Monday, February 25, 2019

Vision Loss in Giant Cell Arteritis

Causes of vision loss —

Permanent loss of vision in GCA results from arteritic anterior ischemic optic neuropathy (AION), central or branch retinal arterial occlusion (CRAO/BRAO), posterior ischemic optic neuropathy (PION), or, rarely, cerebral ischemia

●Anterior ischemic optic neuropathy – At least 80 percent of cases of vision loss in patients with GCA are caused by AION . The ischemic insult in arteritic AION is typically the consequence of occlusion of the posterior ciliary artery, a branch of the ophthalmic artery from the internal carotid artery, and the main arterial supply to the optic nerve.

Only about five percent of the total occurrences of AION are due to GCA, the majority being nonarteritic and secondary to atherosclerotic disease . About 40 percent of patients who suffer nonarteritic AION regain some amount of visual acuity, in contrast to visual loss due to GCA, which is more often massive and irreversible .

●Central retinal artery occlusion – CRAO is responsible for approximately 10 percent of the cases of visual loss in GCA . On the other hand, approximately two percent of older patients with CRAO have underlying GCA . Bilateral CRAOs in an older adult should prompt evaluation for GCA.

●Posterior ischemic optic neuropathy – PION occurs in less than five percent of patients with GCA . It results from the interruption of blood flow to the retrobulbar portion of the optic nerve. Histopathologic examination typically reveals inflammatory occlusion of the short nutrient posterior ciliary arteries .

●Branch retinal artery occlusion – BRAO is distinctly uncommon in GCA, though it has been described.

●Cerebral ischemia — Homonymous hemianopia is a visual field defect involving either the two right or the two left halves of the visual fields of both eyes. The most common cause in GCA is an occipital lobe infarction resulting from a lesion in the vertebrobasilar circulation. In rare cases, bilateral occipital lobe involvement leads to bilateral homonymous field defects and to the development of cortical blindness.

Bhopalwala. H

No comments:

Post a Comment

This is express yourself space. Where you type create something beautiful! <3
Wondering what do I write? Well..
Tell us something you know better. You are a brilliant mind. Yes, you are! ^__^
Ask about something you don't understand @_@?
Compliment... Say something nice! =D
Be a good critic and correct us if something went wrong :|
Go ahead. Comment all you like here! (: