Retinal Anatomy

Question 1

What is the macula?

Answer 1

Area of the retina between temporal arcade vessels

Question 2

What is the fovea?

Answer 2

Thinned centre of the macula responsible for acute vision

Question 3

What are the 10 layers of the retina?

Answer 3

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

Question 4

What is the dual blood supply to the retina?

Answer 4

inner BRB 2/3 (retinal vascular system)

Outer BRB 1/3 (choroidal; choroid and Retinal pigment epithelium)

Question 5

What kind of junctions hold the inner BRB vasculature? what is the pericyte ratio?

Answer 5

tight junctions (not leaky); 1:1

Question 6

What pathology affects the inner BRB?

Answer 6

Diabetic retinopathy

Question 7

What pathology affects the outer BRB?

Answer 7

Age related macular degeneration

Question 8

What is the pathophysiology behind diabetic retinopathy?

Answer 8

1- Thickening of capillary basement membrane
2- Loss of pericytes
3- break down of BRB

Question 9

What is the leading cause of vision loss under the age of 55?

Answer 9

Diabetic retinopathy

Question 10

What are the two main classes of diabetic retinopathy?

Answer 10

Nonproliferative diabetic retinopathy

Proliferative diabetic retinopathy

Question 11

What changes occur with Nonproliferative diabetic retinopathy?

Answer 11

Retinal vessel closure

Altered vascular permeability

Question 12

What changes occur with proliferative diabetic retinopathy?

Answer 12

Abnormal growth of extraretinal fibrovascular tissue as an exaggerated response to retinal ischemia via VEGF (vascular endothelial growth factor)

Question 13

What are some of the clinical findings in nonproliferative retinopathy?

Answer 13

Micro-aneurysms 
Macular edema
Dot blot hemorrhages
hard exudates= fat
nerve fibre layer (flame) hemorrhages

Question 14

What would a intravenous fluroescein angiogram show in Nonproliferative diabetic retinopathy?

Answer 14

Capillary dropout and nonperfusion

micro-aneurysms

Question 15

What is the most common cause of visual loss in NPDR?

Answer 15

Macular edema

Question 16

How does macular edema present in NPDR?

Answer 16

Retinal thickening

with or without exudates

Question 17

How is NPDR related macular edema treated?

Answer 17

Laser, which reduces the rate of vision loss by 50%

Question 18

What is the risk of proliferative diabetic retinopathy?

Answer 18

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

Question 19

How is PDR treated?

Answer 19

PRP : panretinal photocoagulation

Reduce the oxygen demand of the retina and production of VEGF

Question 20

What is the long term prognosis of diabetic retinopathy in terms of visual acuity?

Answer 20

> 20/40 59%

> 20/400 95%

Question 21

Would age related macular degeneration cause peripheral vision loss?

Answer 21

no.

Question 22

What is the pathology of Age related macular degeneration?

Answer 22

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)

Question 23

What is the most common form of AMD?

Answer 23

Dry (85%) vs. wet (15%)

Question 24

What is the clinical presentation of dry AMD?

Answer 24

Drusen

Pigmentation abnormalities

Question 25

What is the clinical presentation of wet AMD?

Answer 25

Choroidal neovascular membrane (CNVM)
blood
hemorrhage
Exudate

Question 26

How is AMD treated?

Answer 26

Intravitreal injection of anti-VEGF