Optical Coherence Tomography Predictors of Risk for Progression to Non-Neovascular Atrophic Age-Related Macular Degeneration

AI in the clinical management of GA: A novel therapeutic universe requires novel tools

Regulatory approval of the first two therapeutic substances for the management of geographic atrophy (GA) secondary to age-related macular degeneration (AMD) is a major breakthrough following failure of numerous previous trials. However, in the absence of therapeutic standards, diagnostic tools are a key challenge as functional parameters in GA are hard to provide. The majority of anatomical biomarkers are subclinical, necessitating advanced and sensitive image analyses. In contrast to fundus autofluorescence (FAF), optical coherence tomography (OCT) provides high-resolution visualization of neurosensory layers, including photoreceptors, and other features that are beyond the scope of human expert assessment. Artificial intelligence (AI)-based methodology strongly enhances identification and quantification of clinically relevant GA-related sub-phenotypes. Introduction of OCT-based biomarker analysis provides novel insight into the pathomechanisms of disease progression and therapeutic, moving beyond the limitations of conventional descriptive assessment. Accordingly, the Food and Drug Administration (FDA) has provided a paradigm-shift in recognizing ellipsoid zone (EZ) attenuation as a primary outcome measure in GA clinical trials. In this review, the transition from previous to future GA classification and management is described. With the advent of AI tools, diagnostic and therapeutic concepts have changed substantially in monitoring and screening of GA disease. Novel technology combined with pathophysiological knowledge and understanding of the therapeutic response to GA treatments, is currently opening the path for an automated, efficient and individualized patient care with great potential to improve access to timely treatment and reduce health disparities.

Rediscovering Age-Related Macular Degeneration with Swept-Source OCT Imaging: The 2022 Charles L. Schepens, MD, Lecture

PURPOSE

Swept-source OCT angiography (SS-OCTA) scans of eyes with age-related macular degeneration (AMD) were used to replace color, autofluorescence, infrared reflectance, and dye-based fundus angiographic imaging for the diagnosis and staging of AMD. Through the use of different algorithms with the SS-OCTA scans, both structural and angiographic information can be viewed and assessed using both cross sectional and en face imaging strategies.

DESIGN

Presented at the 2022 Charles L. Schepens, MD, Lecture at the American Academy of Ophthalmology Retina Subspecialty Day, Chicago, Illinois, on September 30, 2022.

PARTICIPANTS

Patients with AMD.

METHODS

Review of published literature and ongoing clinical research using SS-OCTA imaging in AMD.

MAIN OUTCOME MEASURES

Swept-source OCT angiography imaging of AMD at different stages of disease progression.

RESULTS

Volumetric SS-OCTA dense raster scans were used to diagnose and stage both exudative and nonexudative AMD. In eyes with nonexudative AMD, a single SS-OCTA scan was used to detect and measure structural features in the macula such as the area and volume of both typical soft drusen and calcified drusen, the presence and location of hyperreflective foci, the presence of reticular pseudodrusen, also known as subretinal drusenoid deposits, the thickness of the outer retinal layer, the presence and thickness of basal laminar deposits, the presence and area of persistent choroidal hypertransmission defects, and the presence of treatment-naïve nonexudative macular neovascularization. In eyes with exudative AMD, the same SS-OCTA scan pattern was used to detect and measure the presence of macular fluid, the presence and type of macular neovascularization, and the response of exudation to treatment with vascular endothelial growth factor inhibitors. In addition, the same scan pattern was used to quantitate choriocapillaris (CC) perfusion, CC thickness, choroidal thickness, and the vascularity of the choroid.

CONCLUSIONS

Compared with using several different instruments to perform multimodal imaging, a single SS-OCTA scan provides a convenient, comfortable, and comprehensive approach for obtaining qualitative and quantitative anatomic and angiographic information to monitor the onset, progression, and response to therapies in both nonexudative and exudative AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Repeatability of Rod-Mediated Dark Adaptation Testing in Normal Aging and Early and Intermediate Age-Related Macular Degeneration

PURPOSE

The vulnerability of rod photoreceptors in aging and early and intermediate age-related macular degeneration (AMD) has been well documented. Rod-mediated dark adaptation (RMDA) is a measure of the recovery of light sensitivity in rod photoreceptors following a bright light. Delays in RMDA during early and intermediate AMD have been widely reported. For RMDA's promise as an outcome for trials targeted at early and intermediate AMD to be realized, excellent test-retest reliability, its repeatability, must be established.

METHODS

Test-retest performance in a commonly used RMDA test based on the rod intercept time metric (RIT) was evaluated in participants with early and intermediate AMD and with normal retinal aging with testing approximately 2 weeks apart. The test target was placed at 5° eccentricity superior to the foveal center, an area with maximal rod loss in aging and AMD. Disease severity was identified by a trained and masked grader of fundus photographs using both the AREDS 9-step and Beckman classification systems. Bland-Altman plots and intra-class correlation coefficients (ICC) evaluated repeatability.

RESULTS

The analysis sample consisted of 37 older adults (mean age 76 years, standard deviation 5), with approximately one-third of the sample in each of three groups - normal aging, early AMD, and intermediate AMD. For the total sample, the ICC was 0.98. For individual AMD groups for both AREDS 9-step and Beckman classifications, the ICCs were also very high ranging from 0.82 to 0.99.

CONCLUSION

We demonstrated that RMDA testing using the RIT metric has excellent repeatability when target location is at 5° in studying older adults from normal aging to intermediate AMD, suggesting the reliable use of this functional measure in trials.

The Total Macular Burden of Hyperreflective Foci and the Onset of Persistent Choroidal Hypertransmission Defects in Intermediate AMD

PURPOSE

The association between the total macular burden of hyperreflective foci (HRF) in eyes with intermediate AMD (iAMD) and the onset of persistent choroidal hypertransmission defects (hyperTDs) was studied using swept-source optical coherence tomography (SS-OCT).

DESIGN

Post hoc subgroup analysis of a prospective study.

METHODS

A retrospective review of iAMD eyes from subjects enrolled in a prospective SS-OCT study was performed. All eyes underwent 6×6 mm SS-OCT angiography (SS-OCTA) imaging at baseline and follow-up visits. En face sub-retinal pigment epithelium (subRPE) slabs with segmentation boundaries positioned 64 to 400 µm beneath Bruch's membrane (BM) were used to identify persistent choroidal hyperTDs. None of the eyes had persistent hyperTDs at baseline. The same subRPE slab was used to identify choroidal hypotransmission defects (hypoTDs) attributable to HRF located either intraretinally (iHRF) or along the RPE (rpeHRF) based on corresponding B-scans. A semiautomated algorithm was used by 2 independent graders to validate and refine the HRF outlines. The HRF area and the drusen volume within a 5 mm fovea-centered circle were measured at each visit.

RESULTS

The median follow-up time for the 171 eyes from 121 patients included in this study was 59.1 months (95% CI: 52.0-67.8 months). Of these, 149 eyes (87%) had HRF, and 82 (48%) developed at least one persistent hyperTD during the follow-up. Although univariable Cox regression analyses showed that both drusen volume and total HRF area were associated with the onset of the first persistent hyperTD, multivariable analysis showed that the area of total HRF was the sole significant predictor for the onset of hyperTDs (P < .001). ROC analysis identified an HRF area ≥ 0.07 mm² to predict the onset of persistent hyperTDs within 1 year with an area under the curve (AUC) of 0.661 (0.570-0.753), corresponding to a sensitivity of 55% and a specificity of 74% (P < .001).

CONCLUSIONS

The total macular burden of HRF, which includes both the HRF along the RPE and within the retina, is an important predictor of disease progression from iAMD to the onset of persistent hyperTDs and should serve as a key OCT biomarker to select iAMD patients at high risk for disease progression in future clinical trials.

Predictive factors of age-related macular degeneration with poor response to three loading doses of anti-vascular endothelial growth factor

PURPOSE

To evaluate the predictive factors of neovascular age-related macular degeneration (nAMD) with poor response to three loading doses of intravitreal bevacizumab (IVB).

METHODS

A retrospective cohort study was performed on nAMD patients three loading IVB initial treatment. The patients were divided into two groups, without residual fluid on optical coherence tomography (OCT) images (Group 1) and with residual fluid (Group 2). Demographic data, OCT findings, and morphological features of macular neovascularization (MNV) in optical coherence tomography angiography (OCTA) were recorded.

RESULTS

The study included one hundred thirty-six eyes of 120 patients (Group 1: n = 66 eyes, Group 2: n = 70 eyes). Central macular thickness, presence of intraretinal fluid, subretinal fluid, hyperreflective foci-band, pigment epithelial detachment (PED), and prechoroidal cleft were similar between the two groups. Pre-injection central choroidal thickness (CCT) was 214.17 ± 50.28 µm in Group 1 and 247.40 ± 60.55 µm in Group 2 (p = 0.021). PED width (p = 0.028) and PED area (p = 0.042) were statistically significantly higher in Group 1. When the morphology of MNV in OCTA was examined, branching (p = 0.736), loops (p = 0.442), peripheral arcade (p = 0.600), hypointense halo (p = 0.779), sea fan (p = 0.250), medusa (p = 0.255), pruned vascular tree pattern (p = 0.148), capillary fringe (p = 0.683) were similar in both groups. The presence of a closed circuit pattern was significantly higher in Group 2 (p = 0.028).

CONCLUSION

Initial CCT and closed circuit pattern MNV were higher in IVB-resistant cases. It was observed that PEDs with large bases and areas responded significantly better to loading therapy. The presence of a closed-circuit pattern was an independent risk factor for poor response to loading therapy. Retrospectively registered.

REGISTRATION NUMBER

2011-KAEK-25 2023/05-08.

Structural OCT and OCT angiography biomarkers associated with the development and progression of geographic atrophy in AMD

BACKGROUND

Geographic atrophy (GA) is an advanced, irreversible, and progressive form of age-related macular degeneration (AMD). Structural optical coherence tomography (OCT) and OCT angiography (OCTA) have been largely used to characterize this stage of AMD and, more importantly, to define biomarkers associated with the development and progression of GA in AMD.

METHODS

Articles pertaining to OCT and OCTA biomarkers related to the development and progression of GA with relevant key words were used to search in PubMed, Researchgate, and Google Scholar. The articles were selected based on their relevance, reliability, publication year, published journal, and accessibility.

