Age-related macular degeneration (AMD), a neurodegenerative disease, is the leading cause of visual impairment in industrialized countries. Challenges in defining structural/functional relationships at various stages of disease especially with non-neovascular AMD, have slowed therapeutic development. Development of such sensitive and specific markers associated with AMD progression could provide the basis necessary for future regulatory outcome variables that will be useful in assessing new, innovative AMD therapies. Advanced imaging technologies such as high-resolution optical coherence tomography, fundus autofluorescence and near infrared imaging; and functional tests including rod-mediated dark adaptation, microperimetry, fluorescence lifetime imaging ophthalmoscopy and others will be important in the evaluation of these structure/function correlations. Development of more advanced methods to study structure such as high-resolution OCT and en face OCT offer further opportunities to better correlate structure and function in clinical trials, and to better define useful biomarkers of visual outcome endpoints. Dark adaptation, although correlated with AMD stage, is difficult to incorporate as endpoint in clinical trials because dark adaptation changes slowly and the technique is time consuming. Microperimetry has become a useful outcome variable in many clinical trials and new methodology may improve its utility in structure-function correlation. These and other newer techniques will require further prospective studies to determine their clinical utility in early AMD detection, prediction of disease progression from intermediate to late stages, and the ability to monitor the advancement of non-neovascular AMD.

PURPOSE:To evaluate the impact of pegcetacoplan on its ability to slow the loss of visual function using microperimetry endpoints in eyes with geographic atrophy secondary to age-related macular degeneration (AMD). DESIGN:Post hoc analysis of phase 3 randomized controlled trial data. METHODS:Utilizing data from the OAKS study, which evaluated pegcetacoplan monthly (PM) or every other month (PEOM) vs sham for the treatment of GA secondary to AMD, microperimetry endpoints were assessed at baseline and every 6 months until 24 months, using a 10-2 grid composed of 68 points with a 4-2 threshold strategy. Main outcome measures included the time to development of absolute scotomas in the 4 and 16 central macular points. The number of absolute scotomatous points and mean retinal sensitivity (dB) within the junctional zone extending to 250 µm on either side of autofluorescence-determined GA border was analyzed for change from baseline. RESULTS:Among 605 patients with subfoveal or nonsubfoveal GA, treatment with pegcetacoplan delayed time to development of absolute scotomas of all 4 central macular points compared to sham at 24 months (PM: hazard ratio [HR]: 0.66 [34% risk reduction]; 95% confidence interval [CI]: 0.46, 0.96; P = .0282; PEOM: HR: 0.64 [36% risk reduction]; 95% CI: 0.44, 0.92; P = .0164). Similarly, PM and PEOM treatment delayed time to development of absolute scotomas of all 16 central points (PM: HR: 0.57 [43% risk reduction]; 95% CI: 0.33, 0.96; P = .0361; PEOM: HR: 0.52 [48% risk reduction]; 95% CI: 0.32, 0.85; P = .0084). Across the junctional zone of GA, pegcetacoplan-treated eyes developed fewer absolute scotomatous points (PM difference vs sham pooled: -0.68 points, P = .1444; PEOM difference vs sham pooled: -1.14 points, P = .0140) and experienced decreased loss of mean retinal sensitivity (PM difference vs sham pooled: 0.56 dB, P = .0650; PEOM difference vs sham pooled: 0.71 dB, P = .0202) compared with sham at 24 months. CONCLUSIONS:Microperimetry demonstrates a reduced rate of visual function loss in the central macula and junctional zone with pegcetacoplan treatment in GA due to AMD.

