Progression of geographic atrophy and impact of fundus autofluorescence patterns in age-related macular degeneration

Merging Information From Infrared and Autofluorescence Fundus Images for Monitoring of Chorioretinal Atrophic Lesions

Purpose

To develop a method for automated detection and progression analysis of chorioretinal atrophic lesions using the combined information of standard infrared (IR) and autofluorescence (AF) fundus images.

Methods

Eighteen eyes (from 16 subjects) with punctate inner choroidopathy were analyzed. Macular IR and blue AF images were acquired in all eyes with a Spectralis HRA+OCT device (Heidelberg Engineering, Heidelberg, Germany). Two clinical experts manually segmented chorioretinal lesions on the AF image. AF images were aligned to the corresponding IR. Two random forest models were trained to classify pixels of lesions, one based on the AF image only, the other based on the aligned IR-AF. The models were validated using a leave-one-out cross-validation and were tested against the manual segmentation to compare their performance. A time series from one eye was identified and used to evaluate the method based on the IR-AF in a case study.

Results

The method based on the AF images correctly classified 95% of the pixels (i.e., in vs. out of the lesion) with a Dice's coefficient of 0.80. The method based on the combined IR-AF correctly classified 96% of the pixels with a Dice's coefficient of 0.84.

Conclusions

The automated segmentation of chorioretinal lesions using IR and AF shows closer alignment to manual segmentation than the same method based on AF only. Merging information from multimodal images improves the automatic and objective segmentation of chorioretinal lesions even when based on a small dataset.

Translational Relevance

Merged information from multimodal images improves segmentation performance of chorioretinal lesions.

Optical Coherence Tomography-Angiography in Geographic Atrophy

Geographic atrophy (GA) represents the non-exudative late stage of age-related macular degeneration and constitutes a leading cause of legal blindness in the developed world. It is characterized by areas of loss of outer retinal layers including photoreceptors, degeneration of the retinal pigment epithelium, and rarefication of the choriocapillaris. As all three layers are functionally connected, the precise temporal sequence and relative contribution of these layers towards the development and progression of GA is unclear. The advent of optical coherence tomography angiography (OCT-A) has allowed for three-dimensional visualization of retinal blood flow. Using OCT-A, recent studies have demonstrated that choriocapillaris flow alterations are particularly associated with the development of GA, exceed atrophy boundaries spatially, and are a prognostic factor for future GA progression. Furthermore, OCT-A may be helpful to differentiate GA from mimicking diseases. Evidence for a potential protective effect of specific forms of choroidal neovascularization in the context of GA has been reported. This article aims to give a comprehensive review of the current literature concerning the application of OCT-A in GA, and summarizes the opportunities and limitations with regard to pathophysiologic considerations, differential diagnosis, study design, and patient assessment.

Fundus autofluorescence imaging

Fundus autofluorescence (FAF) imaging is an in vivo imaging method that allows for topographic mapping of naturally or pathologically occurring intrinsic fluorophores of the ocular fundus. The dominant sources are fluorophores accumulating as lipofuscin in lysosomal storage bodies in postmitotic retinal pigment epithelium cells as well as other fluorophores that may occur with disease in the outer retina and subretinal space. Photopigments of the photoreceptor outer segments as well as macular pigment and melanin at the fovea and parafovea may act as filters of the excitation light. FAF imaging has been shown to be useful with regard to understanding of pathophysiological mechanisms, diagnostics, phenotype-genotype correlation, identification of prognostic markers for disease progression, and novel outcome parameters to assess efficacy of interventional strategies in chorio-retinal diseases. More recently, the spectrum of FAF imaging has been expanded with increasing use of green in addition to blue FAF, introduction of spectrally-resolved FAF, near-infrared FAF, quantitative FAF imaging and fluorescence life time imaging (FLIO). This article gives an overview of basic principles, FAF findings in various retinal diseases and an update on recent developments.

Growth Rate of Geographic Atrophy Secondary to Age-Related Macular Degeneration: A Meta-Analysis of Natural History Studies and Implications for Designing Future Trials

INTRODUCTION

There is no effective treatment for geographic atrophy (GA). To help design future GA treatment trials, we conducted a meta-analysis for GA growth rate and its variability in natural history studies.

METHODS

Literatures were searched up to April 30, 2020. Data were extracted independently by 2 authors and analyzed using random-effects models.

RESULTS

The pooled mean GA growth rate was 1.66 mm2/year (SD = 1.27 mm2/year, I2 = 97.0%, p < 0.001) from 23 studies (3,078 patients) reported with growth rate in mm2/year and 0.33 mm/year (SD = 0.17 mm/year, I2 = 83.0%, p < 0.001) from 12 studies (1,808 patients) reported with growth rate in mm/year. Larger mean baseline GA area in mm2 was associated with larger mean growth rate in both mm2/year and mm/year (p < 0.001). The sample size at 85% power for detecting 15% reduction in growth rate in a 2-arm GA trial is 464 and 209 patients per arm, respectively, for using mm2/year and mm/year as the primary outcome.

DISCUSSION/CONCLUSION

GA natural history studies had a pooled mean (SD) GA growth rate of 1.66 (1.27) mm2/year or 0.33 (0.17) mm/year. Because GA growth rate using mm/year requires smaller sample size than using mm2/year, GA growth rate in mm/year is recommended as the primary outcome measure for future GA trials.

Automated Retinal Layer Segmentation Using Graph-based Algorithm Incorporating Deep-learning-derived Information

Regular drusen, an accumulation of material below the retinal pigment epithelium (RPE), have long been established as a hallmark early feature of nonneovascular age-related macular degeneration (AMD). Advances in imaging have expanded the phenotype of AMD to include another extracellular deposit, reticular pseudodrusen (RPD) (also termed subretinal drusenoid deposits, SDD), which are located above the RPE. We developed an approach to automatically segment retinal layers associated with regular drusen and RPD in spectral domain (SD) optical coherence tomography (OCT) images. More specifically, a shortest-path algorithm enhanced with probability maps generated through a fully convolutional neural network was used to segment drusen and RPD, as well as 11 retinal layers in SD-OCT volumes. This algorithm achieves a mean difference that is within the subpixel accuracy range drusen and RPD, alongside the other 11 retinal layers, highlighting the high robustness of this algorithm for this dataset. To the best of our knowledge, this is the first report of a validated algorithm for the automated segmentation of the retinal layers including early AMD features of RPD and regular drusen separately on SD-OCT images.

CLINICOPATHOLOGIC CORRELATION OF GEOGRAPHIC ATROPHY SECONDARY TO AGE-RELATED MACULAR DEGENERATION

Supplemental Digital Content is Available in the Text.

Direct clinicopathologic correlation of an eye with geographic atrophy secondary to age-related macular degeneration provides histologic correlates of features commonly seen by optical coherence tomography, such as end-stages of drusen, subretinal drusenoid deposit, plaques near the Bruch membrane, and hyporeflective wedge.

Purpose:

In an eye with geographic atrophy (GA) secondary to age-related macular degeneration, we correlated ex vivo histologic features with findings recorded in vivo using optical coherence tomography (OCT), near-infrared reflectance imaging, and fundus autofluorescence.

Methods:

In the left eye of an 86-year-old white woman, in vivo near-infrared reflectance and eye-tracked OCT B-scans at each of 6 clinic visits and a baseline fundus autofluorescence image were correlated with high-resolution histologic images of the preserved donor eye.

