Identification and Quantification of the Angiofibrotic Switch in Neovascular AMD

Subretinal fibrosis secondary to neovascular age-related macular degeneration: mechanisms and potential therapeutic targets

Subretinal fibrosis is the end-stage sequelae of neovascular age-related macular degeneration. It causes local damage to photoreceptors, retinal pigment epithelium, and choroidal vessels, which leads to permanent central vision loss of patients with neovascular age-related macular degeneration. The pathogenesis of subretinal fibrosis is complex, and the underlying mechanisms are largely unknown. Therefore, there are no effective treatment options. A thorough understanding of the pathogenesis of subretinal fibrosis and its related mechanisms is important to elucidate its complications and explore potential treatments. The current article reviews several aspects of subretinal fibrosis, including the current understanding on the relationship between neovascular age-related macular degeneration and subretinal fibrosis; multimodal imaging techniques for subretinal fibrosis; animal models for studying subretinal fibrosis; cellular and non-cellular constituents of subretinal fibrosis; pathophysiological mechanisms involved in subretinal fibrosis, such as aging, infiltration of macrophages, different sources of mesenchymal transition to myofibroblast, and activation of complement system and immune cells; and several key molecules and signaling pathways participating in the pathogenesis of subretinal fibrosis, such as vascular endothelial growth factor, connective tissue growth factor, fibroblast growth factor 2, platelet-derived growth factor and platelet-derived growth factor receptor-β, transforming growth factor-β signaling pathway, Wnt signaling pathway, and the axis of heat shock protein 70-Toll-like receptors 2/4-interleukin-10. This review will improve the understanding of the pathogenesis of subretinal fibrosis, allow the discovery of molecular targets, and explore potential treatments for the management of subretinal fibrosis.

Subretinal hyperreflective material in regions of atrophy and fibrosis in eyes with neovascular age-related macular degeneration

BACKGROUND

Subretinal hyperreflective material (SHRM) is a significant biomarker for poor visual outcomes in neovascular age-related macular degeneration (nAMD); however, its relationship with fibrosis and atrophy is not well understood. This study aims to evaluate the relationship between SHRM, atrophy, and fibrosis in eyes receiving antivascular endothelial growth factor therapy for nAMD.

METHODS

Post-hoc analysis of the 65 patients enrolled in the SEVEN-UP study, a multicenter cross-sectional study of patients originally enrolled in the ANCHOR and MARINA trials of ranibizumab. Color fundus photographs (CFP) were reviewed and manually segmented to define regions of atrophy and fibrosis. SHRM borders on OCT volume scans were manually delineated, and thickness measurements were computed and compared in corresponding regions of atrophy and fibrosis on the CFPs.

RESULTS

Of the 65 subjects, 51 eyes showed atrophy and/or fibrosis on CFP and were included in the final analysis. Both atrophy and fibrosis regions exhibited SHRM on OCT. The mean SHRM thickness on OCT was significantly greater in CFP-fibrosis regions (44.19 ± 46.95 μm) compared with CFP-atrophy regions (14.28 ± 13.35 μm; p < 0.001). Additionally, the average maximum height of SHRM in fibrotic regions (268.04 ± 130.05 μm) was significantly thicker than in atrophic regions (121.95 ± 51.17 μm; p < 0.001).

CONCLUSIONS

Although atrophy and fibrosis are thought to be different end-stage outcomes in eyes with nAMD, they both demonstrate SHRM on OCT; the main distinction being thickness. Given these similarities, these regions of nAMD-associated atrophy may be better-termed "atrosis" to distinguish these lesions from typical atrophy in the absence of neovascular disease.

Inner Choroidal Fibrosis: An Optical Coherence Tomography Biomarker of Severity in Chronic Central Serous Chorioretinopathy

PURPOSE

To describe a potential biomarker termed as inner choroidal fibrosis in cases of chronic central serous chorioretinopathy (CSCR) presenting to a tertiary referral center.

DESIGN

Observational case series.

METHODS

Five eyes of 4 patients with CSCR were noted to have a gray-white subretinal lesion in the macula, which was analyzed with multimodal imaging.

RESULTS

The lesions were hypofluorescent on autofluorescence, fundus fluorescein angiography, and indocyanine angiography. In all cases, a characteristic heterogeneous, hyperreflective lesion in the inner choroid was seen on optical coherence tomography (OCT), corresponding to the white subretinal lesions. The lesion was distinct from the adjacent choroid, with greater reflectivity and greater thickness than the adjacent compressed choroidal vasculature. The dilated outer pachyvessels were pushed outward or sideways in all cases. On OCT-angiography, the corresponding lesion showed flow void areas. We have termed this zone of inner choroidal hyperreflectivity "inner choroidal fibrosis." Upon analyzing the clinical course, 3 of the patients had a history of choroidal neovascularization. The contralateral eye in 2 of these 3 patients also developed choroidal neovascularization. Three of the eyes had an overlying focal choroidal excavation.

CONCLUSIONS

We report a potential biomarker of CSCR termed "inner choroidal fibrosis" in 4 cases of chronic CSCR. It can best be identified on enhanced depth or swept source OCT as a region of heterogeneous hyperreflectivity in the inner choroid. This fibrosis could be regarded as a degenerative process secondary to more severe disease in the past.

