Retinal blood flow speed quantification at the capillary level using temporal autocorrelation fitting OCTA [Invited].

Optical coherence tomography angiography (OCTA) can visualize vasculature structures, but provides limited information about blood flow speed. Here, we present a second generation variable interscan time analysis (VISTA) OCTA, which evaluates a quantitative surrogate marker for blood flow speed in vasculature. At the capillary level, spatially compiled OCTA and a simple temporal autocorrelation model, ρ(τ) = exp(-ατ), were used to evaluate a temporal autocorrelation decay constant, α, as the blood flow speed marker. A 600 kHz A-scan rate swept-source OCT prototype instrument provides short interscan time OCTA and fine A-scan spacing acquisition, while maintaining multi mm2 field of views for human retinal imaging. We demonstrate the cardiac pulsatility and assess repeatability of α measured with VISTA. We show different α for different retinal capillary plexuses in healthy eyes and present representative VISTA OCTA in eyes with diabetic retinopathy.

Retinal Pigment Epithelium Aperture Preceding Collapse of Vascular and Avascular Pigment Epithelial Detachments Secondary to AMD.

PURPOSE: To describe retinal pigment epithelium (RPE) aperture preceding the collapse of retinal pigment epithelium detachments (RPED) in eyes with neovascular and non-neovascular age-related macular degeneration (AMD). METHODS: Medical records from five patients with RPE aperture associated with vascular and avascular RPED were reviewed between 2010 and 2021 at the New England Eye Center at Tufts Medical Center. Main outcome measures were analysis of RPE aperture characteristics and temporal course of RPED collapse. RESULTS: RPE apertures were identified in six eyes from five women (mean age of 72.6 years). Two eyes had neovasacular AMD and four eyes had non-neovascular AMD. The RPE aperture initially appeared as a discontinuity at the apex of the RPED without rippling or retraction. Each aperture was associated with hypertransmission of OCT signal into the choroid as well as hyperreflective foci. The mean time between the appearance of the RPE aperture to near complete collapse of the RPED was 9 months. Following RPED collapse, one eye developed choroidal neovascularization, three eyes progressed to geographic atrophy, one eye had recurrence of the RPED, and one eye remained unchanged. CONCLUSION: RPE aperture is a characteristic OCT finding that can be observed in avascular or vascularized RPED secondary to AMD. RPE apertures precede RPED collapse, which are most likely to occur within nine months of RPE aperture detection.

Optical Coherence Tomography Angiography Analysis Toolbox: A Repeatable and Reproducible Software Tool for Quantitative Optical Coherence Tomography Angiography Analysis.

BACKGROUND AND OBJECTIVE: The purpose of this article is to demonstrate the optical coherence tomography angiography (OCTA) Analysis Toolkit (OAT), a custom-designed software package, as a repeatable and reproducible tool for computing OCTA metrics across different devices. MATERIALS AND METHODS: Fourteen participants were imaged using three devices. Foveal avascular zone, vessel index, vessel length index, and vessel diameter index were calculated using the OAT. Repeatability and reproducibility were assessed using the coefficient of variation and interclass correlation coefficient (ICC). RESULTS: Analysis of identical images demonstrated perfect levels of repeatability for all metrics (coefficient of variation 0%), which was a consequence of the software being deterministic (ie, producing the same outputs for the same inputs). Foveal avascular zone ICC values were in the excellent-to-good range (ICC > 0.6) for all devices. All values for vessel index (VI), vessel length index, and vessel diameter index fell in the good-to-fair (ICC > 0.4) or excellent-to-good range, except for vessel index analysis in the Cirrus device (ICC = 0.34). CONCLUSIONS: The OAT appears to be a reliable tool that may enable comparison between OCTA data sets acquired on different imaging instruments, thereby facilitating a more consistent approach to OCTA analysis. [Ophthalmic Surg Lasers Imaging Retina 2023;54:114-122.].

Persistent diabetic macular edema: Definition, incidence, biomarkers, and treatment methods.

Intravitreal antivascular endothelial growth factor (anti-VEGF) treatment has drastically improved the visual and anatomical outcomes in patients with diabetic macular edema (DME); however, success is not always guaranteed, and a proportion of these eyes demonstrate persistent DME (pDME) despite intensive treatment. While standardized criteria to define these treatment-resistant eyes have not yet been established, many studies refer to eyes with no clinical response or an unsatisfactory partial response as having pDME. A patient is considered to have pDME if the retinal thickness improves less than 10-25% after 6 months of treatment. A range of treatment options have been recommended for eyes with pDME, including switching anti-VEGF agents, using corticosteroids and/or antioxidant drugs in adjunct with anti-VEGF therapy, and vitrectomy. In addition, multimodal imaging of DME eyes may be advantageous in predicting the responsiveness to treatment; this is beneficial when initiating alternative therapies. We explore the literature on persistent DME regarding its defining criteria, incidence, the baseline biological markers that may be useful in anticipating the response to treatment, and the available treatment options.

A randomized, sham-controlled trial of intraductal meibomian gland probing with or without topical antibiotic/steroid for obstructive meibomian gland dysfunction.

IMPORTANCE: Obstructive meibomian gland dysfunction (MGD) can be refractory to medical therapy. Intraductal meibomian gland (MG) probing may offer a potential therapeutic approach for these patients, but no randomized trials have been conducted to date. OBJECTIVE: To assess clinical changes after intraductal MG probing for patients with refractory obstructive meibomian gland dysfunction. DESIGN: Randomized, double-masked, sham-controlled clinical trial. SETTING: Single-center, tertiary referral center. PARTICIPANTS: 42 patients with refractory obstructive MGD associated with lid tenderness. INTERVENTIONS: Enrolled patients received one of the following treatments: 1) MG probing plus post-procedural topical sulfacetamide/prednisolone ointment (Blephamide®), 2) MG probing plus post-procedural lubricating ointment (GenTeal), or 3) sham probing plus GenTeal ointment. The probing was performed on the upper lids of both eyes. MAIN OUTCOME MEASURES: Primary outcome measures were symptoms as measured by Ocular Surface Disease Index (OSDI) and Symptom Assessment iN Dry Eye (SANDE), as well as tear break-up time (TBUT). Secondary outcome measures were other clinical signs. Safety of the procedure was also evaluated by investigating the treatment-related adverse events. At baseline and 4 weeks after the procedure a masked observer evaluated the following outcome measures: symptom questionnaires, including OSDI and SANDE, upper lid tenderness, lid margin telangiectasia, corneal fluorescein staining, conjunctival lissamine green staining, TBUT, Schirmer's test, and meibomian glands yielding liquid secretion (MGYLS). RESULTS: Compared to baseline, the MG probing/Blephamide® group showed significant improvements in both OSDI and SANDE scores and the MG probing/GenTeal group demonstrated a significant improvement only in SANDE score. In contrast, the Sham/GenTeal group did not show any statistically significant changes in symptoms. There were no statistically significant changes in clinical signs in any group at the 4-week visit, except for improvement of lid tenderness in the sham probing group. CONCLUSIONS: MG probing/Blephamide® results in a significant improvement in symptoms in patients with refractory obstructive MGD without any significant effect on clinical signs. Larger studies are warranted to determine the efficacy of MG probing. TRIAL REGISTRATION: Clinicaltrials.gov(identifier NCT02256969, Filed on 08/13/2014).