A 54-year-old woman with type 2 diabetes of 11 years has centre-involving diabetic macular oedema in both eyes. Vision is 6/24 right, 6/18 left. She has heard that ‘injections in the eye’ are now used instead of laser and asks which is better, how many injections she will need, and what the risks are.
Examination Findings
Both maculae show diffuse thickening involving the foveal centre with scattered microaneurysms; no new vessels. Vision as above. Intraocular pressure normal. No cataract obscuring treatment.
Investigations
OCT both eyes: centre-involving oedema with central subfield thickening and intraretinal cysts, foveal contour lost. Blood pressure is elevated and is addressed with her physician before starting treatment.
Questions to Think About
- Why is anti-VEGF preferred over laser for centre-involving DMO with reduced vision?
- What does a typical treatment course and follow-up look like, and what are the key risks to counsel?
Diagnosis
Bilateral centre-involving diabetic macular oedema.
Reasoning
Trials showed anti-VEGF injections improve vision in centre-involving DMO more reliably than laser alone, because VEGF drives the vascular leakage — blocking it dries the macula and often gains letters of vision, whereas laser mainly stabilises. Typical management: a loading course of monthly injections, then OCT- and vision-guided re-treatment (treat-and-extend or as-needed per local protocol), often continuing for a year or more; laser may be added later for persistent focal leaks. Counsel on the small but serious risks: endophthalmitis, retinal detachment, lens injury, and transient pressure rise — plus the burden of repeated visits. Systemic control remains essential: poor blood pressure or glycaemia blunts the response. Diagnosis: bilateral centre-involving diabetic macular oedema.
Differential Diagnosis
- Centre-involving DMO — confirmed on OCT: the foveal centre is thickened, which steers treatment toward anti-VEGF.
- Non-centre-involving DMO — ruled out: central subfield is involved, so focal laser alone is not the first choice.
- Vitreomacular traction causing oedema — ruled out: OCT shows no adherent hyaloid pulling the macula.
Management
Start intravitreal anti-VEGF per local protocol (loading doses then OCT-guided re-treatment). Review vision and OCT at each visit; consider focal/grid laser for persistent non-central leaks after the oedema settles. Optimise blood pressure, glycaemia and lipids — uncontrolled hypertension undermines treatment. Counsel on injection risks, the need for long-term follow-up, and red-flag symptoms (pain, redness, sudden vision drop, floaters) requiring urgent review.
Key Learning Points
- Centre involvement decides: centre-involving DMO with vision loss is an anti-VEGF disease in modern practice; laser alone is reserved for non-centre-involving or adjunctive roles.
- Anti-VEGF is a course, not a single shot: counsel the loading phase, OCT-guided re-treatment over months to years, and the small procedural risks before the first injection.
Red Flags
- Eye pain, redness or vision drop after injection — possible endophthalmitis; same-day emergency.
- New floaters or curtain after treatment — retinal tear or detachment needs urgent assessment.
- Oedema unresponsive after a full loading course — reassess: consider macular ischaemia, traction, or switching agent per protocol.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.
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