Diagnosing Persistent Hyper-Transmission Defects on En Face OCT Imaging of Age-Related Macular Degeneration

Hyperreflective Foci Along the Retinal Pigment Epithelium Predict the Onset of Large Choroidal Hypertransmission Defects in Age-Related Macular Degeneration

PURPOSE

In eyes with intermediate age-related macular degeneration (iAMD), we separately quantified the hyperreflective foci (HRF) along the retinal pigment epithelium (rpeHRF) and the intraretinal HRF (iHRF) to determine if the location of the HRF predicted the progression from iAMD to the onset of large persistent choroidal hypertransmission defects (hyperTDs).

DESIGN

Post hoc subgroup cohort analysis of a prospective study.

METHODS

A retrospective analysis was performed on a prospective natural history database of eyes with AMD imaged using swept-source optical coherence tomography (SS-OCT). En face images derived from choroidal slabs positioned 64 to 400 µm beneath Bruch membrane were used with a semiautomated algorithm to identify and quantify hypotransmission defects (hypoTDs) attributable to either iHRF or rpeHRF within a 5-mm fovea-centered circle. iHRF were identified on corresponding B-scans as hyperreflective lesions within the neurosensory retina, and rpeHRF were identified as areas of retinal pigment epithelium thickening. Multivariable survival analysis was performed to determine if the area measurements of either iHRF or rpeHRF were more likely to predict the onset of the first large persistent hyperTD.

RESULTS

Of the 171 eyes with iAMD included in this study, 82 (48%) developed at least 1 large hyperTD during a median follow-up of 59.1 months. Univariable Cox regression analyses showed that rpeHRF area (P < .001), iHRF area (P = .003), and drusen volume (P < .001) were all significantly associated with the onset of the first large persistent hyperTD. However, a multivariable Cox regression model showed that only the rpeHRF area remained a significant predictor of disease progression (P < .001).

CONCLUSIONS

In iAMD eyes, the area of rpeHRF was more predictive of disease progression than either the drusen volume or iHRF, which suggests that these rpeHRF serve as harbingers of focal atrophy formation and may predict where hyperTDs form.

En face OCT: Breakthroughs in understanding the pathoanatomy of retinal disease and clinical applications

En face optical coherence tomography (OCT) is a practical and informative imaging modality to noninvasively visualize distinct retinal and choroidal layers by providing coronal images using boundary-specific segmentation. Ongoing research with this method is generating breakthroughs in the illustration of new perspectives of retinal disease. The clinical value of en face OCT as an advanced retinal imaging tool is growing steadily and it has unveiled many new insights into the pathoanatomy of retinal disorders. Moreover, this modality can capture various en face OCT biomarkers that correspond to different cell or tissue subtypes, which were previously only identified through histological or electron microscopy methods, underscoring the significance of this technique in providing valuable pathoanatomical information. In this comprehensive review, we will systematically summarize the en face OCT findings across a broad spectrum of retinal diseases, including disorders of the vitreoretinal interface and retinal vascular system (e.g. paracentral acute middle maculopathy or PAMM and diabetic retinopathy), in addition to the en face OCT features of other conditions such as age-related macular degeneration, pachychoroid disease spectrum, myopic degeneration, uveitis and inflammatory disorders, inherited retinal dystrophies, and drug toxicity. We will discuss and highlight the unique clinical and pathoanatomical findings uncovered with en face OCT of each these diseases mentioned above.

Comparison between Spectral-domain and Swept-source OCT Angiography Scans for the Measurement of Hyperreflective Foci in Age-related Macular Degeneration

Purpose

Spectral-domain OCT angiography (SD-OCTA) scans were used in an algorithm developed for swept-source OCT angiography (SS-OCTA) scans to determine if SD-OCTA scans yielded similar results for the measurement of hyperreflective foci (HRF) in intermediate age-related macular degeneration (iAMD).

Design

Retrospective study.

Participants

Forty eyes from 35 patients with iAMD.

Methods

Patients underwent SD-OCTA and SS-OCTA imaging at the same visit using a 6 × 6 mm OCTA scan pattern. Hyperreflective foci were detected as hypotransmission defects on en face structural images generated from a custom slab positioned 64 to 400 μm beneath Bruch's membrane and confirmed on corresponding B-scans by the presence of well circumscribed lesions within the neurosensory retina or along the retinal pigment epithelium (RPE) that are of equal or greater reflectivity than that of the RPE. Two independent graders evaluated the en face images and B-scans for the presence of these lesions. Outlines of HRF on en face images were generated using a published semiautomated algorithm developed for SS-OCTA scans and manually corrected by the graders when necessary. The total area measurements of the HRF within the 5-mm circle centered on the fovea were obtained from the algorithm using each imaging method.

Main Outcome Measures

Agreement of the square root (sqrt) of the HRF total areas obtained from SS-OCTA and SD-OCTA.

