Faculty Bibliography

Purpose: To study fractal dimensional of retinal vascular disease in patients with diabetic retinopathy(DR) with and without macular edema using spectral-domain optical coherence tomography angiography(OCTA) Methods: A retrospective study of 49 control eyes from and 58 diabetic eyes. Of the 58 diabetic eyes, 23 had macular edema and 35 did not. OCTA images were acquired using the RTVue XR Avanti(Optovue,Inc.Fremont, CA).Automated segmentation through the superficial and deep capillary plexuses was obtained. Grayscale OCTA images were standardized and binarized using ImageJ(NIH, Bethesda, Maryland, USA). Fractal boxcounting analyses were performed with Fractalyse(TheMA, Besancon Cedex, France). Fractal dimensions(FD) were compared using two-tailed t-tests Results: The mean foveal and parafoveal thickness of all eyes studied was recorded as per OCTA imaging reports (Table 1). The mean FD for the superficial and deep plexuses of control eyes was 1.651(SD=0.05391) and 1.677(SD=0.05325), respectively. The mean FD for diabetic eyes without edema was 1.6(SD=0.07) for the superficial plexus and 1.59(SD=0.07) for the deep plexus. There was significant reduction in nonedematous eyes in the superficial plexus (p=0.001) and deep plexus (p=1.49x10 ). The mean FD for diabetic eyes with edema was 1.57(SD=0.066) for the superficial plexus and 1.53(SD=0.075) for the deep plexus. There was significant reduction in edematous eyes in the superficial plexus (p=2.08x10 ) and deep plexus (p=1.85x10 ) Conclusions: The OCTA FD is significantly lower in the superficial and deep capillary plexuses in eyes with DR whether macular edema is present or not. Utilization of FD gives an objective criterion to assess microvascular disease burden in DR with and without macular edema

Purpose: To evaluate fractal analysis box size resolution and self-similarity breakdown in box counting method of fractal analysis of optical coherence tomography angiography (OCTA) images in eyes with primary open angle glaucoma (POAG) or normal tension glaucoma (NTG) compared to control patients. Methods: This retrospective study used OCTA images obtained on 40 eyes with POAG, 26 eyes with NTG, and 28 control eyes. OCTA images consisted of 4.5x4.5mm peripapillary scans obtained with the RTVue XR Avanti (Optovue Inc., Fremont, CA), standardized and binarized using ImageJ (NIH, Bethesda, MD). Fractal dimension by means of a box-counting algorithm used box sizes with increasing exponential factor of two with grid algorithm on Fractalyse (TheMA, Besancon Cedex, France) was plotted against linear box dimension and first maximum (first peak) that represents the smallest box size resolution before breakdown of self-similarity. Statistical analysis was performed using one-way analysis of variance with post-hoc Tukey HSD. Results: There was significant difference among control, POAG, and NTG groups (p=0.002), with POAG having larger box size (12.8+/-1.54) compared to control (8.0+/-0.0, p=0.008) and NTG groups (8.0+/-0.0, p<0.01). When further divided into early, moderate, and severe subgroups of POAG, there were significant differences between moderate POAG (16+/-5.06, p=0.03) versus control and severe POAG (16.57+/-3.19, p=0.001) versus control. There was also a significant difference between early POAG (9.2+/-1.2) versus severe POAG (p=0.006). Lastly, the NTG group showed a significant difference with moderate POAG (p=0.031) and severe POAG (p=0.001). Conclusions: The first peak box size of fractal dimension as a function of increasing box size represents the smallest box size resolution prior to loss of uniformity of the vascular pattern's fractal dimension. The differences in breakdown size among controls, POAG, and NTG suggest that this resolution is limited by and serves as an indicator for breakdown of self-similarity and reduced capillary density. Breakdown of self-similarity for POAG occurred at significantly higher resolution than that of controls or NTG, and more so for moderate to severe POAG subgroups, suggesting their increased loss of microvasculature and highlighting the potential of fractal analysis in establishing quantitative parameters for evaluation of glaucoma

Purpose: Optical coherence tomography angiography (OCTA) permits non-invasive evaluation of the retinal vasculature. We aim to quantify the fractal dimension (FD) of eyes with birdshot chorioretinopathy compared with control eyes using OCTA. Methods: A retrospective study was performed on 49 eyes from 26 control patients and 12 eyes from 6 patients with birdshot chorioretinopathy from a previously established database. OCTA images were obtained using the RTVue XR Avanti (Optovue Inc., Fremont, CA, USA). Automated 3mm x 3mm macular scans were obtained through both the superficial and deep capillary plexuses for each eye. Grayscale OCTA images were standardized and binarized using ImageJ (National Institutes of Health, Bethesda, Maryland, USA). Fractal box-counting analyses were performed using Fractalyse (TheMA, Besancon Cedex, France). The FD of the deep and superficial plexuses of eyes with birdshot chorioretinopathy was compared with control eyes. Statistical analysis was performed using two-tailed t-tests and one-way analysis of variance with post-hoc Tukey's multiple comparisons test with statistical significance at P<0.05. Results: The mean FD in the superficial capillary plexus of eyes with birdshot chorioretinopathy (1.481, SD=0.082) was significantly lower (P<0.0001) than control eyes (1.651, SD=0.0539). The mean FD in the deep capillary plexus of eyes with birdshot chorioretinopathy (1.512, SD=0.0904) was significantly lower (P<0.0001) than control eyes (1.677, SD=0.0533). There was no difference between the superficial and deep capillary plexuses of eyes with birdshot chorioretinopathy. Conclusions: The fractal dimension in OCTA of birdshot chorioretinopathy is significantly lower compared to control eyes. Since fractal geometry models the branching in the parafoveal microvasculature, this may correlate with a lower density of capillaries with above-threshold flow and provide further insight into pathogenesis of birdshot chorioretinopathy. Utilizing fractal analysis in OCTA imaging has the potential to establish quantitative parameters for parafoveal microvascular pathology in birdshot chorioretinopathy

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 = 4.513 x 10-3) and deep (P = 2.653 x 10-3) capillary plexuses. In diabetic eyes, the vascular density also was significantly reduced in the superficial (P = 8.068 x 10-5) and deep (P = 3.120 x 10-6) 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.

We present a patient with a refractive error of -3.00 -0.25x150 in the right eye and -3.50 -1.50x170 in the left eye who experienced bungee-cord-related corneal lacerations in the left eye. Slitlamp examination revealed a large radial corneal laceration in the vertical meridian and several smaller lacerations in the periphery. Corneal topography showed more central flattening in the left eye than in the right eye. Posttraumatic visual acuity in the left eye was 20/20 with a -1.50 diopter corrective lens. Myopic correction was a surprising outcome of a traumatic corneal laceration that produced a radial-keratotomy-like effect