Results:

Clinical imaging showed a small parafoveal multilobular area of GA, subfoveal soft drusen, refractile drusen, hyperreflective lines near the Bruch membrane, subretinal drusenoid deposit (reticular pseudodrusen), and absence of hyperautofluorescent foci at the GA margin. By histology, soft drusen end-stages included avascular fibrosis with highly reflective cholesterol crystals. These accounted for hyperreflective lines near the Bruch membrane in OCT and plaques in near-infrared reflectance imaging. Subretinal drusenoid deposit was thick, continuous, extracellular, extensive outside the fovea, and associated with distinctive retinal pigment epithelium dysmorphia and photoreceptor degeneration. A hyporeflective wedge corresponded to ordered Henle fibers without cellular infiltration. The external limiting membrane descent, which delimits GA, was best visualized in high-quality OCT B-scans. Retinal pigment epithelium and photoreceptor changes at the external limiting membrane descent were consistent with our recent histologic survey of donor eyes.

Conclusion:

This case informs on the extent, topography, and lifecycle of extracellular deposits. High-quality OCT scans are required to reveal all tissue features relevant to age-related macular degeneration progression to GA, especially the external limiting membrane descent. Histologically validated signatures of structural OCT B-scans can serve as references for other imaging modalities.

Low-vision intervention in individuals with age-related macular degeneration

Purpose:

The objective of this study was to estimate the level of visual impairment in patients diagnosed to have age-related macular degeneration (ARMD) who presented to low-vision care (LVC) clinic at a tertiary eye care center in India, to analyze the type of distant and near devices prescribed to them and to compare the visual benefit in different age groups among patients with ARMD.

Methods:

A retrospective review was done for 91 patients with low-vision secondary to ARMD who were referred to the LVC clinic from 2016 to 2017. Demographic profile: age, gender, occupation, ocular history, visual acuity status, and type of low-vision device (LVD) preferred were documented. The details of LVDs and subsequent improvements were noted.

Result:

Of the 91 patients, 64 (70.3%) were men and 27 (29.7%) were women. Of the cases which were referred, 36.26% had a severe visual impairment (VI), 32.96% had moderate VI, 28.57% had mild VI, and 5.49% had profound VI. The majority of the patients had myopia 57 (62.63%), followed by hyperopia in 25 (27.47%) subjects. The subjects were divided into three groups based on age 40–65 years, 66–75 years, and above 75 years for the analysis of VI. There was a statistically significant improvement (P < 0.01) in near vision with the help of LVDs in all three groups. SEE TV binocular telescope was the most commonly prescribed LVD for viewing distant objects. The most commonly preferred magnifier for near work was half-eye spectacle (56%) followed by stand magnifier (9.9%) and portable video magnifier (9.9%).

Conclusion:

The use of LVDs can help these patients with ARMD in cases where medical and surgical treatment have no or a limited role in restoring useful vision.

Prognostic value of intermediate age-related macular degeneration phenotypes for geographic atrophy progression

BACKGROUND

To characterise early stages of geographic atrophy (GA) development in age-related macular degeneration (AMD) and to determine the prognostic value of structural precursor lesions in eyes with intermediate (i) AMD on the subsequent GA progression.

METHODS

Structural precursor lesions for atrophic areas (lesion size at least 0.5 mm² in fundus autofluorescence images) were retrospectively identified based on multimodal imaging and evaluated for association with the subsequent GA enlargement rates (square-root transformed, sqrt). A linear mixed-effects model was used to account for the hierarchical nature of the data with a Tukey post hoc test to assess the impact of the local precursor on the subsequent GA progression rate.

RESULTS

A total of 39 eyes with GA of 34 patients with a mean age of 74.4±6.7 (±SD) years were included in this study. Five precursor lesions (phenotypes 1-5) preceding GA development were identified: large, sub-retinal pigment epithelial drusen (n=19), reticular pseudodrusen (RPD, n=10), refractile deposits (n=4), pigment epithelial detachment (n=4) and vitelliform lesions (n=2). Precursor lesions exhibited a significant association with the subsequent (sqrt) GA progression rates (p=0.0018) with RPD (phenotype 2) being associated with the fastest GA enlargement (2.29±0.52 (±SE) mm/year.

CONCLUSIONS

The results indicate the prognostic relevance of iAMD phenotyping for subsequent GA progression highlighting the role of structural AMD features across different AMD stages.

Spectral-Domain OCT Analysis of Risk Factors for Macular Atrophy Development in the HARBOR Study for Neovascular Age-Related Macular Degeneration

PURPOSE

To identify baseline risk factors for macular atrophy (MA) development in HARBOR via a longitudinal assessment of monthly spectral-domain (SD)-OCT scans. Previous analyses of MA in HARBOR examined data from color fundus photography (CFP) and fluorescein angiography (FA).

DESIGN

Retrospective, post hoc analysis of SD-OCT images from HARBOR (ClinicalTrials.gov identifier, NCT00891735), a phase 3, multicenter, prospective, randomized, double-blind, active treatment-controlled clinical trial.

PARTICIPANTS

Patients (N = 1097) with subfoveal choroidal neovascularization secondary to neovascular age-related macular degeneration (nAMD) treated with intravitreal ranibizumab 0.5 mg monthly (n = 275), 0.5 mg pro re nata (PRN) after 3 loading doses (n = 275), 2.0 mg monthly (n = 274), or 2.0 mg PRN (n = 273).

METHODS

Evaluable SD-OCT macular cube scans from patients with 24 months of follow-up (N = 941) were examined monthly from baseline to month 24 by masked reading center-trained graders. Atrophy diagnosis criteria were consistent with those proposed by the Classification of Atrophy Meetings (CAM) group: hypertransmission of light into the choroid, loss of retinal pigment epithelium, and loss of outer retinal layers. Multivariable proportional hazards regression was performed for time to atrophy development.

MAIN OUTCOME MEASURES

Risk factors for MA as determined by time to MA development over 24 months of treatment.

RESULTS

Baseline risk factors for MA were confirmed from prior analyses that used CFP and FA data: absence of subretinal fluid, presence of intraretinal cysts, presence of Type 3 neovascularization, and presence of atrophy in the fellow eye. This analysis of SD-OCT data identified new baseline risk factors for MA: higher central drusen volume, lower choroidal thickness, presence of nascent atrophy, presence of reticular pseudodrusen, and increased central foveal thickness. Ranibizumab treatment regimen and dose level were not found to be risk factors for MA development.

CONCLUSIONS

In this analysis of a major nAMD trial using CAM atrophy criteria, new baseline risk factors for MA development were identified using an SD-OCT dataset. Risk factors for MA development identified by prior analyses were confirmed. Monthly treatment with ranibizumab 0.5 mg was not found to be a risk factor for MA development over 24 months.

Mitochondrial dysfunction in age-related macular degeneration: melatonin as a potential treatment

Introduction: Age-related Macular Degeneration (AMD), a retinal neurodegenerative disease is the most common cause of blindness among the elderly in developed countries. The impairment of mitochondrial biogenesis has been reported in human retinal pigment epithelium (RPE) cells affected by AMD. Oxidative/nitrosative stress plays an important role in AMD development. The mitochondrial respiratory system is considered a major site of reactive oxygen species (ROS) generation. During aging, insufficient free radical scavenger systems, impairment of DNA repair mechanisms and reduction of mitochondrial degradation and turnover contribute to the massive accumulation of ROS disrupting mitochondrial function. Impaired mitochondrial function leads to the decline in the autophagic capacity and induction of inflammation and apoptosis in human RPE cells affected by AMD.Areas covered: This article evaluates the ameliorative effect of melatonin on AMD and examines AMD pathogenesis with an emphasis on mitochondrial dysfunction. It also considers the potential effects of melatonin on mitochondrial function.Expert opinion: The effect of melatonin on mitochondrial function results in the reduction of oxidative stress, inflammation and apoptosis in the retina; these findings demonstrate that melatonin has the potential to prevent and treat AMD.

The Light and the Dark of Early and Intermediate AMD: Cone- and Rod-Mediated Changes Are Linked to Fundus Photograph and FAF Abnormalities

Purpose

The purpose of this paper is to describe the extent to which scotopic and photopic measures of visual function predict color fundus photograph (CFP) and fundus autofluorescence (FAF) changes in early and intermediate nonexudative AMD.