RESULTS

Previous reports have highlighted various OCT and OCTA biomarkers linked to the onset and advancement of GA. These biomarkers encompass characteristics such as the size, volume, and subtype of drusen, the presence of hyperreflective foci, basal laminar deposits, incomplete retinal pigment epithelium and outer retinal atrophy (iRORA), persistent choroidal hypertransmission defects, and the existence of subretinal drusenoid deposits (also referred to as reticular pseudodrusen). Moreover, biomarkers associated with the progression of GA include thinning of the outer retina, photoreceptor degradation, the distance between retinal pigment epithelium and Bruch's membrane, and choriocapillaris loss.

CONCLUSION

The advent of novel treatment strategies for GA underscores the heightened need for prompt diagnosis and precise monitoring of individuals with this condition. The utilization of structural OCT and OCTA becomes essential for identifying distinct biomarkers associated with the initiation and progression of GA.

Longitudinal Evaluation of the Distribution of Intraretinal Hyper-Reflective Foci in Eyes with Intermediate Age-Related Macular Degeneration

PURPOSE

Intraretinal hyper-reflective foci (IHRF) are optical coherence tomography (OCT) risk factors for progression of age-related macular degeneration (AMD). In this study we assess the change in the number and distribution of IHRF over two years.

METHODS

The axial distribution of IHRF were quantified in eyes with intermediate AMD (iAMD) at baseline and 24 months, using a series of 5 sequential equidistant en face OCT retinal slabs generated between the outer border of the internal limiting membrane (ILM) and the inner border of the retinal pigment epithelium (RPE). Following thresholding and binarization, IHRF were quantified in each retinal slab using ImageJ. The change in IHRF number in each slab between baseline and month 24 was calculated.

RESULTS

Fifty-two eyes showed evidence of IHRF at baseline, and all continued to show evidence of IHRF at 24 months (M24). The total average IHRF count/eye increased significantly from 4.67 ± 0.63 at baseline to 11.62 ± 13.86 at M24 (p < 0.001) with a mean increase of 6.94 ± 11.12 (range: - 9 to + 60). Overall, at M24, 76.9% eyes showed an increase in IHRF whereas 15.4% of eyes showed a decrease (3 eyes [5.7%] showed no change). There was a greater number of IHRF and a greater increase in IHRF over M24 in the outer slabs.

CONCLUSIONS

IHRF are most common in the outer retinal layers and tend to increase in number over time. The impact of the distribution and frequency of these IHRF on the overall progression of AMD requires further study.

AI-based support for optical coherence tomography in age-related macular degeneration

Artificial intelligence (AI) has emerged as a transformative technology across various fields, and its applications in the medical domain, particularly in ophthalmology, has gained significant attention. The vast amount of high-resolution image data, such as optical coherence tomography (OCT) images, has been a driving force behind AI growth in this field. Age-related macular degeneration (AMD) is one of the leading causes for blindness in the world, affecting approximately 196 million people worldwide in 2020. Multimodal imaging has been for a long time the gold standard for diagnosing patients with AMD, however, currently treatment and follow-up in routine disease management are mainly driven by OCT imaging. AI-based algorithms have by their precision, reproducibility and speed, the potential to reliably quantify biomarkers, predict disease progression and assist treatment decisions in clinical routine as well as academic studies. This review paper aims to provide a summary of the current state of AI in AMD, focusing on its applications, challenges, and prospects.

Targeted High-Density Microperimetry Testing of Nascent Geographic Atrophy in Age-Related Macular Degeneration

Purpose

To examine the effectiveness of a targeted high-density microperimetry testing strategy for detecting visual sensitivity abnormalities in eyes with nascent geographic atrophy (nGA) when compared with standard central microperimetry testing.

Design

Observational study.

Participants

Three-hundred and twenty-one eyes from 176 individuals with nonneovascular age-related macular degeneration (AMD).

Methods

Thirty-five eyes from 33 participants underwent targeted high-density microperimetry testing of atrophic lesions (either nGA or geographic atrophy [GA]) within a 1.75° radius (or approximately 1000 μm diameter) region. Another cohort of 286 eyes from 143 participants with bilateral large drusen at baseline underwent standard microperimetry testing of the central 6° radius region at 6-monthly intervals for up to 36 months and thus included eyes that developed nGA and GA over the follow-up. All eyes underwent 2 tests at each visit to evaluate intrasession measurement repeatability.

Main Outcome Measures

Magnitude of visual sensitivity abnormalities based on mean sensitivity (MS), pointwise sensitivity standard deviation (PSD), and the number of test locations with a threshold of ≤ 10 decibels (dB; or deep defects) in eyes with nGA, compared between eyes that underwent targeted high-density microperimetry testing and standard central microperimetry testing.

Results

The magnitude of visual sensitivity abnormalities based on MS, PSD and the number of deep defects were all significantly greater in eyes with nGA using targeted, high-density microperimetry testing compared with eyes with nGA using standard central microperimetry testing (all P < 0.001) and were all significantly less than eyes with GA using targeted, high-density microperimetry testing (all P ≤ 0.004). The intrasession coefficient of repeatability, where 95% of the test-retest differences are expected to occur, for MS in eyes with atrophic changes was 0.9 dB with the targeted, high-density microperimetry testing, and 1.8 dB with standard central microperimetry testing.

Conclusions

Targeted, high-density microperimetry testing enabled the detection of a significantly greater magnitude of visual sensitivity abnormalities in eyes with nGA than standard microperimetry testing.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Assessment of intraretinal hyperreflective foci using multimodal imaging in eyes with age-related macular degeneration

PURPOSE

This study aimed to investigate the correspondence between intraretinal hyperreflective foci (IHRF) identified on optical coherence tomography (OCT) B-scans with hyperpigmentation on colour fundus photography (CFP) or hyperreflectivity on infrared reflectance (IR) images in eyes with age-related macular degeneration (AMD).

METHODS

Flash CFP, IR images and OCT B-scans obtained at the same visit were evaluated. Individual IHRF identified on OCT B-scans were assessed for the qualitative presence or absence of a hypotransmission tail into the choroid. The corresponding IR image obtained at the time of OCT acquisition was analysed for the presence or absence of hyperreflectivity in this region. The IR images were manually registered to the CFP image, and CFP images were inspected for the presence or absence of hyperpigmentation at the location of IHRF.

RESULTS

From 122 eyes, a total of 494 IHRF were evaluated. For the primary analysis of qualitative presence or absence of hyperpigmentation on CFP and hyperreflectivity on IR at the locations corresponding to IHRF on OCT, 301 (61.0%) of the IHRFs demonstrated evidence of hyperpigmentation on CFP, while only 115 (23.3%) showed evidence of hyperreflectivity on IR. The qualitative determination of the presence or absence of an abnormality on CFP or IR were significantly different (p < 0.0001). 327 (66.2%) of the IHRF showed hypotransmission, and 80.4% of these IHRF showed hyperpigmentation on CFP, though only 23.9% (p < 0.0001) demonstrated hyperreflectivity on IR.

CONCLUSIONS

Less than two-thirds of IHRF evident on OCT manifest as hyperpigmentation on colour photos, though IHRF with posterior shadowing are more likely to be evident as pigment. IR imaging appears to be even more poorly sensitive for visualizing IHRF.

Spatial Analysis Reveals Vascular Changes in Retinal and Choroidal Vessel Perfusion in Intermediate AMD With Reticular Pseudodrusen

Purpose

To examine the effect of reticular pseudodrusen (RPD) on retinal and choroidal vessel perfusion (VP) topography in intermediate age-related macular degeneration (iAMD) using refined spatial analyses.

Methods

This was a retrospective cross-sectional study of 120 individuals with 30 iAMDRPD, 60 iAMDno_RPD, and 30 normal eyes, propensity-score matched by age, sex, and presence of cardiovascular-related disease. VP of the superficial and deep retinal and choriocapillaris vascular slabs was assessed from 6 × 6-mm optical coherence tomography angiography (OCTA) scans divided into 126 × 126 grids, with adjustment for various person- and eye-level factors. Grid-wise VP differences (%) among the groups were spatially assessed according to analyses based on the Early Treatment for Diabetic Retinopathy Study (ETDRS), eccentricity (µm), and degree (°).

Results

VP was significantly decreased between iAMDRPD and iAMDno_RPD, across all vascular slabs in various ETDRS sectors (up to -2.16%; 95% confidence interval, -2.99 to -1.34; P < 0.05). Eccentricity analyses revealed more complex patterns: a bisegmented relationship where VP in iAMDRPD eyes decreased linearly toward 1000 µm then returned toward similar values as iAMDno_RPD, plateauing around 2000 µm in the superficial and 3000 µm in the deep retina (R2 = 0.57-0.9; P < 0.001). Degree-based analysis further showed that the greatest VP differences in iAMDRPD eyes were commonly located superiorly and nasally across all vascular slabs (P < 0.05).

Conclusions

RPD appears to compound the vascular impact of iAMD, displaying complex spatial patterns beyond the ETDRS sectors. This highlights the importance of considering spatial delineations for future work regarding the role of RPD and vascular dysfunction.

Relationship between the distribution of intra-retinal hyper-reflective foci and the progression of intermediate age-related macular degeneration

PURPOSE

To assess the relationship between the distribution of intra-retinal hyper-reflective foci (IHRF) on optical coherence tomography (OCT) and progression of intermediate age-related macular degeneration (iAMD) over 2 years.

METHODS

Cirrus OCT volumes of the macula of subjects enrolled in the Amish Eye Study with 2 years of follow-up were evaluated for the presence of iAMD and IHRF at baseline. The IHRF were counted in a series of 5 sequential en face slabs from outer to inner retina. The number of IHRF in each slab at baseline and the change in IHRF from baseline to year 2 were correlated with progression to late AMD at 2 years.

RESULTS

Among 120 eyes from 71 patients with iAMD, 52 eyes (43.3%) of 42 patients had evidence of both iAMD and IHRF at baseline. Twenty-three eyes (19.0%) showed progression to late AMD after 2 years. The total IHRF count increased from 243 at baseline to 604 at 2 years, with a significant increase in the IHRF number in each slab, except for the innermost slab 5 which had no IHRF at baseline or follow-up. The IHRF count increased from 121 to 340 in eyes that showed progression to late AMD. The presence of IHRF in the outermost retinal slabs 1 and 2 was independently associated with a significant risk of progression to late AMD. A greater increase in IHRF count over 2 years in these same slabs 1 and 2 was also associated with a higher risk of conversion to late AMD.

