A patient with AMD is being treated with intravitreal anti-VEGF. OCT shows a significant reduction in central retinal thickness from 450 µm to 280 µm after 3 injections, with resolution of subretinal fluid. However, on optical coherence tomography angiography (OCTA), a persistent flow signal is still detected within the sub-RPE complex. What does this finding indicate?

• A Treatment failure requiring immediate switch to different anti-VEGF
• B Persistent choroidal neovascular membrane (CNV) with residual active neovascular flow despite fluid resolution ✓
• C Choroidal ischaemia as a complication of anti-VEGF therapy
• D Normal finding — all treated CNV membranes show persistent OCTA flow signal

Explanation

OCTA (OCT angiography) detects blood flow by analysing motion contrast between successive B-scans, allowing non-invasive visualisation of CNV networks without fluorescein dye. A persistent flow signal within the sub-RPE complex after treatment indicates a residual neovascular network that may still be biologically active even if structural OCT shows fluid resolution. This 'quiescent CNV' or residual type 1 CNV may represent a treated-but-not-eradicated network. This finding guides clinicians to continue monitoring rather than discontinuing anti-VEGF. It does not necessarily indicate treatment failure requiring immediate switch; it contextualises the risk of reactivation. Choroidal ischaemia would appear as loss of choriocapillaris flow signals, not a persistent CNV signal.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.