Abstract Purpose To assess the repeatability of a microperimetry methodology for quantifying visual function changes in the junctional zone of eyes with geographic atrophy (GA) in the clinical trial context. Methods A post hoc analysis of the OAKS phase III trial was conducted, which enrolled patients with GA secondary to age-related macular degeneration. Microperimetry using a standard 10 − 2 fovea centered grid was performed at baseline and follow-up visits. GA regions were traced on fundus autofluorescence (FAF) images. Two graders independently registered baseline microperimetry images with baseline FAF images in a sampling of 30 eyes from the OAKS study. Agreement between the two graders’ assessments of mean sensitivity and the number of scotomatous points within a ± 250 𝜇m GA junctional zone was assessed. Results The intraclass correlation (ICC) and coefficient of repeatability (CoR) for the mean junctional zone sensitivity were 0.987 and 0.214 dB, respectively. The ICC and CoR for the total number of scotomatous points within the junctional zone were 0.991 and 1.42, respectively. Conclusions The repeatability of the methodology and its compatibility with standard MP acquisitions appear to make it well-suited for identifying and analyzing retinal sensitivity within high-risk areas of the retina. Summary We present a microperimetry-based methodology for assessing visual function changes in the junctional zone of geographic atrophy lesions using a standard 10 − 2 fovea centered grid in a clinical trial context. The approach’s repeatability and compatibility with standard microperimetry grids may make it useful for assessing the effects of GA therapeutics.

Purpose:To assess the relationship between choriocapillaris (CC) loss and the development of nascent geographic atrophy (nGA) using optical coherence tomography angiography (OCTA) imaging. Methods:In total, 105 from 62 participants with bilateral large drusen, without late age-related macular degeneration (AMD) or nGA at baseline, were included in this prospective, longitudinal, observational study. Participants underwent swept-source OCTA imaging at 6-month intervals. CC flow deficit percentage (FD%) and drusen volume measurements were determined for the visit prior to nGA development or the second-to-last visit if nGA did not develop. Global and local analyses, the latter based on analyses within superpixels (120 × 120-µm regions), were performed to examine the association between CC FD% and future nGA development. Results:A total of 15 (14%) eyes from 12 (19%) participants developed nGA. There was no significant difference in global CC FD% at the visit prior to nGA development between eyes that developed nGA and those that did not (P = 0.399). In contrast, CC FD% was significantly higher in superpixels that subsequently developed nGA compared to those that did not (P < 0.001), and a model utilizing CC FD% was significantly better at predicting foci of future nGA development at the superpixel level than a model using drusen volume alone (P ≤ 0.040). Conclusions:This study showed that significant impairments in CC blood flow could be detected locally prior to the development of nGA. These findings add to our understanding of the pathophysiologic changes that occur with atrophy development in AMD.

Uterine contraction patterns vary during the ovulatory cycle and throughout pregnancy, but prior measurements have produced limited and conflicting information on these patterns. We combined a virally delivered genetically encoded calcium reporter (GCaMP8m) and ultra-widefield imaging in live nonpregnant mice to characterize uterine calcium dynamics at organ scale throughout the estrous cycle. Prior to ovulation (proestrus and estrus), uterine excitations primarily initiated in a region near the oviduct, but after ovulation (metestrus and diestrus), excitations initiated at loci homogeneously distributed throughout the organ. The frequency of excitation events was lowest in proestrus and estrus, higher in metestrus, and highest in diestrus. These results establish a platform for mapping uterine activity and demonstrate that an anatomically localized trigger for uterine excitations depends on the estrous cycle phase.

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.

Recording transcriptional histories of a cell would enable deeper understanding of cellular developmental trajectories and responses to external perturbations. Here we describe an engineered protein fiber that incorporates diverse fluorescent marks during its growth to store a ticker tape-like history. An embedded HaloTag reporter incorporates user-supplied dyes, leading to colored stripes that map the growth of each individual fiber to wall clock time. A co-expressed eGFP tag driven by a promoter of interest records a history of transcriptional activation. High-resolution multi-spectral imaging on fixed samples reads the cellular histories, and interpolation of eGFP marks relative to HaloTag timestamps provides accurate absolute timing. We demonstrate recordings of doxycycline-induced transcription in HEK cells and cFos promoter activation in cultured neurons, with a single-cell absolute accuracy of 30–40 minutes over a 12-hour recording. The protein-based ticker tape design we present here could be generalized to achieve massively parallel single-cell recordings of diverse physiological modalities. Reporter gene expression history in cells is recorded with engineered fluorescent protein fibers.

