Ophthalmology - Diabetic retinopathy

Question 1

What is diabetic retinopathy? Who is screened for this?

Answer 1

-Condition where blood vessels in the retina are damaged by prolonged exposure to hyperglycaemia - causing a progressive deterioration in the health of the retina.

Screening
-All diabetics should be screened annually
-Fundus photography
-Refer those with maculopathy, NPDR and PDR to an ophthalmologist for review
*30% of NPDR develop into PDR within 1 year

Question 2

Name important features of diabtic retinopathy seen on fundoscopy

Answer 2

1. Blot haemorrhages
2. Hard exudates
3. Microaneurisms
4. Venous beading
5. Cotton wool spots
6. Intraretinal microvascular abnormalities
7. Neovascularisation
8. Macular oedema and ischaemic maculopathy

Question 3

Pathophysiology: explain how blot haemorrhages and hard exudates occur

Answer 3

• Hyperglycaemia damages retinal small vessels and endotherlial cells, leading to increased vascular permeability, which causes leakage from the blood vessels, resulting in blot haemorrhages and hard exudates
• Hard exudates are yellow/white deposits of lipids in the retina

Question 4

Pathophysiology: what are microanneurisms, venous beading and intraretinal microvascular abnormalities?

Answer 4

• Damage to BV walls lead to microaneurisms (weakness in walls causes bulges) and beading (walls of veins are no longer straight and parallel and look more like a string of beads)
• Intraretinal microvascular abnormalities (IMRA) is where there are dilated and tortuous capillaries in the retina (can act as a shunt between the arterial and venous vessels in the retina)

Question 5

Pathophysiology: what are cotton wool spots?

Answer 5

Damage to the nerve fibres in teh retinal causes fluffy white patches to form on the retina

Question 6

Pathophysiology: why does neovascularisation occur?

Answer 6

-Ischamia of retina drives the production of growth factors - leads to neovascularisation but these vessels are very prone to bleeding :(

Question 7

What are the categories of classification for diabetic retinopthy?

Answer 7

• Non-proliferative diabetic retinopathy (or pre-proliferative)
• Proliferative diabetic retinopathy
• Diabetic maculopathy: separate category which can apply to either

Question 8

Non-proliferative diabetic retinopathy: outlife the types and their features

Answer 8

• Mild: microaneurisms
• Moderate: microaneurisms, blot haemorrhages, hard exudates, cotton wool spots and venous beading
• Severe: bloor haemorrhages + micronaneurisms in all 4 quadrants, venous beading in 2 quadrants, intraretinal microvascular abnormality in any quadrant

Question 9

Proliferative diabetic retinopathy: what features must be present for this category?

Answer 9

• Neovascularisation
• Vitreous haemorrhage
• Can sometimes also get fibrous tissue forming anterior to the retinal disc

Question 10

What is diabetic maculopathy?

Answer 10

Caused by macular oedema

• Ischaemic maculopathy
• Reduced acuity

Question 11

How should you manage a patient with diabetic retinopathy?

Answer 11

Local manageement

• Laser photocoagulation: burns targetting leaking BVs and neocasvularisation
• Anti-VEGF

Systemic

• Good BP and glycaemic control are essential
• Treat any concurrent disease: high cholesterol, renal disease, anaemia
• Encourage stop smoking