Fibrosis in neovascular age-related macular degeneration: A review of definitions based on clinical imaging

Despite the success of antiangiogenic therapy in controlling exudation in neovascular age-related macular degeneration (nAMD), the involvement of the outer retina in fibrosis results in gradual vision loss over time. The development of drugs that prevent or ameliorate fibrosis in nAMD requires that it is accurately detected and quantified with reliable endpoints and identification of robust biomarkers. Achievement of such an aim is currently challenging due to the lack of a consensus definition of fibrosis in nAMD. As a first step towards the establishment of a clear definition of fibrosis, we provide an extensive overview of the imaging modalities and criteria used to characterize fibrosis in nAMD. We observed variety in the selection of individual and combinations of imaging modalities, and criteria for detection. We also observed heterogeneity in classification systems and severity scales for fibrosis. The most commonly used imaging modalities were color fundus photography, fluorescein angiography and optical coherence tomography (OCT). A multimodal approach was frequently utilized. Our review suggests that OCT offers a more detailed, objective and sensitive characterization than color fundus photography/fluorescein angiography. Thus, we recommend it as a primary modality for fibrosis evaluation. This review provides a basis for future discussions to reach a consensus definition using standardized terms based on a detailed characterization of fibrosis, its presence and evolution, and taking into consideration impact on visual function. Achieving this goal is of paramount importance for the development of antifibrotic therapies.

Optical coherence tomography imaging biomarkers associated with neovascular age-related macular degeneration: a systematic review

The aim of this systematic literature review is twofold, (1) detail the impact of retinal biomarkers identifiable via optical coherence tomography (OCT) on disease progression and response to treatment in neovascular age-related macular degeneration (nAMD) and (2) establish which biomarkers are currently identifiable by artificial intelligence (AI) models and the utilisation of this technology. Following the PRISMA guidelines, PubMed was searched for peer-reviewed publications dated between January 2016 and January 2022.

POPULATION

Patients diagnosed with nAMD with OCT imaging.

SETTINGS

Comparable settings to NHS hospitals.

STUDY DESIGNS

Randomised controlled trials, prospective/retrospective cohort studies and review articles. From 228 articles, 130 were full-text reviewed, 50 were removed for falling outside the scope of this review with 10 added from the author's inventory, resulting in the inclusion of 90 articles. From 9 biomarkers identified; intraretinal fluid (IRF), subretinal fluid, pigment epithelial detachment, subretinal hyperreflective material (SHRM), retinal pigmental epithelial (RPE) atrophy, drusen, outer retinal tabulation (ORT), hyperreflective foci (HF) and retinal thickness, 5 are considered pertinent to nAMD disease progression; IRF, SHRM, drusen, ORT and HF. A number of these biomarkers can be classified using current AI models. Significant retinal biomarkers pertinent to disease activity and progression in nAMD are identifiable via OCT; IRF being the most important in terms of the significant impact on visual outcome. Incorporating AI into ophthalmology practice is a promising advancement towards automated and reproducible analyses of OCT data with the ability to diagnose disease and predict future disease conversion.

SYSTEMATIC REVIEW REGISTRATION

This review has been registered with PROSPERO (registration ID: CRD42021233200).

Review of Fibrosis in Neovascular Age-Related Macular Degeneration

PURPOSE

To report the diagnosis and definitions, epidemiology, risk factors, and visual outcomes of fibrosis in neovascular age-related macular degeneration (nAMD).

DESIGN

Systematic review and meta-analysis.

METHODS

The review was performed using the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Observational studies and randomized controlled trials were included.

RESULTS

Identification of fibrosis is challenging. Optical coherence tomography angiography and polarization-sensitive optical coherence tomography represent novel options in multimodal imaging. The prevalence of fibrosis at baseline, 12, 24, and 60 months was 13%, 32%, 36%, and 56%, respectively. Approximately 60% of the fibrosis burden in nAMD at 5 years was present in the first year of treatment. Fibrosis development was highest in the first 12 months and slowed down over time. The risk factors of fibrosis included classic choroidal neovascularization (CNV), intra-retinal fluid, hemorrhage, hyperreflective material, CNV lesion size, and retinal thickness. Sub-retinal fluid and pigment epithelial detachment may be protective. Treatment-associated factors included disease activity and time to diagnosis. At baseline, the best corrected visual acuity in eyes with fibrosis was poorer than in eyes without fibrosis (-18.50 letters); this difference became larger at 12 months despite treatment (-26.86 letters).

CONCLUSIONS

There is a need to identify effective treatment strategies for fibrosis and to closely monitor at-risk patients. More studies involving multimodal imaging are required to clarify the definitions and grading criteria for fibrosis.

Prediction of the short-term efficacy of anti-VEGF therapy for neovascular age-related macular degeneration using optical coherence tomography angiography

Background

To evaluate whether the specific choroidal neovascularization (CNV) characteristics measured using optical coherence tomography angiography (OCTA) can predict the 6-month prognosis of neovascular age-related macular degeneration (nAMD) after anti-vascular endothelial growth factor (anti-VEGF) therapy.