CONCLUSIONS

The risk of progression to late AMD appears to be significantly associated with the distribution and extent of IHRF in the outermost retinal layers. This observation may point to significant pathophysiologic differences of IHRF in inner versus outer layers of the retina.

A Deep-Learning Algorithm to Predict Short-Term Progression to Geographic Atrophy on Spectral-Domain Optical Coherence Tomography

Importance

The identification of patients at risk of progressing from intermediate age-related macular degeneration (iAMD) to geographic atrophy (GA) is essential for clinical trials aimed at preventing disease progression. DeepGAze is a fully automated and accurate convolutional neural network-based deep learning algorithm for predicting progression from iAMD to GA within 1 year from spectral-domain optical coherence tomography (SD-OCT) scans.

Objective

To develop a deep-learning algorithm based on volumetric SD-OCT scans to predict the progression from iAMD to GA during the year following the scan.

Design, Setting, and Participants

This retrospective cohort study included participants with iAMD at baseline and who either progressed or did not progress to GA within the subsequent 13 months. Participants were included from centers in 4 US states. Data set 1 included patients from the Age-Related Eye Disease Study 2 AREDS2 (Ancillary Spectral-Domain Optical Coherence Tomography) A2A study (July 2008 to August 2015). Data sets 2 and 3 included patients with imaging taken in routine clinical care at a tertiary referral center and associated satellites between January 2013 and January 2023. The stored imaging data were retrieved for the purpose of this study from July 1, 2022, to February 1, 2023. Data were analyzed from May 2021 to July 2023.

Exposure

A position-aware convolutional neural network with proactive pseudointervention was trained and cross-validated on Bioptigen SD-OCT volumes (data set 1) and validated on 2 external data sets comprising Heidelberg Spectralis SD-OCT scans (data sets 2 and 3).

Main Outcomes and Measures

Prediction of progression to GA within 13 months was evaluated with area under the receiver-operator characteristic curves (AUROC) as well as area under the precision-recall curve (AUPRC), sensitivity, specificity, positive predictive value, negative predictive value, and accuracy.

Results

The study included a total of 417 patients: 316 in data set 1 (mean [SD] age, 74 [8]; 185 [59%] female), 53 in data set 2, (mean [SD] age, 83 [8]; 32 [60%] female), and 48 in data set 3 (mean [SD] age, 81 [8]; 32 [67%] female). The AUROC for prediction of progression from iAMD to GA within 1 year was 0.94 (95% CI, 0.92-0.95; AUPRC, 0.90 [95% CI, 0.85-0.95]; sensitivity, 0.88 [95% CI, 0.84-0.92]; specificity, 0.90 [95% CI, 0.87-0.92]) for data set 1. The addition of expert-annotated SD-OCT features to the model resulted in no improvement compared to the fully autonomous model (AUROC, 0.95; 95% CI, 0.92-0.95; P = .19). On an independent validation data set (data set 2), the model predicted progression to GA with an AUROC of 0.94 (95% CI, 0.91-0.96; AUPRC, 0.92 [0.89-0.94]; sensitivity, 0.91 [95% CI, 0.74-0.98]; specificity, 0.80 [95% CI, 0.63-0.91]). At a high-specificity operating point, simulated clinical trial recruitment was enriched for patients progressing to GA within 1 year by 8.3- to 20.7-fold (data sets 2 and 3).

Conclusions and Relevance

The fully automated, position-aware deep-learning algorithm assessed in this study successfully predicted progression from iAMD to GA over a clinically meaningful time frame. The ability to predict imminent GA progression could facilitate clinical trials aimed at preventing the condition and could guide clinical decision-making regarding screening frequency or treatment initiation.

Longitudinal evaluation of the distribution of intraretinal hyper-reflective foci in eyes with intermediate age-related macular degeneration

Purpose

Intraretinal hyper-reflective foci (IHRF) are optical coherence tomography (OCT) risk factors for progression of age-related macular degeneration (AMD). In this study we assess the change in the number and distribution of IHRF over two years.

Methods

The axial distribution of IHRF were quantified in eyes with intermediate AMD (iAMD) at baseline and 24 months, using a series of 5 sequential equidistant en face OCT retinal slabs generated between the outer border of the internal limiting membrane (ILM) and the inner border of the retinal pigment epithelium (RPE). Following thresholding and binarization, IHRF were quantified in each retinal slab using ImageJ. The change in IHRF number in each slab between baseline and month 24 was calculated.

Results

Fifty-two eyes showed evidence of IHRF at baseline, and all continued to show evidence of IHRF at 24 months (M24). The total average IHRF count/eye increased significantly from 4.67 ± 0.63 at baseline to 11.62 ± 13.86 at M24 (p<0.001) with a mean increase of 6.94 ± 11.12 (range: - 9 to + 60). Overall, at M24, 76.9% eyes showed an increase in IHRF whereas 15.4% of eyes showed a decrease (4 eyes [7.6%] showed no change). There was a greater number of IHRF and a greater increase in IHRF over M24 in the outer slabs.

Conclusions

IHRF are most common in the outer retinal layers and tend to increase in number over time. The impact of the distribution and frequency of these IHRF on the overall progression of AMD requires further study.

Spatial Cluster Patterns of Retinal Sensitivity Loss in Intermediate Age-Related Macular Degeneration Features

Purpose

To examine spatial patterns of retinal sensitivity loss in the three key features of intermediate age-related macular degeneration (iAMD).

Methods

One-hundred individuals (53 iAMD, 47 normal) underwent 10-2 mesopic microperimetry testing in one eye. Pointwise sensitivities (dB) were corrected for age, sex, iAMD status, and co-presence of co-localized key iAMD features: drusen load, pigmentary abnormalities, and reticular pseudodrusen (RPD). Clusters (labeled by ranks of magnitude C-2, C-1, C0) were derived from pointwise sensitivities and then assessed by quadrants and eccentricity/rings.

Results

Two clusters of decreased sensitivities were evident in iAMD versus normal: C-2, -1.67 dB (95% CI (confidence intervals), -2.36 to -0.98; P < 0.0001); C-1, -0.93 dB (95% CI, -1.5 to -0.36; P < 0.01). One cluster of decreased sensitivity was independently associated each with increased drusen load (13.57 µm increase per -1 dB; P < 0.0001), pigmentary abnormalities (C-1: -2.23 dB; 95% CI, -3.36 to -1.1; P < 0.01), and RPD (C-1: -1.07 dB; 95% CI, -2 to -0.14; P < 0.01). Sensitivity loss in iAMD was biased toward the superior and central macula (P = 0.16 to <0.0001), aligning with structural distributions of features. However, sensitivity loss associated with drusen load also extended to the peripheral macula (P < 0.0001) with paracentral sparing, which was discordant with the central distribution of drusen.

Conclusions

Drusen load, pigmentary abnormalities, and RPD are associated with patterns of retinal sensitivity loss commonly demonstrating superior and central bias. Results highlighted that a clinical focus on these three key iAMD features using structural measures alone does not capture the complex, spatial extent of vision-related functional impairment in iAMD.

Translational Relevance

Defining the spatial patterns of retinal sensitivity loss in iAMD can facilitate a targeted visual field protocol for iAMD assessment.

Deep survival modeling of longitudinal retinal OCT volumes for predicting the onset of atrophy in patients with intermediate AMD

In patients with age-related macular degeneration (AMD), the risk of progression to late stages is highly heterogeneous, and the prognostic imaging biomarkers remain unclear. We propose a deep survival model to predict the progression towards the late atrophic stage of AMD. The model combines the advantages of survival modelling, accounting for time-to-event and censoring, and the advantages of deep learning, generating prediction from raw 3D OCT scans, without the need for extracting a predefined set of quantitative biomarkers. We demonstrate, in an extensive set of evaluations, based on two large longitudinal datasets with 231 eyes from 121 patients for internal evaluation, and 280 eyes from 140 patients for the external evaluation, that this model improves the risk estimation performance over standard deep learning classification models.

Deep Learning to Predict Geographic Atrophy Area and Growth Rate from Multimodal Imaging

OBJECTIVE

To develop deep learning models for annualized geographic atrophy (GA) growth rate prediction using fundus autofluorescence (FAF) images and spectral-domain OCT volumes from baseline visits, which can be used for prognostic covariate adjustment to increase power of clinical trials.

DESIGN

This retrospective analysis estimated GA growth rate as the slope of a linear fit on all available measurements of lesion area over a 2-year period. Three multitask deep learning models-FAF-only, OCT-only, and multimodal (FAF and OCT)-were developed to predict concurrent GA area and annualized growth rate.

PARTICIPANTS

Patients were from prospective and observational lampalizumab clinical trials.

METHODS

The 3 models were trained on the development data set, tested on the holdout set, and further evaluated on the independent test sets. Baseline FAF images and OCT volumes from study eyes of patients with bilateral GA (NCT02247479; NCT02247531; and NCT02479386) were split into development (1279 patients/eyes) and holdout (443 patients/eyes) sets. Baseline FAF images from study eyes of NCT01229215 (106 patients/eyes) and NCT02399072 (169 patients/eyes) were used as independent test sets.

MAIN OUTCOME MEASURES

Model performance was evaluated using squared Pearson correlation coefficient (r²) between observed and predicted lesion areas/growth rates. Confidence intervals were calculated by bootstrap resampling (B = 10 000).

RESULTS

On the holdout data set, r² (95% confidence interval) of the FAF-only, OCT-only, and multimodal models for GA lesion area prediction was 0.96 (0.95-0.97), 0.91 (0.87-0.95), and 0.94 (0.92-0.96), respectively, and for GA growth rate prediction was 0.48 (0.41-0.55), 0.36 (0.29-0.43), and 0.47 (0.40-0.54), respectively. On the 2 independent test sets, r² of the FAF-only model for GA lesion area was 0.98 (0.97-0.99) and 0.95 (0.93-0.96), and for GA growth rate was 0.65 (0.52-0.75) and 0.47 (0.34-0.60).