Results

The sqrt total areas of the HRF from both imaging modalities were highly concordant, with Lin's concordance correlation coefficient (rc) of 0.94 (95% confidence interval: 0.86-0.97; P < 0.001). The mean sqrt of the total HRF area measurements identified using SS-OCTA and SD-OCTA imaging were 0.390 mm (standard deviation [SD]: 0.170) and 0.393 mm (SD: 0.187), respectively with mean difference of -0.003 (95% confidence interval: -0.021 to 0.015; P=0.76).

Conclusions

Spectral-domain OCT angiography scans yielded results similar to SS-OCTA scans when the same semiautomated algorithm was used to measure HRF in the central 5 mm of the macula, suggesting that either a single 6 × 6 mm SD-OCTA or a SS-OCTA scan pattern can be used to determine the total macular HRF burden in eyes with age-related macular degeneration.

Financial Disclosures

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

Comparison Between Optical Coherence Tomography B-scan and En Face Imaging for the Diagnosis of Early Macular Atrophy in Age-Related Macular Degeneration

PURPOSE

The gradings of complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA) and incomplete RPE and outer retinal atrophy (iRORA) on spectral domain optical coherence tomography (SD-OCT) B-scans were compared with the grading of persistent choroidal hypertransmission defects (hyperTDs) on swept-source optical coherence tomography angiography (SS-OCTA) en face images.

DESIGN

Comparative diagnostic analysis of prospective study data.

METHODS

Patients with late nonexudative age-related macular degeneration underwent same-day 6×6-mm macular scans using both SD-OCT (Spectralis Heidelberg, 512×97, automatic real-time tracking: 9) and SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec, 500×500 angio pattern) instruments. SS-OCTA and SD-OCT en face images were generated from a sub-RPE slab positioned 64 to 400 µm below Bruch's membrane. SD-OCT B-scan gradings, which included an inspection of neighboring B-scans for the diagnosis of cRORA and iRORA, were performed at the Moran Eye Center, and gradings of en face images to identify persistent choroidal hyperTDs were performed at the Bascom Palmer Eye Institute and Tel Aviv Medical Center.

RESULTS

There was a high degree of agreement (99.6%) between the gradings of cRORA lesions and persistent hyperTDs. However, 27.4% of iRORA lesions were found to be contained within persistent hyperTDs. This discrepancy was due to the finding that 27.5% of iRORA lesions were diagnosed as having a greatest linear horizontal dimension of <250 µm on B-scans, but on en face images, these B-scan-defined iRORA lesions were found to have the greatest linear dimensions in the nonhorizontal dimension that were ≥250 µm.

CONCLUSIONS

This report demonstrates the benefits of using en face OCT imaging to identify cRORA lesions and highlights the need to acquire dense raster B-scans with the grading neighboring B-scans when identifying iRORA lesions to assess the full extent of the iRORA lesions in the nonhorizontal dimension. Although neighboring B-scans were inspected, 27.5% of iRORA lesions were actually part of larger cRORA lesions when graded using an en face strategy.

Self-supervised based clustering for retinal optical coherence tomography images

BACKGROUND

In response to the inadequacy of manual analysis in meeting the rising demand for retinal optical coherence tomography (OCT) images, a self-supervised learning-based clustering model was implemented.

METHODS

A public dataset was utilized, with 83,484 OCT images with categories of choroidal neovascularization (CNV), diabetic macular edema (DME), drusen, and normal fundus. This study employed the Semantic Pseudo Labeling for Image Clustering (SPICE) framework, a self-supervised learning-based method, to cluster unlabeled OCT images into binary and four categories, and the performances were compared with baseline models. We also analysed feature distribution using t-SNE, and explored the cluster centers, attention maps, and misclassified images. In addition, DME and CNV subsets were clustered binarily, and the results were interpreted by two retinal specialists.

RESULTS

SPICE demonstrated superior performance in binary and four categories classification tasks, achieving the accuracy of 0.886 and 0.846, respectively. In t-SNE analysis, the four types exhibited significant clustering into distinct groups. The cluster centers corresponded to the human labels, and the heat map revealed that the model focused on important biomarkers. The misclassified images exposed similar features to the inaccurate classes. The model also grouped DME and CNV into two distinct categories respectively.

CONCLUSIONS

Self-supervised clustering effectively distinguished disease variances and revealed common features, with a notable capability to detect disease heterogeneity through biomarkers.

Comparison between Spectral-Domain and Swept-Source OCT Angiography for the Measurement of Persistent Hypertransmission Defects in Age-Related Macular Degeneration

Purpose

Spectral-domain OCT angiography (SD-OCTA) scans were tested in an algorithm developed for use with swept-source OCT angiography (SS-OCTA) scans to determine if SD-OCTA scans yielded similar results for the detection and measurement of persistent choroidal hypertransmission defects (hyperTDs).

Design

Retrospective study.

Participants

Forty pairs of scans from 32 patients with late-stage nonexudative age-related macular degeneration (AMD).

