Diabetic retinopathy

Question 1

What is diabetic retinopathy?

Answer 1

Retinal consequence of chronic progressive diabetic microvascular leakage and occlusion.

Question 2

What are the types of diabetic retinopathy?

Answer 2

Non-proliferative DR: Early stage where blood vessels in eye may leak fluid into the retina, which leads to blurred vision.
Proliferative DR: More advanced form where new blood vessels start to grow in the eye, which are fragile and can haemorrhage.
This may cause vision and scarring of the retina.

Question 3

Aetiology of diabetic retinopathy

Answer 3

Hyperglycaemia is the principal aetiological factor in DR.
Hyperglycaemia causes changes in:
Blood composition including increased viscosity, reduced white cell deformability and changes in procoagulant, anti-fibrinolytic and platelet aggregation activity.
Blood vessel walls, including loss of anti-thrombogenic nature of the endothelial lining.
Blood flow as a result of microthrombus formation, vascular occlusion, and impairment of retinal autoregulation.
These changes result in retinal capillary leakage and non-perfusion, which causes tissue hypoxia and may precipitate alterations in non-vascular retinal tissue.

Question 4

Pathophysiology of diabetic retinopathy

Answer 4

Retinal capillary leakage gives rise to intraretinal haemorrhage, cholesterol exudate deposition, and retinal oedema.
The macula area of the retina may become involved, leading to reduced central vision.
Retinal capillary occlusion leads to microaneurysms, cotton wool spots, intraretinal microvascular abnormalities, and venous calibre irregularities ultimately it results in PDR.
No single pathophysiology mechanism but it is the VEGF pathway that provides the most effective therapeutic means of modifying the course of diabetic retinopathy.

Question 5

Eye examination of diabetic retinopathy

Answer 5

Intraocular pressure and stereoscopic biomicroscopy

Question 6

Clinical signs of diabetic retinopathy

Answer 6

Microaneurysms, intraretinal haemorrhage, cotton wool spots, and lipid exudates.

Question 7

Severe NPDR

Answer 7

Characterised by venous bleeding, intraretinal microvascular abnormalities, and more widespread intraretinal haemorrhage.

Question 8

Ancillary tests

Answer 8

Digital photographs of the fundus

Optical coherence tomography.

Question 9

Differentials of diabetic retinopathy

Answer 9

Ocular ischaemic syndrome.
Radiation retinopathy.
Retinal venous occlusion.
HTN.

Question 10

Management of diabetic retinopathy

Answer 10

-Improve hypertensive and glycaemic control and ensure that sight-threatening disease is arrested before visual loss occurs, as visual loss is easier to prevent than to reverse.
Anti-VEGF therapy (afibercept, ranbizamab or bevacizumab).
Macular laser therapy.