Onset and Progression of Persistent Choroidal Hypertransmission Defects in Intermediate Age-Related Macular Degeneration: A Novel Clinical Trial Endpoint

Drug Approval for the Treatment of Geographic Atrophy: How We Got Here and Where We Need to Go

PURPOSE

To discuss the clinical trial results leading to the US Food and Drug Administration (FDA) approval of anti-complement therapies for geographic atrophy (GA), perspectives on functional data from the GA clinical trials, and how lessons from the FDA approval may guide future directions for basic and clinical research in AMD.

DESIGN

Selected literature review with analysis and perspective METHODS: We performed a targeted review of publicly available data from the clinical trials of pegcetacoplan and avacincaptad for the treatment of GA, as well as scientific literature on the natural history of GA and the genetics and basic science of complement in AMD.

RESULTS

The approval of pegcetacoplan and avacincaptad was based on an anatomic endpoint of a reduction in the rate of GA expansion over time. However, functional data from 2 phase 3 clinical trials for each drug demonstrated no visual benefit to patients in the treatment groups. Review of the genetics of AMD and the basic science of the role for complement in AMD provides only modest support for targeting complement as treatment for GA expansion, and alternative molecular targets for GA treatment are therefore discussed. Reasons for the disconnect between anatomic and functional outcomes in the clinical trials of anti-complement therapies are discussed, providing insight to guide the configuration of future clinical studies for GA.

CONCLUSION

Although avacincaptad and pegcetacoplan are our first FDA-approved treatments for GA, results from the clinical trials failed to show any functional improvement after 1 and 2 years, respectively, calling into question whether the drugs represent a "clinically relevant outcome." To improve the chances of more impactful therapies in the future, we provide basic-science rationale for pursuing non-complement targets; emphasize the importance of ongoing clinical research that more closely pins anatomic features of GA to functional outcomes; and provide suggestions for clinical endpoints for future clinical trials on GA.

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.

Quantitative Autofluorescence at AMD's Beginnings Highlights Retinal Topography and Grading System Differences: ALSTAR2 Baseline

INTRODUCTION

The aims of the study were to describe baseline quantitative (short-wavelength) autofluorescence (qAF) findings in a large pseudophakic cohort at age-related macular degeneration (AMD)'s beginnings and to assess qAF8 as an outcome measure and evaluate Age-Related Eye Disease Study (AREDS) and Beckman grading systems.

METHODS

In the ALSTAR2 baseline cohort (NCT04112667), 346 pseudophakic eyes of 188 persons (74.0 ± 5.5 years) were classified as normal (N = 160 by AREDS, 158 by Beckman), early AMD (eAMD) (N = 104, 66), and intermediate AMD (iAMD) (N = 82, 122). Groups were compared via mean qAF intensities in a 6°-8° annulus (qAF8) and maps of differences between observations and the overall mean, divided by standard deviation (Z-score).

RESULTS

qAF8 did not differ significantly among diagnostic groups by either stratification (p = 0.0869 AREDS; p = 0.0569 by Beckman). Notably, 45 eyes considered eAMD by AREDS became iAMD by Beckman. For AREDS-stratified eyes, Z-score maps showed higher centrally located qAF for normal, near the mean in eAMD, and lower values for iAMD. Maps deviated from this pattern for Beckman-stratified eyes.

CONCLUSIONS

In a large sample of pseudophakic eyes, qAF8 does not differ overall from normal aging to iAMD but also does not capture the earliest AMD activity in the macula lutea. AREDS classification gives results more consistent with a slow decline in histologic autofluorescence than Beckman classification.

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.

Non-Neovascular Age-Related Macular Degeneration Assessment: Focus on Optical Coherence Tomography Biomarkers

The imagistic evaluation of non-neovascular age-related macular degeneration (AMD) is crucial for diagnosis, monitoring progression, and guiding management of the disease. Dry AMD, characterized primarily by the presence of drusen and retinal pigment epithelium atrophy, requires detailed visualization of the retinal structure to assess its severity and progression. Several imaging modalities are pivotal in the evaluation of non-neovascular AMD, including optical coherence tomography, fundus autofluorescence, or color fundus photography. In the context of emerging therapies for geographic atrophy, like pegcetacoplan, it is critical to establish the baseline status of the disease, monitor the development and expansion of geographic atrophy, and to evaluate the retina's response to potential treatments in clinical trials. The present review, while initially providing a comprehensive description of the pathophysiology involved in AMD, aims to offer an overview of the imaging modalities employed in the evaluation of non-neovascular AMD. Special emphasis is placed on the assessment of progression biomarkers as discerned through optical coherence tomography. As the landscape of AMD treatment continues to evolve, advanced imaging techniques will remain at the forefront, enabling clinicians to offer the most effective and tailored treatments to their patients.