Methods

Patients underwent both SD-OCTA and SS-OCTA imaging at the same visit using the 6 × 6 mm OCTA scan patterns. Using a semiautomatic algorithm that helped with outlining the hyperTDs, 2 graders independently validated persistent hyperTDs, which are defined as having a greatest linear dimension ≥250 μm on the en face images generated using a slab extending from 64 to 400 μm beneath Bruch's membrane. The number of lesions and square root (sqrt) total area of the hyperTDs were obtained from the algorithm using each imaging method.

Main Outcome Measures

The mean sqrt area measurements and the number of hyperTDs were compared.

Results

The number of lesions and sqrt total area of the hyperTDs were highly concordant between the 2 instruments (rc = 0.969 and rc = 0.999, respectively). The mean number of hyperTDs was 4.3 ± 3.1 for SD-OCTA scans and 4.5 ± 3.3 for SS-OCTA scans (P = 0.06). The mean sqrt total area measurements were 1.16 ± 0.64 mm for the SD-OCTA scans and 1.17 ± 0.65 mm for the SS-OCTA scans (P < 0.001). Because of the small standard error of the differences, the mean difference between the scans was statistically significant but not clinically significant.

Conclusions

Spectral-domain OCTA scans provide similar results to SS-OCTA scans when used to obtain the number and area measurements of persistent hyperTDs through a semiautomated algorithm previously developed for SS-OCTA. This facilitates the detection of atrophy with a more widely available scan pattern and the longitudinal study of early to late-stage AMD.

Financial Disclosures

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

Estimating Uncertainty of Geographic Atrophy Segmentations with Bayesian Deep Learning

Purpose

To apply methods for quantifying uncertainty of deep learning segmentation of geographic atrophy (GA).

Design

Retrospective analysis of OCT images and model comparison.

Participants

One hundred twenty-six eyes from 87 participants with GA in the SWAGGER cohort of the Nonexudative Age-Related Macular Degeneration Imaged with Swept-Source OCT (SS-OCT) study.

Methods

The manual segmentations of GA lesions were conducted on structural subretinal pigment epithelium en face images from the SS-OCT images. Models were developed for 2 approximate Bayesian deep learning techniques, Monte Carlo dropout and ensemble, to assess the uncertainty of GA semantic segmentation and compared to a traditional deep learning model.

Main Outcome Measures

Model performance (Dice score) was compared. Uncertainty was calculated using the formula for Shannon Entropy.

Results

The output of both Bayesian technique models showed a greater number of pixels with high entropy than the standard model. Dice scores for the Monte Carlo dropout method (0.90, 95% confidence interval 0.87-0.93) and the ensemble method (0.88, 95% confidence interval 0.85-0.91) were significantly higher (P < 0.001) than for the traditional model (0.82, 95% confidence interval 0.78-0.86).

Conclusions

Quantifying the uncertainty in a prediction of GA may improve trustworthiness of the models and aid clinicians in decision-making. The Bayesian deep learning techniques generated pixel-wise estimates of model uncertainty for segmentation, while also improving model performance compared with traditionally trained deep learning models.

Financial Disclosures

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

Relationship between hypertransmission defect size and progression in eyes with intermediate age-related macular degeneration

OBJECTIVES

To determine the associations between the presence of various-sized hypertransmission defects (hyperTDs) and progression to incomplete retinal pigment epithelial (RPE) and outer retinal atrophy (iRORA) and complete RORA (cRORA) in eyes with intermediate age-related macular degeneration (iAMD).

METHODS

Optical coherence tomography (OCT) data from consecutive iAMD patients, were retrospectively reviewed. All of iAMD eyes with or without iRORA (but not cRORA) at baseline were included. Graders evaluated the presence of hyperTDs at baseline (small: 63-124 µm; medium: 125-249 µm; large: ≥ 250 µm in diameter on choroidal en face OCT) and the progression two years later.

RESULTS

Of the 145 eyes that not developed neovascular AMD at two years, the eyes that progressed to or developed iRORA or cRORA included 13 eyes (10.7%), 5 eyes (83.3%), 9 eyes (81.8%), and 6 eyes (85.7%) in the groups with no, small, medium, and large hyperTDs at baseline, respectively (P-value < 0.001). The odds ratios (95% CI) for progression were 41.6 (4.5-383.6), 37.4 (7.3-192.0), and 49.9 (5.6-447.1) in the small, medium, and large hyperTDs groups, compared to no hyperTDs (P-value ≤ 0.001). Eyes with ≥ 2 hyperTDs also showed more frequent progression than eyes with one or no hyperTDs (100% vs. 16.4%; P-value < 0.001).

CONCLUSIONS

While most iAMD eyes with no hyperTDs remained stable on OCT over two years, eyes with hyperTDs of any size appeared to be at a higher risk for progression. HyperTDs may provide an important OCT biomarker for identifying high-risk iAMD patients.

