For the first time in a prospective trial, a bullous configuration was found to be a highly significant predictor for progression in macula-on detachments. Our data support prompt surgery in patients diagnosed with bullous macula-on RRD.
PURPOSE. Contrast agents applicable for optical coherence tomography (OCT) imaging are rare. The intrascleral aqueous drainage system would be a potential application for a contrast agent, because the aqueous veins are of small diameter and located deep inside the highly scattering sclera. We tested lipid emulsions (LEs) as candidate OCT contrast agents in vitro and ex vivo, including milk and the anesthetic substance Propofol. METHODS. Commercial OCT and OCT angiography (OCTA) devices were used. Maximum reflectivity and signal transmission of LE were determined in tube phantoms. Absorption spectra and light scattering was analyzed. The anterior chamber of enucleated porcine eyes was perfused with LEs, and OCTA imaging of the LEs drained via the aqueous outflow tract was performed. RESULTS. All LEs showed a significantly higher reflectivity than water (P < 0.001). Higher milk lipid content was positively correlated with maximum reflectivity and negatively with signal transmission. Propofol exhibited the best overall performance. Due to a high degree of signal fluctuation, OCTA could be applied for detection of LE. Compared with blood, the OCTA signal of Propofol was significantly stronger (P ¼ 0.001). As a proof of concept, time-resolved aqueous angiography of porcine eyes was performed. The three-dimensional (3D) structure and dynamics of the aqueous outflow were significantly different from humans. CONCLUSIONS. LEs induced a strong signal in OCT and OCTA. LE-based OCTA allowed the ability to obtain time-resolved 3D datasets of aqueous outflow. Possible interactions of LE with inner eye's structures need to be further investigated before in vivo application.
Purpose
To develop and compare different analytic approaches for quantifying ischemia in OCT-angiography (OCTA), including vessel-based approaches and intercapillary area analysis.
Methods
En face OCTA (6 × 6) images of the superficial plexus of 20 healthy eyes and 20 eyes with different ischemic retinal diseases were analyzed retrospectively. Included retinal diseases were diabetic retinopathy (
n
= 9), central (
n
= 5) and branch retinal vein occlusion (
n
= 4), hypertensive retinopathy (
n
= 1), and occlusive retinal vasculitis in sarcoidosis (
n
= 1). Vessel-based approaches consisted of the mean gray scale, perfusion density, and vessel density. Intercapillary areas (ICAs) were analyzed measuring the distance of each intercapillary pixel from the surrounding vessels. In particular, we applied a vector method to measure the shortest, the mean, and the longest distance in eight predefined directions. Size of ICAs was determined applying different global or local distance thresholds.
Results
All approaches revealed significant differences between ischemic and healthy retinae (
P
< 0.001, with Bonferroni-Holm correction
P
= 0.001–0.025; Wilcoxon-Mann-Whitney test). Discrimination between the healthy and ischemic retinae based on ROC curves was best in the ICA analysis using a locally set threshold of the shortest distance.
Conclusions
In the present study, ICA analysis was superior to vessel-based approaches in the quantification of retinal ischemia when defining a local or global distance threshold.
Translational Relevance
In order to establish OCTA imaging in everyday clinical and scientific practice, standardized, device-independent image analysis methods are necessary.
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