Diabetic Retinopathy
Diabetic retinopathy is a microvascular complication of diabetes mellitus and an important cause of visual impairment. It is commonly divided into non-proliferative diabetic retinopathy, proliferative diabetic retinopathy, and diabetic macular oedema / diabetic maculopathy.
This updated UKMLA guide to diabetic retinopathy is based on NICE NG242, which covers classification, risk factors, symptoms, diagnosis, NHS diabetic eye screening, and management.
Epidemiology
Diabetic retinopathy is the most common cause of acquired blindness in adults (20-74 y/o) in high-income countries. [Ref]
Risk Factors
- Prolonged duration of diabetes
- Poor glycaemic control
- Hypertension
- Nephropathy
- Dyslipidaemia
Diabetic retinopathy is proportionally more common in type 1 diabetes, as they often have a longer duration of diabetes. [Ref]
But most cases occur in type 2 diabetes because type 2 diabetes is far more prevalent. [Ref]
Classification and Grading
Diabetic retinopathy is graded according to the NHS Diabetic Eye Screening Programme (DESP) classification.
The table below provides a simplified summary of the classification, aligned with traditional teaching. The full DESP classification is more detailed and is not usually expected at a non-specialist level:
| Type of retinopathy | Subtype | Findings |
|---|---|---|
| Diabetic retinopathy | Background retinopathy |
|
| Non-proliferative retinopathy |
|
|
| Proliferative retinopathy | Characterised by new:
|
|
| Diabetic maculopathy* | Any retinal changes within 1 disc diameter of the centre of the fovea | |
*The terms diabetic maculopathy and diabetic macular oedema are often used interchangeably at a non-specialist level.
However, there is a subtle distinction: diabetic maculopathy is the broader term, referring to any diabetes-related pathology affecting the macula, which may include oedematous maculopathy (the most common form) or ischaemic maculopathy.
Clinical Manifestation
Diabetic retinopathy is often asymptomatic in early stages
- The patient may not notice visual changes despite significant retinal pathology, thus the importance of screening [Ref]
Possible symptoms: [Ref]
- Blurred vision – most common
- Metamorphopsia
- Dark spots or scotomas
- Change in colour vision or contrast sensitivity
- Photophobia
- Floaters
Proliferative diabetic retinopathy is at particular risk of profound vision loss, as it can cause: [Ref]
- Vitreous haemorrhage (the new vessels are fragile)
- Retinal detachment (tractional)
Detection and Diagnosis
Diabetic Eye Screening
NHS diabetic eye screening programme:
| Target population | ALL ≥12 y/o diabetic patients |
| Screening method | Visual acuity testing and digital retinal photography |
| Frequency | First invited when diabetes is diagnosed
|
See the ‘classification and grading’ section above.
Investigation and Diagnosis
Diabetic retinopathy is often detected on routine screening (see above): [Ref]
- Any presence of diabetic retinopathy requires a prompt referral to an ophthalmologist
- Immediate referral is necessary if there are proliferative changes, severe non-proliferative changes, or any macular oedema
Further assessment / investigations (done by ophthalmologist): [Ref]
- Slit lamp examination with pupil dilation – to confirm and stage diabetic retinopathy
- Adjuncts / further tests (if unsure on slit lamp)
- Optical coherence tomography (OCT) – to assess for macular oedema
- Fluorescein angiography (FFA) – to visualise retinal blood vessels, leakage and ischaemia
If a diabetic patient develops new visual symptoms (i.e. possible diabetic retinopathy that is NOT detected on screening), they should be referred directly to ophthalmology for a comprehensive eye examination.
Do NOT refer them for digital retinal photography, which is strictly a screening tool.
Management
Standard conservative / general management for ALL patients:
- Optimise blood glucose control (see the Type 1 Diabetes Mellitus (T1DM) and Type 2 Diabetes Mellitus (T2DM) articles)
- Optimise cardiovascular risk factors (e.g. smoking cessation, control blood pressure, statins etc.)