Methods

Patients with type 1, type 2, or mixed-type neovascularization (NV) were prospectively included. Participants underwent an initial loading phase of three consecutive monthly intravitreal injections of Conbercept (0.5 mg) and were switched to a pro re nata (PRN) treatment strategy. OCTA images were evaluated for eyes that underwent follow-up assessments for more than 6 months. CNV lesions were manually segmented, and the CNV area, vessel area, greatest vascular caliber (GVC), and greatest linear dimension (GLD) were compared between responders and non-responders. Two masked graders independently measured the above-mentioned parameters using OCTA, and consistency was assessed using the intraclass correlation coefficient (ICC) values. Multiple logistic regression analysis was performed to evaluate the effect of a 3-month change in the CNV area, GLD, and GVC on the 6-month response to anti-VEGF agents.

Results

Among the 60 eyes of 60 patients with nAMD, 39 were responders and 21 were non-responders. The proportion of CNV types was significantly different between responders and non-responders (P = 0.009). Patients with type 2 or mixed NV seemed more likely to respond to the treatment (28.2% vs. 0.0%, and 30.8% vs. 23.8%, respectively). The change in GVC showed a significant difference between responders (− 4.98 ± 17.17 μm) and non-responders (11.01 ± 14.10 μm) after three monthly intravitreal anti-VEGF injections. Multiple logistic regression analysis showed that only the change in GVC remained significant after controlling for baseline GVC, injection number, and CNV type (adjusted OR = 1.083; P = 0.008).

Conclusions

Type 2 and mixed-type NV were significantly associated with a better response to anti-VEGF therapy. Changes in GVC after 3 months of treatment were significantly associated with a response to anti-VEGF therapy at 6 months.

Long-term Incidence and Risk Factors of Macular Fibrosis, Macular Atrophy, and Macular Hole in Eyes with Myopic Neovascularization

PURPOSE

To identify the risk factors associated with myopic macular neovascularization (mMNV)-related complications in patients treated with intravitreal anti-VEGF agents.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

Myopic eyes (n = 313) with active mMNV and median (interquartile range) follow-up of 42 months (interquartile range, 18-68 months) after initiation of anti-VEGF treatment.

METHODS

Data regarding patients' clinical and mMNV-related characteristics were collected at baseline. Subsequent OCT scans were inspected for mMNV-related complications. Best-measured visual acuity (BMVA) values were retrieved from each visit.

MAIN OUTCOME MEASURES

Incidence rate and hazard ratio (HR, with 95% confidence interval [CI]) of risk factors for fibrosis and macular atrophy calculated with Kaplan-Meier curves and Cox regression models. Crude incidence of macular hole (MH). Longitudinal BMVA changes.

RESULTS

Five-year incidence of fibrosis, atrophy, and MH were 34%, 26%, and 8%, respectively. The rate of fibrosis was 10.3 (95% CI, 8.25-12.6) per 100 person-years. Risk factors were subfoveal mMNV location (HR [95% CI] = 12.7 [2.70-56.7] vs. extrafoveal, P = 0.001) and intraretinal fluid at baseline (HR [95% CI] = 1.75 [1.05-2.98], P = 0.03). The rate of macular atrophy was 6.5 (95% CI, 5-8.3) per 100 person-years. Risk factors were diffuse (HR, 2.20 vs. tessellated fundus; 95% CI, 1.13-5.45; P = 0.02) or patchy chorioretinal atrophy (HR, 3.17 vs. tessellated fundus; 95% CI, 1.32-7.64; P = 0.01) at baseline and more numerous anti-VEGF injections before baseline (HR, 1.21; 95% CI, 1.06-1.38 for each treatment; P = 0.005). Eyes with fibrosis and macular atrophy had faster BMVA decay over follow-up. Twenty eyes (6%) developed MH. Two subtypes of MH were identified: "atrophic" and "tractional."

CONCLUSIONS

Myopic MNV-related complications are common in the long term despite initially successful treatment and have detrimental effects on visual acuity. Insights into their incidence and risk factors may help for future treatments to mitigate sight-threatening outcomes.

MiR-302d inhibits TGFB-induced EMT and promotes MET in primary human RPE cells

PURPOSE

Transforming growth factor-beta (TGFB)-mediated epithelial-mesenchymal transition (EMT) plays a crucial role in the pathogenesis of retinal fibrosis, which is one of the leading causes of impaired vision. Current approaches to treating retinal fibrosis focus, among other things, on inhibiting the TGFB signaling pathway. Transient expression of microRNAs (miRNAs) is one way to inhibit the TGFB pathway post-transcriptionally. Our previous study identified the miRNA miR-302d as a regulator of multiple TGFB-related genes in ARPE-19 cells. To further explore its effect on primary cells, the effect of miR-302d on TGFB-induced EMT in primary human retinal pigment epithelium (hRPE) was investigated in vitro.

METHODS

hRPE cells were extracted from patients receiving enucleation. Transfection of hRPE cells with miR-302d was performed before or after TGFB1 stimulation. Live-cell imaging, immunocytochemistry staining, Western blot, and ELISA assays were utilized to identify the alterations of cellular morphology and EMT-related factors expressions in hRPE cells.

RESULTS

hRPE cells underwent EMT by TGFB1 exposure. The transfection of miR-302d inhibited the transition with decreased production of mesenchymal markers and increased epithelial factors. Meanwhile, the phosphorylation of SMAD2 activated by TGFB1 was suppressed. Moreover, miR-302d expression promoted TGFB1-induced fibroblast-like hRPE cells to revert towards an epithelial stage. As confirmed by ELISA, miR-302d reduced TGFB receptor 2 (TGFBR2) and vascular endothelial growth factor A (VEGFA) levels 48 hours after transfection.