& BULL; PURPOSE: The appearance and growth of persis-tent choroidal hypertransmission defects (hyperTDs) de-tected on en face swept-source optical coherence tomog-raphy (SS-OCT) images from eyes with intermediate age-related macular degeneration (iAMD) were studied to de -termine if they could serve as novel clinical trial end-points. & BULL; DESIGN: Post hoc subgroup analysis of a prospective study. & BULL; METHODS: Subjects with iAMD underwent 6 x 6 mm SS-OCT angiography imaging at their baseline and follow-up visits. The drusen volumes were obtained us-ing a validated SS-OCT algorithm. Two graders indepen-dently evaluated all en face structural images for the pres-ence of persistent hyperTDs. The number and area of all hyperTDs along with drusen volume were obtained from all SS-OCT angiography scans. Eyes were censored from further follow-up once exudative AMD developed. & BULL; RESULTS: A total of 171 eyes from 121 patients with iAMD were included. Sixty-eight eyes developed at least 1 hyperTD. Within 1 year after developing a hyperTD, 25% of eyes developed new hyperTDs for an average of 0.44 additional hyperTDs. Over 2 years, as hyperTDs appeared, enlarged, and merged, the average area growth rate was 0.220 mm/yr using the square-root transforma-tion strategy. A clinical trial design using the onset and enlargement of these hyperTDs for the study of disease progression in eyes with iAMD is proposed. & BULL; CONCLUSIONS: The appearance and growth of persis-tent choroidal hyperTDs in eyes with iAMD can be easily detected and measured using en face OCT imaging and can serve as novel clinical trial endpoints for the study of therapies that may slow disease progression from iAMD to late AMD. (Am J Ophthalmol 2023;254: 11-22. & COPY; 2023 Elsevier Inc. All rights reserved.)

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.].

Purpose:Ultrahigh resolution spectral domain-OCT (UHR SD-OCT) enables in vivo visualization of micrometric structural markers which differentially associate with normal aging versus age-related macular degeneration (AMD). This study explores the hypothesis that UHR SD-OCT can detect and quantify sub-retinal pigment epithelium (RPE) deposits in early AMD, separating AMD pathology from normal aging. Design:Prospective cross-sectional study. Participants:A total of 53 nonexudative (dry) AMD eyes from 39 patients, and 63 normal eyes from 39 subjects. Methods:Clinical UHR SD-OCT scans were performed using a high-density protocol. Exemplary high-resolution histology and transmission electron microscopy images were obtained from archive donor eyes. Three trained readers evaluated and labeled outer retina morphological features, including the appearance of a hyporeflective split within the RPE-RPE basal lamina (RPE-BL)-Bruch's membrane (BrM) complex on UHR brightness (B)-scans. A semi-automatic segmentation algorithm measured the thickness of the RPE-BL-BrM split/hyporeflective band. Main Outcome Measures:Qualitative description of outer retinal morphological changes on UHR SD-OCT B-scans; the proportion of the RPE-BL-BrM complex with visible split (%) and the thickness of the resulting hyporeflective band (μm). Results:In young normal eyes, UHR SD-OCT consistently revealed an RPE-BL-BrM split/hyporeflective band. Its visibility and thickness were less in eyes of advanced age. However, the split/hyporeflective band was again visible in early AMD eyes. Both qualitative reading and quantitative thickness measurements showed significantly elevated visibility and thickness of the RPE-BL-BrM split/hyporeflective in early AMD eyes compared to age-matched controls. Conclusions:Our imaging results strongly support the hypothesis that appearance of the RPE-BL-BrM split/hyporeflective band in older subjects is dominated by the BL deposit, an indicator of early AMD well known from histology. Ultrahigh resolution SD-OCT can be used to investigate physiological aging as well as early AMD pathology in clinical imaging studies. Developing quantifiable markers associated with disease pathogenesis and progression can facilitate drug discovery, as well as reduce clinical trial times. Financial Disclosures:Proprietary or commercial disclosure may be found after the references.

