PurposeWe quantified retinal and choriocapillaris microvascular changes in healthy control eyes and different stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).MethodsThis retrospective cross-sectional study included 137 eyes of 86 patients with different stages of DR and 44 eyes of 26 healthy age-matched controls. Participants were imaged with a commercial OCTA device (RTVue-XR Avanti). We analyzed the superficial (SCP) and deep (DCP) retinal capillary plexus, the full retina, and choriocapillaris for the following OCTA parameters: foveal avascular zone, vessel density, percent area of nonperfusion (PAN), and adjusted flow index (AFI). We adjusted for age, sex, and the correlation between eyes of the same study participant in our statistical models.ResultsAll OCTA parameters showed a significant linear correlation with DR severity (P < 0.05) in the univariate models except for AFI measured in the SCP and these correlations remained significant after correcting for covariates. Compared to the other capillary layers, the AFI at the DCP decreased significantly with DR severity. When comparing individual disease severity groups as categories, eyes of subjects with diabetes without DR had significantly increased PAN and AFI in the SCP compared to healthy subjects (P < 0.05).ConclusionsRetinal and choriocapillaris vascular nonperfusion in OCTA is correlated significantly with disease severity in eyes with DR. Higher flow in the SCP may be an early marker of diabetic microvascular changes before clinical signs of DR. The steep decline of blood flow in the DCP with increasing DR severity suggests that alterations at the DCP warrant further investigation.

PurposeTo quantify microvasculature changes in the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP) in diabetic retinopathy (DR).MethodsRetrospective cross-sectional study at a tertiary academic referral center, in which 26 controls (44 eyes), 27 diabetic subjects without retinopathy (44 eyes), 32 subjects with nonproliferative retinopathy (52 eyes), and 27 subjects with proliferative retinopathy (40 eyes) were imaged with optical coherence tomography angiography (OCTA). Outcome measures included parafoveal vessel density (VD), percentage area of nonperfusion (PAN), and adjusted flow index (AFI) at the different plexuses.ResultsMCP VD and MCP AFI decreased with worsening DR, while PAN increased, mirroring changes within the DCP. The fitted regression line for MCP and DCP AFI were significantly different than the SCP, while DCP PAN differed from SCP PAN with disease progression. Higher SCP AFI and PAN were different in eyes with diabetes without retinopathy compared with controls. Unexpectedly, sex was found to independently influence MCP VD and AFI with worsening disease.ConclusionsOCTA parameters in the MCP and DCP displayed parallel changes with DR progression, different from the SCP, emphasizing the importance of physiologic considerations in the retinal capillaries. Thus, segmentation protocols that include the MCP within the SCP may be confounded. A difference in DCP PAN with worsening DR was unmasked relative to a prior study that included the MCP with SCP. We confirm that SCP AFI and PAN may serve as early indicators of microvascular changes in DR and identify an interaction between sex and the MCP deserving further study.

AimsTo quantify the change in drusen volume over time and identify its prognostic value for individual risk assessment.MethodsA prospective observational study over a minimum of 3 years and maximum of 5 years and follow-up examination every 3 months was conducted at the ophthalmology department of the Medical University of Vienna. 109 patients presenting early and intermediate age-related macular degeneration (AMD) were included, of which 30 patients concluded a regular follow-up for at least 3 years. 50 eyes of 30 patients were imaged every 3 months using spectral-domain and polarisation-sensitive optical coherence tomography (OCT). Drusen volume was measured using an automated algorithm. Data of a 6-month follow-up were segmented manually by expert graders.ResultsGradings from 24 000 individual B-scans showed solid correlation between manual and automated segmentation with an initial mean drusen volume of 0.17 mm3. The increase in drusen volume was shown to be comparable among all eyes, and a model for long-term drusen volume development could be fitted as a cubic polynomial function and an R2=0.955. Spontaneous drusen regression was observed in 22 of 50 eyes. In this group, four eyes developed choroidal neovascularisation and three geographic atrophy.ConclusionsDrusen volume increase over time can be described by a cubic function. Spontaneous regression appears to precede conversion to advanced AMD. OCT might be a promising tool for predicting the individual risk of progression of AMD.

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IMPORTANCE Large amounts of optical coherence tomographic (OCT) data of diabetic macular edema (DME) are acquired, but many morphologic features have yet to be identified and quantified.OBJECTIVE To examine the volumetric change of intraretinal fluid (IRF) and subretinal fluid (SRF) in DME during anti-vascular endothelial growth factor treatment using deep learning algorithms.

