Definition
Anterior ischemic optic neuropathy involving a 1 mm segment of the optic nerve papilla, also known as the optic disc, is seen as swelling of the optic disc.
Etiology
The cause is unknown in most patients; some specific etiologies have been reported that may be associated with anterior ischemic optic neuropathy
A: sleep apnea syndrome (SAS)
B: Drugs (e.g., interferon, Sildenafil)
C: optic disc vitreous warts
Risk factors
Most common cause of acute optic neuropathy in those aged over 50 years
No difference in incidence between men and women
Pathogenesis
So far undetermined, presumably due to inadequate blood supply or infarction of the short posterior ciliary artery in the posterior part of the sieve plate of the optic nerve papilla.
A cup-to-disc ratio of less than 0.3, self-regulation of blood flow, nocturnal hypotension, venous insufficiency, and vascular disease risk factors (hypertension, diabetes, smoking, etc.) may be involved in the pathogenesis.
Symptomatic presentation
The typical patient presents with acute, unilateral, painless loss of vision; some patients present with headache and eye pain that can be easily confused with optic neuritis; 2/3 of patients have been reported to have onset during awakening; most patients feel obscured below their eyes.
Clinical diagnosis and differentiation
Diagnosis based on typical presentation, fundus changes (congestion and edema, peri-disc lamellar hemorrhage), and small visual cup in the contralateral eye.
It is important to differentiate arteritis anterior ischemic optic neuropathy (giant cell arteritis) and optic neuritis.
Laboratory tests
For patients older than 50 years, blood sedimentation and C-reactive protein are checked to exclude giant cell arteritis.
For patients younger than 50 years of age but with a history of unexplained thrombosis or family history, check for hypercoagulable states.
Enhanced MRI scan of the head and orbit to rule out optic neuritis, inflammatory and compressive optic neuropathy.
Treatment
There is no proven effective treatment. The reported drugs include antiplatelet and anticoagulant drugs, corticosteroids, etc.
Regression
The recovery of vision was observed in 13-42% of the patients with varying degrees of vision.
Recurrence was observed in 3-8% of the affected eyes.
Contralateral eye involvement was observed in 15-24% of patients within 5 years.