Retinal Anatomy Flashcards
What is the macula?
Area of the retina between temporal arcade vessels
What is the fovea?
Thinned centre of the macula responsible for acute vision
What are the 10 layers of the retina?
Inner limiting membrane Nerve fibre layer Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer Outer limiting membrane Photoreceptor layer Choroid
What is the dual blood supply to the retina?
inner BRB 2/3 (retinal vascular system)
Outer BRB 1/3 (choroidal; choroid and Retinal pigment epithelium)
What kind of junctions hold the inner BRB vasculature? what is the pericyte ratio?
tight junctions (not leaky); 1:1
What pathology affects the inner BRB?
Diabetic retinopathy
What pathology affects the outer BRB?
Age related macular degeneration
What is the pathophysiology behind diabetic retinopathy?
1- Thickening of capillary basement membrane
2- Loss of pericytes
3- break down of BRB
What is the leading cause of vision loss under the age of 55?
Diabetic retinopathy
What are the two main classes of diabetic retinopathy?
Nonproliferative diabetic retinopathy
Proliferative diabetic retinopathy
What changes occur with Nonproliferative diabetic retinopathy?
Retinal vessel closure
Altered vascular permeability
What changes occur with proliferative diabetic retinopathy?
Abnormal growth of extraretinal fibrovascular tissue as an exaggerated response to retinal ischemia via VEGF (vascular endothelial growth factor)
What are some of the clinical findings in nonproliferative retinopathy?
Micro-aneurysms Macular edema Dot blot hemorrhages hard exudates= fat nerve fibre layer (flame) hemorrhages
What would a intravenous fluroescein angiogram show in Nonproliferative diabetic retinopathy?
Capillary dropout and nonperfusion
micro-aneurysms
What is the most common cause of visual loss in NPDR?
Macular edema
How does macular edema present in NPDR?
Retinal thickening
with or without exudates
How is NPDR related macular edema treated?
Laser, which reduces the rate of vision loss by 50%
What is the risk of proliferative diabetic retinopathy?
New vessels don’t have pericytes and are very fragile
Vitreous pulls away from retina with age–> if PDR, it will pull on blood vessels
Blood vessels pull on the retina–> leads to tractional retinal detachment
if blood vessel breaks–> leads to bleeding and vitreous hemorrhage
How is PDR treated?
PRP : panretinal photocoagulation
Reduce the oxygen demand of the retina and production of VEGF
What is the long term prognosis of diabetic retinopathy in terms of visual acuity?
> 20/40 59%
> 20/400 95%
Would age related macular degeneration cause peripheral vision loss?
no.
What is the pathology of Age related macular degeneration?
Breakdown of outer BRB Drusen deposition Thickening of Bruch's membrane Loss of RPE Growth of abnormal vessels into the retina (which could rupture causing wet AMD)
What is the most common form of AMD?
Dry (85%) vs. wet (15%)
What is the clinical presentation of dry AMD?
Drusen
Pigmentation abnormalities
What is the clinical presentation of wet AMD?
Choroidal neovascular membrane (CNVM)
blood
hemorrhage
Exudate
How is AMD treated?
Intravitreal injection of anti-VEGF