Purpose/Aim of the study To assess the ability of optical coherence tomographic angiography (OCTA) to visualize the normal iris vasculature as well as neovascularization of the iris (NVI). Materials and Methods Study participants with healthy eyes, patients at risk of NVI development and patients with active or regressed NVI were consecutively included in this cross-sectional observational study. Imaging was performed using a commercially available OCTA system (RTVue- XR Avanti, Optovue Inc., Fremont, CA, USA). Abnormal iris vessels were graded on OCTA according to a modified clinical staging system and compared to slitlamp and gonioscopic findings. Results Fifty eyes of 26 study participants (16 healthy eyes, 19 eyes at risk, 15 eyes with different stages of NVI) were imaged using OCTA. In 11 out of 16 healthy eyes (69%) with light or moderately dark iris pigmentation, we observed physiological, radially aligned iris vasculature on OCTA imaging, which could not be visualized in five eyes (31%) with darkly pigmented irides. One eye in the “eyes at risk” group was diagnosed with NVI based on OCTA, which was not observed clinically. Fifteen eyes with clinically active or regressed NVI were imaged. Different stages of NVI could be differentiated by OCTA, corresponding well to an established clinical grading system. Four eyes showed regressed NVI by OCTA, not seen clinically, and were graded as a newly defined stage 4. Conclusions This pilot clinical study showed that OCTA for imaging of the iris vasculature in health and disease is highly dependent on iris pigmentation. Fine, clinically invisible iris vessels can be visualized by OCTA in the very early stages as well as in the regressed stage of NVI.

We present a novel polarization sensitive optical coherence tomography (PS-OCT) system with an integrated retinal tracker. The tracking operates at up to 60 Hz, correcting PS-OCT scanning positions during the acquisition to avoid artifacts caused by eye motion. To demonstrate the practical performance of the system, we imaged several healthy volunteers and patients with AMD both with B-scan repetitions for frame averaging and with 3D raster scans. Under large retinal motions with up to 1 mm amplitude at 0.5 ~a few Hz frequency range, motion artifact suppression in the PS-OCT images as well as standard deviation noise reduction in the frame averaged retardation images are presented. References and links1. M. R. Hee, D. Huang, E. A. Swanson, and J. G. Fujimoto, "Polarization-Sensitive Low-Coherence Reflectometer for Birefringence Characterization and Ranging," J. Opt. Soc. Am. B 9(6), 903-908 (1992). 2. J. F. de Boer, T. E. Milner, M. J. C. van Gemert, and J. S. Nelson, "Two-dimensional birefringence imaging in biological tissue by polarization-sensitive optical coherence tomography," Opt. Lett. 22(12), 934-936 (1997). 3. J. F. De Boer, S. M. Srinivas, A. Malekafzali, Z. P. Chen, and J. S. Nelson, "Imaging thermally damaged tissue by polarization sensitive optical coherence tomography," Opt. Express 3(6), 212-218 (1998). 4. J. F. de Boer, T. E. Milner, and J. S. Nelson, "Determination of the depth-resolved Stokes parameters of light backscattered from turbid media by use of polarization-sensitive optical coherence tomography," Opt. Lett. 24(5), 300-302 (1999). 5. C. K. Hitzenberger, E. Goetzinger, M. Sticker, M. Pircher, and A. F. Fercher, "Measurement and imaging of birefringence and optic axis orientation by phase resolved polarization sensitive optical coherence tomography," Opt. Express 9(13), 780-790 (2001 Hitzenberger, "Value of polarisation-sensitive optical coherence tomography in diseases affecting the retinal pigment epithelium," Br. J. Ophthalmol. 92(2), 204-209 (2008). 18. C. Ahlers, E. Götzinger, M. Pircher, I. Golbaz, F. Prager, C. Schütze, B. Baumann, C. K. Hitzenberger, and U.Schmidt-Erfurth, "Imaging of the retinal pigment epithelium in age-related macular degeneration using polarization-sensitive optical coherence tomography," Invest. Ophthalmol. Vis. Sci. 51(4), 2149-2157 (2010). 36. E. Götzinger, B. Baumann, M. Pircher, and C. K. Hitzenberger, "Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography," Opt. Express 17(25), 22704-22717 (2009

Purpose To perform a quantitative study of the vascular microstructure in actively treated choroidal neovascularization (CNV) by optical coherence tomographic angiography (OCTA). Methods Patients undergoing individualized anti-vascular endothelial growth factor (anti-VEGF) therapy of minimum 12 months duration were included in this cross-sectional observational study and imaged using OCTA. En face OCTA images were analyzed for quantitative features such as junction density, vessel length and lacunarity using validated software (Angiotool). Patients were divided into two groups depending on their individualized treatment interval: “Good responders, treated less frequently than 6 weeks” vs. “poor responders, treated every 6 weeks or more frequently”. Nonparametric testing was used to assess differences between these groups. Results Twenty-five eyes of 23 consecutive patients with a median 58-month history of CNV, treated by median of 34 anti-VEGF injections, were included in the analysis. There was no significant difference between any of the microvascular CNV features between the two groups (p > 0.05). Conclusion The semi-automated vessel segmentation software provides an objective and quantitative approach for CNV characterization. The consistently non-significant outcomes between the groups may provide evidence to support the “normalization hypothesis”. This would suggest that regardless of treatment interval, individualized therapy in these eyes established vessel stability.