Biruni University Faculty of Medicine, Department of Ophthalmology, İstanbul, Türkiye.
İstanbul Retina Institute, İstanbul, Türkiye.
Turk J Ophthalmol. 2023 Feb 24;53(1):37-43. doi: 10.4274/tjo.galenos.2022.23855.
To investigate choriocapillaris flow voids (FV) with a new optical coherence tomography angiography (OCTA) image processing strategy that can eliminate artifacts caused by vitreous opacities, sub-retinal pigment epithelium fluid and deposits, and subretinal fluid (SRF) by thresholding the en-face OCT image of the outer retina.
We retrospectively reviewed medical records of patients with drusen and patients with active central serous chorioretinopathy (CSC). FV number (FVn), average area (FVav), and maximum area (FVmax) and the percentage of nonperfused choriocapillaris area (PNPCA) obtained using the proposed strategy were compared with those obtained by removing only artifacts caused by the superficial capillary plexus (SCP).
The SRF group included 21 eyes with active CSC and the drusen group included 29 eyes with nonexudative age-related macular degeneration. FVav, FVmax, FVn, and PNPCA obtained using the algorithm were significantly lower than those obtained by removing only SCP-related artefacts in both groups (all p<0.05). The algorithm was also able to remove 96.9% of artifacts secondary to vitreous opacities and all artifacts secondary to serous pigment epithelial detachments.
Choriocapillaris nonperfusion areas on OCTA images may be overestimated in eyes with RPE abnormalities and SRF due to artifacts. These artifact areas on choriocapillaris OCTA images can be removed using thresholded images of the outer retina en-face OCT scans. Our new artifact-removal strategy is useful in the assessment of choriocapillaris FV in eyes with SRF, drusen, drusen-like deposits, and pigment epithelial detachment.
利用一种新的光学相干断层扫描血管造影（OCTA）图像处理策略，通过对视网膜外层的 en-face OCT 图像进行阈值处理，消除玻璃体混浊、视网膜色素上皮下积液和沉积物以及视网膜下液（SRF）引起的伪影，从而研究脉络膜毛细血管无灌注区（FV）。
我们回顾性分析了有玻璃膜疣和有活动性中心性浆液性脉络膜视网膜病变（CSC）的患者的病历。采用提出的策略获得的 FV 数量（FVn）、平均面积（FVav）、最大面积（FVmax）和无灌注脉络膜毛细血管面积百分比（PNPCA）与仅去除浅层毛细血管丛（SCP）引起的伪影获得的结果进行比较。
SRF 组包括 21 只活动期 CSC 眼，玻璃膜疣组包括 29 只无渗出性年龄相关性黄斑变性眼。在两组中，使用算法获得的 FVav、FVmax、FVn 和 PNPCA 均明显低于仅去除 SCP 相关伪影获得的结果（均 P<0.05）。该算法还能够去除 96.9%的玻璃体混浊引起的伪影和所有由浆液性色素上皮脱离引起的伪影。
由于伪影的存在，在 RPE 异常和 SRF 的眼中，OCTA 图像上脉络膜毛细血管无灌注区可能会被高估。可以使用视网膜外层 en-face OCT 扫描的阈值图像去除脉络膜毛细血管 OCTA 图像上的这些伪影区域。我们的新的去除伪影策略可用于评估有 SRF、玻璃膜疣、玻璃膜疣样沉积物和色素上皮脱离的眼中的脉络膜毛细血管 FV。