Structural en face optical coherence tomography in neovascular and nonneovascularage-related macular degeneration: Use and utility in clinical practice

Age-related macular degeneration (AMD) is a leading cause of blindness and visual impairment worldwide. Structural en face optical coherence tomography (OCT) is an innovative imaging technology that has recently attracted interest because of its potential for assessing AMD features. We conducted a comprehensive review of its application in AMD. In neovascular AMD, structural en face OCT can detect exudative activity, monitor the neovascularization area, study the choroid in polypoidal choroidal vasculopathy, and visualize neovascular membranes in pigment epithelial detachments. Moreover, in nonneovascular AMD, this study provides details on geographic atrophy and drusen, the identification of intraretinal retinal pigment epithelium migration, and the detection of different patterns of outer retinal tubulations. Our study revealed that structural en face OCT can provide relevant information on patients with AMD.

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.

Evaluating the persistence of large choroidal hypertransmission defects using SS-OCT imaging

In age-related macular degeneration (AMD), large choroidal hypertransmission defects (hyperTDs) are identified on en face optical coherence tomography (OCT) images as bright lesions measuring at least 250 μm in greatest linear dimension (GLD). These choroidal hyperTDs arise from focal attenuation or loss of the retinal pigment epithelium (RPE). We previously reported that once large hyperTDs formed, they were likely to persist compared with smaller lesions that were more likely to be transient. Due to their relative persistence, these large persistent choroidal hyperTDs are a point-of-no-return in the progression of intermediate AMD to the late stage of atrophic AMD. Moreover, the onset of these large choroidal hyperTDs can serve as a clinical trial endpoint when studying therapies that might slow disease progression from intermediate AMD to late atrophic AMD. To confirm the persistence of these large choroidal hyperTDs, we studied an independent dataset of AMD eyes enrolled in an ongoing prospective swept-source OCT (SS-OCT) natural history study to determine their overall persistence. We identified a total of 202 eyes with large choroidal hyperTDs containing 1725 hyperTDs followed for an average of 46.6 months. Of the 1725 large hyperTDs, we found that 1718 (99.6%) persisted while only 7 hyperTDs (0.4%) were non-persistent. Of the 7 non-persistent large hyperTDs in 6 eyes, their average GLD at baseline was 385 μm. Of the large hyperTDs ranging in size between 250 and 300 μm when first detected, only one was not persistent with a baseline GLD of 283 μm. In 6 of the non-persistent hyperTDs, the loss of a detectable large hyperTD was due to the accumulation of hyperreflective material along the retinal pigment epithelium (RPE) and in the retina over the area where the hyperTD was located. This hyperreflective material is thought to represent the migration and aggregation of RPE cells into this focal region where the choroidal hyperTD arose due to attenuated or lost RPE.

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.

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.

Intergrader Agreement in Grading Optical Coherence Tomography Morphologic Features in Eyes With Intermediate Nonexudative Age-Related Macular Degeneration

Purpose

To determine the reliability of a nine-point summary scale for grading intermediate age-related macular degeneration (AMD) image morphologic features based on the Early Treatment Diabetic Retinopathy Study (ETDRS) grid.

Methods

Two trained graders independently divided spectral domain-optical coherence tomography (SD-OCT) scans into nine subfields and then graded each subfield for the presence of intraretinal hyperreflective foci (HRF), reticular pseudodrusen (RPD), and incomplete or complete retinal pigment epithelium and outer retinal atrophy (iRORA or cRORA). Grading results were assessed by summing the subfield grades into a nine-point summary score and also by using an eye-level binary grade for presence of the finding in any subfield. Gwet's first-order agreement coefficient (AC1) was calculated to assess intergrader agreement.

Results

Images of 79 eyes from 52 patients were evaluated. Intergrader agreement was higher when the OCT grades were summarized with a nine-point summary score (Gwet's AC1 0.92, 0.89, 0.99, and 0.99 for HRF, RPD, iRORA, and cRORA, respectively) compared with the eye-level binary grade (Gwet's AC1 0.75, 0.76, 0.97, and 0.96 for HRF, RPD, iRORA, and cRORA, respectively), with significant differences detected for HRF and RPD.

Conclusions

The use of a nine-point summary score showed higher reliability in grading when compared to the binary subfield- and eye-level data, and thus may offer more precise estimation of AMD disease staging.

Translational Relevance

These findings suggest that a nine-point summary score could be a useful means of disease staging by using findings on OCT in clinical studies of AMD.

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.

Calcified Drusen Prevent the Detection of Underlying Choriocapillaris Using Swept-Source Optical Coherence Tomography Angiography

Purpose

In age-related macular degeneration (AMD), choriocapillaris flow deficits (CCFDs) under soft drusen can be measured using established compensation strategies. This study investigated whether CCFDs can be quantified under calcified drusen (CaD).

