quadrant and arcuate defects also occur;
• dyschromatopsia is proportional to the level of visual impairment, in contrast to optic neuritis, in which color vision may be severely impaired even when visual acuity is quite good;
• The disc is pale, with diffuse or sectoral edema, and may be surrounded by several streak-like hemorrhages. The edema gradually resolves, but the pallor remains.

FAG during the acute stage reveals focal disc hyperfluorescence that becomes more intense and eventually involves the entire disc. With the onset of optic atrophy, FAG reveals uneven choroidal filling in the arterial phase; in the late stages, disc hyperfluorescence increases.

Special investigations include serologic testing, lipid profile, and fasting blood glucose. Exclusion of occult giant cell arteritis and other autoimmune diseases is also very important.

Forecast

There is no definitive therapy; treatment includes treatment of predisposing conditions, nonarteritic systemic diseases, and smoking cessation. Most patients do not experience subsequent vision loss, although some experience continued vision loss for 6 weeks. In 30-50% of patients, the fellow eye is affected after several months or years, but this is less likely with aspirin. If the other eye is affected, there is atrophy of the optic nerve in one eye and swelling of the other disc, resulting in "pseudo-Foster-Kennedy syndrome."

NB: Anterior ischemic neuropathy does not recur in the same eye.

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Anterior ischemic optic neuropathy associated with arteriitis

Giant cell arteritis is an emergency condition, since prevention of blindness is determined by the speed of diagnosis and treatment. The disease usually develops after 65 years, affects medium and large-caliber arteries (especially the superficial temporal, ophthalmic, posterior ciliary and proximal vertebral). The severity and extent of the lesion depend on the amount of elastic tissue in the media and adventitia of the artery. Intracranial arteries, in which there is little elastic tissue, are usually preserved. There are 4 most important diagnostic criteria for GCA: pain in the masticatory muscles when chewing, cervical 6oli, C-reactive protein level >2.45 mg / dL and ESR >47 mm / h. Ocular complications of giant cell arteritis:

Anterior ischemic optic neuropathy associated with arteritis is the most common case. It occurs in 30-50% of untreated patients, in 1/3 of cases the lesion is bilateral.

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