An automated framework to quantify areas of regional ischemia in retinal vascular diseases with OCT angiography

Retinal Vascular Changes during the Menstrual Cycle Detected with Optical Coherence Tomography Angiography

Purpose

To evaluate the effects of the menstrual cycle on the retinal vascular status of healthy women by optical coherence tomography angiography (OCTA).

Materials and Methods

Healthy women with regular natural menstrual cycles of 28 to 30 days were recruited for this prospective study. The women's retinal vascular status was measured by OCTA at 3 time points: the early follicular, ovulatory, and midluteal phases of the menstrual cycle. The main outcome measures were foveal avascular zone (FAZ) parameters, perfusion density (PD) percentage in the superficial retinal capillary plexus (SCP), and PD percentage in the deep retinal capillary plexus (DCP). The mean arterial pressure (MAP), spherical equivalent (SE), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and axial (AL) were also measured in a same menstrual cycle.

Results

In total, 62 right eyes of 62 women were included in the study. The mean age was 27.0 ± 1.73 (range, 24 to 31) years, and the mean menstrual cycle was 28.90 ± 0.84 (range, 28 to 30) days. The mean values of the DCP-PD parameters were significantly decreased in the nasal and inferior ETDRS subfields during the ovulatory phase. The mean DCP-PD in the nasal ETDRS subfield in the early follicular, ovulatory, and luteal phases was 54.11 ± 2.85, 56.39 ± 3.03, and 55.70 ± 3.27, respectively. The mean DCP-PD in the inferior ETDRS subfield in the early follicular, ovulatory, and midluteal phases was 52.90 ± 3.30, 54.86 ± 2.51, and 55.21 ± 2.64, respectively. No significant differences were found in MAP, SE, AL, IOP, FAZ area, or other quadrants of PD parameters, and no significant correlation was found between parameters by OCTA and age, MAP,SE, axial length, or IOP.

Conclusions

The DCP-PD decreased in the nasal and inferior ETDRS subfields during the ovulatory phase in our study. This may indicate the need to consider the menstrual phase when interpreting DCP-PD parameters by OCTA in healthy women.

Association of foveal avascular zone with the metamorphopsia in epiretinal membrane

This study was to investigate the relationship between the metamorphopsia and foveal avascular zone (FAZ) parameter in eyes with epiratinal membrane (ERM). We studied patients with an ERM visited retinal service unit at the Kagoshima University Hospital or Shirai Hospital. The best-corrected visual acuity (BCVA), and the degree of metamorphopsia by M -CHARTS™ were evaluated. The 3 × 3 mm optical coherence tomography angiography (OCTA) images of the superficial layer were obtained. Area (mm²), the circularity, eigen value were calculated using ImageJ software. The relationship between visual function, such as best corrected visual acuity (BCVA) and metamorphopsia, and FAZ parameters were studied by Pearson's correlational coefficient. Fifty-four eyes of 51 patients (24 men and 27 women) with an ERM were studied. The mean age of the patients was 69.6 ± 8.20 years. The mean BCVA and metamorphopsia score was 0.31 ± 0.29 logMAR units and 0.49 ± 0.42. There was no significant relationship between BCVA and FAZ parameters. While, metamorphopsia score was significantly and negatively correlated with all of FAZ parameters (area R = - 0.491, P < 0.001; circularity R = - 0.385, P = 0.004; eigenvalue ratio R = - 0.341; P = 0.012). Multiple regression analysis showed the FAZ area was solely and significantly correlated with metamorphopsia score (β - 0.479, P < 0.001). The size but not the shape of the FAZ was significantly correlated with the degree of metamorphopsia suggesting that it could be an objective parameter of metamorphopsia in ERM patients.

Cooperative Low-Rank Models for Removing Stripe Noise From OCTA Images

Optical coherence tomography angiography (OCTA) is an emerging non-invasive imaging technique for imaging the microvasculature of the eye based on phase variance or amplitude decorrelation derived from repeated OCT images of the same tissue area. Stripe noise occurs during the OCTA acquisition process due to the involuntary movement of the eye. To remove the stripe noise (or 'destriping') effectively, we propose two novel image decomposition models to simultaneously destripe all the OCTA images of the same eye cooperatively: cooperative uniformity destriping (CUD) model and cooperative similarity destriping (CSD) model. Both the models consider stripe noise by low-rank constraint but in different ways: the CUD model assumes that stripe noise is identical across all the layers while the CSD model assumes that the stripe noise at different layers are different and have to be considered in the model. Compared to the CUD model, CSD is a more general solution for real OCTA images. An efficient solution (CSD+) is developed for model CSD to reduce the computational complexity. The models were extensively evaluated against state-of-the-art methods on both synthesized and real OCTA datasets. The experiments demonstrated not only the effectiveness of the CSD and CSD+ models in terms of peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) and CSD+ is twice faster than CSD, but also their beneficiary effect on the vessel segmentation of OCTA images. We expect our models will become a powerful tool for clinical applications.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

Biomarkers of Peripheral Nonperfusion in Retinal Venous Occlusions Using Optical Coherence Tomography Angiography

Purpose

To study the association between the assessment of central macular vascular layers by optical coherence tomography angiography (OCT-A) and peripheral nonperfusion evaluated by fluorescein angiography (FA) in patients with retinal venous occlusion (RVO).

Methods

Retrospective review of RVO patients without macular edema. Patients underwent a comprehensive ophthalmic examination including FA, spectral-domain OCT, and OCT-A. Significant ischemia was defined as nonperfusion areas superior or equal to the equivalent of one retinal quadrant on FA. Vascular density (VD) and foveal avascular zone were measured using AngioAnalytics software. Fractal dimension (FD) and lacunarity (LAC) were computed using an algorithm designed by MATLAB (MathWorks, Natick, MA). These variables were used to build a model that translates their association with OCT-A parameters.

Results

There were 48 eyes (48 patients) of which 19 had significant peripheral nonperfusion. Deep capillary plexus FD, VD, and LAC were associated with significant ischemia. In fact, regarding the association with this outcome, LAC alone had the highest area under the curve (AUC = 0.88) followed by FD (AUC = 0.85) and VD (AUC = 0.73). The multivariable model that included LAC and VD, adjusted by best-corrected visual acuity (BCVA) achieved the best performance for the identification of severe nonperfusion on wide-field FA (AUC = 0.93).

Conclusions

The characteristics of the central macular deep capillary plexus on OCT-A may be associated with peripheral nonperfusion on FA, particularly the combination of LAC and vessel density after adjusting by BCVA.

Translational Relevance

Fractal-based metrics applied to OCT-A may become a valuable marker of ischemia in RVO and help guide the clinical decision to perform invasive angiography.

An update on inflammatory choroidal neovascularization: epidemiology, multimodal imaging, and management

Inflammatory choroidal neovascular membranes are challenging to diagnose and manage. A number of uveitic entities may be complicated by the development of choroidal neovascularization leading to a decrease in central visual acuity. In conditions such as punctate inner choroidopathy, development of choroidal neovascularization is extremely common and must be suspected in all cases. On the other hand, in patients with conditions such as serpiginous choroiditis, and multifocal choroiditis, it may be difficult to differentiate between inflammatory choroiditis lesions and choroidal neovascularization. Multimodal imaging analysis, including the recently introduced technology of optical coherence tomography angiography, greatly aid in the diagnosis and management of inflammatory choroidal neovascularization. Management of these neovascular membranes consists of anti-vascular growth factor agents, with or without concomitant anti-inflammatory and/or corticosteroid therapy.