Diabetic Retinopathy

Question 1

Diabetic retinopathy is the most common cause of blindness in what age group?

Answer 1

Adults aged 35-65

Question 2

What percentage have ocular problems when diabetes presents?

Answer 2

30% , but the majority remain asymptomatic until advance disease takes hold (at which point little can be done)

Question 3

Describe the pathogenesis

Answer 3

Microangiopathy in capillaries causes:
1) vascular occlusion leading to ischaemia +/- new vessel formation (which bleed). Ischaemia causes cotton wool spots

2) vascular leakage as pericytes are lost - capillaries bulge (micro aneurysms) and there is oedema and hard exudates. Rupture of micro aneurysms can cause flame shaped haemorrhages or blot haemorrhages

Question 4

What are cotton wool spots?

Answer 4

Ischaemic nerve fibres

Question 5

What is the impact of hyperglycaemia?

Answer 5

Increased retinal blood flow and abnormal metabolism in retinal vessel walls - damage to endothelial cells and pericytes

Question 6

What does endothelial dysfunction lead to?

Answer 6

Increased vascular permeability - causes the characteristic exudates seen on fundoscopy

Question 7

What does pericyte dysfunction predispose?

Answer 7

Micro aneurysms

Question 8

What is neovasculisation thought to be caused by?

Answer 8

Production of growth factors in response to ischaemia

Question 9

What are hard exudates comprised of?

Answer 9

Lipoprotein and lipid filled macrophages. It has leaked from abnormal retinal capillaries, so often associated retinal oedema

Question 10

What are the two types of diabetic retinopathy?

Answer 10

Non-proliferative diabetic retinopathy

Proliferative diabetic retinopathy

Question 11

How is NPDR rated?

Answer 11

Mild
Moderate
Severe

Depending on degree of ischaemia

Question 12

Describe mild NPDR

Answer 12

1 or more micro aneurysms (small red dots often in clusters), do not affect vision

Question 13

Describe moderate NPDR

Answer 13

Micro aneurysms
Blot haemorrhages
Hard exudates
Cotton wool spots, venous beading/ looping and intraretinal microvascular abnormalities less severe than in severe NPDR

Question 14

Describe severe NPDR

Answer 14

Blot haemorrhages and micro aneurysms in 4 quadrants
Venous bleeding in at least 2 quadrants
Itraretinal microvascular abnormalities at least 1 quadrant

Question 15

Describe proliferative diabetic retinopathy

Answer 15

Fine new vessels appear on optic disc, retina and can cause vitreous haemorrhage

Question 16

What is maculopathy?

Answer 16

When macula is affected by retinopathy

Leakage of vessels close to macula can cause macula oedema - can significantly threaten vision

Question 17

Who should be referred urgently for assessment and treatment?

Answer 17

Those with:
Maculopathy
Severe NPDR
PDR

Question 18

How can DM cause glaucoma?

Answer 18

DM causes ocular ischaemia, which can cause new blood vessels to form on the iris - these can block the drainage of aqueous fluid

Question 19

The formation of age related cataracts is accelerated in DM. True or false?

Answer 19

True

Question 20

How often should those with DM type 1 and 2 have their eyes screened?

Answer 20

At time of diagnosis and then at least annually

Question 21

Screening is done by…

Answer 21

Dilated fundus photography - referrals then made accordingly
Lesions mostly at posterior pole and can be seen by ophthalmoscope

Question 22

Proliferative retinopathy heightens the risk of…

Answer 22

Retinal detachment

Fibrosis and connective tissue develops - asserts traction

Question 23

What do micro aneurysms look like?

Answer 23

Small red dots often in clusters

Question 24

What are the earliest clinically visible changes of diabetic retinopathy?

Answer 24

Micro aneurysms

Question 25

Do micro aneurysms affect vision?

Answer 25

No

Question 26

Intraretinal haemorrhages may be dot, blot or flame depending on...

Answer 26

Their depth within the retina The capillary layer in the posterior retina has 2 layers - superficial in nerve fibre layer and deeper on within nuclear layer. Haemorrhages within nerve fibre layer = flame shaped, inner layer haemorrhages = dot or blot

Question 27

The hard exudates (intra retinal deposits) can vary from small specks to large patches and may evolve into rings known as...

Answer 27

Circinates

Question 28

Where are the hard exudates principally found?

Answer 28

Macular region and as the extend into fovea, vision can be severely compromised

Question 29

What do cotton wool spots look like?

Answer 29

Greyish white patches in the nerve fibre layer which has fluffy edges.

Question 30

What are intraretinal microvascular abnormalities?

Answer 30

Areas of capillary dilatation and intraretinal new vessel formation. Arise within ischaemic retina

Question 31

When neovascularisation occurs, where are the new vessels usually found?

Answer 31

Initially seen as fine tufts on surface of the disc | Large veins

Question 32

What is a sub-hyaloid haemorrhage?

Answer 32

New vessels form abnormal adhesions with vitreous. Where there is areas of detachment of vitreous, blood can accumulate between retina and vitreous = sub hyaloid haemorrhage

Question 33

What is used to treat maculopathy and proliferative retinopathy?

Answer 33

Photocoagulation Trans pupillary laser applied so as to produce a retinal burn - used to treat the new blood vessels It does not improve vision, it is intended to prevent blindness

Question 34

What can accelerate retinopathy?

Answer 34

``` Pregnancy Hypertension Renal disease Dyslipidaemia Smoking Anaemia ```

Question 35

What is used to treat macula oedema?

Answer 35

Intravitreal triamcinolone and anti VEGF drugs | Focal laser treatment to seal any leaking micro aneurysms

Question 36

What can reduce the risk of visual deterioration in patients with diabetic macula oedema by at least 50% ?

Answer 36

Grid laser therapy

Question 37

What are some side effects of laser treatment?

Answer 37

Loss of peripheral vision, colour vision, night vision

Question 38

How can diabetic retinopathy be prevented?

Answer 38

Keep blood sugar levels as close to normal as possible Control BP <140/80 or < 130/80 if end organ damage Lower cholesterol

Question 39

What examinations can be done?

Answer 39

Slit lamp/ ophthalmoscope Fluorescein angiography to assess damage Optic coherence tomography to assess if any macula oedema

Question 40

What is fluorescein angiography?

Answer 40

A test to examine the back of the eye - see if there are any problems with the vessels there. Vein injected with the yellow sodium fluorescein dye - travels round body. Retina illuminated with blue light. Angiogram obtained by photographing the green light that is emitted.

Question 41

What symptoms occur with diabetic retinopathy?

Answer 41

Early stages usually no symptoms Some people may notice trouble reading or seeing objects far away In later stages - vessels start to bleed into vitreous gel - dark, floating spots or streaks that look like cobwebs If macular oedema present: blurry vision due to extra fluid

Question 42

Why can diabetic retinopathy cause retinal detachment?

Answer 42

It can cause scars to form at back of eye | These scars can pull the retina away from the back of the eye