OCT Angiography

What it does

OCT Angiography reads OCTA volumes and en-face slabs, which image the retinal capillary plexuses without dye injection. Standard 3×3 mm and 6×6 mm macular scans and widefield scans are accepted, and the run reads the superficial and deep capillary plexus slabs separately.

It segments the foveal avascular zone and measures its area, perimeter and circularity; segments the vessels and reports vessel and perfusion density per ETDRS sector; and on widefield scans maps areas of capillary non-perfusion, intraretinal microvascular abnormalities and neovascularisation, combining them into a DR grade. Every metric is returned with the device it was computed from, because OCTA metrics differ between manufacturers.

Intended use

Decision support for physicians using OCTA in diabetic retinopathy and retinal vein occlusion, and for studies of the retinal microvasculature in systemic disease: reproducible FAZ and density measurements instead of manual tracing, and non-perfusion maps that are tedious to draw.

Who it is for

Medical retina specialists, ophthalmology residents and fellows, diabetic eye clinics with OCTA devices, and research groups in ophthalmology, neurology and cardiovascular medicine who use capillary metrics as biomarkers. Developers add the run to OCTA viewers and to the image pipelines of multicentre studies.

Accepted input

• DICOM: OCT En Face objects (OCTA slabs), Ophthalmic Tomography and OCT B-scan Volume Analysis objects.
• Vendor files: OCTA exports from the major device manufacturers, converted to DICOM on upload.
• One study is one or both eyes of one visit.

Requirements

Requirement	Why
Superficial and deep plexus en-face slabs (or the volume to derive them)	FAZ and density are plexus-specific
Scan size (3×3, 6×6 mm or widefield) and pixel spacing	Areas in mm² and densities need the true field of view
Device manufacturer and model	Metrics are vendor-defined and not interchangeable
Widefield or ultra-widefield scan	Peripheral non-perfusion and neovascularisation
Laterality (tag or detected)	Sectors and findings are reported per eye (OD/OS)

Signal strength and motion are checked before measurement; a scan that fails is reported with the reason instead of metrics.

Optional context

Diagnosis (diabetes and its duration, vein occlusion, AMD), treatment history and the clinical question go in clinical_context.

The result

Section	Content
Foveal avascular zone	FAZ mask, area, perimeter and circularity for the superficial and deep plexus
Vessel and perfusion density	Vessel masks, vessel density and perfusion density per ETDRS sector
Non-perfusion and neovascularisation	Non-perfusion areas, IRMA and neovascularisation masks with a DR grade
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• DICOM: SEG for FAZ, vessel and non-perfusion masks; SR TID 1500 with TID 2120 and TID 2127 ophthalmic measurement groups; KOS key images and Encapsulated PDF.
• Sectors: densities are reported on the ETDRS grid.
• Metrics: there is no consensus standard for OCTA vessel and perfusion density; values follow vendor-style definitions and carry the device in the device field so they are compared only within one device.