CONCLUSIONS

We show the feasibility of using baseline FAF images and OCT volumes to predict individual GA area and growth rates using a multitask deep learning approach. The deep learning-based growth rate predictions could be used for covariate adjustment to increase power of clinical trials.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Hyper-Reflective Foci in Intermediate Age-Related Macular Degeneration: Spatial Abundance and Impact on Retinal Morphology

Purpose

The purpose of this study was to analyze spatially resolved structural changes at retinal locations in presence (+) or absence (-) of hyper-reflective foci (HRF) in eyes with subretinal pigment epithelium (RPE) drusen in intermediate age-related macular degeneration (iAMD).

Methods

Patients with IAMD (n = 40; mean age = 69.7 ± 9.2 [SD] years) and healthy controls (n = 27; 64.2 ± 9.0) underwent spectral-domain optical-coherence-tomography imaging and fundus-controlled perimetry testing. After reviewing retinal layer segmentation, presence of HRF was annotated and retinal layer thicknesses (RLTs) extracted using ImageJ. Localized RLTs were compared between +HRF and -HRF positions. Univariate mixed linear models were used to investigate associations among RLT, HRF presence, and HRF size.

Results

In iAMD eyes, a mean of 11.1 ± 12.5 HRF were detected with a peak abundance at 0.5 to 1.5 mm eccentricity to the fovea. At +HRF positions, outer nuclear layer (ONL; P = 0.0013, average difference = -12.4 µm) and retinal pigment epithelium drusen complex (RPEDC; P < 0.0001, +45.6 µm) thicknesses differed significantly compared to -HRF positions, even after correcting for accompanying drusen-related RPEDC layer thickening (P = 0.01). Mixed linear models revealed a significant association between increasing HRF area and decreasing ONL (association score = -0.17, P < 0.0001; 95% confidence interval [CI] = -0.22 to -0.11), and inner photoreceptor segments (IS) layer thicknesses (-0.08, P = 0.005; 95% CI = -0.14 to -0.03). Spearman rank correlation analysis yielded a significant correlation between total HRF area and mesopic (P = 0.015), but not scotopic (P = 0.305) retinal sensitivity losses.

Conclusions

Descriptive analysis of this study demonstrated a predominant distribution of HRF at a foveal eccentricity of 0.5 to 1.5 mm, whereas further refined topographic analysis revealed a significant ONL layer thinning in presence of HRF even after correction for sub-RPE drusen presence compared to lesions in absence of HRF. Longitudinal studies are further needed to analyze the prognostic impact as well as the role of HRF presence in the context of iAMD.

Automated Region of Interest Selection Improves Deep Learning-Based Segmentation of Hyper-Reflective Foci in Optical Coherence Tomography Images

Hyperreflective foci (HRF) have been associated with retinal disease progression and demonstrated as a negative prognostic biomarker for visual function. Automated segmentation of HRF in retinal optical coherence tomography (OCT) scans can be beneficial to identify the formation and movement of the HRF biomarker as a retinal disease progresses and can serve as the first step in understanding the nature and severity of the disease. In this paper, we propose a fully automated deep neural network based HRF segmentation model in OCT images. We enhance the model's performance by using a patch-based strategy that increases the model's compute on the HRF pixels. The patch-based strategy is evaluated against state of the art HRF segmentation pipelines on clinical retinal image data. Our results shows that the patch-based approach demonstrates a high precision score and intersection over union (IOU) using a ResNet34 segmentation model with Binary Cross Entropy loss function. The HRF segmentation pipeline can be used for analyzing HRF biomarkers for different retinopathies.

Hyperreflective Foci in Age-Related Macular Degeneration are Associated with Disease Severity and Functional Impairment

PURPOSE

To analyze presence of hyperreflective foci (HRF) across different age-related macular degeneration (AMD) severities and examine its correlation with other structural and functional AMD features.

DESIGN

Longitudinal, single-center, case-control study.

PARTICIPANTS

One hundred and fifty-eight participants aged > 50 years old with varying AMD severities (including no AMD).

METHODS

Color fundus imaging was used to assess AMD severity and hyperpigmentation (PGM) presence. Subretinal drusenoid deposits (SDD) and HRF were detected on OCT volumes. The correlations of HRF with additional AMD features were evaluated using linear and logistic mixed-effects models. One study eye per participant underwent dark adaptation (DA) testing to measure rod intercept time (RIT) for structure function associations. Eyes were followed longitudinally and changes in AMD severity and RIT were measured relative to HRF presence.

MAIN OUTCOME MEASURES

The primary outcome was presence of HRF, which was compared with presence of other AMD features and DA impairment.

RESULTS

One hundred and fifty-eight participants (median baseline age of 73.1 [interquartile range (IQR) = 66-79] years) contributing 1277 eye visits were included. Hyperreflective foci (HRF) were detected more frequently in higher AMD severities. Hyperreflective-foci presence was significantly associated with PGM presence (odds ratio 832.9, P < 0.001) and SDD presence (odds ratio 9.42, P = 0.017). Eyes with HRF demonstrated significantly longer DA (median 27.1 [IQR = 16-40] minutes) than those without HRF (13.5 [10-22] minutes) but less than eyes with SDD only (40 [28-40] minutes). Highest RIT values were found in eyes with both HRF and SDD (40.0 [40-40] minutes). Age and HRF explained a similar proportion of RIT variability as age and SDD. Eyes that developed HRF demonstrated baseline RITs closer to eyes with HRF at baseline, compared with eyes that never developed HRF (29.1 [16-40], 38.5 [22-40] versus 13.1 [10-22] minutes; Kruskal-Wallis P < 0.001).

CONCLUSIONS

The progressively increased presence of HRF in higher AMD severities, and its correlation with previously associated AMD biomarkers, suggests HRF is an important OCT feature adding to the understanding of disease progression. Hyperreflective foci presence was associated with delays in DA, indicating HRF is a marker for visual cycle impairment.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosure may be found after the references.

Impact of Reticular Pseudodrusen on Choriocapillaris Flow Deficits and Choroidal Structure on Optical Coherence Tomography Angiography

PURPOSE

To examine the impact of reticular pseudodrusen (RPD) on choriocapillaris blood flow and choroidal structure in individuals with intermediate age-related macular degeneration (AMD).

METHODS

Individuals with bilateral large drusen underwent optical coherence tomography (OCT), color fundus photography, near-infrared reflectance, and fundus autofluorescence imaging to determine the presence of RPD. These participants also underwent swept-source OCT angiography (SS-OCTA) imaging to determine (1) choriocapillaris flow deficit (FD) parameters, including the percentage, mean size, and number of FDs present; and (2) choroidal structural parameters, including mean choroidal thickness and choroidal vascularity index. Differences in these parameters between eyes with and without coexistent RPD were examined with and without adjustment for potential key confounders such as drusen volume from the SS-OCTA scans and age.

RESULTS

This study included 102 eyes from 51 individuals with bilateral large drusen, and the analyses showed that there were no significant differences in the choriocapillaris FD parameters (P ≥ 0.062 for all) and choroidal structural parameters (P ≥ 0.059 for all), with or without adjustment for potential confounders in this cohort. However, the percentage of FDs and the mean FD size were both significantly greater with increasing drusen volume (P ≤ 0.038 for both).

CONCLUSIONS

The coexistence of RPD in eyes of individuals with intermediate AMD was not associated with significant impairments in choriocapillaris blood flow and choroidal vascular structural changes, with or without adjustment for key confounders. These findings suggest that macular changes in these vascular parameters may not be associated with the presence of RPD.

The Fovea-Protective Impact of Double-Layer Sign in Eyes With Foveal-Sparing Geographic Atrophy and Age-Related Macular Degeneration

Purpose

The purpose of this study was to investigate the impact of double-layer sign (DLS) on geographic atrophy (GA) progression in eyes with foveal-sparing GA and age-related macular degeneration (AMD).

Methods

This is a retrospective, consecutive case series of eyes with foveal-sparing GA secondary to AMD with more than 6 months of follow-up. The size of the foveal-sparing area was measured on the fundus autofluorescence images at the first and last visits. Each eye was evaluated for the presence or absence of DLS inside the foveal-sparing area. We graded eyes based on the presence of DLS within the foveal-sparing area and compared the progression of GA between two groups (DLS (+) versus DLS (-)).

Results

We identified 25 eyes with foveal-sparing GA with at least 2 follow-up visits (average interval = 22.7 ± 11.8 months between visits). The mean foveal sparing area was 1.74 ± 0.87 mm2 (range = 0.42-4.14 mm2) at baseline and 1.26 ± 0.75 mm2 (range = 0.25-2.92 mm2) at the last visit. Seventeen eyes (65.3%) were graded as DLS (+) within the foveal-sparing area. Square root progression of GA toward the fovea was significantly faster in the DLS (-) eyes (0.149 ± 0.078 mm/year) compared to the DLS (+) group (0.088 ± 0.052 mm/year; P = 0.04).

Conclusions

The DLS (-) group showed significantly faster centripetal GA progression than the DLS (+) group. Our data suggest that the presence of DLS in the spared foveal area could be a protective factor against foveal progression of GA in eyes with AMD.

Reticular Pseudodrusen Are Associated With More Advanced Para-Central Photoreceptor Degeneration in Intermediate Age-Related Macular Degeneration

Purpose

The purpose of this study was to examine retinal topographical differences between intermediate age-related macular degeneration (iAMD) with reticular pseudodrusen (RPD) versus iAMD without RPD, using high-density optical coherence tomography (OCT) cluster analysis.

Methods

Single eyes from 153 individuals (51 with iAMD+RPD, 51 with iAMD, and 51 healthy) were propensity-score matched by age, sex, and refraction. High-density OCT grid-wise (60 × 60 grids, each approximately 0.01 mm2 area) thicknesses were custom-extracted from macular cube scans, then compared between iAMD+RPD and iAMD eyes with correction for confounding factors. These "differences (µm)" were clustered and results de-convoluted to reveal mean difference (95% confidence interval [CI]) and topography of the inner retina (retinal nerve fiber, ganglion cell, inner plexiform, and inner nuclear layers) and outer retina (outer plexiform/Henle's fiber/outer nuclear layers, inner and outer segments, and retinal pigment epithelium-to-Bruch's membrane [RPE-BM]). Differences were also converted to Z-scores using normal data.

