Diabetes and the eye: screening and grading
- Eye and systemic disease
Diabetic retinopathy causes no symptoms until late, so every person with diabetes needs regular retinal screening. Found early, it is treatable.
See it in 3D: Retina · Macula · Optic disc
What it is
Diabetes damages the small vessels of the retina: they leak (macular oedema) and close (ischaemia), and the ischaemic retina grows fragile new vessels (proliferative retinopathy). It is a leading cause of visual loss in working-age adults and is silent until late. Screening with a dilated exam or retinal photographs, good control of glucose, blood pressure and lipids, and timely laser or injections prevent most blindness.
Eye findings
- Non-proliferative retinopathy: microaneurysms, dot and blot haemorrhages, hard exudates, cotton-wool spots, venous beading.
- Proliferative retinopathy: new vessels on the disc or elsewhere, which can bleed or pull the retina off.
- Diabetic macular oedema: the commonest cause of visual loss in diabetes; it can occur at any stage.
- Other effects: earlier cataract, blurred vision with glucose swings, third, fourth or sixth nerve palsies, neovascular glaucoma.
Step by step
- Ask about blurred or fluctuating vision and measure visual acuity.
- Examine the retina through dilated pupils, or take retinal photographs for remote grading.
- Grade the retinopathy (none, mild, moderate or severe non-proliferative, proliferative) and look for macular oedema.
Screening and follow-up
- Type 2 diabetes: screen at diagnosis, because retinopathy may already be present.
- Type 1 diabetes: screen from about five years after diagnosis (and at puberty).
- Then screen at least every one to two years if there is no retinopathy, and more often if there is.
- Pregnancy can worsen retinopathy: exam early in pregnancy and during it.
- A very rapid fall in glucose can transiently worsen retinopathy: examine before intensifying treatment if retinopathy is advanced.
Next step / Initial management
- No retinopathy: repeat screening every one to two years and optimise glucose, blood pressure and lipids.
- Mild to moderate non-proliferative retinopathy without macular oedema: ophthalmology follow-up within months.
- Macular oedema: ophthalmology within weeks for OCT and anti-VEGF injections.
- Severe non-proliferative or proliferative retinopathy: urgent ophthalmology for laser (panretinal photocoagulation) or injections.
- Sudden loss of vision, shower of floaters or a painful red eye: same day (vitreous haemorrhage, detachment, neovascular glaucoma).
Test yourself
Think of the answer, then tap the question to see it.
When should retinal screening start in type 2 diabetes?
At diagnosis, because retinopathy may already be present.
What is the commonest cause of visual loss in diabetes?
Diabetic macular oedema.
What defines proliferative diabetic retinopathy?
New vessels on the optic disc or elsewhere on the retina, which can bleed or cause a tractional detachment.
Connections
See it in 3D3
The structures of Durgical's 3D anatomy where it is found.
In Pharmacology3
Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once.
Sources: Diabetic Retinopathy (StatPearls Publishing (NCBI Bookshelf), 2023); Diabetic Macular Edema (StatPearls Publishing (NCBI Bookshelf), 2023); Guía de práctica clínica para el diagnóstico, tratamiento y seguimiento de la diabetes mellitus tipo 2 en la población mayor de 18 años (Ministerio de Salud y Protección Social de Colombia, 2016).
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Representative model, for educational purposes only.