Free previewYou're reading the free part of this topic. The rest is included with Clinical.See what's included
Orbital blood supply
Neuro-Ophthalmology
Key Points
- •The ophthalmic artery is the first intracranial branch of the ICA; the CRA is an end artery supplying the inner 2/3 of the retina; the short posterior ciliary arteries supply the choroid, outer retina, and optic nerve head via the circle of Zinn-Haller
- •The major arterial circle of the iris is formed by long posterior ciliary arteries + 7 anterior ciliary arteries (2 from each rectus except 1 from LR) - detaching >2 recti risks anterior segment ischaemia
- •CRAO is a retinal stroke equivalent - cherry-red spot, end-artery occlusion, mandatory systemic workup (carotid Doppler, echo, ESR/CRP for GCA); cilioretinal artery (present in ~33%) can spare central vision
- •NAION results from watershed zone ischaemia at the optic nerve head (SPCA territory); 'disc at risk' (small cup) in fellow eye; no proven treatment (IONDT trial negative)
- •Venous drainage via superior/inferior ophthalmic veins → cavernous sinus - no valves in orbital veins allows bidirectional flow and spread of facial/sinus infection to the cavernous sinus
Free preview ends here
Keep reading Orbital blood supply
12 more sections are included with the Clinical plan.
- Definition
- Epidemiology
- Aetiology and causes
- Pathogenesis
- Classification
- Clinical features