Methods

Sixty-nine observers were recruited: 56 AMD patients (mean age, 73 ± 12.98 years) and 13 controls (mean age, 67.77 ± 9.72 years). A nonmydriatic retinal camera was used to obtain stereo fundus photographs and FAF images were recorded with a cSLO Heidelberg Spectralis HRA+OCT. Visual acuity (VA) was measured using an Early Treatment of Diabetic Retinopathy Study chart. Contrast sensitivity (CS) was assessed with a Pelli-Robson chart. Dark adaptation (DA) curves were recorded at 3° eccentricity using a PC-based technique. Analysis of these curves yielded five parameters: cone threshold (CT), cone time constant (CC), cone-rod break (α), slope of the second rod component (S2), and rod-rod break (β).

Results

Both cone and rod sensitivity recovery were grossly abnormal in the patients. The rod recovery slope (S2) most accurately predicted the fundus photograph-based grade and the FAF classification (ρ = 0.61 and ρ = 0.60, respectively; both P < 0.0001). CS showed a strong association with FAF (ρ = 0.50, P < 0.0001) and with fundus photograph-based grade (ρ = 0.38, P < 0.002). There was no correlation between VA and either imaging method.

Conclusions

Dynamic, rod-based measures most accurately reflect the severity of early AMD. Although less specific to AMD than DA changes, static photopic abnormalities such as CS also correspond with morphologic changes. Assessment of function in early AMD should include dynamic rod- and cone-mediated measurements of sensitivity recovery.

Risk factors for progression of age-related macular degeneration

Purpose

Age‐related macular degeneration (AMD) is a degenerative disease of the macula, often leading to progressive vision loss. The rate of disease progression can vary among individuals and has been associated with multiple risk factors. In this review, we provide an overview of the current literature investigating phenotypic, demographic, environmental, genetic, and molecular risk factors, and propose the most consistently identified risk factors for disease progression in AMD based on these studies. Finally, we describe the potential use of these risk factors for personalised healthcare.

Recent findings

While phenotypic risk factors such as drusen and pigment abnormalities become more important to predict disease progression during the course of the disease, demographic, environmental, genetic and molecular risk factors are more valuable at earlier disease stages. Demographic and environmental risk factors such as age and smoking are consistently reported to be related to disease progression, while other factors such as sex, body mass index (BMI) and education are less often associated. Of all known AMD variants, variants that are most consistently reported with disease progression are rs10922109 and rs570618 in CFH, rs116503776 in C2/CFB/SKIV2L, rs3750846 in ARMS2/HTRA1 and rs2230199 in C3. However, it seems likely that other AMD variants also contribute to disease progression but to a lesser extent. Rare variants have probably a large effect on disease progression in highly affected families. Furthermore, current prediction models do not include molecular risk factors, while these factors can be measured accurately in the blood. Possible promising molecular risk factors are High‐Density Lipoprotein Cholesterol (HDL‐C), Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), zeaxanthin and lutein.

Summary

Phenotypic, demographic, environmental, genetic and molecular risk factors can be combined in prediction models to predict disease progression, but the selection of the proper risk factors for personalised risk prediction will differ among individuals and is dependent on their current disease stage. Future prediction models should include a wider set of genetic variants to determine the genetic risk more accurately, and rare variants should be taken into account in highly affected families. In addition, adding molecular factors in prediction models may lead to preventive strategies and personalised advice.

A Deep Learning Model for Segmentation of Geographic Atrophy to Study Its Long-Term Natural History

PURPOSE

To develop and validate a deep learning model for the automatic segmentation of geographic atrophy (GA) using color fundus images (CFIs) and its application to study the growth rate of GA.

DESIGN

Prospective, multicenter, natural history study with up to 15 years of follow-up.

PARTICIPANTS

Four hundred nine CFIs of 238 eyes with GA from the Rotterdam Study (RS) and Blue Mountain Eye Study (BMES) for model development, and 3589 CFIs of 376 eyes from the Age-Related Eye Disease Study (AREDS) for analysis of GA growth rate.

METHODS

A deep learning model based on an ensemble of encoder-decoder architectures was implemented and optimized for the segmentation of GA in CFIs. Four experienced graders delineated, in consensus, GA in CFIs from the RS and BMES. These manual delineations were used to evaluate the segmentation model using 5-fold cross-validation. The model was applied further to CFIs from the AREDS to study the growth rate of GA. Linear regression analysis was used to study associations between structural biomarkers at baseline and the GA growth rate. A general estimate of the progression of GA area over time was made by combining growth rates of all eyes with GA from the AREDS set.

MAIN OUTCOME MEASURES

Automatically segmented GA and GA growth rate.

RESULTS

The model obtained an average Dice coefficient of 0.72±0.26 on the BMES and RS set while comparing the automatically segmented GA area with the graders' manual delineations. An intraclass correlation coefficient of 0.83 was reached between the automatically estimated GA area and the graders' consensus measures. Nine automatically calculated structural biomarkers (area, filled area, convex area, convex solidity, eccentricity, roundness, foveal involvement, perimeter, and circularity) were significantly associated with growth rate. Combining all growth rates indicated that GA area grows quadratically up to an area of approximately 12 mm², after which growth rate stabilizes or decreases.

CONCLUSIONS

The deep learning model allowed for fully automatic and robust segmentation of GA on CFIs. These segmentations can be used to extract structural characteristics of GA that predict its growth rate.

Deep-learning-based Prediction of Late Age-Related Macular Degeneration Progression

Both genetic and environmental factors influence the etiology of age-related macular degeneration (AMD), a leading cause of blindness. AMD severity is primarily measured by fundus images and recently developed machine learning methods can successfully predict AMD progression using image data. However, none of these methods have utilized both genetic and image data for predicting AMD progression. Here we jointly used genotypes and fundus images to predict an eye as having progressed to late AMD with a modified deep convolutional neural network (CNN). In total, we used 31,262 fundus images and 52 AMD-associated genetic variants from 1,351 subjects from the Age-Related Eye Disease Study (AREDS) with disease severity phenotypes and fundus images available at baseline and follow-up visits over a period of 12 years. Our results showed that fundus images coupled with genotypes could predict late AMD progression with an averaged area under the curve (AUC) value of 0.85 (95%CI: 0.83–0.86). The results using fundus images alone showed an averaged AUC of 0.81 (95%CI: 0.80–0.83). We implemented our model in a cloud-based application for individual risk assessment.

[Fundus Autofluorescence Imaging: Clinical Application and Diagnostic Relevance]

Non-invasive fundus autofluorescence (FAF) imaging visualizes fluorophores at the level of the photoreceptors, the subneurosensory space and the retinal pigment epithelium. It gives important information over and above other imaging techniques. FAF imaging has improved the pathophysiological understanding of various retinal diseases. In combination with fundus photography, fluorescence angiography, optical coherence tomography, and electrophysiological examinations, FAF imaging is useful with regard to diagnostics and monitoring both during the natural course and after therapies. This review highlights basic principles of FAF and its clinical application in various retinal diseases.

Blue-Light Fundus Autofluorescence Imaging following Ruthenium-106 Brachytherapy for Choroidal Melanoma

PURPOSE

To describe changes in blue-light fundus autofluorescence (FAF) and corresponding alterations in optical coherence tomography (OCT) within the irradiation field after ruthenium-106 brachytherapy (RBT) for choroidal melanoma.

METHODS

Consecutive patients with choroidal melanoma were included in a retrospective case series. Patients were treated with RBT at a single institution. As part of their routine examination patients underwent multimodal imaging including ultrasonography, fundus photography, OCT, and FAF imaging (excitation = 488 nm). FAF images were analysed for changes within the irradiation field.

