Ocular: Retina II Flashcards
Retina has a high demand for _______
Oxygen
Outer retina is supplied by _________
Choroid
Inner retina is supplied by _______ ________
Retinal vessels
Is there overlap in the retinal vasculature (by what it supplies)?
NO
What is the outer blood-retina barrier is made up of?
-Tight junctions (zonula occludens) between the RPE cells
What is the inner blood-retina barrier made up of?
Tight junctions between the non-fenestrated endothelial cells of the retinal capillaries
What happens if the blood retinal barrier is compromised?
There is potential for things to get through that shouldn’t be there
Vessels that supply the choroid:
-Ophthalmic artery
-central retinal artery
-lateral and medial posterior ciliary trunks
-SPCA
-lateral and medial LPCA
SPCA pierce the posterior sclera and enter the suprachoroidal space to form the…
Major arterial circle of the iris
Cilioretinal artery:
-retinal supply to the macula
-if occlusion to central retinal artery, this will keep retina intact
-30% of population have that
How does the central retinal artery enter the eye?
Through an aperture in the lamina cribrosa of the optic disc
How is the central retinal artery positioned in regards to the optic nerve and central retinal vein?
Nasal to both :)
Does central retinal artery have a tunica elasticum?
No, it loses it upon entering the eye
What is the tunica elasticum replaced with?
Prominent tunica media which is a smooth muscle that enhances constriction of retina blood vessels
Tunica adventitia of the retinal layer vessels:
-outermost layer of blood vessels
-connective tissue layer of the vessel
-thicker in veins
-autoregulated!
Tunica Adventitia in retinal vasculature responds to changes in:
-oxygen
-IOP
-systemic pressure
-metabolic waste levels
Structure of the retinal capillaries:
-endothelium
-basement membrane (basal laminate)
-Pericyte
What does Pericyte in capillary do?
Maintain the the integrity of the capillary and help it contract to move the blood through it
What can loss of Pericytes in diabetic patients cause?
Microaneursyms, hemorrhages, exudates, and fluid in the macular region
Two retinal capillary layers:
-deep capillary plexus
-superficial capillary plexus
What capillary layer do dot and blot heme hemorrhages come from?
From deep capillary plexus in inner nuclear layer
Which capillary layer do flame hemorrhages come from?
Superficial capillary plexus in the retinal nerve fiber layer
What is the foveal avascular zone?
Zone within the fovea with no vasculature to allow light to enter without being interrupted
Diabetic macular edema
Protein leaking into the foveal avascular zone which can cause loss of vision
Central retinal vein occlusion
-this vein is at risk for occlusion bc its thinner
-if compressed, congestion of venous outflow thsat leaks into the inner retinal layer
-cause sudden, immediate loss of vision
Branch retinal vein occlusion:
-blood leaking into nerve fiber layers
-protein leaking into macula
Branch retinal vein occlusion most often occurs where? And why?
in supratemporal compartment bc more crossing of arteries over the veins
Sclerosing or compression of Tunica adventitia in central retinal vasculature clinical relevance importance:
AV nicking that can occlude vein
Why does Neovasculazation occur?
Retina is not getting the oxygen that it needs!
Why does Central retinal artery occlusion casues milky white retina?
Ischemia
Branch retinal artery occlusions most often cause:
VF deficits
Central retinal arteries course superficial to the vein but they share a ________ ___________
tunica adventitia