Methods

CCFDs were measured in normal eyes (n = 30) and AMD eyes with soft drusen (n = 30) or CaD (n = 30). CCFD density masks were generated to highlight regions with higher CCFDs. Masks were also generated for soft drusen and CaD based on both structural en face OCT images and corresponding B-scans. Dice similarity coefficients were calculated between the CCFD density masks and both the soft drusen and CaD masks. A phantom experiment was conducted to simulate the impact of light scattering that arises from CaD.

Results

Area measurements of CCFDs were highly correlated with those of CaD but not soft drusen, suggesting an association between CaD and underlying CCFDs. However, unlike soft drusen, the detected optical coherence tomography (OCT) signals underlying CaD did not arise from the defined CC layer but were artifacts caused by the multiple scattering property of CaD. Phantom experiments showed that the presence of highly scattering material similar to the contents of CaD caused an artifactual scattering tail that falsely generated a signal in the CC structural layer but the underlying flow could not be detected. Similarly, CaD also caused an artifactual scattering tail and prevented the penetration of light into the choroid, resulting in en face hypotransmission defects and an inability to detect blood flow within the choriocapillaris. Upon resolution of the CaD, the CC perfusion became detectable.

Conclusions

The high scattering property of CaD leads to a scattering tail under these drusen that gives the illusion of a quantifiable optical coherence tomography angiography signal, but this signal does not contain the angiographic information required to assess CCFDs. For this reason, CCFDs cannot be reliably measured under CaD, and CaD must be identified and excluded from macular CCFD measurements.

Atrophic Lesions Associated with Age-Related Macular Degeneration: High-Resolution versus Standard OCT

OBJECTIVE

The objective of this study was to determine whether high-resolution OCT (HR-OCT) could enhance the identification and classification of atrophic features in age-related macular degeneration (AMD) compared with standard resolution OCT.

DESIGN

Prospective, observational, cross-sectional study.

SUBJECTS

The study included 60 eyes from 60 patients > 60 years of age with a diagnosis of AMD.

METHODS

The participants underwent volume OCT scanning using HR-OCT and standard resolution OCT devices. Trained graders reviewed and graded the scans, identifying specific regions of interest for subsequent analysis.

MAIN OUTCOME MEASURES

The study focused on identifying and classifying complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA), incomplete RORA (iRORA), and other nonatrophic AMD features. Additionally, qualitative and quantitative features associated with atrophy were assessed.

RESULTS

The agreement among readers for classifying atrophic lesions was substantial to perfect for both HR-OCT (0.88) and standard resolution OCT(0.82). However, HR-OCT showed a higher accuracy in identifying iRORA lesions compared with standard OCT. Qualitative assessment of features demonstrated higher agreement for HR-OCT, particularly in identifying external limiting membrane (ELM) (0.95) and ellipsoid zone (EZ) disruption (0.94). Quantitative measurements of features such as hypertransmission defects, RPE attenuation/disruption, EZ disruption width, and ELM disruption width showed excellent interreader agreement with HR-OCT (> 0.90 for all features) but only moderate agreement with standard OCT (0.51-0.60).

CONCLUSIONS

The study results suggest that HR-OCT improves the accuracy and reliability of classifying and quantifying atrophic lesions associated with AMD compared with standard resolution OCT. The quantitative findings in particular may have implications for future research and clinical practice, especially with the availability of therapeutic agents for treating geographic atrophy and the development of commercially available HR-OCT devices.

FINANCIAL DISCLOSURE(S)

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

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.

PREVALENCE AND PERSISTENCE OF HYPERTRANSMISSION DEFECTS OF VARIOUS SIZES IN EYES WITH INTERMEDIATE AGE-RELATED MACULAR DEGENERATION

PURPOSE

To determine the prevalence and rate of persistence over 2 years of various-sized hypertransmission defects (hyperTDs) in eyes with intermediate age-related macular degeneration.

METHODS

Retrospective analysis of optical coherence tomography data from consecutive intermediate age-related macular degeneration patients. Choroidal en face optical coherence tomography images were evaluated for the presence and number of hyperTDs of three different sizes based on greatest linear dimension (small, 63-124 µ m; medium, 125-249 µ m; large, ≥250 µ m) at baseline and at the 2-year follow-up. Interreader agreement was determined by Gwet's agreement coefficient. Disagreements between graders were resolved by the senior investigator to yield a single consensus for all cases.

RESULTS

From 273 intermediate age-related macular degeneration eyes (247 patients), 72 and 76 hyperTD lesions were independently identified by two graders at baseline and overall agreement coefficient was 0.89 (95% CI, 0.86-0.93). After adjudication by the senior grader, the final consensus yielded 78 hyperTD lesions from 46 eyes (16.8%) of 42 patients (17.0%) in this study cohort. Among eyes with follow-up optical coherence tomography, 32 of 45 hyperTD lesions (71.1%) persisted. The rates of persistence were 100.0%, 72.7%, and 53.3% in large, medium, and small hyperTD sizes, respectively.