Association Between Quantitative and Qualitative Imaging Biomarkers and Geographic Atrophy Growth Rate

PURPOSE

Investigate associations between geographic atrophy (GA) growth rate and multimodal imaging biomarkers and patient demographics in patients with advanced non-neovascular age-related macular degeneration (nnAMD).

DESIGN

Prospective cohort study.

METHODS

One hundred twenty-one eyes of 66 patients with advanced nnAMD with GA enrolled in the University of Colorado AMD Registry from August 2014 to June 2021, with follow-up through June 2023. Multimodal images were reviewed by two graders for imaging biomarkers at enrollment. GA growth rate and square-root transformed (SQRT) GA growth rate were measured between enrollment and final visit. Associations between the outcome SQRT GA growth rate and imaging biomarkers, baseline GA lesions characteristics, and patient demographics were evaluated.

RESULTS

Average GA growth rate was 1.430 mm2/year and SQRT GA growth rate was 0.268 mm/year over a mean of 3.7 years. SQRT GA growth rate was positively associated with patient age (P = .010) and female sex (0.035), and negatively associated with body mass index (0.041). After adjustment for these demographic factors, SQRT GA growth rate was positively associated with presence of non-exudative subretinal fluid (P < .001), non-exudative subretinal hyperreflective material (P = .037), and incomplete retinal pigment epithelium and outer retina atrophy (P = .022), and negatively associated with subfoveal choroidal thickness (P = .031) and presence of retinal pseudocysts (P = .030). Larger baseline GA size at enrollment was associated with faster GA growth rate (P = .002) but not SQRT GA growth rate.

CONCLUSIONS

Select patient demographic factors and basic clinically-relevant imaging biomarkers were associated with GA growth rate. These biomarkers may guide patient selection when considering treating GA patients with novel therapeutics.

En Face and Volumetric Comparison of Hypertransmission Defects Evaluated by Cirrus and Spectralis Optical Coherence Tomography

PURPOSE

To evaluate and compare en face and 3-dimensional (3-D) properties of hypertransmission defects (HTDs) between different optical coherence tomography (OCT) devices using OCT volumes and reconstructed en face images.

SETTINGS

Comparative diagnostic evaluation study.

METHODS

Thirty eyes with dry age-related macular degeneration (AMD) that underwent dense OCT macular volume scans with both the Spectralis (97 B-scans/volume; 2910 B-scans in total) and Cirrus OCT (128 B-scans/volume; 3840 B-scans in total) from the Amish Eye Study cohort were included in this analysis. HTD regions were labeled on each B-scan and reconstructed into en face and 3-D volume images. Properties of HTD volume were compared between the 2 devices.

RESULTS

The qualitative score of en face images for HTD was higher for the Cirrus compared to the Spectralis (P < .01). The quality of Spectralis en face images improved after preprocessing and reconstruction. The 2-D HTD area on en face obtained from 2-D projections of 3-D volume did not differ between devices (P = .478, ICC = 0.998; Jaccard index 0.721 ± 0.086). There was no difference in the number, volume, PALs, and surface areas of HTDs between devices in the volumetric analysis (all P ≥ .090). The signal intensity of HTD normalized by the mean choroidal signal intensity did not differ between devices (P = .861).

CONCLUSIONS

The visualization of HTD on en face images from Spectralis OCT could be enhanced through image processing. The equivalence in 3-D HTD parameters between the 2 devices suggests interchangeability for assessing these lesions in AMD.

Choroidal signal hypertransmission on optical coherence tomography imaging: Association with development of geographic atrophy in age-related macular degeneration

BACKGROUND

To examine the association between large choroidal signal hypertransmission ≥250 μm (LHyperT) on optical coherence tomography (OCT) with the risk of developing geographic atrophy (GA) and compare this risk with those associated with nascent geographic atrophy (nGA).

METHODS

Two hundred and eighty eyes from 140 participants with bilateral large drusen and without late age-related macular degeneration (AMD) or nGA at baseline underwent OCT imaging and colour fundus photography (CFP) at 6-monthly intervals up to 5 years. OCT scans were graded for the presence of LHyperT and nGA, and CFPs were graded for the presence of GA.

RESULTS

The five-year incidence of LHyperT and nGA were 37% and 27% respectively (p = 0.003), and the two-year probability of their progression to GA were 17% and 40%, respectively (p = 0.002). LHyperT and nGA explained 81% and 91% of the variance in the time to develop GA, respectively (p = 0.032), and they were both associated with a significantly higher rate of GA development compared to eyes without these lesions (adjusted hazard ratio = 110.8 and 183.2, respectively; p < 0.001 for both).