RESULTS

31 patients (mean age 65.7 years) were treated with RBT for unilateral choroidal melanoma. Mean tumour height before therapy was 2.7 mm (SD 1.0). Mean follow-up time was 23.3 months (SD 13.3). Main FAF characteristics attributable to RBT emerged as increased FAF with speckled decreased FAF (FAF mottling) within the irradiation field and a rim of increased FAF at its border. OCT scans demonstrated loss of the ellipsoid zone and the external limiting membrane, thinning of the neurosensory retina, and alterations of the retinal pigment epithelium like clumping, migration, and atrophy.

CONCLUSIONS

FAF changes in the irradiation field after RBT of choroidal melanomas follow a characteristic pattern that correlates with distinct OCT alterations. FAF and OCT imaging give additional information to monitor effects of RBT and, therefore, complement multimodal imaging techniques after plaque therapy.

A Review of Macular Atrophy of the Retinal Pigment Epithelium in Patients with Neovascular Age-Related Macular Degeneration: What is the Link? Part II

Introduction

To explore the potential link between macular atrophy (MA) of the retinal pigment epithelium (RPE) in patients with neovascular age-related macular degeneration (nAMD) and anti-vascular endothelial growth factor (anti-VEGF) treatment.

Methods

Through a balanced overview of the field from a largely clinical perspective, we looked at available evidence on the topic of MA correlation with anti-VEGF therapy and examined possible risk factors for MA development in the context of nAMD treatment with anti-VEGF.

Results

Links have been reported to connect both MA incidence and progression to treatment frequency and to the anti-VEGF drug type.

Conclusions

All reports agree on the fact that de novo development of MA in anti-VEGF-treated eyes is frequent and multifactorial. Research data shows an expansion of atrophy during anti-VEGF treatment. There are mixed conclusions about the correlation of MA incidence or progression with treatment-related risk factors. It mostly appears that there is no straightforward link. More clinical research is still needed to further understand this association.

[Fundus autofluorescence in the diagnosis of age-related macular degeneration]

At present, age-related macular degeneration (AMD) takes third place among the causes of blindness and low vision in the middle-aged and senile persons. The medical and social significance of this pathology is motivated by the possibility of losing central vision and general ability to perform professional duties. One of the modern methods of diagnostics of this disease is eye fundus autofluorescence. Its introduction into everyday clinical practice increases the effectiveness of detecting early signs of AMD and helps clarify the indications for the appointment of conservative treatment.

Age-related macular degeneration: A two-level model hypothesis

Age-related diseases, including age-related macular degeneration (AMD), are of growing importance in a world where population ageing has become a dominant global trend. Although a wide variety of risk factors for AMD have been identified, age itself remains by far the most important risk factor, making it an urgent priority to understand the connections between underlying ageing mechanisms and pathophysiology of AMD. Ageing is both multicausal and variable, so that differences between individuals in biological ageing processes are the focus of a growing number of pathophysiological studies seeking to explain how ageing contributes to chronic, age-related conditions. The aim of this review is to integrate the available knowledge on the pathophysiology of AMD within the framework of the biology of ageing. One highly significant feature of biological ageing is systemic inflammation, which arises as a second-level response to a first level of molecular damage involving oxidative stress, mutations etc. Combining these insights, the various co-existing pathophysiological explanations in AMD arrange themselves according to a two-level hypothesis. Accordingly, we describe how AMD can be considered the consequence of age-related random accumulation of molecular damage at the ocular level and the subsequent systemic inflammatory host response thereof. We summarize evidence and provide original data to enlighten where evidence is lacking. Finally, we discuss how this two-level hypothesis provides a foundation for thoughts and future studies in prevention, prognosis, and intervention.

Natural History of Geographic Atrophy Secondary to Age-Related Macular Degeneration: Results from the Prospective Proxima A and B Clinical Trials

PURPOSE

To better characterize visual function decline and geographic atrophy (GA) progression secondary to age-related macular degeneration (AMD).

DESIGN

Proxima A (NCT02479386)/Proxima B (NCT02399072) were global, prospective, noninterventional, observational clinical trials.

PARTICIPANTS

Eligible patients were aged ≥50 years. Patients in Proxima A had bilateral GA without choroidal neovascularization (CNV) in either eye (N = 295). Patients in Proxima B had GA without CNV in the study eye and CNV±GA in the fellow eye (fellow eye CNV cohort, n = 168) or GA without CNV in the study eye, no CNV/GA in the fellow eye (fellow eye intermediate AMD cohort, n = 32).

METHODS

Changes in visual function and imaging/anatomic parameters were evaluated over time using a mixed model for repeated measurement accounting for key baseline characteristics.

MAIN OUTCOME MEASURES

Prespecified end points included change in GA area from baseline, best-corrected visual acuity (BCVA) score assessed by Early Treatment Diabetic Retinopathy Study (ETDRS), and visual acuity under low-luminance (LLVA).

RESULTS

At 24 months, adjusted mean (standard error) change in GA lesion area from baseline was 3.87 (0.15) mm² in participants with bilateral GA (Proxima A), 3.55 (0.16) mm² in the fellow eye CNV cohort (Proxima B), and 2.96 (0.25) mm² in the fellow eye intermediate AMD cohort (Proxima B). Progression of GA was greater in patients with baseline nonsubfoveal (vs. subfoveal) GA lesions and tended to increase as baseline low-luminance deficit increased (all patients). Conversion to GA or CNV in the fellow eye occurred in 30% and 6.7% of participants, respectively, in the Proxima B intermediate AMD cohort at month 12. Adjusted mean (standard error) changes in BCVA and LLVA (ETDRS letters) in the study eye from baseline to 24 months were -13.88 (1.40) and -7.64 (1.20) in Proxima A, -9.49 (1.29) and -7.57 (1.26) in Proxima B fellow eye CNV cohort, and -11.48 (3.39) and -8.37 (3.02) in Proxima B fellow eye intermediate AMD cohort, respectively.

CONCLUSIONS

The prospective Proxima A and B studies highlight the severe functional impact of GA and the rapid rate of GA lesion progression over a 2-year period, including in patients with unilateral GA at baseline.

Outer Retinal Thickness and Fundus Autofluorescence in Geographic Atrophy

PURPOSE

Most studies of fundus autofluorescence (FAF) in geographic atrophy (GA) have been nonquantitative, with inadequate registration of image modalities. Furthermore, as pointed out in the recent Consensus Definition for Atrophy Associated with Age-Related Macular Degeneration on OCT, it is unclear whether decreased FAF would be correlated exclusively with a single category of OCT-defined atrophy. We sought to determine how FAF intensity in eyes with GA correlates with structural changes of the outer retina and choroid as seen on co-registered spectral domain OCT (SD-OCT) images.

DESIGN

Retrospective cross-sectional.

PARTICIPANTS

Twenty eyes of 11 patients with GA secondary to non-neovascular age-related macular degeneration (AMD).

METHODS

Spectral domain OCT and FAF images for each eye were co-registered using MATLAB (MathWorks Inc, Natick, MA). On B-scans, the choroid, retinal pigment epithelium (RPE), photoreceptor (PR) layer, and outer nuclear layer (ONL) were segmented. Regions of interest (ROIs) including all atrophic and border regions were selected manually on the FAF scans. Regions of interest were subdivided into quartiles of FAF level to correlate with retinal thickness measurements taken along the B-scans. Mean choroid, RPE, PR, and ONL thicknesses were compared across quartiles using an analysis of variance factorial design testing for interaction effects, adjusted for repeated measures (on both eyes) with a within-subjects factor.

RESULTS

Seventeen eyes of 10 patients were selected for analysis. The mean choroidal thicknesses were not significantly different across FAF quartiles, but the overall differences in mean RPE, PR layer, and ONL thicknesses across quartiles were statistically significant (analysis of variance, P < 0.001, P < 0.001, and P = 0.015, respectively). Post hoc analysis demonstrated significant differences in thickness among quartiles 1, 2, and 3 for the RPE and PR layers (Tukey, P < 0.01 in each case). The FAF quartiles within GA did not correlate exclusively with single categories of Consensus Definition for Atrophy Associated with Age-Related Macular Degeneration-defined atrophy.