- Monitor diabetic retinopathy progression (see below for details)
- Screen for other microvascular complications of diabetes (e.g. diabetic nephropathy, diabetic neuropathy)
Non-Proliferative Diabetic Retinopathy
No active intraocular treatment is necessary (esp. mild and moderate)
The mainstay of management is:
- Standard conservative / general management (see above)
- Monitor retinopathy progression via hospital eye services
- Moderate → every 6-12 months
- Severe / very severe → every 3-6 months
Pregnancy may worsen diabetic retinopathy, especially if retinopathy is present at conception.
Therefore, NICE recommends more frequent retinal assessment during pregnancy for those with pre-existing diabetes: [Ref]
- At the first antenatal appointment, offer retinal assessment by digital imaging with mydriasis using tropicamide (unless they have had a retinal assessment in the last 3 months)
- If the initial retinal assessment identified diabetic retinopathy:
- Offer an additional retinal assessment at 16-20 weeks
- Offer another retinal assessment at 28 weeks
Proliferative Diabetic Retinopathy
Active Intra-Ocular Treatment
- 1st line: panretinal laser photocoagulation (start within 4 weeks)
- If ineffective → anti-VEGF (ranibizumab)
Anti-VEGF (ranibizumab) can also be used as a temporary treatment if panretinal photocoagulation is not appropriate, including:
- Vitreous haemorrhage secondary to proliferative diabetic retinopathy that is preventing photocoagulation
- Severe cataract preventing photocoagulation
Management of vitreous haemorrhage associated with proliferative diabetic retinopathy
- 1st line: 3 months of active observation
- If the vitreous haemorrhage has not cleared within 3 months → consider vitrectomy
Other indications for vitrectomy in proliferative diabetic retinopathy:
- Retinal detachment that is macula-involving or macula-threatening
- Recurrent vitreous haemorrhage and retinal detachment despite completed panretinal photocoagulation
Monitoring and Assessing Disease Regression
Consider using ultrawide-field fundus imaging alongside clinical examination
Monitoring timing and frequency:
- 2-3 months after the end of treatment
- If retinopathy regressed after treatment → monitor for another 12 months (individualised frequency) → discharge to diabetic eye screening programme (if eligible, or else 12 monthly review)
Pregnancy may worsen diabetic retinopathy, especially if retinopathy is present at conception.
Therefore, NICE recommends more frequent retinal assessment during pregnancy for those with pre-existing diabetes: [Ref]
- At the first antenatal appointment, offer retinal assessment by digital imaging with mydriasis using tropicamide (unless they have had a retinal assessment in the last 3 months)
- If the initial retinal assessment identified diabetic retinopathy:
- Offer an additional retinal assessment at 16-20 weeks
- Offer another retinal assessment at 28 weeks
Diabetic Macular Oedema
Active Intra-Ocular Treatment
As mentioned above, the terms diabetic maculopathy and diabetic macular oedema are often used interchangeably at a non-specialist level.
However, there is a subtle distinction: diabetic maculopathy is the broader term, referring to any diabetes-related pathology affecting the macula, which may include oedematous maculopathy (the most common form) or ischaemic maculopathy.
Active treatment is only indicated if there is clinically significant diabetic macular oedema – suggested by retinal thickening at or near the macula (NOT just any diabetic maculopathy).
Overview of treatment options:
- 1st line: non-corticosteroid therapy
- Macular laser treatment, OR
- Anti-VEGF (ranibizumab)
- 2nd line: intravitreal steroid implant (dexamethasone / fluocinolone acetonide)
- Last resort: consider vitrectomy
The exact choice of 1st line (non-corticosteroid therapy) depends on the location of the macular oedema
| Location | Vision | Treatment |
|---|---|---|
| Non-centre involving | Macular laser treatment | |
| Centre-involving | Good | Observation OR macular laser treatment |
| Impaired (6/9 or worse) | Anti-VEGF OR macular laser treatment
*If central retinal thickness ≥400 → anti-VEGF is preferred |
|
Monitoring and Assessing Disease Regression
Use OCT to assess disease resolution and monitoring.
Monitoring timing and frequency:
- If maculopathy resolved after treatment → monitor for another 12 months (individualised frequency) → discharge to diabetic eye screening programme (if eligible, or else 12 monthly review)
References
Related Articles
Type 1 Diabetes Mellitus (T1DM)