CONCLUSIONS

LHyperT and nGA were both high-risk features for GA development, but the latter showed a higher rate of GA progression and explained a significantly greater proportion of the variance in the time to develop GA. As such, nGA may be a more robust surrogate endpoint than LHyperT for the conventional clinical endpoint of CFP-defined GA for intervention trials in the early stages of AMD.

Deep-learning-based automated measurement of outer retinal layer thickness for use in the assessment of age-related macular degeneration, applicable to both swept-source and spectral-domain OCT imaging

Effective biomarkers are required for assessing the progression of age-related macular degeneration (AMD), a prevalent and progressive eye disease. This paper presents a deep learning-based automated algorithm, applicable to both swept-source OCT (SS-OCT) and spectral-domain OCT (SD-OCT) scans, for measuring outer retinal layer (ORL) thickness as a surrogate biomarker for outer retinal degeneration, e.g., photoreceptor disruption, to assess AMD progression. The algorithm was developed based on a modified TransUNet model with clinically annotated retinal features manifested in the progression of AMD. The algorithm demonstrates a high accuracy with an intersection of union (IoU) of 0.9698 in the testing dataset for segmenting ORL using both SS-OCT and SD-OCT datasets. The robustness and applicability of the algorithm are indicated by strong correlation (r = 0.9551, P < 0.0001 in the central-fovea 3 mm-circle, and r = 0.9442, P < 0.0001 in the 5 mm-circle) and agreement (the mean bias = 0.5440 um in the 3-mm circle, and 1.392 um in the 5-mm circle) of the ORL thickness measurements between SS-OCT and SD-OCT scans. Comparative analysis reveals significant differences (P < 0.0001) in ORL thickness among 80 normal eyes, 30 intermediate AMD eyes with reticular pseudodrusen, 49 intermediate AMD eyes with drusen, and 40 late AMD eyes with geographic atrophy, highlighting its potential as an independent biomarker for predicting AMD progression. The findings provide valuable insights into the ORL alterations associated with different stages of AMD and emphasize the potential of ORL thickness as a sensitive indicator of AMD severity and progression.

Biomarkers for the Progression of Intermediate Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of severe vision loss worldwide, with a global prevalence that is predicted to substantially increase. Identifying early biomarkers indicative of progression risk will improve our ability to assess which patients are at greatest risk of progressing from intermediate AMD (iAMD) to vision-threatening late-stage AMD. This is key to ensuring individualized management and timely intervention before substantial structural damage. Some structural biomarkers suggestive of AMD progression risk are well established, such as changes seen on color fundus photography and more recently optical coherence tomography (drusen volume, pigmentary abnormalities). Emerging biomarkers identified through multimodal imaging, including reticular pseudodrusen, hyperreflective foci, and drusen sub-phenotypes, are being intensively explored as risk factors for progression towards late-stage disease. Other structural biomarkers merit further research, such as ellipsoid zone reflectivity and choriocapillaris flow features. The measures of visual function that best detect change in iAMD and correlate with risk of progression remain under intense investigation, with tests such as dark adaptometry and cone-specific contrast tests being explored. Evidence on blood and plasma markers is preliminary, but there are indications that changes in levels of C-reactive protein and high-density lipoprotein cholesterol may be used to stratify patients and predict risk. With further research, some of these biomarkers may be used to monitor progression. Emerging artificial intelligence methods may help evaluate and validate these biomarkers; however, until we have large and well-curated longitudinal data sets, using artificial intelligence effectively to inform clinical trial design and detect outcomes will remain challenging. This is an exciting area of intense research, and further work is needed to establish the most promising biomarkers for disease progression and their use in clinical care and future trials. Ultimately, a multimodal approach may yield the most accurate means of monitoring and predicting future progression towards vision-threatening, late-stage AMD.

Unleashing the power of optical attenuation coefficients to facilitate segmentation strategies in OCT imaging of age-related macular degeneration: perspective

The use of optical attenuation coefficients (OAC) in optical coherence tomography (OCT) imaging of the retina has improved the segmentation of anatomic layers compared with traditional intensity-based algorithms. Optical attenuation correction has improved our ability to measure the choroidal thickness and choroidal vascularity index using dense volume scans. Algorithms that combine conventional intensity-based segmentation with depth-resolved OAC OCT imaging have been used to detect elevations of the retinal pigment epithelium (RPE) due to drusen and basal laminar deposits, the location of hyperpigmentation within the retina and along the RPE, the identification of macular atrophy, the thickness of the outer retinal (photoreceptor) layer, and the presence of calcified drusen. OAC OCT algorithms can identify the risk-factors that predict disease progression in age-related macular degeneration.