In Vivo Mapping of the Choriocapillaris in High myopia: a Widefield Swept Source Optical Coherence Tomography Angiography

Abstract

To report variation of choriocapillaris (CC) flow in widefield in high in myopic subjects compared with an age-matched normal control group using ultra widefield optical coherence tomography angiography (UW-OCTA). This is a Prospective, cross-sectional study. Thirty high myopia subjects and fifty healthy subjects were enrolled. Healthy and high myopia subjects were imaged with the SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). For each eye, five 12 × 12-mm OCTA volume scans were acquired. The en face CC images were then exported to imageJ and a semi-automated algorithm was used for subsequent quantitative analysis. The main outcome was a quantitative analysis of the CC. This analysis was performed in three different regions: (i) peripapillary, (ii) macular, and (iii) periphery. In addition, CC variables were further investigated in distinct fields within these three different regions. Thirty myopic eyes (32 subjects; myopic group) and fifty eyes (50 subjects; control group) without elevated myopia were included in the analysis. Mean ± SD age was 26.9 ± 2.9 years [median: 27 years; range: 20.0–40.0 years]. Mean ± SD axial length was 26.6 ± 0.6 mm [median: 26.2 mm; range: 26.1 to 28.0 mm]. Mean ± SD axial length was 26.6 ± 0.6 mm [median: 26.2 mm; range: 26.1 to 28.0 mm] in the myopic group and 23.9 ± 1.1 mm [median: 23.9 mm; range: 21.8 to 25.9 mm] in the control group. The total signal void area was significantly greater in myopic eyes compared with control group. The peripapillary region exhibited the greatest total signal void area (p < 0.0001 vs macular region, p < 0.0001 vs peripheral region). Within the macular region, the foveal area exhibited a greater total signal void area in comparison with both the parafoveal area (p < 0.0001) and the perifoveal area (p < 0.0001). In conclusion we report quantitative mapping of the choriocapillaris in myopic eyes compared with an age-matched normal control group. The CC perfusion appears to have a wide topographical variation.

Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study

“…Second, all our participants had myopic prescription, where 71% had low-moderate myopia (− 0.25D to − 5D) while the rest had high myopia (− 5.50D to − 10.25D). It has been shown previously that myopic eyes tended to have more flow voids 34 . In particular, the choriocapillaris flow were more reduced within the foveal area, than the para- or peri-foveal regions 34 .…”

“…It has been shown previously that myopic eyes tended to have more flow voids 34 . In particular, the choriocapillaris flow were more reduced within the foveal area, than the para- or peri-foveal regions 34 . Nevertheless, we excluded the foveal area from the analysis.…”

“…First, in healthy eyes, the flow voids in the FAZ region were less detectable than those outside the FAZ region39. Second, in myopic eyes, the flow voids tended to be more reduced within the foveal area, than the para- or peri-foveal regions 34 . Considering that all our participants are myopic, we wanted to perform the analysis that would be less affected by myopia and more generalizable to general population.…”

Photoreceptor alteration in intermediate age-related macular degeneration

“…Furthermore, we excluded poor quality images with a signal strength index lower than 7 (a measurement in a scale 0–10 indicating the level of retinal tissue signal with respect to the noise or background level in OCT data), as recommended by manufacturers and applied in previous studies 18 , 33 .…”

Retinal vascular metrics difference by comparison of two image acquisition modes using a novel OCT angiography prototype

“…The perfusion density (PD) was thus calculated as a unitless proportion of the number of pixels over the threshold divided by the total number of pixels in the analyzed area. Successively, the SCP and DCP images obtained after binarization were skeletonized and these images were employed to measure the vessel length density (VLD) calculated as the total length of the perfused vasculature divided by the total number of pixels in the analyzed area on the skeletonized image ( Fig 2 ) [ 5 , 12 ]. The vessel diameter index (VDI) which represents the average vessel caliber, was calculated by dividing the total vessel area in binarized image by the total vessel length in the skeletonized image in both SCP and DCP ( Fig 2 ) [ 9 ].…”