Fractal Dimensional Analysis of Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

Abstract

Citation: Zahid S, Dolz-Marco R, Freund KB, et al. Fractal dimensional analysis of optical coherence tomography angiography in eyes with diabetic retinopathy. Invest Ophthalmol Vis Sci. 2016;57:4940-4947. DOI:10.1167/iovs.16-19656 PURPOSE. We used fractal dimensional analysis to analyze retinal vascular disease burden in eyes with diabetic retinopathy using spectral-domain optical coherence tomography angiography (OCTA). METHODS.A retrospective study was performed of 13 eyes with diabetic retinopathy without diabetic macular edema and 56 control eyes. Optical coherence tomography angiography images were acquired using the RTVue XR Avanti. Automated segmentation was obtained through the superficial and deep capillary plexuses for each eye. Grayscale OCTA images were standardized and binarized using ImageJ. Fractal box-counting analyses were performed using Fractalyse. Fractal dimensions (FD) as well as software-generated vascular density analyses of the superficial and deep capillary plexuses were compared between diabetic and control eyes using 2-tailed t-tests and 1-way multivariate ANOVA (MANOVA) analyses. RESULTS.The superficial and deep plexuses from diabetic and control eyes were analyzed. The average FD for diabetic eyes was significantly lower than control eyes for the superficial (P ¼ 4.513 3 10 À3 ) and deep (P ¼ 2.653 3 10 À3 ) capillary plexuses. In diabetic eyes, the vascular density also was significantly reduced in the superficial (P ¼ 8.068 3 10 À5 ) and deep (P ¼ 3.120 3 10 À6 ) capillary plexuses. One-way MANOVA showed a significant difference between diabetic and control eyes.CONCLUSIONS. The OCTA FD is significantly reduced in the superficial and deep capillary plexuses in eyes with diabetic retinopathy. Applying fractal analysis to OCTA imaging holds the potential to establish quantitative parameters for microvascular pathology.

Optical Coherence Tomography Angiography in Healthy Subjects and Diabetic Patients

“…The vascular perfusion damage seemed progressively increasing from the early stages of nonproliferative DR to proliferative DR (PDR). Similar findings were also documented for 13 eyes suffering from DR that underwent split-spectrum amplitude-decorrelation angiography followed by fractal dimension analysis to quantify macular perfusion [20]. Our group, in a recently published study, did not highlight any statistically significant difference in total vascular surface between the SCP and the DCP both among diabetic patients and among healthy subjects.…”

Macular Vascular Fractal Dimension in the Deep Capillary Layer as an Early Indicator of Microvascular Loss for Retinopathy in Type 2 Diabetic Patients

“…29,30 As expected, the ROC curve analysis revealed that fractal dimensions in the deep retinal capillary layer had higher discriminating powers than the superficial retinal capillary layer to detect the earlier microvascular network loss. Because our study did not include patients with moderate or severe retinopathy or longitudinal follow-up of the patients, we 15 2017 T2DM No and minimal DR Microvessels SS-OCT-A FD increased in the DR compared with the diabetic patients with no DR; FD was positively correlated with increasing DR severity levels Zahid et al 16 2016 DM DR Microvessels SD-OCT-A FD was significantly reduced in the superficial and deep capillary plexuses in eyes with DR Kim et al 17 2016 DM DR Microvessels SD-OCT-A Decreasing FD was associated with worsening DR Tǎlu et al 25 2015 DM NPDR Large vessels Fundus photographs FD increased in mild NPDR, but decreased in moderate and more serious NPDR Broe et al 9 2014 T1DM PDR Large vessels Retinal photographs Lower FD was associated with the diabetic microvascular complications Cheung et al 31 2012 DM No DR and NPDR Large vessels Retinal photographs No significant changes were found in FD Yau et al 7 2010 DM DR Large vessels Fundus photographs FD increased in eyes with or without overt retinopathy, but no significant changes were found in mild, moderate to severe DR Grauslund et al 11 2010 T1DM PDR Large vessels Retinal photographs Lower FD was associated with PDR, neuropathy and nephropathy Cheung et al 5 2009 T1DM DR Large vessels Seven-field stereoscopic retinal photographs FD increased in early diabetic microvascular damage Kunicki et al 24 2009 DM NPDR Large vessels Digital retinal images No significant changes were found in FD Lim et al 6 2009 T1DM Mild NPDR Large vessels Seven-field stereoscopic retinal photographs FD was not associated with incident of early DR Avakian et al 10 2002 DM NPDR Whole vasculature Fundus FA FD decreased in the macula, but no changes were found in the paramacular region Daxer et al 32 1993 cannot determine if the retinal microvascular fractal dimensions, especially in the deep retinal capillary layer, could predict the development of DR. However, our results nonetheless suggest that OCT-A with fractal analysis of the multiple retinal capillary layers can be used to identify preclinical lesions of retinal capillaries related to retinopathy in diabetic patients and may constitute an early indicator to predict DR development.…”

“…Moreover, this technique provides in-depth information, allowing the visualization of the retinal microvascular network in different retinal layers. [12][13][14] Recently, studies using OCT-A have revealed abnormalities of fractal dimensions in patients with DR [15][16][17] ; however, the results remain controversial. Importantly, it is noteworthy that the OCT-A studies did not evaluate changes of fractal dimension in diabetic patients with no DR.…”

Radiation Maculopathy After Proton Beam Therapy for Uveal Melanoma: Optical Coherence Tomography Angiography Alterations Influencing Visual Acuity

“…Fractal dimension has previously been used to investigate the retinal microvasculature in fundus [49][50][51][52] or OCTA 10,12,13 images. By evaluating pattern repetition at different scales, 53 fractal dimension is particularly adapted to assess the integrity of arborized vascular networks.…”

“…Moreover, the recent adjunction of quantitative tools to OCTA provides access to retinal microcirculatory metrics, such as foveal avascular zone (FAZ) dimensions, 5,6 capillary density, 7,8 and capillary network fractal dimension, 9 at the level of both plexuses. Fractal dimension is a promising endpoint to measure vascular network disorganization in OCTA images, which has been used successfully in diabetic retinopathy [10][11][12] and posterior uveitis. 13 Ocular irradiation by I-125 plaque brachytherapy induces microvascular changes detected by OCTA.…”