CONCLUSIONS

The protective effect of miR-302d might be a promising approach for ameliorating retinal fibrosis and neovascularization. MiR-302d suppresses TGFB-induced EMT in hRPE cells via downregulation of TGFBR2, even reversing the process. Furthermore, miR-302d reduces the constitutive secretion of VEGFA from hRPE cells.

Characterisation of macular neovascularisation subtypes in age-related macular degeneration to optimise treatment outcomes

The aim of this review is to identify the common characteristics and prognoses of different subtypes of neovascular age-related macular degeneration (nAMD). We also propose recommendations on how to tailor treatments to the subtype of neovessels to optimise patient outcomes. The authors, selected members of the Vision Academy, met to discuss treatment outcomes in nAMD according to macular neovascularisation (MNV) subtypes, using evidence from a literature search conducted on the PubMed database (cut-off date: March 2019). This review article summarises the recommendations of the Vision Academy on how the characterisation of MNV subtypes can optimise treatment outcomes in nAMD. The identification of MNV subtypes has been facilitated by the advent of multimodal imaging. Findings from fluorescein angiography, indocyanine green angiography and spectral-domain optical coherence tomography collectively help refine and standardise the determination of the MNV subtype. To date, three subtypes have been described in the literature and have specific characteristics, as identified by imaging. Type 1 MNV is associated with better long-term outcomes but usually requires more intense anti-vascular endothelial growth factor dosing. Type 2 MNV typically responds quickly to treatment but is more prone to the development of fibrotic scars, which may be associated with poorer outcomes. Type 3 MNV tends to be highly sensitive to anti-vascular endothelial growth factor treatment but may be associated with a higher incidence of outer retinal atrophy, compared with other subtypes. Accurately assessing the MNV subtype provides information on prognosis and helps to optimise the management of patients with nAMD.

Morphological characterization of subretinal hyper-reflective material in posterior uveitis using swept-source optical coherence tomography and optical coherence tomography angiography

Purpose

To analyze the structural features of subretinal hyper-reflective material (SHRM) in posterior uveitis using swept-source optical coherence tomography (SS-OCT) and optical coherence tomography angiography (SS-OCTA).

Methods

In this observational study, subjects with quiescent posterior uveitis and the presence of SHRM on SS-OCT were subjected to SS-OCTA to identify the presence of an intrinsic choroidal neovascular (CNV) network. OCT features were compared for SHRM harboring CNV (vascular SHRM) with those without CNV network (avascular SHRM) to identify clinical signs pointing toward the presence of CNVM inside SHRM.

Results

Forty-two eyes of 33 subjects (18 males; mean age: 29.52 ± 12.56 years) were evaluated. Two-thirds (28/42) of eyes having SHRM on SS-OCT harbored intrinsic neovascular network (vascular SHRM). Increased reflectivity of SHRM (P < 0.001) and increased transmission of OCT signal underlying SHRM (P = 0.03) were suggestive of the absence of CNVM. The presence of intra/subretinal fluid (P = 0.08) and pitchfork sign (P = 0.017) were important markers of vascular SHRM.

Conclusion

SHRM is an important OCT finding in eyes with posterior uveitis. Meticulous assessment of SHRM characteristics on SS-OCT can aid in identifying the underlying intrinsic neovascular network.

Baseline predictors for subretinal fibrosis in neovascular age-related macular degeneration

To find baseline predictors for subretinal fibrosis (SF) in neovascular age-related macular degeneration (nAMD). Forty-five eyes of 45 participants with treatment-naïve nAMD were consecutively enrolled and treated according to a standardized treat-and-extend protocol. Spectral-domain optical coherence tomography (OCT), color fundus photography and fluorescein angiography as well as novel imaging modalities polarization-sensitive OCT and OCT angiography (OCTA) were performed to detect SF after 1 year and find baseline predictors for SF development. Baseline OCTA scans were evaluated for quantitative features such as lesion area, vessel area, vessel junctions, vessel length, vessel endpoints and mean lacunarity. Additionally, the type of macular neovascularization, the presence of subretinal fluid, intraretinal fluid (IRF), subretinal hyperreflective material (SHRM), retinal hemorrhage as well as best-corrected visual acuity (BCVA) were evaluated. After 12 months 8 eyes (18%) developed SF. Eyes with SF had worse baseline BCVA (p = .001) and a higher prevalence of IRF (p = .014) and SHRM at baseline (p = .017). There was no significant difference in any of the evaluated quantitative OCTA parameters (p > .05) between eyes with and without SF. There were no quantitative baseline microvascular predictors for SF in our study. Low baseline BCVA, the presence of IRF and SHRM, however, are easily identifiable baseline parameters indicating increased risk.

Quantitative assessment of retinal fluid in neovascular age-related macular degeneration under anti-VEGF therapy

The retinal world has been revolutionized by optical coherence tomography (OCT) and anti-vascular endothelial growth factor (VEGF) therapy. The numbers of intravitreal injections are on a constant rise and management in neovascular age-related macular degeneration (nAMD) is mainly driven by the qualitative assessment of macular fluid as detected on OCT scans. The presence of macular fluid, particularly subretinal fluid (SRF) and intraretinal fluid (IRF), has been used to trigger re-treatments in clinical trials and the real world. However, large discrepancies can be found between the evaluations of different readers or experts and especially small amounts of macular fluid might be missed during this process. Pixel-wise detection of macular fluid uses an entire OCT volume to calculate exact volumes of retinal fluid. While manual annotations of such pixel-wise fluid detection are unfeasible in a clinical setting, artificial intelligence (AI) is able to overcome this hurdle by providing real-time results of macular fluid in different retinal compartments. Quantitative fluid assessments have been used for various post hoc analyses of randomized controlled trials, providing novel insights into anti-VEGF treatment regimens. Nonetheless, the application of AI-algorithms in a prospective patient care setting is still limited. In this review, we discuss the use of quantitative fluid assessment in nAMD during anti-VEGF therapy and provide an outlook to novel forms of patient care with the support of AI quantifications.

