Table 1 Characteristics of the commercial OCTA instruments and datasets.
From: Towards standardising retinal OCT angiography image analysis with open-source toolbox OCTAVA
Instrument, manufacturer | Cirrus 5000, Carl Zeiss Meditec AG24 | Revo NX 130, Optopol Technology25 | RTVue-XR Avanti, Optovue Inc.26* | Spectralis OCT2 module, Heidelberg Engineering27 |
|---|---|---|---|---|
Data collection city, country | Hong Kong, China | Bydgoszcz, Poland | Perth, Australia | Hong Kong, China |
Image quantity/number of participants | 32 | 30 | 31 | 27 |
Instrument definition of analysed retinal layer | SRLS | SVP | SVP, total retina** | SVC |
Defined retinal layer segmentation upper boundary | ILM | ILM | ILM (SVP) ILM (total retina) | ILM |
Defined retinal layer segmentation lower boundary | ILM + 70% \(\times\) TILM-OPL | IPL (offset: -15 µm) | IPL (offset: -10 µm) (SVP) OPL (offset: +10 µm) (total retina) | IPL (offset: -17 µm) |
Image size [mm] | 3 \(\times\) 3 | 3 \(\times\) 3 | 3 \(\times\) 3 | 3 \(\times\) 3 |
Number of A-scans along x-axis | 245 | 320 | 304 | 512 |
Number of B-scans along y-axis | 245 | 320 | 304 | 512 |
Central wavelength [nm] | 840 | 850 | 840 | 880 |
Imaging speed [A-scan rate, Hz] | 68,000 | 130,000 | 70,000 | 85,000 |
Axial resolution [µm]*** | 5 | 5 | 5 | 5.7 |
Transverse resolution [µm] | 15 | 18 | 22 | 11.4 |
Sampling density [1]**** | 1.23 | 1.92 | 2.23 | 1.95 |
Projection artefacts removal function | Yes | No | Yes | Yes |
Angiogram construction algorithm | Optical micro-angiography (OMAG)28 | Spectral domain absolute complex difference29 | Split-spectrum amplitude-decorrelation (SSADA)30 | Full-spectrum amplitude decorrelation31 |
En face projection | Maximum intensity projection | Average intensity projection | Maximum intensity projection | Sum projection + contrast function |
Automated image quality indicator | Yes | Yes | Yes | Yes |
Instrument name of the quality indicator | Zeiss signal strength | Quality index | Scan quality index | Q score |
Image quality indicator threshold (range) | > 6 (0–10) | > 6 (0–10) | ≥ 6 (0–10) | > 15 (0–40) |
Interscan time [ms] | Not specified | Not specified | Not specified | Not specified |
Maximum detectable blood flow velocity [mm/s] | Not specified | Not specified | Not specified | Not specified |
Instrument defined ocular axial length [mm]***** | 24.46 | 22.10 | 23.95 | 24.39 |
En face image exported from the OCTA instrument: number of pixels and image type | 717 \(\times\) 717 tif | 640 \(\times\) 640 bmp | 304 \(\times\) 304 png | 1000 \(\times\) 1000 bmp |
