Exploring choriocapillaris under reticular pseudodrusen using OCT-Angiography

Abstract

OCT-A reveals a distinct reduction in CC vessel density and CC decorrelation signal index in eyes affected by RPD, which emphasizes the relevance of the CC layer in RPD pathogenesis.

Optical Coherence Tomography Angiography Offers New Insights into Choriocapillaris Perfusion

“…CC OCTA in Early/Intermediate AMD Our group reported for the first time significantly reduced CC vessel density and reduced CC flow in eyes with reticular pseudodrusen (RPD) compared with healthy control eyes, suggesting a CC functional compromise in RPD eyes [28]. Later, Nesper et al [40] confirmed these results using an OCTA metric for CC nonperfusion.…”

“…This can produce artifacts, but allows for a more robust visualization of vasculature [26]. The exact localization and thickness of the CC slab vary between 0 and 34 µm below the RPE/Bruch's membrane reference and between 4.4 and 30 µm, respectively, depending on the device used [17,20,27,28]. Notably, manufacturers use various definitions of the CC slab level, and not all of them offer a presetting for CC examination yet (Table 1).…”

“…For calculating the CC decorrelation signal index, OCTA CC images were converted into grayscale values, attributing each pixel a value that represents the strength of the decorrelation signal. The CC decorrelation signal index was defined as the average decorrelation value of all pixels in the en face CC angiogram [28]. Binarization of OCTA images was described by Nicolò et al [32] using the Otsu method, which is an automatic threshold selection from DOI: 10.1159/000485261 gray-level histograms.…”

Comparison of Choriocapillaris Flow Measurements between Two Optical Coherence Tomography Angiography Devices

“…CC decorrelation signal index was defined as the average decorrelation value of all pixels in the en face CC angiogram [8,16] . This method has been described previously [17] and must not be confused with other methods described in the literature [18,19] . The OCT-A scans on both devices were performed consecutively within a few minutes in between to eliminate the potential effects of diurnal variation [20] .…”

“…A previous OCT-A study based on the SSADA showed a comparable variability between the first and the second CC measurements. The included subjects in that study were distinctly older [17] . Pechauer et al [16] also reported a similar variability when assessing the peripapillary retinal flow index in healthy subjects also using the SSA-DA.…”