OCT Macula Reference Card: Normal Thickness, DME and Hole Staging
Last updated: October 2026
A one-screen checklist for macular OCT reports: is the scan trustworthy, which layer is involved, how thick is it compared with normal, and which disease-specific cut-offs apply?
Step 1: is the scan reliable?
- Signal strength or quality index above the manufacturer's threshold (for example Cirrus signal strength 6/10 or more; Spectralis Q score about 20 dB or more).
- Centred on the fovea, with no segmentation errors. Always look at the B-scans, not just the thickness map: misplaced lines produce false "thinning" or "thickening".
- Compare with the previous scan using the same device and the follow-up (registration) mode.
Step 2: normal central subfield thickness (CST)
| Device | Typical normal CST | Centre-involved DME threshold (DRCR Retina Network) |
|---|---|---|
| Zeiss Cirrus | About 250–270 µm | Women 290 µm or more; men 305 µm or more |
| Heidelberg Spectralis | About 270–300 µm | Women 305 µm or more; men 320 µm or more |
| Other devices (Topcon, Optovue and others) | Use the device's own normative database. Thickness values are not interchangeable between machines, because they place the outer boundary at different layers. | |
Step 3: name the layer, then the disease
| Finding and location | Think of |
|---|---|
| Intraretinal cysts (inner or outer nuclear layer) | DME, RVO, uveitic and post-cataract CME (Irvine-Gass), wet AMD, retinitis pigmentosa, epiretinal membrane traction |
| Subretinal fluid, smooth dome | CSCR (look for a thick choroid and RPE bumps), wet AMD, VKH (multiple loculated pockets with septae) |
| Sub-RPE elevation | Drusen (dome, medium reflectivity), PED: serous (hollow), fibrovascular (filled), drusenoid; polypoidal lesions (sharp-peaked PED, "double-layer sign") |
| Hyper-reflective material above the RPE | Type 2 MNV, subretinal haemorrhage, vitelliform material, fibrosis |
| Outer retinal loss with choroidal hypertransmission | Atrophy: cRORA when 250 µm or more. See geographic atrophy. |
| Inner retinal hyper-reflectivity, then thinning | Acute and old artery occlusion; PAMM (middle-layer band) |
| Ellipsoid zone disruption only | Solar or laser injury, MEWDS, AZOOR, early hydroxychloroquine toxicity (parafoveal "flying saucer" sign), MacTel |
Step 4: vitreomacular interface
| Condition | Key cut-offs (International Vitreomacular Traction Study, 2013) |
|---|---|
| Vitreomacular adhesion (VMA) | Perifoveal vitreous separation with attachment within 3 mm of the fovea, normal foveal contour |
| Vitreomacular traction (VMT) | As VMA, but with distortion of the fovea. Focal: 1500 µm or less; broad: over 1500 µm. |
| Full-thickness macular hole: size (minimum linear diameter) | Small 250 µm or less; medium over 250 to 400 µm; large over 400 µm. Note whether VMT is present. |
| Lamellar hole vs macular pseudohole (2020 consensus) | Lamellar hole: irregular foveal contour, foveal cavity with undermined edges and loss of foveal tissue (often epiretinal proliferation). Pseudohole: steep foveal walls from an ERM without tissue loss. |
| Epiretinal membrane (Govetto staging) | Stage 1: foveal pit present. Stage 2: pit lost, layers identifiable. Stage 3: continuous ectopic inner foveal layers (EIFL). Stage 4: EIFL with disorganised layers. Higher stage means worse vision and outcome. |
Step 5: disease-specific markers
- DME biomarkers: DRIL (disorganised retinal inner layers), hyper-reflective foci, subretinal fluid, ellipsoid zone integrity and vitreomacular interface. See OCT biomarkers in DMO.
- Wet AMD activity: new or increased intraretinal or subretinal fluid, a growing PED, or new haemorrhage. Persistent stable subretinal fluid can be tolerated in treat-and-extend regimens; intraretinal fluid is worse for vision.
- CSCR: subretinal fluid with a thick choroid (pachychoroid) and dilated Haller vessels; check for a small PED at the leak point.
- Hydroxychloroquine screening: look for parafoveal (or, in Asian patients, pericentral) loss of the ellipsoid zone. See the screening schedules card.
Common artefacts: segmentation errors in high myopia, ERM and large PEDs; mirror artefacts; decentration; and media opacity giving false thinning. If the number does not fit the picture, trust the B-scan.
Related: how to read an OCT (detailed tips), macular hole staging and retinal layers.
Key sources
- Duker JS et al. The International Vitreomacular Traction Study Group classification. Ophthalmology 2013;120:2611–9
- Hubschman JP et al. Optical coherence tomography-based consensus definition for lamellar macular hole. Br J Ophthalmol 2020;104:1741–7
- Govetto A et al. Insights into epiretinal membranes: a new OCT staging scheme. Am J Ophthalmol 2017;175:99–113
- DRCR Retina Network protocol definitions of centre-involved DME (Protocol V and later)
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