Results

In iAMD+RPD compared to iAMD eyes, the inner retina was thicker (up to +5.89 [95% CI = +2.44 to +9.35] µm, P < 0.0001 to 0.05), the outer para-central retina was thinner (up to -3.21 [95% CI = -5.39 to -1.03] µm, P < 0.01 to 0.001), and the RPE-BM was thicker (+3.38 [95% CI = +1.05 to +5.71] µm, P < 0.05). The majority of effect sizes (Z-scores) were large (-3.13 to +1.91).

Conclusions

OCT retinal topography differed across all retinal layers between iAMD eyes with versus without RPD. Greater para-central photoreceptor thinning in RPD eyes was suggestive of more advanced degeneration, whereas the significance of inner retinal thickening was unclear. In the future, quantitative evaluation of photoreceptor thicknesses may help clinicians monitor the potential deleterious effects of RPD on retinal integrity.

Fundus autofluorescence and optical coherence tomography biomarkers associated with the progression of geographic atrophy secondary to age-related macular degeneration

OBJECTIVES

To investigate the impact of qualitatively graded and deep learning quantified imaging biomarkers on growth of geographic atrophy (GA) secondary to age-related macular degeneration.

METHODS

This prospective study included 1062 visits of 181 eyes of 100 patients with GA. Spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) images were acquired at each visit. Hyperreflective foci (HRF) were quantitatively assessed in SD-OCT volumes using a validated deep learning algorithm. FAF images were graded for FAF patterns, subretinal drusenoid deposits (SDD), GA lesion configuration and atrophy enlargement. Linear mixed models were calculated to investigate associations between all parameters and GA progression.

RESULTS

FAF patterns were significantly associated with GA progression (p < 0.001). SDD was associated with faster GA growth (p = 0.005). Eyes with higher HRF concentrations showed a trend towards faster GA progression (p = 0.072) and revealed a significant impact on GA enlargement in interaction with FAF patterns (p = 0.01). The fellow eye status had no significant effect on lesion enlargement (p > 0.05). The diffuse-trickling FAF pattern exhibited significantly higher HRF concentrations than any other pattern (p < 0.001).

CONCLUSION

Among a wide range of investigated biomarkers, SDD and FAF patterns, particularly in interaction with HRF, significantly impact GA progression. Fully automated quantification of retinal imaging biomarkers such as HRF is both reliable and merited as HRF are indicators of retinal pigment epithelium dysmorphia, a central pathogenetic mechanism in GA. Identifying disease markers using the combination of FAF and SD-OCT is of high prognostic value and facilitates individualized patient management in a clinical setting.

Depth-resolved visualization and automated quantification of hyperreflective foci on OCT scans using optical attenuation coefficients

An automated depth-resolved algorithm using optical attenuation coefficients (OACs) was developed to visualize, localize, and quantify hyperreflective foci (HRF) seen on OCT imaging that are associated with macular hyperpigmentation and represent an increased risk of disease progression in age related macular degeneration. To achieve this, we first transformed the OCT scans to linear representation, which were then contrasted by OACs. HRF were visualized and localized within the entire scan by differentiating HRF within the retina from HRF along the retinal pigment epithelium (RPE). The total pigment burden was quantified using the en face sum projection of an OAC slab between the inner limiting membrane (ILM) to Bruch's membrane (BM). The manual total pigment burden measurements were also obtained by combining manual outlines of HRF in the B-scans with the total area of hypotransmission defects outlined on sub-RPE slabs, which was used as the reference to compare with those obtained from the automated algorithm. 6×6 mm swept-source OCT scans were collected from a total of 49 eyes from 42 patients with macular HRF. We demonstrate that the algorithm was able to automatically distinguish between HRF within the retina and HRF along the RPE. In 24 test eyes, the total pigment burden measurements by the automated algorithm were compared with measurements obtained from manual segmentations. A significant correlation was found between the total pigment area measurements from the automated and manual segmentations (P < 0.001). The proposed automated algorithm based on OACs should be useful in studying eye diseases involving HRF.

Reticular Pseudodrusen on the Risk of Progression in Intermediate Age-Related Macular Degeneration

PURPOSE

To examine the association between reticular pseudodrusen (RPD) and progression to late age-related macular degeneration (AMD) in individuals with intermediate AMD.

DESIGN

Prospective cohort study.

METHODS

Two hundred eighty eyes from 140 participants with bilateral large drusen underwent multimodal imaging (MMI), including optical coherence tomography (OCT), near-infrared reflectance (NIR), fundus autofluorescence, and color fundus photography (CFP), at 6-monthly intervals up over a 36-month follow-up period. The presence of RPD per eye was determined based on either a combined MMI criterion, or each individual imaging modality, and their extent measured on combined OCT and NIR imaging. The association between the presence of RPD on different imaging modalities, and their extent, with the development of late AMD (including OCT-defined atrophy) was evaluated.

RESULTS

The presence of RPD on MMI, or any of its individual modalities, at baseline was not significantly associated with an increased rate of developing late AMD, with or without adjusting for risk factors for AMD progression (age, drusen volume on OCT, and pigmentary abnormalities on CFP; all P ≥ 0.205). The extent of RPD present was also not significantly associated with an increased rate of developing late AMD, with or without adjustment for risk factors for AMD progression (both P ≥ 0.522).

CONCLUSIONS

In this cohort with bilateral large drusen, the presence of RPD was not significantly associated with an increased risk of developing late AMD. Additional longitudinal studies in all stages of AMD are needed to understand the implications of RPD on vision loss in this condition.

High-Density Optical Coherence Tomography Analysis Provides Insights Into Early/Intermediate Age-Related Macular Degeneration Retinal Layer Changes

Purpose

To topographically map all of the thickness differences in individual retinal layers between early/intermediate age-related macular degeneration (AMDearly/AMDint) and normal eyes and to determine interlayer relationships.

Methods

Ninety-six AMDtotal (48 AMDearly and 48 AMDint) and 96 normal eyes from 192 participants were propensity-score matched by age, sex, and refraction. Retrospective optical coherence tomography (OCT) macular cube scans were acquired, and high-density (60 × 60 0.01-mm2) grid thicknesses were custom extracted for comparison between AMDtotal and normal eyes corrected for confounding. Resultant "normal differences" underwent cluster, interlayer correlation, and dose-response analyses for the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL+HFL), inner and outer segment (IS/OS) thickness, and retinal pigment epithelium (RPE) to Bruch's membrane (BM) thickness.

Results

AMDtotal inner retinal clusters demonstrated extensively thinned RNFL, GCL, IPL, and paracentral INL and thickened INL elsewhere, with normal difference means ranging from -8.13 µm (95% confidence interval [CI], -11.12 to -5.13) to 1.58 µm (95% CI, 1.07-2.09) (P < 0.0001 to P < 0.05). Outer retinal clusters displayed thinned paracentral OPL/ONL+HFL, central IS/OS, and peripheral RPE-BM and thickened central RPE-BM, with means ranging from -1.31 µm (95% CI, -2.06 to -0.55) to 2.99 µm (95% CI, 0.97-5.01] (P < 0.0001 to P <0.05). Effect sizes (-2.56 to 9.93 SD), cluster sizes, and eccentricity effects varied. All interlayer correlations were negligible to moderate regardless of AMD severity. Only the RPE-BM was partly thicker with greater AMD severity (up to 5.44 µm; 95% CI, 4.88-6.00; P < 0.01).

Conclusions

From the early stage, AMD eyes demonstrate thickness differences compared to normal with unique topographies across all retinal layers. Poor interlayer correlations highlight that the outer retina inadequately reflects complete retinal health. The clinical importance of OCT assessment across all individual retinal layers in early/intermediate AMD requires further investigation.

Intersession Repeatability of Structural Biomarkers in Early and Intermediate Age-Related Macular Degeneration: A MACUSTAR Study Report

Purpose

To analyze the intersession repeatability of structural biomarkers in eyes with early and intermediate age-related macular degeneration (iAMD) within the cross-sectional part of the observational multicenter MACUSTAR study.

Methods

Certified site personnel obtained multimodal imaging data at two visits (38 ± 20 [mean ± standard deviation] days apart), including spectral-domain optical coherence tomography (SD-OCT). One junior reader performed systematic and blinded grading at the central reading center, followed by senior reader review. Structural biomarkers included maximum drusen size classification (>63 to ≤125 µm vs. >125 µm), presence of large pigment epithelium detachments (PEDs), reticular pseudodrusen (RPD), vitelliform lesions, and refractile deposits. Intrasession variability was assessed using Cohen's κ statistics.

Results

At the first visit, 202 study eyes of 202 participants were graded as manifesting with either early (n = 34) or intermediate (n = 168) AMD. Grading of imaging data between visits revealed perfect agreement for the maximum drusen size classification (κ = 0.817; 95% confidence interval, 0.70–0.94). In iAMD eyes, perfect to substantial agreement was determined for the presence of large PEDs (0.87; 0.69–1.00) and RPD (0.752; 0.63–0.87), while intersession agreement was lower for the presence of vitelliform lesions (0.649; 0.39–0.65) and refractile deposits (0.342; −0.029–0.713), respectively.

Conclusions

Multimodal retinal imaging analysis between sessions showed a higher repeatability for structural biomarkers with predefined cutoff values than purely qualitative defined parameters.

Translational Relevance

A high repeatability of retinal imaging biomarkers will be important to implement automatic grading approaches and to establish robust and meaningful structural clinical endpoints for future interventional clinical trials in patients with iAMD.

