Diabetic retinopathy

Question 1

Describe the pathogenesis which leads to diabetic retinopathy

Answer 1

Hyperglycaemia is thought to cause increased retinal blood flow and abnormal metabolism in the retinal vessel walls. This precipitates damage to endothelial cells and pericytes

• Endothelial dysfunction leads to increased vascular permeability which causes the characteristic exudates seen on fundoscopy.
• Pericyte dysfunction predisposes to the formation of microaneurysms ==> leakage and ischaemia
• Neovasculization is thought to be caused by the production of growth factors in response to retinal ischaemia

Question 2

Where do new vessels tend to grow in diabetic retinopathy ?

Answer 2

On the optic disc or the peripheries of the retina

Question 3

What are the symptoms of diabetic retinopathy ?

Answer 3

Initial stages usually asymptomatic

Later stages:

• Floaters,
• Blurred vision,
• Distortion,
• Progressive visual acuity loss.

Question 4

What are the signs of diabetic retinopathy seen when looking at the retina ?

Answer 4

• Microaneurysms - appear as small red dots
• Dot and blot hemorrhages - look similar to microaneurysms but occur due to there rupture
• Flame shaped hemorrhages
• Retina hard exudates (presence of microaneurysms differentiates it from drusen) - yellow spots
• Cotton wool spots
• Engorged torturous veins
• Neovascularization

Question 5

Diabetic retinopathy can be classified as proliferative and non-proliferative, what is the hallmark sign of proliferative retinopathy?

Answer 5

Neovascularisation - formation of new blood vessels

Question 6

What are the complications of diabetic retinopathy which result in the loss of vision ?

Answer 6

• Retinal oedema affecting the fovea
• Vitreous haemorrhage- new vessels likely to rupture
• Scarring
• Retinal detachment
• Maculopathy - due to leakage of nearby vessels causing oedema on macula threatening vision

Question 7

What is the treatment of diabetic retinopathy without maculopathy ?

Answer 7

• 1st line = optimise diabetic control
• 2nd line = pan-retinal photocoagulopathy
• 3rd line = vitrectomy

Question 8

If there is maculopathy present due to diabetic retinopathy how would the treatment differ ?

Answer 8

You would give intravitreal anti-VEGF and macular laser therapy and then treat the diabetic retinopathy as per guidance previously stated dependent on severity

Question 9

How is the severity of diabetic retinopathy classified ?

Answer 9

Nonproliferative diabetic retinopathy:

• Mild: Indicated by the presence of at least 1 microaneurysm
• Moderate: Includes the presence of hemorrhages, microaneurysms, and hard exudates
• Severe (4-2-1): Characterized by hemorrhages and microaneurysms in 4 quadrants, with venous beading in at least 2 quadrants and intraretinal microvascular abnormalities in at least 1 quadrant

Proliferative diabetic retinopathy:

• Neovascularization: Hallmark of PDR

Question 10

Hypertension can also affect the retina, what are the features of hypertensive retinopathy ?

Answer 10

• Attenuated blood vessels-copper or silver wiring
• Cotton wool spots
• Hard exudates
• Retinal haemorrhage
• Optic disc oedema

Question 11

Note hypertensive changes of the retina can occur in young patients due to accelerated hypertension

Question 12

Appreciate that many other systemic conditions can have manifestations in the eye

Answer 12

e.g. sjorgens syndrome, thyroid eye disease etc etc