Magesan Kowsigan, Gnanaraj Ramya, Tojjar Jasaman, Amose T, Alagorie Ahmed Roshdy, Mahalingam Maanasi, Sen Parveen, Verma Aditya, Sadda SriniVas R
Elite School of Optometry, Unit of Medical Research Foundation, Chennai, Tamil Nadu, India.
Shri Bhagwan Mahavir Vitreoretinal Services, Medical Research Foundation, Chennai, Tamil Nadu, India.
Graefes Arch Clin Exp Ophthalmol. 2023 Oct;261(10):2787-2794. doi: 10.1007/s00417-023-06117-x. Epub 2023 May 18.
This cross-sectional observational study evaluated the relationship between retinal vascular fractal dimension (FD) and age, as well as other vascular parameters in healthy eyes using swept-source optical coherence tomography angiography (SS-OCTA).
The study cohort consisted of 222 eyes of 116 healthy participants with no ocular or systemic disease. SS-OCTA images were captured and analyzed using the Plex Elite 9000 and software tools available in the advanced retinal imaging (ARI) network hub. The retinal vascular layers were defined by the instrument's automatic retinal layer segmentation. The fractal analysis was performed on the superficial capillary plexus (SCP), deep capillary plexus (DCP), and the whole retina. Grayscale OCTA images were standardized and binarized using ImageJ and fractal box-counting analyses were performed using Fractalyse software. Pearson's correlation was used to analyze the correlation between FD and retinal vascular parameters.
The results showed that FD values were significantly higher in the 6 mm ring and the whole 6 × 6 scan region when compared to the 1 mm ETDRS central subfield. The correlation between age and FD was weak with a significant positive correlation between age and FD of the SCP in the 6 mm ring and between age and FD of the DCP in the 1 mm ring. Overall, differences in FD values in these healthy eyes were extremely small regardless of age or macular location.
FD values in normal eyes show little variation with age and are relatively stable across the macula. This suggests that FD values may not need adjustment for age or location when evaluated in the context of retinal disease.
本横断面观察性研究使用扫频光学相干断层扫描血管造影（SS-OCTA）评估了健康眼睛的视网膜血管分形维数（FD）与年龄以及其他血管参数之间的关系。
研究队列包括116名无眼部或全身性疾病的健康参与者的222只眼睛。使用Plex Elite 9000和高级视网膜成像（ARI）网络中心提供的软件工具采集并分析SS-OCTA图像。视网膜血管层由仪器的自动视网膜层分割定义。对浅表毛细血管丛（SCP）、深部毛细血管丛（DCP）和整个视网膜进行分形分析。使用ImageJ对灰度OCTA图像进行标准化和二值化处理，并使用Fractalyse软件进行分形盒计数分析。采用Pearson相关性分析FD与视网膜血管参数之间的相关性。
结果显示，与1mm早期糖尿病性视网膜病变研究（ETDRS）中心子区域相比，6mm环和整个6×6扫描区域的FD值显著更高。年龄与FD之间的相关性较弱，6mm环中SCP的年龄与FD之间以及1mm环中DCP的年龄与FD之间存在显著正相关。总体而言，无论年龄或黄斑位置如何，这些健康眼睛中FD值的差异都非常小。
正常眼睛的FD值随年龄变化很小，并且在黄斑区域相对稳定。这表明在视网膜疾病背景下进行评估时，FD值可能无需根据年龄或位置进行调整。