CONCLUSION

HyperTDs were present in a significant proportion of intermediate age-related macular degeneration eyes. Acceptable interreader agreement was demonstrated in identifying hyperTD. Larger hyperTD lesions were more likely to persist over 2 years.

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.

Comparison between B-Scan and En Face Images for Incomplete and Complete Retinal Pigment Epithelium and Outer Retinal Atrophy

PURPOSE

To evaluate and compare the detection of incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) and complete retinal pigment epithelium and outer retinal atrophy (cRORA) assessed on OCT B-scans versus persistent choroidal hypertransmission defects (hyperTDs) assessed by en face choroidal OCT images.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Patients with late atrophic age-related macular degeneration imaged on the same day using both Spectralis OCT and Cirrus OCT.

MAIN OUTCOME MEASURE

Agreement between the B-scan and en face OCT for the detection of hyperTDs, cRORA, and iRORA.

METHODS

Two independent graders examined en face OCT and structural OCT to determine the presence and location of hyperTDs, iRORA, and cRORA.

RESULTS

A total of 239 iRORA and cRORA lesions were detected on the B-scans, and 249 hyperTD lesions were identified on the en face OCT images. There was no significant difference (P = 0.88) in the number of lesions. There was no significant difference in the 134 cRORA lesions identified on B-scans and the 131 hyperTDs detected on en face OCT images (P = 0.13). A total of 105 iRORA lesions were identified by B-scan assessment; however, 50 of these iRORA lesions met the criteria for persistent hyperTDs on en face OCT images (P < 0.001). When considering the topographic correspondence between B-scan and en face OCT detected lesions, the mean percentage of agreement between B-scan detection of cRORA lesions with en face OCT detection was 97.6 % (P = 0.13).

CONCLUSIONS

We observed high overall agreement between cRORA lesions identified on B-scans and persistent hyperTDs identified on en face OCT. However, en face imaging was able to detect iRORA lesions that had a greatest linear dimension ≥ 250 μm in a nonhorizontal en face dimension.

FINANCIAL DISCLOSURE(S)

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

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

PURPOSE

The appearance and growth of persistent choroidal hypertransmission defects (hyperTDs) detected on en face swept-source optical coherence tomography (SS-OCT) images from eyes with intermediate age-related macular degeneration (iAMD) were studied to determine if they could serve as novel clinical trial endpoints.

DESIGN

Post hoc subgroup analysis of a prospective study.

METHODS

Subjects with iAMD underwent 6 × 6 mm SS-OCT angiography imaging at their baseline and follow-up visits. The drusen volumes were obtained using a validated SS-OCT algorithm. Two graders independently evaluated all en face structural images for the presence of persistent hyperTDs. The number and area of all hyperTDs along with drusen volume were obtained from all SS-OCT angiography scans. Eyes were censored from further follow-up once exudative AMD developed.

RESULTS

A total of 171 eyes from 121 patients with iAMD were included. Sixty-eight eyes developed at least 1 hyperTD. Within 1 year after developing a hyperTD, 25% of eyes developed new hyperTDs for an average of 0.44 additional hyperTDs. Over 2 years, as hyperTDs appeared, enlarged, and merged, the average area growth rate was 0.220 mm/yr using the square-root transformation strategy. A clinical trial design using the onset and enlargement of these hyperTDs for the study of disease progression in eyes with iAMD is proposed.

CONCLUSIONS

The appearance and growth of persistent choroidal hyperTDs in eyes with iAMD can be easily detected and measured using en face OCT imaging and can serve as novel clinical trial endpoints for the study of therapies that may slow disease progression from iAMD to late AMD.

Decreased Central Macular Choriocapillaris Perfusion Correlates With Increased Low Luminance Visual Acuity Deficits

PURPOSE

Correlations between low luminance visual acuity deficits (LLVADs) and central choriocapillaris perfusion deficits were investigated to help explain how increases in LLVAD scores at baseline predict annual growth rates of geographic atrophy (GA).

DESIGN

Prospective cross-sectional study.

METHODS

Photopic luminance best-corrected visual acuity (PL-BCVA) and low luminance BCVA (LL-BCVA) were measured using the Early Treatment Diabetic Retinopathy Study chart. LL-BCVA was measured using a 2.0-log unit neutral density filter. LLVADs were calculated as the difference between PL-BCVA and LL-BCVA. Within a fovea-centered 1-mm circle, the percentage of choriocapillaris flow deficits (CC FD%), drusen volume, optical attenuation coefficient (OAC) elevation volume, and outer retinal layer (ORL) thickness were assessed.

