Diabetic Retinopathy

Background

• Microaneurysms
• Retinal haemorrhages +/- any exudate

Pre-Prolif

• Venous Beading
• Venous looping
• IRMA
• Multiple deep round haemorrhages
• Cotton Wool Spots

Prolif

• NVD
• NV Elsewhere
• Pre-retinal/vit haem
• Pre-retinal fibrosis/tractional ret det

Photocoagulation

• Focal/grid macular
• Peripheral scatter
• Pain
• No driving that day
• Loss of visual field

Maculopathy

• Exudate within a disc area centred on fovea
• Circinate/group of exudates within macula
• Retinal thickening within a DA centred on fovea (seen on stereo photo)
• Microaneurysm/haem within a DA centred on fovea if assoc with best VA of 6/12
  

Optometric Management of DR

History

• before insulin DR wasn't recognised and insulin dependent diabetics died early. Type II were diet controlled
• 1950s-1970s diabetes becomes a controlled disease and DR was recognised. Hypoxia was recognised as the trigger for the neovascular process
• Laser treatment - pan retinal photocoagulation - focal treatment to stop specific leaks
• Newest development c.2000 - intensive diabetic control via continuous control, slow release insulin, insulin pumps

There were two big trials

1. Diabetes control and complications trial - type I diabetes (insulin cells destroyed)
   
2. UK prospective diabetes study - type II diabetes (high blood glu, relative insulin def)

Glucose tests for diabetes

• Fasting blood sugar = >7.8mmol/litre
• Random blood sugar = >11.1mmol/litre
• Two hour post load = >11.1mmol/litre = you're diabetic
• Two hour post load = >7.8mmol/litre = you have impaired glucose tolerance

Glycosylated Haemoglobin = Glu bound to haemoglobin. Measuring it is good because it correlates w/blood sugar average over 6-8 weeks:

• Normal <6% (corr w/ 7.6mmol/l)
  
• Controlled diabetic = 9% (corr w/10mmol/l)
  
• Intensive control = <7%>

If you're intensively controlled then there's only a 7% chance of you developing DR after nine years and if you're 9% controlled then it's around 20%. So intense control is way beneficial.

Initial Adverse Effects - sudden intensive control leads to increased DR in 6/9 months. Phase it in!

Factors which aggravate DR

• smoking
  
• hypertension
• hyperlipidaemia
• obesity
• renal disease
• pregnancy
• puberty

The challenge currently is to get 100% of diabetics an annual eye exam w/high level of accuracy (or every 6 mths for the high risk people) Strategies for screening include

• GP w/ophthalmoscope - good recruitment but poorest accuracy
• Special screenings + photo
• Optom - good accuracy but poorest recruitment. Optom has skill, equipment, accuracy and knowledge

Scottish National Screening Program

• Want to detect referable sight threatening retinopathy to reduce the risk of sight loss
• To detect lesser degrees of DR

This was launched April 2002. Target px were everyone >12yrs old, both type I and II, excluding everyone that already has ophth. care, the irreversibly blind and the medically untreatable. Working out national register of all diabetics, system of appts/feedback/followup. The whole thing is audited and coordinated

Screening process

1. Digital camera - 80% can have non-dilated. Pic stored for analysis
2. Digital photo w/mydriatics
3. Volk

Photos are then graded by technicians or optoms

The importance of screening must be stressed to ppl. Remember tell em not to drive after mydriasis/light sensitivity

Results

• Retinopathy yes/no?
• Follow-up (screen or referral)
• GP and ophthalmologist informed