CONCLUSIONS

Not only RPE but also PR layer thickness on SD-OCT varies significantly with FAF levels in GA. This suggests that although the RPE cells are losing thickness and function, evidenced by decreased FAF from fluorophores, delicate PR cells also succumb early in the disease process. These relationships should be pursued as a possibly better-detailed mechanism in GA.

[Are There Different Phenotypes in Geographic Atrophy of AMD? - Pilot Study on Differentiation Using Multimodal Imaging]

BACKGROUND

Geographic atrophy (GA) in patients with age-related macular degeneration (AMD) involves a loss of photoreceptors (PR), retinal pigment epithelium (RPE) and choriocapillaris (CC). For treatment decisions, it is crucial to discern which of these layers the damage originates, subsequently spreading to the others. It has long been thought that the RPE, with its accumulation of lipofuscin, is the site of primary damage in the development of GA. However, histological studies have shown that in some patients, the PR are affected first, followed by secondary damage to the RPE and CC, and in others regression of the CC is the first manifestation. The aim of this study was to use multimodal imaging to determine the extent of the damage at the levels of the PR, RPE and CC, to characterise the individual phenotypic variations of GA and to investigate the corresponding functional impairment.

PATIENTS AND METHODS

Twenty eyes of 20 patients (mean age 78 years; 14 female, 6 male) with the clinical diagnosis of GA were examined by means of fundus autofluorescence (FAF) to evaluate the damage to the RPE, en face SD-OCT at the level of the PR to characterise the area of cell loss in this layer and OCT angiography (OCT-A, AngioVue, Optovue; 50 µm CC-segmentation with localization below the RPE) to assess regression of the CC. The affected area of each layer was measured. Best-corrected visual acuity (BCVA) test and fundus correlated automated 10° microperimetry (MAIA Microperimetry, CENTERVUE; 4-2 strategy, 68 stimuli) were performed in all patients. The results of these examinations were evaluated and correlated.

RESULTS

All eyes showed a different extent of the areas of atrophy in the PR, RPE and CC. The layer with the largest area of atrophy was the RPE in 13 eyes (65%), the PR in 3 eyes (15%) and the CC in 4 eyes (20%). While the visual loss depended entirely on the presence of foveal sparing, microperimetry revealed a correlation between the extent of detectable functional deficit and the largest atrophic area.

CONCLUSIONS

Multimodal imaging with FAF, en face OCT, OCT-A and a correlation with microperimetry enables a clinical phenotypic differentiation in GA as well as a more precise characterisation of the associated functional impairment. This confirms clinically the histologically demonstrated diversity of the damaged structure (PR, RPE or CC) in patients with GA. However, the variations identified in this pilot study must be confirmed in Reading Center-based larger cohorts. The approach described here may lead to differentiated consideration of the anatomical and functional aspects of the disease and turn out to be helpful in patient selection as well as in identifying and monitoring future therapeutic approaches.

Progression characteristics of ellipsoid zone loss in macular telangiectasia type 2

PURPOSE

To investigate the progression characteristics of ellipsoid zone (EZ) loss in eyes with macular telangiectasia type 2 (MacTel) as reflected by area and linear measurements, and their relevance for visual acuity.

METHODS

Participants were selected from the MacTel Study cohort. Linear and area measurements of EZ loss were performed in Spectral-Domain Optical Coherence Tomograph (SD-OCT) volume scans. Progression characteristics and correlations between linear and area measurements were analysed using linear mixed effects models.

RESULTS

A total of 134 eyes of 70 patients were included (85 eyes with follow-up, mean 4.7 years, range: 1.4-8 years). Ellipsoid zone (EZ) loss significantly progressed at a mean annual increment of 0.057 mm² (p = 0.005). The progression rate was non-linear and interacted significantly with initial EZ lesion size indicating an exponential growth before reaching a plateau. There was a strong heterogeneity in area sizes between fellow eyes. EZ break length had a significant linear effect on EZ break area (b = 1.06, p < 0.001) and could predict it. The location of the EZ break had a significant impact on visual acuity.

CONCLUSION

Ellipsoid zone (EZ) loss in MacTel has a non-linear progression characteristic, and its rate depends on area size at baseline, which must be taken into account at sample selection in clinical trials. Our results show a good correlation of linear and area measures of EZ loss and a segregation of best-corrected visual acuity by EZ location, which may help routine clinical practice.

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40-60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

Efficacy and Safety of Lampalizumab for Geographic Atrophy Due to Age-Related Macular Degeneration: Chroma and Spectri Phase 3 Randomized Clinical Trials

Importance

Geographic atrophy (GA) secondary to age-related macular degeneration is a leading cause of visual disability in older individuals. A phase 2 trial suggested that lampalizumab, a selective complement factor D inhibitor, reduced the rate of GA enlargement, warranting phase 3 trials.

Objective

To assess the safety and efficacy of lampalizumab vs sham procedure on enlargement of GA.

Design, Setting, and Participants

Two identically designed phase 3 double-masked, randomized, sham-controlled clinical trials, Chroma and Spectri, enrolled participants from August 28, 2014, to October 6, 2016, at 275 sites in 23 countries. Participants were aged 50 years or older, with bilateral GA and no prior or active choroidal neovascularization in either eye and GA lesions in the study eye measuring 2.54 to 17.78 mm2 with diffuse or banded fundus autofluorescence patterns.

Interventions

Participants were randomized 2:1:2:1 to receive 10 mg of intravitreous lampalizumab every 4 weeks, sham procedure every 4 weeks, 10 mg of lampalizumab every 6 weeks, or sham procedure every 6 weeks, through 96 weeks.

Main Outcomes and Measures

Safety and efficacy assessed as mean change from baseline in GA lesion area at week 48 from centrally read fundus autofluorescence images of the lampalizumab arms vs pooled sham arms, in the intent-to-treat population and by complement factor I-profile genetic biomarker.

Results

A total of 906 participants (553 women and 353 men; mean [SD] age, 78.1 [8.1] years) were enrolled in Chroma and 975 participants (578 women and 397 men; mean [SD] age, 77.9 [8.1] years) were enrolled in Spectri; 1733 of the 1881 participants (92.1%) completed the studies through 48 weeks. The adjusted mean increases in GA lesion area from baseline at week 48 were 1.93 to 2.09 mm2 across all groups in both studies. Differences in adjusted mean change in GA lesion area (lampalizumab minus sham) were -0.02 mm2 (95% CI, -0.21 to 0.16 mm2; P = .80) for lampalizumab every 4 weeks in Chroma, 0.16 mm2 (95% CI, 0.00-0.31 mm2; P = .048) for lampalizumab every 4 weeks in Spectri, 0.05 mm2 (95% CI, -0.13 to 0.24 mm2; P = .59) for lampalizumab every 6 weeks in Chroma, and 0.09 mm2 (95% CI, -0.07 to 0.24 mm2; P = .27) for lampalizumab every 6 weeks in Spectri. No benefit of lampalizumab was observed across prespecified subgroups, including by complement factor I-profile biomarker. Endophthalmitis occurred after 5 of 12 447 injections (0.04%) or in 5 of 1252 treated participants (0.4%) through week 48.

Conclusions and Relevance

In Chroma and Spectri, the largest studies of GA conducted to date, lampalizumab did not reduce GA enlargement vs sham during 48 weeks of treatment. Results highlight the substantial and consistent enlargement of GA, at a mean of approximately 2 mm2 per year.

Trial Registration

ClinicalTrials.gov Identifier: NCT02247479 and NCT02247531.