RESULTS

In all 90 eyes (30 normal eyes; 31 drusen-only eyes; 29 non-foveal GA eyes), significant correlations were found between the central CC FD% and PL-BCVA (r = -0.393, P < .001), LL-BCVA (r = -0.534, P < .001), and the LLVAD (r = 0.439, P < .001). Central cube root (cubrt) drusen volume, cubrt OAC elevation volume, and ORL thickness were correlated with PL-BCVA, LL-BCVA, and LLVADs (all P < .05). Stepwise regression models showed that central cubrt OAC elevation volume and ORL thickness were associated with PL-BCVA (R2 = 0.24, P < .05); central CC FD%, cubrt OAC elevation volume, and ORL thickness were associated with LL-BCVA (R2 = 0.44, P < .01); and central CC FD% and ORL thickness were associated with LLVAD (R2 = 0.24, P < .01).

CONCLUSIONS

The significant correlations between central CC FD% and LLVAD support the hypothesis that the ability of LLVAD to predict the growth of GA is mediated through a decrease in macular choriocapillaris perfusion.

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.

Symmetry of Macular Fundus Features in Age-Related Macular Degeneration

PURPOSE

The symmetry of major macular fundus features in both eyes of the same patient with age-related macular degeneration (AMD) was investigated using swept-source(SS)-OCT.

DESIGN

Retrospective review of a prospective study.

PARTICIPANTS

Patients with AMD.

METHODS

Grading was performed on the first SS-OCT images obtained on the patients. Two graders diagnosed the presence of drusen, geographic atrophy (GA), and exudative AMD (eAMD) in each eye. Medical records were reviewed to assess prior exudation. To assess symmetry, 1 eye of each patient was randomly selected as the index eye and compared with the fellow eye. The kappa statistic (κ) was used to assess the symmetry of diagnosis. The intraclass correlation coefficient (ICC) was used to assess the symmetry of drusen area and volume.

MAIN OUTCOME MEASURES

Interocular symmetry of the AMD stages: drusen, GA, and eAMD.

RESULTS

A total of 1310 patients with AMD were included. The average age was 78 years (range, 50-102; 60% women). Of the 1310 subjects, 54% (701) presented with symmetric disease: 20% with bilateral drusen, 11% with bilateral GA, and 22% with bilateral eAMD. Only 0.5% of the subjects had both GA and eAMD in both eyes. Of the randomly selected index eyes, 825 (47%) were right eyes. Overall, limited interocular agreement was observed between the index and fellow eyes (54%; κ = 0.29). Kappa coefficients were poor (< 0.4) for index eyes diagnosed with drusen (κ = 0.27), eAMD (κ = 0.17), and mixed disease (κ = 0.03). There was moderate agreement between the index and fellow eyes for GA (κ = 0.50). Of the 265 patients with bilateral drusen, the symmetry of drusen area measurements had moderate ICC values of 0.70, 0.71, and 0.70 in the 3- and 5-mm diameter foveal-centered circles and in the total scan area, respectively. The ICC values for the drusen volumes were 0.65, 0.66, and 0.64, respectively.

CONCLUSIONS

Interocular symmetry was poor for eyes with drusen, eAMD, and mixed disease, but moderate for GA. Although the diagnosis of drusen was not very symmetric between eyes, when present in both eyes, the drusen area and volume measurements were moderately symmetric.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

OPTICAL COHERENCE TOMOGRAPHY FEATURES RELEVANT TO NEOVASCULAR AGE-RELATED MACULAR DEGENERATION MANAGEMENT AND NONNEOVASCULAR AGE-RELATED MACULAR DEGENERATION PROGRESSION: CLINICOPATHOLOGIC CORRELATION

PURPOSE

Clinicopathologic correlation of two optical coherence tomography (OCT) features in neovascular age-related macular degeneration.

METHODS

Case report, clinicopathologic correlation.

RESULTS

A patient in her 90s was diagnosed with Type 3 macular neovascularization secondary to age-related macular degeneration in the index right eye and underwent intravitreal antivascular endothelial growth factor treatment for 5 years. A double-layer sign on in vivo OCT was correlated to calcified drusen on histology. Furthermore, hyperfluorescence on fluorescein angiography corresponded on histology to choroidal hypertransmission on OCT and retinal pigment epithelium atrophy above calcified drusen.

CONCLUSION

A double-layer sign on OCT can represent nonneovascular subretinal pigment epithelium material including wide and flat calcific nodules. Furthermore, hyperfluorescence on FA, among different origins, can be due to a window defect corresponding to retinal pigment epithelium atrophy, which can be confirmed with OCT. Clinicopathological correlation using high-resolution histology can demonstrate the fine details available to clinical decision making through currently available in vivo OCT imaging.

Advances in swept-source optical coherence tomography and optical coherence tomography angiography

Background

The fast development of swept-source optical coherence tomography (SS-OCT) and swept-source optical coherence tomography angiography (SS-OCTA) enables both anterior and posterior imaging of the eye. These techniques have evolved from a research tool to an essential clinical imaging modality.