Morphologic and Microvascular Differences Between Macular Neovascularization With and Without Subretinal Fibrosis

Purpose

To evaluate morphologic and microvascular differences between eyes with and without subretinal fibrosis (SF) caused by neovascular age-related macular degeneration (nAMD).

Methods

Patients with nAMD with a minimum history of 12 months of anti-VEGF treatment were prospectively included in this cross-sectional study. Patients were imaged using standard imaging, swept-source optical coherence tomography angiography for quantitative microvascular analysis and polarization-sensitive OCT as an ancillary method for automated SF segmentation. The presence of reticular pseudodrusen, hyperreflective foci (HRF), and outer retinal tubulation (ORT) were also evaluated.

Results

Sixty eyes of 60 participants (37 female) with nAMD and a mean 3.1 (±2.7)-year history of anti-VEGF treatment were included, 20 (33%) of which were diagnosed with SF. Eyes with SF had a higher prevalence of ORT (P < 0.001) and a lower prevalence of HRF (P = 0.004) than eyes without SF. Fifty eyes were analyzed quantitatively for microvascular biomarkers. Eyes with SF had a larger greatest vascular caliber (P = 0.001) and greatest linear diameter (P = 0.042), a larger microvascular neovascularization (MNV) area (P = 0.026), larger vessel area (P = 0.037), higher number of vessel junctions (P = 0.025), longer total vessel length (P = 0.027), higher number of vessel endpoints (P = 0.007), and higher endpoint density (P = 0.047).

Conclusions

This multimodal imaging approach demonstrated in vivo microvascular and morphological differences in eyes with and without SF. Eyes with SF tend to have larger MNV lesions with thicker vessels and are often associated with the presence of ORT.

Translational Relevance

This study points out imaging biomarkers in patients with SF, which may help identifying high-risk patients.

Long-Term Outcomes of Bacillary Layer Detachment in Neovascular Age-Related Macular Degeneration

PURPOSE

To evaluate the clinical characteristics, multimodal imaging features, and long-term treatment outcomes of eyes with neovascular age-related macular degeneration (nAMD) and bacillary layer detachment (BALAD) treated with intravitreal anti-VEGF therapy.

DESIGN

Retrospective, longitudinal, case series.

PARTICIPANTS

Treatment-naive patients with nAMD (n = 30) showing BALAD on OCT and undergoing anti-VEGF therapy.

METHODS

Clinical records and multimodal imaging results of up to 4 years after diagnosis were reviewed.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA) values were compared over time. The cumulative risk of and risk factors for subretinal fibrosis were assessed using Cox regression analyses, and adjusted hazard ratio (aHR) was computed.

RESULTS

Thirty eyes of 30 patients were included. Macular neovascularization (MNV) subtypes were distributed as follows: type 1, 63%; type 2, 27%; mixed type 1 and 2, 3%; type 3, 3%; aneurysmal type 1, 3%. The BCVA significantly improved after anti-VEGF loading phase (Snellen equivalent, from 20 of 118 to 20 of 71, P = 0.03), but it returned to the baseline levels at 4 years (Snellen equivalent, 20 of 103, P = 0.6). The cumulative risk of subretinal fibrosis was 77% at 4 years. The risk factors associated with subretinal fibrosis included hemorrhagic BALAD (aHR, 2.02; 95% confidence interval [CI] 1.54-3.22; P < 0.01) and the presence of subretinal hyperreflective material (aHR, 1.83; 95% CI 1.35-3.14; P < 0.01).

CONCLUSIONS

BALAD was found in association with all types of MNV in patients with nAMD. Long-term observation revealed poor functional outcomes related to the high risk of subretinal fibrosis.

Subretinal fibrosis in neovascular age-related macular degeneration: current concepts, therapeutic avenues, and future perspectives

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the human retina which in its most aggressive form is associated with the formation of macular neovascularization (MNV) and subretinal fibrosis leading to irreversible blindness. MNVs contain blood vessels as well as infiltrating immune cells, myofibroblasts, and excessive amounts of extracellular matrix proteins such as collagens, fibronectin, and laminin which disrupts retinal function and triggers neurodegeneration. In the mammalian retina, damaged neurons cannot be replaced by tissue regeneration, and subretinal MNV and fibrosis persist and thus fuel degeneration and visual loss. This review provides an overview of subretinal fibrosis in neovascular AMD, by summarizing its clinical manifestations, exploring the current understanding of the underlying cellular and molecular mechanisms and discussing potential therapeutic approaches to inhibit subretinal fibrosis in the future.

