About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Leading cause of blindness in working-age adults in UK. Present to some degree in ~40% of diabetics
- Screening: annual digital retinal photography for ALL diabetics from age 12 (T1DM) or from diagnosis (T2DM)
- Classification: R0 (none), R1 (background: microaneurysms, dot/blot haemorrhages, hard exudates), R2 (pre-proliferative: cotton wool spots, venous beading, IRMA), R3 (proliferative: new vessels disc/elsewhere)
- Maculopathy (M1): any feature within 1 disc diameter of foveal centre — main cause of visual loss
- Treatment: proliferative → pan-retinal laser photocoagulation or anti-VEGF. Maculopathy → intravitreal anti-VEGF (ranibizumab, aflibercept)
- Prevention: tight glycaemic control (HbA1c ≤48), BP control (<140/80), statin therapy
Overview
Diabetic retinopathy is a microvascular complication of diabetes characterised by progressive damage to the retinal vasculature from chronic hyperglycaemia. It is the leading cause of vision loss in working-age adults in the UK. Pathogenesis involves pericyte loss, basement membrane thickening, endothelial dysfunction, and capillary occlusion, leading to retinal ischaemia. Ischaemia drives VEGF production, which causes neovascularisation (proliferative disease) and increased vascular permeability (macular oedema). The disease is classified as non-proliferative (background → pre-proliferative) and proliferative (neovascularisation). Diabetic maculopathy (oedema near the fovea) is the commonest cause of visual impairment. The UK NHS Diabetic Eye Screening Programme (DESP) detects sight-threatening retinopathy through annual digital retinal photography.
Epidemiology
Approximately 40% of people with diabetes have some degree of retinopathy at any time. Sight-threatening retinopathy (proliferative or maculopathy) affects approximately 7%. Risk factors include: duration of diabetes (strongest risk factor), poor glycaemic control, hypertension, dyslipidaemia, diabetic nephropathy (albuminuria is a strong predictor), pregnancy, and smoking. In T1DM, retinopathy is rare within the first 5 years but affects virtually all patients after 20 years. In T2DM, retinopathy may be present at diagnosis (reflecting pre-diagnostic hyperglycaemia). The NHS DESP screens approximately 2.5 million people annually.
Clinical Features
Symptoms
Early disease is ASYMPTOMATIC — hence the importance of screening
Gradual painless visual loss (macular oedema — blurring of central vision)
Floaters and/or sudden visual loss (vitreous haemorrhage from new vessels)
Flashing lights or shadow/curtain across vision (tractional retinal detachment — late proliferative)
Signs
R1 Background: microaneurysms (earliest sign — tiny red dots), dot/blot haemorrhages, hard exudates (yellow lipid deposits)
R2 Pre-proliferative: cotton wool spots (retinal infarcts), venous beading/looping, IRMA (intraretinal microvascular abnormalities), deep dark blot haemorrhages
R3 Proliferative: neovascularisation at disc (NVD) or elsewhere (NVE), pre-retinal/vitreous haemorrhage, fibrous tissue, tractional retinal detachment
M1 Maculopathy: any lesion or thickening within 1 disc diameter of foveal centre — hard exudates, haemorrhages, or oedema
Investigations
First-line
Digital retinal photography (screening)2 standard-field images per eye (disc-centred and macula-centred) through dilated pupil. Graded as R0/R1/R2/R3 and M0/M1
Second-line
Optical coherence tomography (OCT)Cross-sectional retinal imaging — gold standard for detecting and monitoring macular oedema
Fluorescein angiographyIdentifies areas of retinal ischaemia, leakage, and neovascularisation. Specialist investigation for treatment planning
Specialist
Wide-field retinal imagingCaptures greater retinal area — detects peripheral retinopathy that may be missed on standard screening
B-scan ultrasonographyIf vitreous haemorrhage obscures retinal view — assess for retinal detachment
Management
NHS Diabetic Eye Screening Programme; NICE NG17/NG28; Royal College of Ophthalmologists Guidelines1
Prevention and screening
- Annual digital retinal screening for ALL diabetes patients — from age 12 (T1DM) or diagnosis (T2DM)
- Optimise HbA1c (≤48 mmol/mol T1DM target; individualise for T2DM)
- BP control: <140/80 mmHg (or lower if renal/retinal disease)
- Lipid management: statin therapy as per NICE guidance
- Avoid rapid glucose correction (can transiently worsen retinopathy)
2
Referral pathways
- R1 (background): annual screening. Reassurance — does not need ophthalmology referral
- R2 (pre-proliferative): refer to ophthalmology. Urgent (within 6–13 weeks)
- R3 (proliferative): URGENT referral to ophthalmology (within 2 weeks)
- M1 (maculopathy): refer to ophthalmology — urgent
3
Proliferative retinopathy treatment
- Pan-retinal photocoagulation (PRP): laser burns to peripheral retina → reduces VEGF production → regression of new vessels
- Intravitreal anti-VEGF injections (ranibizumab, aflibercept): increasingly first-line for sight-threatening disease
- Vitrectomy: for non-clearing vitreous haemorrhage or tractional retinal detachment
4
Maculopathy treatment
- Intravitreal anti-VEGF (ranibizumab, aflibercept): first-line for centre-involving diabetic macular oedema
- Macular laser: if non-centre-involving macular oedema
- Intravitreal steroid implant (dexamethasone, fluocinolone): for refractory macular oedema or pseudophakic patients
Complications
- Visual impairment and blindness: Leading cause of blindness in working-age UK adults. Preventable with screening and treatment
- Vitreous haemorrhage: From ruptured new vessels — sudden painless visual loss. May clear spontaneously or require vitrectomy
- Tractional retinal detachment: Fibrovascular proliferation pulls retina off — causes field loss or total visual loss. Requires urgent vitrectomy
- Neovascular glaucoma: New vessels grow on iris → block trabecular meshwork → raised IOP. Painful, sight-threatening
UKMLA Exam Tips
- 1Microaneurysms = earliest sign of diabetic retinopathy (tiny red dots on fundoscopy)
- 2Cotton wool spots = pre-proliferative (retinal infarcts from ischaemia). NOT the same as hard exudates (which are background)
- 3New vessels = PROLIFERATIVE disease = sight-threatening = URGENT ophthalmology referral
- 4Maculopathy is the commonest cause of visual loss in diabetic retinopathy — central vision affected
- 5Annual screening: digital retinal photography through dilated pupils. R0–R3 grading + M0/M1
- 6Anti-VEGF (ranibizumab, aflibercept) is now first-line for both proliferative disease and macular oedema
- 7Rapid glucose correction can WORSEN retinopathy transiently ("treatment-related retinopathy") — warn patients and ophthalmologists
practicetest your knowledge on diabetic retinopathyApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — endocrine and beyond.
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