Faculty Bibliography

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: 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

OBJECTIVE: To report the clinical, histopathologic, and electron microscopic features of band-shaped and whorled microcystic corneal epithelial dystrophy. DESIGN: Two interventional case reports. PARTICIPANTS: Two patients, two eyes. INTERVENTION: The involved area of corneal epithelium was scraped from each cornea. RESULTS: Histopathologic examination showed microscopic vacuoles in the epithelial cytoplasm in both cases. Electron microscopic examination revealed mainly empty cytoplasmic vacuoles with scant nonspecific osmophilic material. The process recurred clinically in one patient. Changes in corneal topography are documented in one patient. CONCLUSION: Clinical findings and pathologic studies seem nearly identical to those in the original report. No pattern of systemic disorder or medication use was found. The cause of this condition remains unknown