Fundus: Diabetic Retinopathy

Question 0

What is believed to be the primary cause of the microvascular complications of diabetes, including retinopathy?

Answer 0

Hyperglycaemia.
Glycosylation of tissue proteins may play a major role.

The clinical manifestations can be explained by the twin processes of small vessel occlusion and increased permeability (loss of the blood-retinal barrier).

Question 1

List 5 relatively common ocular complications of diabetes.

Answer 1

1. Diabetic retinopathy
2. Extraocular muscle palsy
3. Stroke
4. Retinal vascular occlusions
5. Cataract

Question 2

Which two things are visual loss usually caused by in diabetes?

Answer 2

1. Maculopathy (may be slight at first, but gradually progressive without treatment).
2. Vitreous haemorrhage (often acute and dense, with severe loss of vision. Small haemorrhages suspended within the vitreous gel cause the appearance of a net curtain or blot in the vision).

If maculopathy, preproliferative or proliferative retinopathy suspected, refer for ophthalmological assessment.

Question 3

Clinical features of diabetic retinopathy.

Answer 3

• Microaneurysms and dot haemorrhages are very similar.
• Blot haemorrhages are darker and larger.
• Exudates (discrete yellow deposits of protein-rich material, occur due to leakage) should be differentiated from whiter, fluffy cotton wool spots (areas of infarcted retina, due to ischaemia)
• Retinal oedema: dull and loss of normal sheen; at the macula, the oedema is cystoid in appearance.
• Venous changes (subtle): loops, doubling and beading.
• Neovascularisation: may remain within the retina (IRMAs, intraretinal microvascular anomalies), or may project forwards into the vitreous.

Question 4

Describe the features of new blood vessels in neovascularisation in diabetic retinopathy, and a possible consequence.

Answer 4

New vessels are fragile, so bleed easily, and are accompanied by a fibrotic element. This contractile structure can lead to tractional retinal detachment.

Question 5

Name 3 classifications of diabetic retinopathy (+2 extra).

Answer 5

1. Background
2. Pre-proliferative
3. Proliferative
4. Maculopathy (changes similar to background retinopathy)
5. Advanced disease (Rx has failed, eye is blind. There may me neovascularisation on the iris (rubeosis, leading to severe glaucoma), persistent vitreous haemorrhage, and tractional retinal detachment).

Question 6

List 4 features of background diabetic retinopathy.

Answer 6

1. Microaneurysms
2. Dot and blot haemorrhages
3. Exudates
4. Oedema

Background retinopathy is due to leakage.

Question 7

List 3 features of pre-proliferative diabetic retinopathy.

Answer 7

1. Marked venous changes: beading, doubling, loops.
2. Cotton wool spots (areas of infarcted retina)
3. IRMAs (intraretinal microvascular anomalies)

There is a substantial likelihood of progression to pre-retinal neovascularisation.

Question 8

List features of proliferative diabetic retinopathy.

Answer 8

1. NVD (new vessels at the disc)

2. NVE (new vessels elsewhere, usually along the temporal vascular arcades).

Question 9

Name two differential diagnoses for diabetic retinopathy.

Answer 9

1. Retinal vein occlusion

2. Hypertensive retinopathy

Question 10

Which diabetics should undergo fundus examination screening, and how often?

Answer 10

All diabetics, at least once a year.
The best method of screening is yet to be determined. Techniques include direct ophthalmoscopy by optometrist, GP or diabetic physician, and fundus photography with examination of photographs by a specialist or trained technician.

Question 11

3 recommendations to pt to retard both onset of retinopathy and its progression?

Answer 11

1. Effective control of hyperglycaemia
2. Optimal control of hypertension
3. Stop smoking

Question 12

Treatments for maculopathy, neovascularisation, and persistent vitreous haemorrhage?

Answer 12

1. Macular laser for maculopathy (reduces focal leakage and improves resorption of retinal oedema).
2. Panretinal laser for neovascularisation (requires destruction of ischaemic areas).
3. Vitrectomy for persistent vitreous haemorrhage (may resorb spontaneously, but if persistent it will prevent observation and laser treatment).

Rx of preproliferative retinopathy is controversial, but severe changes warrant prophylactic laser application.
Tractional retinal detachment is difficult to treat and visual outcome is usually poor.