Identification and quantification of fibrotic areas in the human retina using polarization-sensitive OCT

Subretinal fibrosis is one of the most prevalent causes of blindness in the elderly population, but a true gold standard to objectively diagnose fibrosis is still lacking. Since fibrotic tissue is birefringent, it can be detected by polarization-sensitive optical coherence tomography (PS-OCT). We present a new algorithm to automatically detect, segment, and quantify fibrotic lesions within 3D data sets recorded by PS-OCT. The algorithm first compensates for the birefringence of anterior ocular tissues and then uses the uniformity of the birefringent optic axis as an indicator to identify fibrotic tissue, which is then segmented and quantified. The algorithm was applied to 3D volumes recorded in 57 eyes of 57 patients with neovascular age-related macular degeneration using a spectral domain PS-OCT system. The results of fibrosis detection were compared to the clinical diagnosis based on color fundus photography (CFP), and the precision of fibrotic area measurement was assessed by three repeated measurements in a sub-set of 15 eyes. The average standard deviation of the fibrotic area obtained in eyes with a lesion area > 0.7 mm2 was 15%. Fibrosis detection by CFP and PS-OCT agreed in 48 cases, discrepancies were only observed in cases of lesion area < 0.7 mm2. These remaining discrepancies are discussed, and a new method to treat ambiguous cases is presented.

AI-based monitoring of retinal fluid in disease activity and under therapy

Retinal fluid as the major biomarker in exudative macular disease is accurately visualized by high-resolution three-dimensional optical coherence tomography (OCT), which is used world-wide as a diagnostic gold standard largely replacing clinical examination. Artificial intelligence (AI) with its capability to objectively identify, localize and quantify fluid introduces fully automated tools into OCT imaging for personalized disease management. Deep learning performance has already proven superior to human experts, including physicians and certified readers, in terms of accuracy and speed. Reproducible measurement of retinal fluid relies on precise AI-based segmentation methods that assign a label to each OCT voxel denoting its fluid type such as intraretinal fluid (IRF) and subretinal fluid (SRF) or pigment epithelial detachment (PED) and its location within the central 1-, 3- and 6-mm macular area. Such reliable analysis is most relevant to reflect differences in pathophysiological mechanisms and impacts on retinal function, and the dynamics of fluid resolution during therapy with different regimens and substances. Yet, an in-depth understanding of the mode of action of supervised and unsupervised learning, the functionality of a convolutional neural net (CNN) and various network architectures is needed. Greater insight regarding adequate methods for performance, validation assessment, and device- and scanning-pattern-dependent variations is necessary to empower ophthalmologists to become qualified AI users. Fluid/function correlation can lead to a better definition of valid fluid variables relevant for optimal outcomes on an individual and a population level. AI-based fluid analysis opens the way for precision medicine in real-world practice of the leading retinal diseases of modern times.

Clinical Features, Prognosis, and Long-Term Response to Ranibizumab of Macular CNVs in Pattern Dystrophies Spectrum: A Pilot Study

Introduction

To analyze the morphological and functional features of choroidal neovascularizations (CNVs) in eyes affected by pattern dystrophies (PD), evaluating their long-term response to intravitreal ranibizumab, and comparing them with CNVs in age-related macular degeneration (AMD). The mean goal is to identify possible disease biomarkers and to evaluate the long-term prognosis of CNVs in PD.

Materials and Methods

A retrospective study of 42 patients with naïve CNV (26 PD and 16 AMD), for a total of 47 eyes (29 eyes in the PD group and 18 eyes in the AMD group). Each patient received a loading dose of ranibizumab (one monthly for three months) followed by pro re nata (PRN) reinjection protocol for a period of at least three years. Morphological OCT parameters (CRT, central retinal thickness; SRF, subretinal fluid; IRF, intraretinal fluid; SHRM, subretinal hyperreflective material; HRF, hyperreflective foci; HCD, hyperreflective crystalline deposits; cCT, central choroidal thickness; slCT, sublesional choroidal thickness; EZd, ellipsoid zone disruption; and best corrected visual acuity (BCVA in logMAR scale)) were reported at baseline and last follow-up.

Results

At baseline, no significant differences were found between the two groups, except for choroidal thickness parameters that were significantly greater in the PD group (p = 0.009). Longitudinal PD analysis demonstrated reduction in BCVA (p = 0.009), decrease in CRT (p = 0.046), resolution of SRF in 61.6% of cases (p = 0.004) and SHRM in 30% (p = 0.034), and choroidal thinning both centrally (p = 0.004) and sublesional (p = 0.011) compared to baseline. At 3 years, the PD group received significantly more injections than the AMD (p = 0.011) and showed significantly thicker choroid (p = 0.033) and more frequent HRF (p = 0.006). Regarding the PD group, we found a negative correlation between age and choroidal thicknesses at baseline and at 3 years (p < 0.05); significant positive correlations were found between baseline BCVA and at 3 years (p < 0.001), BCVA at 3 years and IRF (p = 0.003) and SHRM at 3 years (p = 0.003); CRT baseline and CRT 3 years (p = 0.017); HCD at 3 years was associated with greater CRT (p = 0.04) and IRF at 3 years (p = 0.019).

Conclusions

Early and long-term morphofunctional features of CNVs in PD and in AMD are overlapping. CNVs in PD have poorer long-term response to ranibizumab and higher choroidal thickness suggesting different pathogenetic and evolutionary mechanisms.