Optometry Australia's chairside reference for the diagnosis and management of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in people over the age of 50 years in Australia. Optometry Australia has developed this AMD chairside reference in consultation with a member-based working group comprised of experienced practitioners. It provides an evidence-based approach to current best practice in the diagnosis and management of AMD. Optometrists should be competent in assessing patients with or at risk of developing AMD, so that they are able to provide evidence-based management including appropriate communication, diagnosis and referral when indicated. This AMD chairside reference covers risk factors for the development of AMD or progression to late-stage AMD; the current clinical classification of AMD; common signs and symptoms; optometric assessment including ocular imaging and biomarkers; differential diagnoses; and management of early, intermediate and late AMD. Optometry Australia's chairside reference is intended as a general guide for optometrists, and is not a formal management protocol.

Geographic Atrophy and OCT Angiography: Descriptive Study and Correlation With Autofluorescence

BACKGROUND AND OBJECTIVE

Geographic atrophy (GA) involves the progressive loss of retinal pigment epithelium (RPE), photoreceptors, and choriocapillaris (CC). CC flow within a GA area is severely impaired in patients with atrophic age-related macular degeneration. The aim of this study was to compare GA area measured on optical coherence tomography angiography (OCTA) (CC nonperfusion area) and on fundus autofluorescence (FAF).

PATIENTS AND METHODS

In this prospective, observational, cross-sectional study, OCTA and FAF were performed in patients with GA. On OCTA (CC segmentation), the CC nonperfusion area was measured manually using calipers. On FAF, GA was manually delimited, and the total surface was obtained using Region Finder software. The primary endpoint was to compare the CC nonperfusion area measured on OCTA and on the gold standard method (FAF).

RESULTS

Forty eyes of 34 patients with a mean age of 82.63 years ± 9.21 years (range: 66 years to 100 years) were included. The mean GA area measured on FAF and OCTA was, respectively, 2.184 ± 3.045 mm² and 2.349 ± 3.237 mm² (P = .035). The mean difference was 0.165 ± 0.290 mm². A strong correlation was found between both measurements (r = 0.97; P < .0001; confidence interval: 0.98-0.99), although the CC nonperfusion area was larger than the GA area on FAF (P = .035).

CONCLUSIONS

In this study, the authors showed that in GA, the CC nonperfusion area correlates linearly with the GA area assessed by FAF. Also, the CC nonperfusion area is larger than the GA area measured by FAF, suggesting that CC degeneration could occur before RPE degeneration in GA. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e222-e228.].

Percentage of Foveal vs Total Macular Geographic Atrophy as a Predictor of Visual Acuity in Age-Related Macular Degeneration

Purpose

This article investigates the relationship between visual acuity (VA), total area of geographic atrophy (GA), and percentage of foveal GA.

Methods

A multicenter, retrospective, cross-sectional study was conducted of patients with GA due to age-related macular degeneration. Demographics, VA, fundus autofluorescence (FAF), and spectral-domain optical coherence tomography (SD-OCT) images were collected. Using FAF images aided by SD-OCT, fovea-sparing status, GA pattern, total GA size, and percentage of GA covering the foveal area-within a 1.5-mm-diameter circle centered on the fovea centralis-were assessed. Univariable and multiple linear regression analyses were performed.

Results

Fifty-four eyes (mean age, 78.7 ±7.7 years [SD], 60.0% female) were studied. Mean VA was 0.8 ± 0.6 logarithm of the minimum angle of resolution (Snellen equivalent 20/126 ± 20/80), mean total GA 8.8 ± 6.7 mm², and mean percentage of foveal GA was 71.5 ± 30.9%. Of all assessed eyes, 48.2% (n = 26) presented with multifocal GA, and 18.5% (n =10) had foveal sparing. Multiple regression analysis revealed that, controlling for age and GA pattern, the percentage of foveal GA presented a statistically significant association with VA (ß =0.41, P = .004). No significant associations were observed with mean total GA size, while controlling for the same variables (ß=0.010, P = .440).

Conclusions

Percentage of foveal GA was significantly associated with VA impairment, although the same was not verified for total GA area. These findings suggest that percentage of foveal GA may represent a more useful tool for assessing the impact of GA on VA. Further validation is needed in larger cohorts.

Long-term outcomes of switching to aflibercept for treatment-resistant neovascular age-related macular degeneration

PURPOSE

To report 4-year outcomes following the switch to aflibercept in treatment-resistant neovascular age-related macular degeneration (nAMD).

METHODS

In this prospective, open-label, non-controlled, clinical trial, 49 patients with treatment-resistant nAMD received 2 mg intravitreal aflibercept as three loading doses every 4 weeks, followed by injections every 8 weeks for the first 48 weeks, then an individualized regimen for a further 36 months, following previous treatment with ranibizumab and/or bevacizumab. Outcome measures included best-corrected visual acuity (BCVA), central retinal thickness (CRT), pigment epithelial detachment (PED) height and geographic atrophy (GA) surface area.

RESULTS

Of the 49 patients who were initially recruited, data from 39 eyes of 39 patients were available at 48-month follow-up. Mean age was 76.7 ± 7.2 years. Over the 48 months, these eyes received a mean of 32.1 ± 5.6 injections. The mean BCVA improved significantly following 12 months of treatment (4.9 ± 9.0 ETDRS letters, p < 0.001); however, this was not maintained and was similar to baseline after 48 months (mean difference -0.4 ± 13.3 letters between baseline and 48 months, p < 0.001). The reduction in CRT from baseline was 170.3 ± 143.3 μm (p < 0.001) with absence of macular fluid in 56% of the 39 eyes at the end of month 48. PED height reduced by a mean 77.5 ± 20.0 μm, and geographic atrophy increased by a mean of 4.1 ± 3.4 mm² (p < 0.01) over the 48 months.

CONCLUSION

Aflibercept is an effective alternative therapy for treatment-resistant nAMD. Good anatomical and stable functional responses are achievable with continued therapy. The lack of continued visual improvement may be representative of GA progression, reflecting the progression of late-stage nAMD in these patients.

Late-onset night blindness with peripheral flecks accompanied by progressive trickle-like macular degeneration

PURPOSE

To report the clinical and genetic characteristics of 6 cases with late-onset night blindness with peripheral flecks accompanied by progressive trickle-like macular degeneration.

METHODS

Clinical and genetic data were collected from 6 independent patients who complained of night blindness in their fifth to eighth decade of life. The ophthalmological examinations included ophthalmoscopy, fundus autofluorescence (FAF), and full-field electroretinography (ERG). Whole exome sequencing with target gene analysis was performed to determine the causative genes and variants.

RESULTS

All of the patients first complained of night blindness at the ages of 40-71 years. Funduscopic examinations demonstrated white or atrophic flecks scattered in the posterior pole and peripheral retina bilaterally. FAF showed patchy hypo-autofluorescence spots in the posterior pole similar to that of the trickling type of age-related macular degeneration (AMD). The region of abnormal FAF rapidly expanded with age, and one eye developed a choroidal neovascularization. The full-field scotopic ERGs with 20 min of dark adaptation were severely reduced or extinguished in all cases. There was partial recovery of the ERGs after 180 min of dark adaptation. The cone ERGs were reduced in all cases. Whole exome sequencing revealed no pathogenic variants of 301 retinal disease-associated genes.

CONCLUSIONS

The six cases had some common features with the flecked retina syndrome, familial drusen, and late-onset retinal degeneration although none had pathogenic variants causative for these disorders. These cases may represent a subset of severe trickling AMD or a new clinical entity of acquired pan-retinal visual cycle deficiency of unknown etiology.

Human Retinal Pigment Epithelium: In Vivo Cell Morphometry, Multispectral Autofluorescence, and Relationship to Cone Mosaic

Purpose

To characterize in vivo morphometry and multispectral autofluorescence of the retinal pigment epithelial (RPE) cell mosaic and its relationship to cone cell topography across the macula.