Main text

The longer wavelength and faster speed of SS-OCT and SS-OCTA facilitate better visualization of structure and vasculature below pigmented tissue with a larger field of view of the posterior segment and 360-degree visualization of the anterior segment. In the past 10 years, algorithms dealing with OCT and OCTA data also vastly improved the image quality and enabled the automated quantification of OCT- and OCTA-derived metrics. This technology has enriched our current understanding of healthy and diseased eyes. Even though the high cost of the systems currently limited the widespread use of SS-OCT and SS-OCTA at the first beginning, the gap between research and clinic practice got obviously shortened in the past few years.

Conclusions

SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift toward more widespread adoption of new imaging technology in clinical practice.

Detection of Nonexudative Macular Neovascularization on Structural OCT Images Using Vision Transformers

PURPOSE

A deep learning model was developed to detect nonexudative macular neovascularization (neMNV) using OCT B-scans.

DESIGN

Retrospective review of a prospective, observational study.

PARTICIPANTS

Normal control eyes and patients with age-related macular degeneration (AMD) with and without neMNV.

METHODS

Swept-source OCT angiography (SS-OCTA) imaging (PLEX Elite 9000, Carl Zeiss Meditec, Inc) was performed using the 6 × 6-mm scan pattern. Individual B-scans were annotated to distinguish between drusen and the double-layer sign (DLS) associated with the neMNV. The machine learning model was tested on a dataset graded by humans, and model performance was compared with the human graders.

MAIN OUTCOME MEASURES

Intersection over Union (IoU) score was measured to evaluate segmentation network performance. Area under the receiver operating characteristic curve values, sensitivity, specificity, and positive predictive value (PPV) and negative predictive value (NPV) were measured to assess the performance of the final classification performance. Chance-corrected agreement between the algorithm and the human grader determinations was measured with Cohen's kappa.

RESULTS

A total of 251 eyes from 210 patients, including 182 eyes with DLS and 115 eyes with drusen, were used for model training. Of 125 500 B-scans, 6879 B-scans were manually annotated. A vision transformer segmentation model was built to extract DLS and drusen from B-scans. The extracted prediction masks from all B-scans in a volume were projected to an en face image, and an eye-level projection map was obtained for each eye. A binary classification algorithm was established to identify eyes with neMNV from the projection map. The algorithm achieved 82%, 90%, 79%, and 91% sensitivity, specificity, PPV, and NPV, respectively, on a separate test set of 100 eyes that were evaluated by human graders in a previous study. The area under the curve value was calculated as 0.91 (95% confidence interval, 0.85-0.98). The results of the algorithm showed excellent agreement with the senior human grader (kappa = 0.83, P < 0.001) and moderate agreement with the junior grader consensus (kappa = 0.54, P < 0.001).

CONCLUSIONS

Our network (code is available at https://github.com/uw-biomedical-ml/double_layer_vit) was able to detect the presence of neMNV from structural B-scans alone by applying a purely transformer-based model.

Multimodal Imaging and En Face OCT Detection of Calcified Drusen in Eyes with Age-Related Macular Degeneration

Purpose

En face OCT imaging was investigated as a method for the detection and monitoring of calcified drusen in eyes with nonexudative age-related macular degeneration (AMD).

Design

Retrospective case series of a prospective study.

Participants

Patients with nonexudative AMD.

Methods

A retrospective review was performed of same-day color fundus (CF), fundus autofluorescence (FAF), near-infrared (NIR), and en face swept-source (SS) OCT images to identify eyes with nonexudative AMD and calcified drusen. The appearance and progression of these lesions were compared using the different imaging methods.

Main Outcome Measures

Comparison between the presence of calcified drusen observed on CF images with the detection of these lesions on FAF, NIR, and en face SS OCT images.

Results

Two hundred twenty eyes from 139 patients with nonexudative AMD were studied, with 42.7% of eyes containing calcified drusen either at baseline or during follow-up visits. On the en face SS OCT images, calcified drusen appeared as dark focal lesions referred to as choroidal hypotransmission defects (hypoTDs) that were detected in the choroid using a sub-retinal pigment epithelium (RPE) slab. The corresponding B-scans showed drusen with heterogenous internal reflectivity, hyporeflective cores, and hyperreflective caps. In most calcified drusen, choroidal hypertransmission defects (hyperTDs) were observed to develop over time around the periphery of the hypoTDs, giving them the appearance of a donut lesion on the en face SS OCT images. These donut lesions were associated with significant attenuation of the overlying retina, and the corresponding FAF images showed hypoautofluorescence at the location of these lesions. The donut lesions fulfilled the requirement for a persistent hyperTD, which is synonymous with complete RPE and outer retinal atrophy (cRORA). Six eyes displayed regression of the calcified drusen without cRORA developing. B-scans at the location of these regressed calcified drusen showed deposits along the RPE, with outer retinal thinning in the regions where the calcified lesions previously existed.

Conclusions

En face OCT imaging is a useful method for the detection and monitoring of calcified drusen and can be used to document the evolution of these drusen as they form donut lesions or foci of cRORA.