Dark Adaptation and Its Role in Age-Related Macular Degeneration

Dark adaptation (DA) refers to the slow recovery of visual sensitivity in darkness following exposure to intense or prolonged illumination, which bleaches a significant amount of the rhodopsin. This natural process also offers an opportunity to understand cellular function in the outer retina and evaluate for presence of disease. How our eyes adapt to darkness can be a key indicator of retinal health, which can be altered in the presence of certain diseases, such as age-related macular degeneration (AMD). A specific focus on clinical aspects of DA measurement and its significance to furthering our understanding of AMD has revealed essential findings underlying the pathobiology of the disease. The process of dark adaptation involves phototransduction taking place mainly between the photoreceptor outer segments and the retinal pigment epithelial (RPE) layer. DA occurs over a large range of luminance and is modulated by both cone and rod photoreceptors. In the photopic ranges, rods are saturated and cone cells adapt to the high luminance levels. However, under scotopic ranges, cones are unable to respond to the dim luminance and rods modulate the responses to lower levels of light as they can respond to even a single photon. Since the cone visual cycle is also based on the Muller cells, measuring the impairment in rod-based dark adaptation is thought to be particularly relevant to diseases such as AMD, which involves both photoreceptors and RPE. Dark adaptation parameters are metrics derived from curve-fitting dark adaptation sensitivities over time and can represent specific cellular function. Parameters such as the cone-rod break (CRB) and rod intercept time (RIT) are particularly sensitive to changes in the outer retina. There is some structural and functional continuum between normal aging and the AMD pathology. Many studies have shown an increase of the rod intercept time (RIT), i.e., delays in rod-mediated DA in AMD patients with increasing disease severity determined by increased drusen grade, pigment changes and the presence of subretinal drusenoid deposits (SDD) and association with certain morphological features in the peripheral retina. Specifications of spatial testing location, repeatability of the testing, ease and availability of the testing device in clinical settings, and test duration in elderly population are also important. We provide a detailed overview in light of all these factors.

Multimodal assessments of drusenoid pigment epithelial detachments in the Age-Related Eye Disease Study 2 Ancillary (A2A) spectral-domain optical coherence tomography (SD-OCT) study cohort

PURPOSE

To identify features correlating with drusenoid pigment epithelial detachment (DPED) progression in the AREDS2 Ancillary (A2A) spectral-domain optical coherence tomography (SD-OCT) study cohort.

METHODS

In this retrospective analysis of a prospective longitudinal study, eyes with intermediate age-related macular degeneration (AMD) and DPEDs were followed longitudinally with annual multimodal imaging.

RESULTS

Thirty-one eyes of 25 participants (mean age 72.6 years) in the A2A AREDS2 substudy had DPED identified in color fundus images. SD-OCT inspection confirmed a sub-retinal pigment epithelium drusenoid elevation of ≥433 µm diameter in 25 (80.6%) eyes. Twenty-four of these eyes were followed longitudinally (median 4.0 years) during which 7 eyes (29.2%) underwent DPED collapse (with 3/7 further progressing to geographic atrophy), 6 (25.0%) developing neovascular AMD, and 11 (45.8%) maintaining DPED persistence without late AMD. On Kaplan-Meier analysis, mean time to DPED collapse was 3.9 years. Both DPED collapse and progression to neovascular AMD were preceded by the presence of hyperreflective foci over the DPED.

CONCLUSION

The natural history of DPED comprises: collapse - sometimes followed by the development of atrophy, vascularization followed by exudation, or DPED persistence. SD-OCT can confirm RPE elevation caused by drusenoid accumulation and facilitate the identification of high-risk features that correlate with progression.

Long-Term Analysis of Clinical Features and Treatment Outcomes of Inflammatory Choroidal Neovascularization

PURPOSE

To investigate the long-term clinical features and treatment outcomes of patients with inflammatory choroidal neovascularization (CNV) treated with intravitreal anti-vascular endothelial growth factor (anti-VEGF).

DESIGN

Retrospective, interventional, consecutive case series.

METHODS

Sixty-five eyes of 65 patients with inflammatory CNV treated with anti-VEGF injections and followed up at least 12 months were included. Retrospective chart review was conducted at a single tertiary referral center.

RESULTS

Study participants were followed up for 60.6 ± 42.8 (range, 16-160) months. Mean age was 33.4 ± 10.8 years, and mean refractive error was -3.94 ± 1.35 D in spherical equivalent. Final best-corrected visual acuity (BCVA) was 0.21 ± 0.20 logMAR after treatment. Patients were treated with bevacizumab (76.9%), ranibizumab (4.6%), aflibercept (3.1%), and drug combinations (15.4%). Systemic corticosteroid or immunosuppressant use was not correlated with visual outcome, required number of anti-VEGF injections, and recurrence. Commonly occurring optical coherence tomography (OCT) features included ellipsoid zone disruption, choroidal hypertransmission, retinal pigment epithelium atrophy or absence (RPEA), intraretinal hyperreflective foci (HRF), choroidal vessel engorgement, focal choroidal excavation, and irregular vascular loops (on OCT angiography). RPEA after treatment (β = 0.238, P = .036) and BCVA (β = 0.267, P = .029) showed significant correlation with final BCVA. A total of 28 patients (43.1%) experienced recurrence; intraretinal HRF after treatment was the single risk factor for recurrence (odds ratio = 2.712, P = .031).

CONCLUSIONS

Inflammatory CNV recurrence showed higher rates over time after anti-VEGF treatment than previously reported, even though the overall visual outcome was good. Baseline BCVA and RPEA after treatment are significant predictors for visual outcome. Intraretinal HRF after anti-VEGF treatment suggests the potential risk of recurrence.

Risk Classification for Progression to Subfoveal Geographic Atrophy in Dry Age-Related Macular Degeneration Using Machine Learning-Enabled Outer Retinal Feature Extraction

BACKGROUND AND OBJECTIVE

To evaluate the utility of spectral-domain optical coherence tomography biomarkers to predict the development of subfoveal geographic atrophy (sfGA).

PATIENTS AND METHODS

This was a retrospective cohort analysis including 137 individuals with dry age-related macular degeneration without sfGA with 5 years of follow-up. Multiple spectral-domain optical coherence tomography quantitative metrics were generated, including ellipsoid zone (EZ) integrity and subretinal pigment epithelium (sub-RPE) compartment features.

RESULTS

Reduced mean EZ-RPE central subfield thickness and increased sub-RPE compartment thickness were significantly different between sfGA convertors and nonconvertors at baseline in both 2-year and 5-year sfGA risk assessment. Longitudinal change assessment showed a significantly higher degradation of EZ integrity in sfGA convertors. The predictive performance of a machine learning classification model based on 5-year and 2-year risk conversion to sfGA demonstrated an area under the receiver operating characteristic curve of 0.92 ± 0.06 and 0.96 ± 0.04, respectively.

CONCLUSIONS

Quantitative outer retinal and sub-RPE feature assessment using a machine learning-enabled retinal segmentation platform provides multiple parameters that are associated with progression to sfGA. [Ophthalmic Surg Lasers Imaging. 2022;53:31-39.].

Significance of Hyperreflective Foci as an Optical Coherence Tomography Biomarker in Retinal Diseases: Characterization and Clinical Implications

Hyperreflective foci (HRF) is a term coined to depict hyperreflective dots or roundish lesions within retinal layers visualized through optical coherence tomography (OCT). Histopathological correlates of HRF are not univocal, spacing from migrating retinal pigment epithelium cells, lipid-laden macrophages, microglial cells, and extravasated proteinaceous or lipid material. Despite this, HRF can be considered OCT biomarkers for disease progression, treatment response, and prognosis in several retinal diseases, including diabetic macular edema, age-related macular degeneration (AMD), retinal vascular occlusions, and inherited retinal dystrophies. The structural features and topographic location of HRF guide the interpretation of their significance in different pathological conditions. The presence of HRF less than 30 μm with reflectivity comparable to the retinal nerve fiber layer in the absence of posterior shadowing in diabetic macular edema indicates an inflammatory phenotype with a better response to steroidal treatment. In AMD, HRF overlying drusen are associated with the development of macular neovascularization, while parafoveal drusen and HRF predispose to macular atrophy. Thus, HRF can be considered a key biomarker in several common retinal diseases. Their recognition and critical interpretation via multimodal imaging are vital to support clinical strategies and management.

Retinal Progression Biomarkers of Early and Intermediate Age-Related Macular Degeneration

Early and intermediate AMD patients represent a heterogeneous population with an important but variable risk of progression to more advanced stages of the disease. The five-year progression from early and intermediate AMD to late disease is known to range from 0.4% to 53%. This wide variation explains the particular interest in searching predictive AMD biomarkers. Clinical parameters such as drusen size, presence of pigmentary abnormalities, and fellow eye status were, traditionally, the more important predictive elements. Multimodal retinal assessment (Color Fundus Photography, Optical Coherence Tomography, Optical Coherence Angiography and Fundus Autofluorescence) is providing new and accurate image biomarkers, useful in research and in daily practice. If individual progression risk could be anticipated, then management plans should be adapted accordingly, considering follow-up intervals and therapeutic interventions. Here, we reviewed the most important image progression biomarkers of early and intermediate AMD with relevant interest in clinical practice.

Should clinical automated perimetry be considered for routine functional assessment of early/intermediate age-related macular degeneration (AMD)? A systematic review of current literature

Purpose

There is growing interest in functional testing for early/intermediate age‐related macular degeneration (iAMD). However, systematic evaluation of existing clinical functional tests is lacking. This systematic review examines evidence for using clinical automated perimetry in routine assessment of early/iAMD.

Recent findings

PubMed, Web of Science Core Collection, and Embase were searched from inception to October 2020 to answer, is there evidence of visual field defects in early/iAMD, and if so, are early/iAMD visual field defects linked to real‐world patient outcomes? Articles using clinical automated perimetry (commercially accessible and non‐modified devices/protocols) were included. Microperimetry was excluded as this has yet to be incorporated into clinical guidelines. The primary outcome was global visual field indices including mean deviation (MD), pattern standard deviation (PSD), mean sensitivity (MS) and frequency of defects. The secondary outcome was any real‐world patient outcome including quality of life and/or activities of daily living indices. Twenty‐six studies were eligible for inclusion and all studies were observational. There was consistent evidence of worsened MD, PSD, MS and frequency of defects for early/iAMD compared to normal eyes under photopic, low‐photopic and scotopic conditions. Meta‐analysis of studies using standard automated perimetry (SAP) under photopic conditions revealed worsened MD (−1.52dB [−2.27, −0.78 dB]) and MS (−1.47dB [−2, −0.94 dB]) in early/iAMD compared to normal eyes, representing large statistical effect sizes but non‐clinically meaningful reductions. There was insufficient data for meta‐analyses regarding other clinical automated perimetry protocols. Only one study assessed a real‐world patient outcome (on‐road driving performance), with no significant link to visual field outcomes in early/iAMD.

Summary

Significant reduction of global visual field indices is present in early/iAMD, but not clinically meaningful using SAP under photopic conditions. Translational relevance of visual field outcomes to patient outcomes in early/iAMD remains unclear. Thus, SAP under photopic conditions is unlikely to be useful for routine assessment of early/iAMD.