Methods

RPE cell morphometrics were computed in regularly spaced regions of interest (ROIs) from contiguous short-wavelength autofluorescence (SWAF) and photoreceptor reflectance images collected across the macula in one eye of 10 normal participants (23–65 years) by using adaptive optics scanning light ophthalmoscopy (AOSLO). Infrared autofluorescence (IRAF) images of the RPE were collected with AOSLO in seven normal participants (22–65 years), with participant overlap, and compared to SWAF quantitatively and qualitatively.

Results

RPE cell statistics could be analyzed in 84% of SWAF ROIs. RPE cell density consistently decreased with eccentricity from the fovea (participant mean ± SD: 6026 ± 1590 cells/mm² at fovea; 4552 ± 1370 cells/mm² and 3757 ± 1290 cells/mm² at 3.5 mm temporally and nasally, respectively). Mean cone-to-RPE cell ratio decreased rapidly from 16.6 at the foveal center to <5 by 1 mm. IRAF revealed cells in six of seven participants, in agreement with SWAF RPE cell size and location. Differences in cell fluorescent structure, contrast, and visibility beneath vasculature were observed between modalities.

Conclusions

Improvements in AOSLO autofluorescence imaging permit efficient visualization of RPE cells with safe light exposures, allowing individual characterization of RPE cell morphometry that is variable between participants. The normative dataset and analysis of RPE cell IRAF and SWAF herein are essential for understanding microscopic characteristics of cell fluorescence and may assist in interpreting disease progression in RPE cells.

A lasered mouse model of retinal degeneration displays progressive outer retinal pathology providing insights into early geographic atrophy

Early stages of geographic atrophy (GA) age-related macular degeneration is characterised by the demise of photoreceptors, which precedes the loss of underlying retinal pigment epithelial (RPE) cells. Sight-loss due to GA has no effective treatment; reflecting both the complexity of the disease and the lack of suitable animal models for testing potential therapies. We report the development and characterisation of a laser-induced mouse model with early GA-like pathology. Retinas were lasered at adjacent sites using a 810 nm laser (1.9 J/spot), resulting in the development of confluent, hypopigmented central lesions with well-defined borders. Optical Coherence Tomography over 2-months showed progressive obliteration of photoreceptors with hyper-reflective outer plexiform and RPE/Bruch’s membrane (BrM) layers within lesions, but an unaffected inner retina. Light/electron microscopy after 3-months revealed lesions without photoreceptors, leaving the outer plexiform layer apposed to the RPE. We observed outer segment debris, hypo/hyperpigmented RPE, abnormal apical-basal RPE surfaces and BrM thickening. Lesions had wedge-shaped margins, extended zones of damage, activated Müller cells, microglial recruitment and functional retinal deficits. mRNA studies showed complement and inflammasome activation, microglial/macrophage phagocytosis and oxidative stress providing mechanistic insights into GA. We propose this mouse model as an attractive tool for early GA studies and drug-discovery.

Treatments for dry age-related macular degeneration and Stargardt disease: a systematic review

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of visual loss in older people. Advanced AMD takes two forms, neovascular (wet) and atrophic (dry). Stargardt disease (STGD) is the commonest form of inherited macular dystrophy.

OBJECTIVE

To carry out a systematic review of treatments for dry AMD and STGD, and to identify emerging treatments where future NIHR research might be commissioned.

DESIGN

Systematic review.

METHODS

We searched MEDLINE, EMBASE, Web of Science and The Cochrane Library from 2005 to 13 July 2017 for reviews, journal articles and meeting abstracts. We looked for studies of interventions that aim to preserve or restore vision in people with dry AMD or STGD. The most important outcomes are those that matter to patients: visual acuity (VA), contrast sensitivity, reading speed, ability to drive, adverse effects of treatment, quality of life, progression of disease and patient preference. However, visual loss is a late event and intermediate predictors of future decline were accepted if there was good evidence that they are strong predictors of subsequent visual outcomes. These include changes detectable by investigation, but not necessarily noticed by people with AMD or STGD. ClinicalTrials.gov, the World Health Organization search portal and the UK Clinical Trials gateway were searched for ongoing and recently completed clinical trials.

RESULTS

The titles and abstracts of 7948 articles were screened for inclusion. The full text of 398 articles were obtained for further screening and checking of references and 112 articles were included in the final report. Overall, there were disappointingly few good-quality studies (including of sufficient size and duration) reporting useful outcomes, particularly in STGD. However we did identify a number of promising research topics, including drug treatments, stem cells, new forms of laser treatment, and implantable intraocular lens telescopes. In many cases, research is already under way, funded by industry or governments.

LIMITATIONS

In AMD, the main limitation came from the poor quality of much of the evidence. Many studies used VA as their main outcome despite not having sufficient duration to observe changes. The evidence on treatments for STGD is sparse. Most studies tested interventions with no comparison group, were far too short term, and the quality of some studies was poor.

FUTURE WORK

We think that the topics on which the Health Technology Assessment (HTA) and Efficacy Mechanism and Evaluation (EME) programmes might consider commissioning primary research are in STGD, a HTA trial of fenretinide (ReVision Therapeutics, San Diego, CA, USA), a visual cycle inhibitor, and EME research into the value of lutein and zeaxanthin supplements, using short-term measures of retinal function. In AMD, we suggest trials of fenretinide and of a potent statin. There is epidemiological evidence from the USA that the drug, levodopa, used for treating Parkinson's disease, may reduce the incidence of AMD. We suggest that similar research should be carried out using the large general practice databases in the UK. Ideally, future research should be at earlier stages in both diseases, before vision is impaired, using sensitive measures of macular function. This may require early detection of AMD by screening.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016038708.

FUNDING

The National Institute for Health Research HTA programme.

Macular Atrophy of the Retinal Pigment Epithelium in Patients with Neovascular Age-Related Macular Degeneration: What is the Link? Part I: A Review of Disease Characterization and Morphological Associations

Introduction

The purpose of this review was to explore the potential link between macular atrophy (MA) of the retinal pigment epithelium in patients with neovascular age-related macular degeneration (nAMD) with the disease characteristics and morphological features.

Methods

To this end, we performed a search of peer-reviewed articles published on the PubMed database and included all relevant papers. We then examined these papers for possible risk factors for MA development in the context of nAMD treated with anti-vascular endothelial growth factor drugs, as well as possible protective factors.

Results

Our review of the relevant publications revealed that areas of MA can be directly visualized through multiple imaging modalities. Associations have been identified between MA of the retinal pigment epithelium and choroidal neovascular membrane characteristics, intra- and subretinal fluid, pigment epithelial detachment, choroidal thickness, subretinal hyperreflective material, outer retinal tubulations, hemorrhage, subretinal drusenoid deposits, refractile drusen, hyperreflective foci, retinal angiomatous proliferation, polypoidal choroidal vasculopathy, geographic atrophy in the fellow eye, genetic factors, and age.

Conclusion

The findings of this review indicate that a multimodal approach is recommended for the assessment of MA. The conclusions drawn to date on the correlation between MA development or progression of MA and specific risk factors and possible protective factors are mixed. More clinical research is needed to reach a better understanding of this association.

Characterization of Patients With Geographic Atrophy in Routine Clinical Practice

BACKGROUND AND OBJECTIVE

Geographic atrophy (GA) affects millions of patients with age-related macular degeneration (AMD) worldwide, leading to significant, irreversible visual impairment. This study aims to characterize the visual impairment of patients with GA in a routine clinical practice.

PATIENTS AND METHODS

This single-center, cross-sectional study used a novel natural language processing to select 1,045 GA cases utilizing the macula examination records from 19,359 patients with AMD.

RESULTS

Patients were classified based on the diagnosis of the fellow-eye as follow: 502 in group 1 (GA:GA), 403 in group 2 (GA : choroidal neovascularization), and 234 in group 3 (GA : early / intermediate AMD). Best-corrected visual acuity (BCVA) in the affected eye was 50.3 (± 22.1) letters in group 1, 52.5 (± 21.3) letters in group 2, and 48.5 (± 23.6) letters in group 3 (P < .05). Visual impairment (ineligibility for an unrestricted driver license) was present in 70.5% of group 1, 59.7% of group 2, and 39.6% of group 3. Legal blindness (BCVA < 20 letters in the best-seeing eye) was seen in 2.2% of group 1, 3% of group 2, and 0.8% of group 3.

