DIABETIC RETINOPATHY

Question 1

What is the pathophysiology of diabetic retinopathy?

Answer 1

Hyperglycaemia causes increases blood flow to retinal arteries and abnormal metabolism in retinal vessel walls. This leads to damage of the endothelial cells and pericytes. The damaged endothelium and pericytes will then leak and bleed. Eventually there will be ischaemia and this is the point where neovascularization will occur.

Question 2

What are the two broadly divided stages of diabetic retinopathy?

Answer 2

Non-proliferative

Proliferative

Question 3

What are the non-proliferative features (seen on fundoscopy) of diabetic retinopathy?

Answer 3

Microaneurysms

Haemorrhages - dot, blot and flame

Thickening and oedema

Hard exudate

Cotton wool spots

Venous beading - sausage like venules of changing calibre

Tortuous vessels

Intraretinal microvascular abnormalities

Question 4

What is the difference between hard exudate and cotton wool spots, both seen in no-n-proliferative diabetic retinopathy?

Answer 4

Hard exudate: Lipoprotein deposits - sign of leakage

Sharp, well demarcated yellow blobs which are deeper to superficial retinal blood vessels

Cotton wool spots: Axoplasmic fluid - sign of ischaemia

Superficial white fluffy retinal blobs, not usually crossed by retinal blood vessels

Question 5

What are the additional features (seen on fundoscopy) of proliferative diabetic retinopathy? (Additional to non-proliferative diabetic retinopathy)

Answer 5

Neovascularization of the disc (NVD)

Neovascularization elsewhere

Pre-retinal or vitreous haemorrhage

Vitreoretinal traction - adhesions between vitreous and retina leading to retinal elevation.

Question 6

Non-proliferative diabetic retinopathy is classified by severity: mild, moderate, severe and very severe. What are the features of mild non-proliferative diabetic retinopathy?

Answer 6

At least one microaneurysm

But criteria not met for moderate

Question 7

Non-proliferative diabetic retinopathy is classified by severity: mild, moderate, severe and very severe. What are the features of moderate non-proliferative diabetic retinopathy?

Answer 7

Intraretinal haemorrhages

Microaneuryms

Hard exudates

AND / OR

Cotton wool spots

Venous beading

But criteria not met for severe

Question 8

Non-proliferative diabetic retinopathy is classified by severity: mild, moderate, severe and very severe. What are the features of severe non-proliferative diabetic retinopathy?

Answer 8

One of:

Blot haemorrhages in all four 4 quadrants

Venous beading in 2 or more quadrants

Intraretinal microvascular abnormalities in at least 1 quadrant

Question 9

Non-proliferative diabetic retinopathy is classified by severity: mild, moderate, severe and very severe. What are the features of very severe non-proliferative diabetic retinopathy?

Answer 9

Two or more of:

Blot haemorrhages in all four 4 quadrants

Venous beading in 2 or more quadrants

Intraretinal microvascular abnormalities in at least 1 quadrant

Question 10

What is the older/classical version of classifying non-proliferative diabetic retinopathy?

Answer 10

Background DN

Pre-proliferative DN

Question 11

The older/classical version of classifying non-proliferative diabetic retinopathy split it into background and pre-proliferative DN. What are the features of background DN?

Answer 11

Microaneurysms (dots)

Blot haemorrhages - less than 4

Hard exudates

Question 12

The older/classical version of classifying non-proliferative diabetic retinopathy split it into background and pre-proliferative DN. What are the features of pre-proliferative DN?

Answer 12

Cotton wool spots (soft exudates; ischaemic nerve fibres)

4 or more blot haemorrhages

Venous beading/looping

Deep/dark cluster haemorrhages

Question 13

What are the symptoms of diabetic retinopathy?

Answer 13

Patients will be asymptomatic for a long time, hence the need for the screening programme.

With advanced disease they may present with:

Sudden increase in number of floaters

Sudden painless loss of vision due to haemorrhage

There should be no relative afferent pupil defect - if present consider alternative diagnosis

Question 14

Which type of diabetes is most associated with diabetic retinopathy?

Answer 14

Type 1 due to length of time

Type 2 is more associated with diabetic maculopathy

Question 15

At what point in the development of diabetic retinopathy do we initiate treatment beyond glycaemic control?

Answer 15

Proliferative stage

Question 16

What are the treatment options for diabetic retinopathy?

Answer 16

Pan-retinal laser photocoagulation - (Although any coexistent maculopathy should be treated first - also with laser) this is the mainstay

Medical:

Protein kinase C inhibitors - ruboxistaurin

Intravitreal anti-VEG-F - avastin (bevacizumab)

Question 17

How does laser photocoagulation work in the treatment of diabetic retinopathy?

Answer 17

Ablate and destroy the ischaemic retina, which is producing VEG-F and hence stimulating neovascularization.

Question 18

How many weeks post-laser treatment for diabetic retinopathy do we assess response?

Answer 18

6-8 weeks

Question 19

How do we treat persistent vitreous haemorrhage (over 3 months) as a result of diabetic retinopathy?

Answer 19

Vitrectomy with internal laser

Question 20

What are the complications of proliferative diabetic retinopathy?

Answer 20

Loss of sight

Neovascular (rubeotic) glaucoma

Question 21

What is neovascular glaucoma?

Answer 21

Complication of proliferative diabetic retinopathy where new vessels grow on the iris (rubreosis) and into the angle leading to fibrosis and eventual closure of the angle.