Associations of Variation in Retinal Thickness With Visual Acuity and Anatomic Outcomes in Eyes With Neovascular Age-Related Macular Degeneration Lesions Treated With Anti-Vascular Endothelial Growth Factor Agents

Question

Are fluctuations in retinal thickness associated with visual and anatomic outcomes in eyes with neovascular age-related macular degeneration treated with anti–vascular endothelial growth factor drugs?

Findings

In this study of 1731 participants from 2 randomized clinical trials, increasing variation in retinal thickness was associated with worse outcomes in post hoc analyses of protocol-directed treatment regimens.

Meaning

These findings suggest that fluctuating activity may be a marker for poor prognosis in eyes with neovascular age-related macular degeneration treated with anti–vascular endothelial growth factor drugs.

Importance

When initiating anti–vascular endothelial growth factor (VEGF) treatment for patients with neovascular age-related macular degeneration (nAMD), knowledge of prognostic factors is important for advising patients and guiding treatment. We hypothesized that eyes with greater fluctuation in retinal thickness over time have worse outcomes than eyes with less variation.

Objective

To investigate whether visual and anatomic outcomes in eyes with nAMD initiating anti-VEGF treatment are associated with fluctuations in retinal thickness.

Design, Setting, and Participants

In this study using data from the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) and the Inhibition of VEGF in Age-Related Choroidal Neovascularization (IVAN) randomized clinical trial, people with previously untreated nAMD were included. Data were collected from February 2008 to November 2012, and data were analyzed from April 2017 to April 2020.

Main Outcomes and Measures

Foveal center point thicknesses (FCPTs) were extracted from 1165 study eyes from CATT and 566 study eyes from the IVAN trial, excluding those with 3 measurements or less. For each eye, the SD of FCPT was calculated. Eyes were grouped by FCPT SD quartile. Associations of FCPT SD quartile with outcomes were quantified at month 24 or the last available visit by linear or logistic regression, adjusting for baseline best-corrected visual acuity (BCVA) and randomized allocations to drug and treatment regimen, for BCVA, development of fibrosis, and development of macular atrophy.

Results

Of the 1731 included patients, 1058 (61.1%) were female, and the mean (SD) age was 78.6 (7.4) years. The median (interquartile range) FCPT SD was 40.2 (27.1-61.2) in the IVAN cohort and 59.0 (38.3-89.4) in the CATT cohort. After adjustment for baseline BCVA and trial allocations, BCVA worsened significantly across the quartiles of FCPT SD; the difference between the first and fourth quartiles was −6.27 Early Treatment Diabetic Retinopathy Study letters (95% CI, −8.45 to −4.09). The risk of developing fibrosis and macular atrophy also increased across FCPT SD quartiles. Odds ratios ranged from 1.40 (95% CI, 1.03 to 1.91) for quartile 2 to 1.95 (95% CI, 1.42 to 2.68) for quartile 4 for fibrosis and from 1.32 (95% CI, 0.90 to 1.92) for quartile 2 to 2.10 (95% CI, 1.45 to 3.05) for quartile 4 for macular atrophy.

Conclusions and Relevance

Greater variation in retinal thickness in eyes with nAMD during treatment with anti-VEGF was associated with worse BCVA and development of fibrosis and macular atrophy in these post hoc analyses, despite protocol-directed treatment frequency. Practitioners may want to consider variation in retinal thickness when advising patients about their prognosis.

End-to-End Deep Learning Model for Predicting Treatment Requirements in Neovascular AMD From Longitudinal Retinal OCT Imaging

Neovascular age-related macular degeneration (nAMD) is nowadays successfully treated with anti-VEGF substances, but inter-individual treatment requirements are vastly heterogeneous and currently poorly plannable resulting in suboptimal treatment frequency. Optical coherence tomography (OCT) with its 3D high-resolution imaging serves as a companion diagnostic to anti-VEGF therapy. This creates a need for building predictive models using automated image analysis of OCT scans acquired during the treatment initiation phase. We propose such a model based on deep learning (DL) architecture, comprised of a densely connected neural network (DenseNet) and a recurrent neural network (RNN), trainable end-to-end. The method starts by sampling several 2D-images from an OCT volume to obtain a lower-dimensional OCT representation. At the core of the predictive model, the DenseNet learns useful retinal spatial features while the RNN integrates information from different time points. The introduced model was evaluated on the prediction of anti-VEGF treatment requirements in nAMD patients treated under a pro-re-nata (PRN) regimen. The DL model was trained on 281 patients and evaluated on a hold-out test set of 69 patient. The predictive model achieved a concordance index of 0.7 in regressing the number of received treatments, while in a classification task it obtained an 0.85 (0.81) AUC in detecting the patients with low (high) treatment requirements. The proposed model outperformed previous machine learning strategies that relied on a set of spatio-temporal image features, showing that the proposed DL architecture successfully learned to extract the relevant spatio-temporal patterns directly from raw longitudinal OCT images.

ANALYSIS OF FLUID VOLUME AND ITS IMPACT ON VISUAL ACUITY IN THE FLUID STUDY AS QUANTIFIED WITH DEEP LEARNING

PURPOSE

To investigate quantitative differences in fluid volumes between subretinal fluid (SRF)-tolerant and SRF-intolerant treat-and-extend regimens for neovascular age-related macular degeneration and analyze the association with best-corrected visual acuity.