Reticular pseudodrusen: A critical phenotype in age-related macular degeneration

Reticular pseudodrusen (RPD), or subretinal drusenoid deposits (SDD), refer to distinct lesions that occur in the subretinal space. Over the past three decades, their presence in association with age-related macular degeneration (AMD) has become increasingly recognized, especially as RPD have become more easily distinguished with newer clinical imaging modalities. There is also an increasing appreciation that RPD appear to be a critical AMD phenotype, where understanding their pathogenesis will provide further insights into the processes driving vision loss in AMD. However, key barriers to understanding the current evidence related to the independent impact of RPD include the heterogeneity in defining their presence, and failure to account for the confounding impact of the concurrent presence and severity of AMD pathology. This review thus critically discusses the current evidence on the prevalence and clinical significance of RPD and proposes a clinical imaging definition of RPD that will help move the field forward in gathering further key knowledge about this critical phenotype. It also proposes a putative mechanism for RPD formation and how they may drive progression to vision loss in AMD, through examining current evidence and presenting novel findings from preclinical and clinical studies.

Low-Reflectivity Drusen With Overlying RPE Damage Revealed by Spectral-Domain OCT: Hint for the Development of Age-Related Macular Degeneration

Purpose: To observe the relationship between the characteristic changes in the drusen morphology revealed by the spectral-domain optical coherence tomography (SD-OCT) and the progression of age-related macular degeneration (AMD). Methods: A total of 380 drusen in 45 eyes in 35 patients with the intermediate drusen were longitudinally followed up every 6 months by SD-OCT for a period of 24 months. The drusen were divided into the dynamic group and stable group according to the following parameters: number, volume, concurrent retinal pigment epithelium (RPE)/ellipsoid zone (EZ) damage, and the development of advanced AMD. The morphological characteristics of the progressive or stable drusen were further analyzed. Odds ratios (ORs) and the risk for the drusen progression were calculated. Results: The level of interobserver and intraobserver agreement for each drusen tomographic morphological parameters ranged from 82.7 to 90%. At the end of an average follow-up of 15.92 ± 6.99 months, six patients developed choroidal neovascularization and no patients developed geographic atrophy. Finally, 139 drusen changed and 241 drusen remained stable. The drusen with low reflectivity (p < 0.001; OR: 5.26; 95% CI: 2.24-12.36), non-homogeneity without a core (p < 0.001; OR: 4.31; 95% CI: 2.08-8.92), RPE damage (p < 0.001; OR: 28.12; 95% CI: 9.43-83.85), and the EZ damage (p < 0.001; OR: 14.01; 95% CI: 5.28-37.18) were significantly associated with active change; the drusen with low reflectivity (p = 0.01; OR: 2.95; 95% CI: 1.29-6.75) and decreased overlying RPE reflectivity (p < 0.001; OR: 21.67; 95% CI: 9.20-51.02) were the independent predictors for progression. The drusen with high reflectivity were significantly associated with stabilization (p = 0.03; OR: 0.17; 95% CI: 0.04-0.84). Conclusion: Spectral-domain optical coherence tomography is an optimized, accurate, and efficient method to follow-up the drusen. The intermediate non-exudative AMD prognosis of the patient was most strongly correlated with the drusen reflectivity and disruption of the overlying RPE layer. The drusen with low reflectivity and overlying RPE damage were more likely to progress and required frequent follow-up.

Location-Specific Thickness Patterns in Intermediate Age-Related Macular Degeneration Reveals Anatomical Differences in Multiple Retinal Layers

Purpose

To examine individual retinal layers’ location-specific patterns of thicknesses in intermediate age-related macular degeneration (iAMD) using optical coherence tomography (OCT).

Methods

OCT macular cube scans were retrospectively acquired from 84 iAMD eyes of 84 participants and 84 normal eyes of 84 participants propensity-score matched on age, sex, and spherical equivalent refraction. Thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL_+HFL), inner- and outer-segment layers (IS/OS), and retinal pigment epithelium to Bruch's membrane (RPE-BM) were calculated across an 8 × 8 grid (total 24° × 24° area). Location-specific analysis was performed using cluster_(normal) and grid_(iAMD)-to-cluster_(normal) comparisons.

Results

In iAMD versus normal eyes, the central RPE-BM was thickened (mean difference ± SEM up to 27.45% ± 7.48%, P < 0.001; up to 7.6 SD-from-normal), whereas there was thinned outer (OPL, ONL_+HFL, and non-central RPE-BM, up to −6.76% ± 2.47%, P < 0.001; up to −1.6 SD-from-normal) and inner retina (GCL and IPL, up to −4.83% ± 1.56%, P < 0.01; up to −1.7 SD-from-normal) with eccentricity-based effects. Interlayer correlations were greater against the ONL_+HFL (mean |r| ± SEM 0.19 ± 0.03, P = 0.14 to < 0.0001) than the RPE-BM (0.09 ± 0, P = 0.72 to < 0.0001).

Conclusions

Location-specific analysis suggests altered retinal anatomy between iAMD and normal eyes. These data could direct clinical diagnosis and monitoring of AMD toward targeted locations.

Joint segmentation of multi-class hyper-reflective foci in retinal optical coherence tomography images

Hyper-reflective foci (HRF) refers to the spot-shaped, block-shaped areas with characteristics of high local contrast and high reflectivity, which is mostly observed in retinal optical coherence tomography (OCT) images of patients with fundus diseases. HRF mainly appears hard exudates (HE) and microglia (MG) clinically. Accurate segmentation of HE and MG is essential to alleviate the harm in retinal diseases. However, it is still a challenge to segment HE and MG simultaneously due to similar pathological features, various shapes and location distribution, blurred boundaries, and small morphology dimensions. To tackle these problems, in this paper, we propose a novel global information fusion and dual decoder collaboration-based network (GD-Net), which can segment HE and MG in OCT images jointly. Specifically, to suppress the interference of similar pathological features, a novel global information fusion (GIF) module is proposed, which can aggregate the global semantic information efficiently. To further improve the segmentation performance, we design a dual decoder collaborative workspace (DDCW) to comprehensively utilize the semantic correlation between HE and MG while enhancing the mutual influence on them by feedback alternately. To further optimize GD-Net, we explore a joint loss function which integrates pixel-level with image-level. The dataset of this study comes from patients diagnosed with diabetic macular edema at the department of ophthalmology, University Medical Center Groningen, the Netherlands. Experimental results show that our proposed method performs better than other state-of-the-art methods, which suggests the effectiveness of the proposed method and provides research ideas for medical applications.

Biomarkers for Nonexudative Age-Related Macular Degeneration and Relevance for Clinical Trials: A Systematic Review

TOPIC

The purpose of the review was to identify structural, functional, blood-based, and other types of biomarkers for early, intermediate, and late nonexudative stages of age-related macular degeneration (AMD) and summarize the relevant data for proof-of-concept clinical trials.

CLINICAL RELEVANCE

AMD is a leading cause of blindness in the aging population, yet no treatments exist for its most common nonexudative form. There are limited data on the diagnosis and progression of nonexudative AMD compared to neovascular AMD. Our objective was to provide a comprehensive, systematic review of recently published biomarkers (molecular, structural, and functional) for early AMD, intermediate AMD, and geographic atrophy and to evaluate the relevance of these biomarkers for use in future clinical trials.

METHODS

A literature search of PubMed, ScienceDirect, EMBASE, and Web of Science from January 1, 1996 to November 30, 2020 and a patent search were conducted. Search terms included "early AMD," "dry AMD," "intermediate AMD," "biomarkers for nonexudative AMD," "fundus autofluorescence patterns," "color fundus photography," "dark adaptation," and "microperimetry." Articles were assessed for bias and quality with the Mixed-Methods Appraisal Tool. A total of 94 articles were included (61,842 individuals).

RESULTS

Spectral-domain optical coherence tomography was superior at highlighting detailed structural changes in earlier stages of AMD. Fundus autofluorescence patterns were found to be most important in estimating progression of geographic atrophy. Delayed rod intercept time on dark adaptation was the most widely recommended surrogate functional endpoint for early AMD, while retinal sensitivity on microperimetry was most relevant for intermediate AMD. Combinational studies accounting for various patient characteristics and machine/deep-learning approaches were best suited for assessing individualized risk of AMD onset and progression.

CONCLUSION

This systematic review supports the use of structural and functional biomarkers in early AMD and intermediate AMD, which are more reproducible and less invasive than the other classes of biomarkers described. The use of deep learning and combinational algorithms will gain increasing importance in future clinical trials of nonexudative AMD.

Imaging and artificial intelligence for progression of age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of severe vision loss. With our aging population, it may affect 288 million people globally by the year 2040. AMD progresses from an early and intermediate dry form to an advanced one, which manifests as choroidal neovascularization and geographic atrophy. Conversion to AMD-related exudation is known as progression to neovascular AMD, and presence of geographic atrophy is known as progression to advanced dry AMD. AMD progression predictions could enable timely monitoring, earlier detection and treatment, improving vision outcomes. Machine learning approaches, a subset of artificial intelligence applications, applied on imaging data are showing promising results in predicting progression. Extracted biomarkers, specifically from optical coherence tomography scans, are informative in predicting progression events. The purpose of this mini review is to provide an overview about current machine learning applications in artificial intelligence for predicting AMD progression, and describe the various methods, data-input types, and imaging modalities used to identify high-risk patients. With advances in computational capabilities, artificial intelligence applications are likely to transform patient care and management in AMD. External validation studies that improve generalizability to populations and devices, as well as evaluating systems in real-world clinical settings are needed to improve the clinical translations of artificial intelligence AMD applications.

Intraretinal, sub-retinal, and sub-retinal pigmented epithelium fluid in non-exudative age-related macular degeneration: follow-up with OCT imaging

BACKGROUND/OBJECTIVES

To evaluate the presence and evolution of fluid in non-exudative age-related macular degeneration (AMD) through serial OCT.

SUBJECTS/METHODS

A retrospective analysis of eyes with non-exudative AMD with a minimum of 4 year follow-up was done. Parameters including intraretinal fluid (IRF), subretinal fluid (SRF), and sub-retinal pigment epithelium (RPE) fluid (SRPEF); subfoveal choroidal thickness (SFCT) and type of drusen were evaluated using optical coherence tomography (OCT) scans at baseline and follow up visits.