This study reports the development of prototype swept-source optical coherence tomography (SS-OCT) technology for imaging the anterior eye. Advances in vertical-cavity surface-emitting laser (VCSEL) light sources, signal processing, optics and mechanical designs, enable a unique combination of high speed, long range, and deep penetration that addresses the challenges of anterior eye imaging. We demonstrate SS-OCT with a 325 kHz A-scan rate, 12.2 µm axial resolution (in air), and 15.5 mm depth range (in air) at 1310 nm wavelength. The ultrahigh 325 kHz A-scan rate not only facilitates biometry measurements by minimizing acquisition time and thus reducing motion, but also enables volumetric OCT for comprehensive structural analysis and OCT angiography (OCTA) for visualizing vasculature. The 15.5 mm (~ 11.6 mm in tissue) depth range spans all optical surfaces from the anterior cornea to the posterior lens capsule. The 1310 nm wavelength range enables structural OCT and OCTA deep in the sclera and through the iris. Achieving high speed and long range requires linearizing the VCSEL wavenumber sweep to efficiently utilize analog-to-digital conversion bandwidth. Dual channel recording of the OCT and calibration interferometer fringe signals, as well as sweep to sweep wavenumber compensation, is used to achieve invariant 12.2 µm (~ 9.1 µm in tissue) axial resolution and optimum point spread function throughout the depth range. Dynamic focusing using a tunable liquid lens extends the effective depth of field while preserving the lateral resolution. Improved optical and mechanical design, including parallax “split view” iris cameras and stable, ergonomic patient interface, facilitates accurate instrument positioning, reduces patient motion, and leads to improved imaging data yield and measurement accuracy. We present structural and angiographic OCT images of the anterior eye, demonstrating the unique imaging capabilities using representative scanning protocols which may be relevant to future research and clinical applications.

PURPOSE. The local growth rates of geographic atrophy (GA) adjacent to non-exudative type 1 macular neovascularization (MNV) were investigated to determine if MNV influ-enced GA growth. METHODS. Eyes with GA and non-exudative type 1 MNV were followed for at least 1 year. Both GA and the MNV were imaged and measured using swept-source optical coher-ence tomography angiography (SS-OCTA) scans. Pearson correlations were computed between local growth rates of GA, which were estimated using a biophysical GA growth model, and local distances-to-MNV. Corresponding P values for the null hypothesis of no Pearson correlation were computed using a Monte Carlo approach that adjusts for spatial autocorrelations. RESULTS. Nine eyes were included in this study. There were positive correlations (Pearson's r > 0) between distance-to-MNV and local GA growth in eight (89%) of the eyes; however, in all but one eye (11%), correlations were relatively weak and statistically nonsignificant after Bonferroni correction (corrected P > 0.05). CONCLUSIONS. SS-OCTA imaging combined with GA growth modeling and spatial statistical analysis enabled quantitative assessment of correlations between local GA growth rates and local distances-to-MNV. Our results are not consistent with non-exudative type 1 MNV having a strong inhibitory effect on local GA growth rates.

Purpose:To compare the accuracies of the previously proposed square-root-transformed and perimeter-adjusted metrics for estimating length-type geographic atrophy (GA) growth rates.Design:Cross-sectional and simulation-based study.Participants:Thirty-eight eyes with GA from 27 patients.Methods:We used a previously developed atrophy-front growth model to provide analytical and numerical evaluations of the square-root-transformed and perimeter-adjusted growth rate metrics on simulated and semisimulated GA growth data.Main Outcome Measures:Comparison of the accuracies of the square-root-transformed and perimeter-adjusted metrics on simulated and semisimulated GA growth data.Results:Analytical and numerical evaluations showed that the accuracy of the perimeter-adjusted metric is affected minimally by baseline lesion area, focality, and circularity over a wide range of GA growth rates. Average absolute errors of the perimeter-adjusted metric were approximately 20 times lower than those of the square-root-transformed metrics, per evaluation on a semisimulated dataset with growth rate characteristics matching clinically observed data.Conclusions:Length-type growth rates have an intuitive, biophysical interpretation that is independent of lesion geometry, which supports their use in clinical trials of GA therapeutics. Taken in the context of prior studies, our analyses suggest that length-type GA growth rates should be measured using the perimeter-adjusted metric, rather than square-root-transformed metrics.

Optical coherence tomography angiography (OCTA) is a clinically promising modality to image retinal vasculature. For this end, optical coherence tomography (OCT) volumes are repeatedly scanned and intensity changes over time are used to compute OCTA images. Because of patient movement and variations in blood ow, OCTA data are prone to noise.