Diabetic macular oedema
At a glance
Diabetes-related retinal leakage affects the macula. Central involvement and visual function guide management.
CAVE
- Check for ischaemia, vitreomacular traction and other causes of reduced vision.
- Thickness alone does not predict function.
Clinical presentation
- Blurred central vision, reduced contrast or asymptomatic thickening detected at assessment.
Diagnosis & investigations
- Measure best-corrected acuity/refraction and obtain OCT in both eyes. Define centre involvement, intraretinal/subretinal fluid, vitreomacular traction and epiretinal membrane; inspect segmentation before relying on thickness.
- Assess retinopathy stage, ischaemia when relevant, lens status, IOP/glaucoma, HbA1c, blood pressure and renal function. Consider angiography for unexplained poor vision, suspected ischaemia or laser planning. Distinguish diabetic oedema from postoperative, venous or inflammatory causes.
Differential diagnosis
- Vein-occlusion oedema, postsurgical cystoid oedema, neovascular AMD and tractional thickening.
Treatment
- Choose the pathway from centre involvement and visual function, then assess feasibility of repeated visits. Check systemic control without delaying indicated ocular treatment.
- Do not label one injection a treatment failure. Compare acuity and OCT after adequate loading, confirming attendance and the intended interval. Persistent thickening with improving vision differs from declining vision with traction or macular ischaemia; the latter needs diagnostic reassessment before adding injections.
| Finding | Action | Timing / detail |
|---|---|---|
| Non-centre-involving clinically significant oedema | Consider focal/grid laser when appropriate; optimise systemic risk factors | Assess progression toward the centre; do not use acuity alone to define centre involvement |
| Centre-involving DME with good acuity, e.g. 20/25 or better in Protocol V | Planned observation can be reasonable with reliable attendance and rescue treatment if vision worsens | Trial-based observation had scheduled reassessment; OCT thickening alone was not the trial’s trigger for injections |
| Centre-involving DME with visual impairment | Anti-VEGF is generally first-line; follow the selected agent’s loading and response assessment | National reimbursement cut-offs are not universal biological treatment thresholds |
| Incomplete response, unsuitable anti-VEGF or major visit burden | Recheck diagnosis and treatment exposure; consider intravitreal steroid in selected eyes, laser adjuncts or surgery for relevant traction | Steroids require lens/IOP risk assessment and monitoring; pseudophakia reduces cataract concern, not glaucoma risk |
Follow-up
- During initial active treatment, assessment is commonly monthly, following the chosen regimen. Observation with good vision still needs a scheduled acuity/OCT review, initially within about 8 weeks in the Protocol V approach, then adjusted to stability.
- Define rescue criteria in advance and bring review forward for visual decline. After steroid implantation, include IOP checks as specified for the product and individual risk; a dry OCT does not remove pressure risk.
Risk factors & context
- Review systemic control and previous retinal treatment.
- Identify whether visual loss also reflects cataract, ischaemia or traction.
Complications
- Chronic oedema and ischaemia can limit recovery.
- Intravitreal steroids may elevate IOP and accelerate cataract; injections carry a risk of infection.
When to refer
- Refer for visually significant central oedema, persistent activity or traction requiring surgical assessment.
References 3
- NICE · Diabetic retinopathy: management and monitoring ↗NG242 · 13 August 2024 · 1.6 Diabetic macular oedema
- AAO · Diabetic Retinopathy Preferred Practice Pattern ↗2025 · Diagnosis; management; follow-up
- NEI / DRCR Retina Network · Protocol V ↗2019 · randomised trial · Good baseline acuity; planned observation and rescue treatment
UK guidance: referral pathways and funding criteria may differ elsewhere.