Diabetic retinopathy I

Question 1

What are the risk factors for diabetic retinopathy?

Answer 1

Duration of diabetes:
Incidence DR after 10 years is 30%
Incidence DR after 30 years is 90%

Good metabolic control
Delays, but does not prevent onset of DR. Conversely poor control may develop sooner.

Miscellaneous:
Pregnancy, High blood pressure, Kidney disease, Anaemia

Question 2

What happens to the blood vessels in DR?

Answer 2

blocks, bleeds, leaks and haemorrhages

Question 3

What happens due to blocks, bleeds and leaks?

Answer 3

Blocks - leads to ischaemia, promotes new blood vessel formation, retina/iris/angle, Retina stops working
Bleeds - Retinal haemorrhage, Vitreous haemorrhage
Leaks - exudates, macula swelling

Question 4

What types of haemorrhages are there?

Answer 4

Dot haemorrhages - small round red dots – could be small haemorrhages or microaneurysms.
Blot haemorrhage - Larger than diameter of retinal vein as crosses optic disc, often indicate ischaemia.
Flame haemorrhage - Arise in NFL which gives them the characteristic shape

Question 5

What happens when there is leaking of retinal blood vessels?

Answer 5

Hard exudates - can be standalone or circinate.
often at edge of non-oedematous and oedematous retina, yellow/waxy appearance with distinct margins.
Oedema - can be seen clinically with binocular indirect examination, can be seen on OCT.

Question 6

What are new blood vessels?

Answer 6

A sign of Proliferative Retinopathy - can be seen at optic disc (NVD), can be see elsewhere (NVE), often at junction between ischaemic and non-ischaemic retina, may appear fibrotic.
Can be seen on iris (rubeosis) or in the angle (NVA).
Rubeotic glaucoma.

Question 7

What is rubeosis?

Answer 7

is a disease characterized by the appearance of newly formed vessels on the anterior surface of the iris.

Question 8

What are other vascular changes that can occur on the retina?

Answer 8

1. Intraretinal microvascular abnormalities (IRMA) - sometimes resemble very early NVE, sign of ischaemia, usually develop into NVE.
2. Venous beading - sign of ischaemia
3. Cotton-wool spots - usually associated with ischaemia, but not predictive or used in grading. Caused by a local cessation of active transport in the nerve fibre, so the nerve fibres swell in that region.

Question 9

How do you classify diabetic retinopathy?

Answer 9

1. non-proliferative diabetic retinopathy (NPDR) – AAO and Scottish DES.
   Mild
   Moderate
   Severe
2. Proliferative retinopathy (PDR)
   Low risk
   High risk
3. Maculopathy - centre involving DMO

Question 10

How do you classify non-proliferative DR?

Answer 10

1. Mild NPDR - Dots only
2. Moderate NPDR - Dots and blots
3. Severe NPDR - 4:2:1 rule -> any one of below;
   >=4 blots in all 4 quadrants
   2 quadrants of venous beading
   1 IRMA
4. Very severe NPDR - more than one of the 4:2:1 rule.

Question 11

How do you classify proliferative DR?

Answer 11

Asymptomatic – until bleed -> floaters/loss vision.
1. Location;
NVD – less than 1DD from the margin of the disc.
NVE – more than 1DD from the margin of the disc.
2. Severity - Early, High-risk characteristics, Florrid, Gliotic

Question 12

How do you classify diabetic maculopathy?

Answer 12

1. Ischaemic
2. non-ischaemic
   Leakage from macula blood vessels
   Vision reduced due to macula oedema
   Clinically significant macular oedema (defunct).
   Classification superseded since advent of OCT.
   Centre-involving DMO.

Question 13

What are the features of diabetic macular oedema?

Answer 13

Retinal thickening/oedema – volk lens
Hard exudates:
Either scattered
Circinate with oedema within
Microaneurysms.
Blot haemorrhages.