Diabetic Retinopathy Flashcards
What is DR?
- Raised blood sugar leads to loss of pericytes (cells that surround & support retinal capillaries)
- Capillaries Damaged:
o Blood retinal barrier breaks down
Leak
Blocked
o Leaking capillaries cause maculopathy
o Blocked capillaries cause ischaemia and proliferative retinopathy
Symptoms of DR?
- May be asymptomatic —> if nothing covering macula and just out in periphery
o Most common symptom - Blurred/distorted vision —> if something covering central macular area
- Sudden onset reduced vision —> something happening to BVs
o Least common symptom
Signs of DR?
- Microaneurysms
- Haemorrhages
- Exudates - deposits of lipid in retina caused by chronic leakage from capillaries
- Cotton wool spots
- Venous beading
- New vessels (in response to VEGF)
- IRMA - Intra-Retinal Microvascular Abnormalites
- Vitreous haemorrhage
- Traction detachment
As more capillaries are blocked, retina becomes ischaemic & signs of ischaemia appear, such as venous beading and new vessels
DR Classification?
- Background DR:
o 1-5 Microaneurysms (MAs)
o Retinal haemorrhages
o Venous loop
o Any exudates
o Any Cotton Wool Spots (CWS) - Pre-Proliferative DR:
o Venous beading
o Blot haemorrhages
o IRMAs
More signs of ischaemia - Proliferative DR:
o Stable pre-retinal fibrosis
o Stable fibrous proliferation
o NVDs – neovascularisation at disc
o NVEs – neovascularisation elsewhere
o New fibrosis/ vitreous haemorrhage – if any of vessels bleed
o New Tractional Retinal Detachment (TRD) – if BVs continue to grow into vitreous, can pull on retina & cause TRD
Risk factors of DR?
- Duration:
o Longer have diabetes, greater risk of DR – not everyone w/ diabetes has DR - Hyperglycaemia – poor diabetic control
- Hypertension – poor blood pressure control
o Poorly controlled diabetes
o Hypertension
o Obesity
Must be controlled to minimise risk of eye disease
Scottish DR Grading Scheme -> R0? R1? R2? R3? R4?
- R0 = No retinopathy
- R1 = Mild (1 or more microaneurysms, haemorrhages, hard exudates but less than R2) – recall 12/12
- R2 = Moderate (≥4 haemorrhages in one half/hemifield of retina -> horizontal -> superior vs inferior) – observable, recall 6/12
- R3 = Severe (≥4 haemorrhages in both halves/hemifields of retina AND/OR venous beading AND/OR IRMA) – referable
- R4 = Proliferative (active new BVs AND/OR vitreous haemorrhage)
When to refer based off DR Grading Scheme?
R0 – R2 = Observe (Check with GP that diabetes and other risk factors controlled, Review annually, Refer if suspect clinically significant macular oedema)
R3 – R4 = Refer to ophthalmologist
- If see diabetic and do see changes make sure they have screening appointment or are in screening service – ask px to go to GP or write to GP
What can neovacularisation lead to?
- Elevated new vessels
- Haemorrhages (pre-retinal (in front of retina but not in vitreous)/subhyaloid & intra-vitreal)
- Fibrosis – scar tissue can contract & pull retain with it
o Leads to tractional retinal detachment - Secondary glaucoma – particularly if new BVs on iris can grow into angle -> aqueous can’t drain properly -> can cause ↑in pressure & damage to back of retina
R3 Management?
- No new BVs yet but on their way
- Management:
o Refer to ophthalmologist who will monitor closely – not emergency same day check w/ GP all factors are well controlled
o Not usually treated with laser unless:
Other eye has poor sight
Clinically significant macular oedema
o Check with GP that DM and risk factors are well controlled
R4 Management?
- New BVs
- Management:
o Refer to ophthalmologist URGENTLY
o Urgent unless have advanced changes of retinal detachment or huge retinal bleed –> EMERGENCY
Management of Proliferative Diabetic Retinopathy (PDR)?
- Pan-retinal laser:
o 2-4000 laser burns applied to peripheral retina to reduce demand for O2 & reverse up regulation of VEGF
o Makes new vessels shrivel up, but they do not disappear completely - Vitrectomy:
o Advanced PDR
Vitreous haemorrhage
Traction retinal detachment
o Vitrectomy clears vitreous and removes fibrovascular tissue that causes RD - Intravitreal ranibizumab/aflibercept
o May be as effective or better than laser
o Laser is more convenient for px and avoids risk of intraocular injection - When eye has both severe maculopathy & proliferative retinopathy, regular anti-VEGF injections are good way of treating both at same time
Scottish DM Grading Scheme?
- M0 = No maculopathy <2DD of centre of fovea
- M1 = Early (exudates >1 & <2 Disc Diameter (DD) from fovea) – observable 6/12
- M2= Advanced (haemorrhages AND/OR exudates <1DD from fovea)
When to refer based off DM grading scheme?
M0 – M1 = Observe (Check with GP that diabetes and other risk factors controlled, Review annually, Refer if suspect clinically significant macular oedema)
M2 = Refer to ophthalmologist (unless VA is >6/7.5)
- If see diabetic and do see changes make sure they have screening appointment or are in screening service – ask px to go to GP or write to GP
DM management?
- Management:
o Check with GP that DM & other risk factors controlled – if have DM see GP every 6-12months for blood checks – check had blood check recently –> <~3weeks ago
o Review manually
o Refer if suspect clinically significant macular oedema
Management in hosp:
* M2 threatening fovea (VA 6/9+)
o Laser treatment reduces oedema & exudates
o Does not improve VA but may prevent future vision loss
* Macular oedema affecting fovea (VA <6/12)
o Anti-VEGF injections (aflibercept – given every 2 months)
Some pxs require continuous injections, as oedema recurs when injections stop
Requires repeated injections
In others, 6-month course may be sufficient to cure oedema permanently
o Improves vision by 10+ letters in 50%
15+ letters in 30%
o Steroid implants (long-acting) as 2nd line treatment – if injections are ineffective or px is unable to comply with frequent injections
What would you see in an OCT of DM?
Severe maculopathy shows ↑ in central foveal thickness caused by both intra-retinal & sub-retinal fluid.
Presence of sub-retinal fluid is a good sign as it is associated with greater improvement in vision following treatment