RESULTS

Seventy-two eyes (in 63 patients) were followed up for an average of 5.83 ± 2.17 years. A total of 26/72 (36%) and 29/65 (52%) of the non-exudative eyes had fluid during baseline and the last visit. Seven eyes (10%) out of 72 eyes converted into exudative AMD or neo-vascular AMD (nAMD) during the study period. SRPEF at baseline was most common fluid location for non-exudative eyes that eventually converted to nAMD.

CONCLUSION

Non-exudative fluid including IRF, SRF, and SRPEF is seen in patients with non-exudative AMD with increasing incidence during long term follow-up.

COMPARISON OF SINGLE DRUSEN SIZE ON COLOR FUNDUS PHOTOGRAPHY AND SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To determine the relationship of drusen size as determined by spectral-domain optical coherence tomography (SD-OCT) with that measured on registered color fundus photography (CFP) images and to derive an OCT-based classification system that was comparable with that determined by CFP.

METHODS

Custom software was developed to register CFP images to the scanning laser ophthalmoscopy fundus images obtained simultaneously with the corresponding SD-OCT images, so that individual drusen observed on CFP could be matched with those seen on SD-OCT. Single druse size (diameter, area, volume, and height) on CFP and SD-OCT images from a phase two clinical trial was determined with the Duke OCT Retinal Analysis Program.

RESULTS

The sizes of 213 individual drusen were measured on CFP and SD-OCT. The drusen diameter measured on CFP was significantly correlated with those determined on SD-OCT (R: 0.879, P < 0.001). Based on the corresponding formula: drusen diameter on SD-OCT = 0.77 × (drusen diameter on CFP) + 50.67 µm, large drusen defined as ≥125 µm on CFP had a diameter ≥145 µm on OCT, medium drusen defined as 63 µm to 124 µm on CFP had diameters 100 µm to 144 µm on OCT, and small drusen defined as <63 µm on CFP had diameters <100 µm on OCT.

CONCLUSION

With our registration software and imaging processing algorithms, we were able to correlate individual druse sizes measured on CFP with those determined on SD-OCT. These data can be used to develop an SD-OCT-based grading scale, analogous to the CFP Age-Related Eye Disease Study drusen scale that may be useful in the clinic and in clinical trials.

Lipid accumulation and protein modifications of Bruch's membrane in age-related macular degeneration

Age-related macular degeneration (AMD) is a progressive retinal disease, which is the leading cause of blindness in western countries. There is an urgency to establish new therapeutic strategies that could prevent or delay the progression of AMD more efficiently. Until now, the pathogenesis of AMD has remained unclear, limiting the development of the novel therapy. Bruch's membrane (BM) goes through remarkable changes in AMD, playing a significant role during the disease course. The main aim of this review is to present the crucial processes that occur at the level of BM, with special consideration of the lipid accumulation and protein modifications. Besides, some therapies targeted at these molecules and the construction of BM in tissue engineering of retinal pigment epithelium (RPE) cells transplantation were listed. Hopefully, this review may provide a reference for researchers engaged in pathogenesis or management on AMD.

Measuring the Contributions of Basal Laminar Deposit and Bruch's Membrane in Age-Related Macular Degeneration

Purpose

Basal laminar deposit (BLamD) is a consistent finding in age-related macular degeneration (AMD). We quantified BLamD thickness, appearance, and topography in eyes of aged donors with and without AMD and evaluated its relationship to other components of the retinal pigment epithelium-basal lamina/Bruch's membrane (RPE-BL-BrM) complex.

Methods

Donor eyes (n = 132) were classified as normal (n = 54), early to intermediate AMD (n = 24), geographic atrophy (GA; n = 13), and neovascular AMD (NV; n = 41). In high-resolution histology, we assessed RPE, BLamD, and BrM thicknesses and phenotypes at 3309 predefined locations in the central (foveal and perifovea) and superior (perifoveal) sections. Pre-mortem optical coherence tomography (OCT) imaging of a 90-year-old woman was compared to postmortem histopathology.

Results

In non-atrophic areas of AMD eyes, the RPE-BLamD is thick (normal = 13.7 µm, early-intermediate = 16.8 µm, GA = 17.4 µm, NV = 18.7 µm), because the BLamD is thick (normal = 0.3 µm, early-intermediate = 5.5 µm, GA = 4.1 µm, NV = 5.3 µm). RPE layer thickness is similar across these stages. Disease-associated variants of BLamD (thick, late, basal mounds) cluster subfoveally. A thick BLamD is visible on OCT as a hyporeflective split in the RPE-BL-BrM complex. BrM is thin (3.5 µm) in NV (normal = 4.2 µm, early to intermediate = 4.4 µm, and GA = 4.2 µm).

Conclusions

The RPE-BL-BrM complex is thick in AMD, driven by the accumulation and expansion of BLamD rather than expansion of either three-layer BrM, RPE-BL, or RPE. BLamD is clinically appreciable by OCT in some patients as a non-neovascular "split RPE-BL-BrM complex" or "double-layer sign." BLamD may contribute toward the formation and progression of high-risk drusen yet also exhibit protective properties.

Radial Peripapillary Capillary Plexus Sparing and Underlying Retinal Vascular Impairment in Intermediate Age-Related Macular Degeneration

Purpose

To examine location-specific retinal vascular changes in intermediate age-related macular degeneration (iAMD) using age-matched, high-density en face optical coherence tomography angiography (OCTA) cluster analysis.

Methods

En face OCTA images of the 6 × 6 mm macular area were retrospectively acquired from 60 iAMD eyes and 60 age-matched normal eyes and then subdivided into 126 × 126 (47.62 × 47.62 µm) grids within the superficial and deep vascular complex. Grid-wise vessel perfusion (VP) were compared between iAMD and normal eyes from the corresponding 10-yearly age cohort, forming difference plots. Difference plots were further separated by normative topographical map spatial clusters (C_1-6), derived from normal_database eyes (n = 236, 20–81 years old).

Results

Overall difference plots showed decreased VP in the superficial (−12.19%) and deep vascular complex (−6.44%) of iAMD compared to normal eyes (P < 0.0001 both comparisons). Cluster-based difference plots highlighted nonuniform changes in the superficial vascular complex, with sparing of VP at the nasal macula (corresponding to the radial peripapillary capillary plexus) versus decreased VP toward the temporal macula and foveal avascular zone (FAZ) (C_1–6 all comparisons P < 0.0001, except C₁ vs. C₂P > 0.99 and C₄ vs. C₅P = 0.11). The deep vascular complex displayed diffusely decreased VP, greater at the FAZ (P < 0.0001).

Conclusions

High-density en face OCTA cluster analysis suggests relative sparing of the radial peripapillary capillary plexus and impairment of underlying retinal vasculature, supporting potential anterograde transsynaptic degeneration in iAMD. These location-specific data may better guide future diagnostic and management protocol of iAMD.

Spatio-temporal alterations in retinal and choroidal layers in the progression of age-related macular degeneration (AMD) in optical coherence tomography

Age-related macular degeneration (AMD) is the predominant cause of vision loss in the elderly with a major impact on ageing societies and healthcare systems. A major challenge in AMD management is the difficulty to determine the disease stage, the highly variable progression speed and the risk of conversion to advanced AMD, where irreversible functional loss occurs. In this study we developed an optical coherence tomography (OCT) imaging based spatio-temporal reference frame to characterize the morphologic progression of intermediate age-related macular degeneration (AMD) and to identify distinctive patterns of conversion to the advanced stages macular neovascularization (MNV) and macular atrophy (MA). We included 10,040 OCT volumes of 518 eyes with intermediate AMD acquired according to a standardized protocol in monthly intervals over two years. Two independent masked retina specialists determined the time of conversion to MNV or MA. All scans were aligned to a common reference frame by intra-patient and inter-patient registration. Automated segmentations of retinal layers and the choroid were computed and en-face maps were transformed into the common reference frame. Population maps were constructed in the subgroups converting to MNV (n=135), MA (n=50) and in non-progressors (n=333). Topographically resolved maps of changes were computed and tested for statistical significant differences. The development over time was analysed by a joint model accounting for longitudinal and right-censoring aspect. Significantly enhanced thinning of the outer nuclear layer (ONL) and retinal pigment epithelium (RPE)–photoreceptorinner segment/outer segment (PR-IS/OS) layers within the central 3 mm and a faster thinning speed preceding conversion was documented for MA progressors. Converters to MNV presented an accelerated thinning of the choroid and appearance changes in the choroid prior to MNV onset. The large-scale automated image analysis allowed us to distinctly assess the progression of morphologic changes in intermediate AMD based on conventional OCT imaging. Distinct topographic and temporal patterns allow to prospectively determine eyes with risk of progression and thereby greatly improving early detection, prevention and development of novel therapeutic strategies.

Reliability of Retinal Pathology Quantification in Age-Related Macular Degeneration: Implications for Clinical Trials and Machine Learning Applications

Purpose

To investigate the interreader agreement for grading of retinal alterations in age-related macular degeneration (AMD) using a reading center setting.

Methods

In this cross-sectional case series, spectral-domain optical coherence tomography (OCT; Topcon 3D OCT, Tokyo, Japan) scans of 112 eyes of 112 patients with neovascular AMD (56 treatment naive, 56 after three anti-vascular endothelial growth factor injections) were analyzed by four independent readers. Imaging features specific for AMD were annotated using a novel custom-built annotation platform. Dice score, Bland-Altman plots, coefficients of repeatability, coefficients of variation, and intraclass correlation coefficients were assessed.

Results

Loss of ellipsoid zone, pigment epithelium detachment, subretinal fluid, and drusen were the most abundant features in our cohort. Subretinal fluid, intraretinal fluid, hypertransmission, descent of the outer plexiform layer, and pigment epithelium detachment showed highest interreader agreement, while detection and measures of loss of ellipsoid zone and retinal pigment epithelium were more variable. The agreement on the size and location of the respective annotation was more consistent throughout all features.

Conclusions

The interreader agreement depended on the respective OCT-based feature. A selection of reliable features might provide suitable surrogate markers for disease progression and possible treatment effects focusing on different disease stages.

Translational Relevance

This might give opportunities for a more time- and cost-effective patient assessment and improved decision making as well as have implications for clinical trials and training machine learning algorithms.