METHODS

Macular fluid (SRF and intraretinal fluid) was quantified on optical coherence tomography volumetric scans using a trained and validated deep learning algorithm. Fluid volumes and complete resolution was automatically assessed throughout the study. The impact of fluid location and volumes on best-corrected visual acuity was computed using mixed-effects regression models.

RESULTS

Baseline fluid quantifications for 348 eyes from 348 patients were balanced (all P > 0.05). No quantitative differences in SRF/intraretinal fluid between the treatment arms was found at any study-specific time point (all P > 0.05). Compared with qualitative assessment, the proportion of eyes without SRF/intraretinal fluid did not differ between the groups at any time point (all P > 0.05). Intraretinal fluid in the central 1 mm and SRF in the 1-mm to 6-mm macular area were negatively associated with best-corrected visual acuity (-2.8 letters/100 nL intraretinal fluid, P = 0.007 and -0.20 letters/100 nL SRF, P = 0.005, respectively).

CONCLUSION

Automated fluid quantification using artificial intelligence allows objective and precise assessment of macular fluid volume and location. Precise determination of fluid parameters will help improve therapeutic efficacy of treatment in neovascular age-related macular degeneration.

Principal Cause of Poor Visual Acuity after Neovascular Age-Related Macular Degeneration: Age-Related Eye Disease Study 2 Report Number 23

PURPOSE

To analyze the principal cause for poor vision in eyes with best-corrected visual acuity (BCVA) of 20/200 or worse 2 years after neovascular age-related macular degeneration (nAMD).

DESIGN

Prospective cohort study of participants enrolled in a clinical trial of oral supplements.

PARTICIPANTS

Age-Related Eye Disease Study 2 (AREDS2) participants whose eyes began anti-vascular endothelial growth factor (VEGF) therapy for incident nAMD and had data available at 2 years.

METHODS

Participants underwent refracted BCVA testing, ophthalmoscopic examination, and fundus photography at baseline and annual visits. Self-reports of anti-VEGF injections were collected.

MAIN OUTCOME MEASURES

Principal cause of BCVA of 20/200 or worse at 2 years, detected on fundus photography grading.

RESULTS

Of the 594 eligible eyes, the number with BCVA of 20/200 or worse at 2 years was 56 (9.4%). Mean BCVA was 14.9 letters (standard deviation [SD], 12.3 letters; Snellen equivalent, 20/500), versus 70.1 letters (SD, 12.8 letters; Snellen equivalent, 20/40) in the other group. Of the 55 eyes with fundus photography available at 2 years, 33 (60.0%) had central macular atrophy and 22 (40.0%) had central subretinal fibrosis assessed as the principal cause for poor vision. The group with poor BCVA had a higher proportion of non-White participants (8.9% vs. 1.7%; P = 0.006), lower BCVA 2 years earlier (mean, 38.0 letters [SD, 26.7 letters; Snellen equivalent, 20/160] vs. 71.8 letters (SD, 11.9 letters; Snellen equivalent, 20/40]; P < 0.0001), higher proportion with macular atrophy 2 years earlier (26.8% vs. 12.3%; P = 0.003), higher proportion with macular hemorrhage (25.5% vs. 13.2%; P = 0.014), and fewer anti-VEGF injections (7.6 vs. 10.2; P = 0.001).

CONCLUSIONS

Visual acuity data and fundus photography were obtained in a clinical trial environment, but were related to anti-VEGF therapy given in routine clinical practice. At 2 years after starting anti-VEGF therapy, almost 1 in 10 eyes showed BCVA at the level of legal blindness. From fundus photography grading, the cause of poor vision appeared to be macular atrophy in 60% and subretinal fibrosis in 40%. These data may be useful in understanding the long-term limits to good vision in nAMD.

Subretinal Fibrosis Detection Using Polarization Sensitive Optical Coherence Tomography

Purpose

Subretinal fibrosis (SRFib) is an important cause of permanent loss-of-vision diseases with submacular neovascularization, but a reliable diagnostic method is currently missing. This study uses polarization-sensitive optical coherence tomography (PS-OCT) to detect SRFib within retinal lesions by measurement of its birefringent collagen fibers.

Methods

Twenty-five patients were enrolled with retinal pathology in one or both eyes containing (1) suspected SRFib, (2) lesions suspected not to be fibrotic, or (3) lesions with doubtful presence of SRFib. All eyes were evaluated for SRFIb using conventional diagnostics by three retinal specialists. PS-OCT images were visually evaluated for SRFib based on cumulative phase retardation, local birefringence, and optic axis uniformity.

Results

Twenty-nine eyes from 22 patients were scanned successfully. In 13 eyes, SRFib was diagnosed by all retinal specialists; of these, 12 were confirmed by PS-OCT and one was inconclusive. In nine eyes, the retinal specialists expected no SRFib, which was confirmed by PS-OCT in all cases. In seven eyes, the retinal specialists’ evaluations were inconsistent with regard to the presence of SRFib. PS-OCT confirmed the presence of SRFib in four of these eyes and the absence of SRFib in two eyes and was inconclusive in one eye.

Conclusions

In 21 out of 22 eyes, PS-OCT confirmed the evaluation of retinal specialists regarding the presence of SRFib. PS-OCT provided additional information to distinguish SRFib from other tissues within subretinal neovascular lesions in 6 out of 7 eyes.

Translational Relevance

PS-OCT can identify and quantify SRFib in doubtful cases for which a reliable diagnosis is currently lacking.