CONCLUSION

Differences in visual impairment between subgroups of patients with GA can be seen in routine clinical practice. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:93-98.].

Regeneration of the zebrafish retinal pigment epithelium after widespread genetic ablation

The retinal pigment epithelium (RPE) is a specialized monolayer of pigmented cells within the eye that is critical for maintaining visual system function. Diseases affecting the RPE have dire consequences for vision, and the most prevalent of these is atrophic (dry) age-related macular degeneration (AMD), which is thought to result from RPE dysfunction and degeneration. An intriguing possibility for treating RPE degenerative diseases like atrophic AMD is the stimulation of endogenous RPE regeneration; however, very little is known about the mechanisms driving successful RPE regeneration in vivo. Here, we developed a zebrafish transgenic model (rpe65a:nfsB-eGFP) that enabled ablation of large swathes of mature RPE. RPE ablation resulted in rapid RPE degeneration, as well as degeneration of Bruch’s membrane and underlying photoreceptors. Using this model, we demonstrate for the first time that zebrafish are capable of regenerating a functional RPE monolayer after RPE ablation. Regenerated RPE cells first appear at the periphery of the RPE, and regeneration proceeds in a peripheral-to-central fashion. RPE ablation elicits a robust proliferative response in the remaining RPE. Subsequently, proliferative cells move into the injury site and differentiate into RPE. BrdU incorporation assays demonstrate that the regenerated RPE is likely derived from remaining peripheral RPE cells. Pharmacological disruption using IWR-1, a Wnt signaling antagonist, significantly reduces cell proliferation in the RPE and impairs overall RPE recovery. These data demonstrate that the zebrafish RPE possesses a robust capacity for regeneration and highlight a potential mechanism through which endogenous RPE regenerate in vivo.

Diseases resulting in retinal pigment epithelium (RPE) degeneration are among the leading causes of blindness worldwide, and no therapy exists that can replace RPE or restore lost vision. One intriguing possibility is the development of therapies focused on stimulating endogenous RPE regeneration. For this to be possible, we must first gain a deeper understanding of the mechanisms underlying RPE regeneration. Here, we develop a transgenic zebrafish system through which we ablate large swathes of mature RPE and demonstrate that zebrafish regenerate RPE after widespread injury. Injury-adjacent RPE proliferate and regenerate RPE, suggesting that they are the source of regenerated tissue. Finally, we demonstrate that Wnt signaling may be involved in RPE regeneration. These findings establish a versatile in vivo model through which the molecular and cellular underpinnings of RPE regeneration can be further characterized.

The Rate of Progression of Geographic Atrophy Decreases With Increasing Baseline Lesion Size Even After the Square Root Transformation

Purpose

To determine the relationship between the progression of geographic atrophy (GA) and its baseline area (BA) using the square root transformation (sqrt) for different atrophy sizes.

Methods

Single eyes of patients with GA visiting the Institut de la Màcula (Barcelona, Spain) between December 2009 and January 2018 with a follow-up of ≥6 months were included. The main outcome was the correlation between BA and growth after the sqrt using Pearson's r and Spearman's rho. The graphical relationship was explored using linear and LOWESS regression. In a secondary, prespecified analysis, progression was compared by BA categories (Age-Related Eye Disease Study [AREDS] classification and BA tertiles). In post hoc analyses, the results were evaluated in subgroups defined by location of atrophy, number of lesions, fundus autofluorescence pattern, and fellow-eye status.

Results

We included 128 eyes (mean follow-up, 3.1 years). The correlation between BA and progression was negative (r = -0.30, P = 0.0005; rho = -0.25, P = 0.0042). There was a decrease in the rate of progression in mm/year with increasing BA, but this was significant for tertiles (P = 0.0078) and not AREDS (P = 0.20). The descending trend was driven by high-risk features.

Conclusions

The correlation between GA progression and BA using the sqrt is negative. This has implications for the expected prediction of progression of a given lesion and to avoid overestimating the beneficial effects of interventional therapies.

Translational Relevance

The GA progression/BA relationship using the sqrt currently is regarded as independent. Our results suggest the sqrt slope actually is negative, which should be kept in mind to avoid misinterpretation of results in advanced therapies.

[Update from France Macula Federation: Diagnosis of wet AMD]

PURPOSE

To update the recommendations of the France Macula Federation for the diagnosis of wet age-related macular degeneration (AMD).

METHODS

Analysis of literature and expert opinion.

RESULTS

The FMF recommends diagnosing wet AMD by combining the results of fundus examination (or color or monochromatic fundus photographs), optical coherence tomography (OCT) showing exudative signs, and morphological visualization of the neovascular membrane, which may be obtained non-invasively (OCT-angiography) or invasively (fluorescein and/or indocyanine green angiography). Under optimal conditions in which all these tools are available, the FMF recommends using non-invasive methods as first-line tools and resorting to dye angiography if diagnostic doubt remains.

CONCLUSION

As observed in other fields of medical imaging, non-invasive methods are preferred to invasive methods for the diagnosis of wet AMD, while the latter are reserved for more difficult cases.

Multimodal Imaging of Nonneovascular Age-Related Macular Degeneration

Nonneovascular (dry) AMD is a retinal disease with potential for significant central visual impairment. The hallmarks of this disease are macular drusen, RPE alterations, and geographic atrophy (GA). Classification schemes for nonneovascular AMD have evolved over the years as major advances in retinal imaging have enabled a greater understanding of disease pathophysiology. The original classifications of nonneovascular AMD were based on color fundus photography (CFP), while more modern schemes rely on a multimodal imaging approach. Effective diagnosis and management of nonneovascular AMD requires a thorough understanding of its multimodal imaging features as detailed in this review. Future imaging modalities and imaging biomarkers that may aid in diagnosis and management are also discussed.

The Border of Macular Atrophy in Age-Related Macular Degeneration: A Clinicopathologic Correlation

PURPOSE

To correlate in vivo imaging to histology in an eye with macular atrophy owing to age-related macular degeneration (AMD; complete retinal pigment epithelium [RPE] and outer retinal atrophy [cRORA]) to evaluate the utility of new optical coherence tomography (OCT) suggested by previous histology.

DESIGN

Case study with clinicopathologic correlation.

METHODS

In vivo eye-tracked cross-sectional OCT scans at 13 and 8 months before death were compared to postmortem histopathology. On OCT, the atrophy border was identified as either the descent of the external limiting membrane (ELM) toward the Bruch membrane (BrM) (representing gliosis) or the presence of choroidal hypertransmission (representing lack of shadowing by RPE). Thicknesses of RPE, basal laminar deposit (BLamD), and BrM were measured at 500 and 100 μm on the nonatrophic and atrophic sides of these borders, on in vivo eye-tracked OCT and histology matched to the same location.

RESULTS

In all OCT scans, the ELM descent was visible. The RPE-BLamD band significantly thickened toward it (P < .005), over time (P = .015 and P = .043, at 500 and 100 μm, respectively). On OCT, the ELM descent delineated a smaller atrophic area than did hypertransmission. RPE-BLamD thicknesses manually measured on OCT overestimated histologic thicknesses. BrM visibility varied with RPE status.

CONCLUSION

Visible on OCT, the ELM descent is a histopathologic atrophy border supporting new terminology of cRORA, whereas hypertransmission reveals RPE degeneration. RPE-BLamD thickening across the macula, toward the atrophy and over time is confirmed. The presence of gliosis and thick RPE-BLamD suggests that macular atrophy is a late stage in disease progression, encouraging anatomic endpoints at earlier AMD stages than atrophy enlargement.