![]() They can arise from intrinsic characteristics of the eye, eye movements, OCTA image acquisition, image processing and display strategies. Since OCTA is a light source-dependent technology, artifacts are very common and can lead to incorrect interpretations of OCTA images. Thus, it allows deeper penetration into the tissue of 3 mm (compared to 2 mm), with the compromise of a slightly lower axial resolution of 6,3 µm (compared to 5 µm, personal communication with Zeiss). The newer generations, on the other hand, apply swept-source OCT (SS-OCT) technology, which uses a longer wavelength of nearly 1050 nm (compared to 840 nm in SD-OCT) and a higher scan speed of 100,000 A-scans/s (compared to 68,000 A-scans/s). In the older-generation units, light is emitted by a spectral domain OCT (SD-OCT) with a wavelength of nearly 840 nm near the infrared range. Since this technology’s introduction in 2014, OCTA has developed rapidly and there are currently several generations of OCTA from different companies available. Briefly, OCTA technology employs motion contrast to image blood flow and thereby vessels through different segmented areas in the eye, thus eliminating the need for intravascular dyes. While conventional imaging techniques such as fluorescein and indocyanine green angiography can only partially depict the CC, optical coherence tomography angiography (OCTA) enables us to assess and quantify the CC blood flow. Changes in CC blood flow are known to occur physiologically with increasing age and are associated with a variety of chorioretinal diseases such as age-related macular degeneration (AMD) and central serous chorioretinopathy (CSC). The choriocapillaris (CC) is a few-µm-thin layer of capillaries of relatively large diameter located in the inner aspect of the choroid below the retinal pigmented epithelium (RPE). In this study, we describe the presence of SRF as an important shadow-causing artifact source for CC OCTA analysis which can be mitigated but not completely eliminated by employing SS-OCTA. Understanding OCTA artifacts is critical to ensure accurate clinical evaluations. Despite this significant attenuation of signal voids, SS-OCTA continued to reveal signal voids below SRF and more pixels with reduced OCTA signals in CSC patients compared to controls (7.6% ± 6.3%, 0.1% ± 0.1%, p < 0.0001). Compared to SD-OCTA, SS-OCTA delivered a more homogenous OCTA signal and reduced signal voids in the CC underneath SRF in both RD and CSC (CSC, 7.6% ± 6.3% vs, 19.7% ± 9.6%, p < 0.01). In CCS, the voids were predominantly located in the area with SRF. ![]() Both devices demonstrated CC signal voids in CSC and RD, respectively. SS-OCTA yielded a more homogeneous OCTA signal from the CC than SD-OCTA, offering less signal dispersion and variability in healthy and diseased eyes. To investigate the influence of SRF on CC OCTA signal, the extent of SRF was quantified with a macular heatmap and compared with the corresponding OCTA signal of the CC. Abnormal CC decorrelation signals were quantitatively compared in CSC and controls by means of custom image processing. Ten patients with acute central serous chorioretinopathy (CSC), three patients with partial macular-off retinal detachment (RD) and ten healthy, age-matched controls were included. This is a prospective case-control study of 23 eyes. To characterize the choriocapillaris (CC) structure in relation to subretinal fluid (SRF) as a possible systematic error source using spectral domain (SD-OCTA) compared to swept-source optical coherence tomography angiography (SS-OCTA).
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