Modelling the natural history of geographic atrophy in patients with age-related macular degeneration

Progression of Geographic Atrophy: Epistemic Uncertainties Affecting Mathematical Models and Machine Learning

Purpose

The purpose of this study was to identify a taxonomy of epistemic uncertainties that affect results for geographic atrophy (GA) assessment and progression.

Methods

An important source of variability is called "epistemic uncertainty," which is due to incomplete system knowledge (i.e. limitations in measurement devices, artifacts, and human subjective evaluation, including annotation errors). In this study, different epistemic uncertainties affecting the analysis of GA were identified and organized into a taxonomy. The uncertainties were discussed and analyzed, and an example was provided in the case of model structure uncertainty by characterizing progression of GA by mathematical modelling and machine learning. It was hypothesized that GA growth follows a logistic (sigmoidal) function. Using case studies, the GA growth data were used to test the sigmoidal hypothesis.

Results

Epistemic uncertainties were identified, including measurement error (imperfect outcomes from measuring tools), subjective judgment (grading affected by grader's vision and experience), model input uncertainties (data corruption or entry errors), and model structure uncertainties (elucidating the right progression pattern). Using GA growth data from case studies, it was demonstrated that GA growth can be represented by a sigmoidal function, where growth eventually approaches an upper limit.

Conclusion

Epistemic uncertainties contribute to errors in study results and are reducible if identified and addressed. By prior identification of epistemic uncertainties, it is possible to (a) quantify uncertainty not accounted for by natural statistical variability, and (b) reduce the presence of these uncertainties in future studies.

Translational Relevance

Lowering epistemic uncertainty will reduce experimental error, improve consistency and reproducibility, and increase confidence in diagnostics.

Modeling of atrophy size trajectories: variable transformation, prediction and age-of-onset estimation

Background

To model the progression of geographic atrophy (GA) in patients with age-related macular degeneration (AMD) by building a suitable statistical regression model for GA size measurements obtained from fundus autofluorescence imaging.

Methods

Based on theoretical considerations, we develop a linear mixed-effects model for GA size progression that incorporates covariable-dependent enlargement rates as well as correlations between longitudinally collected GA size measurements. To capture nonlinear progression in a flexible way, we systematically assess Box-Cox transformations with different transformation parameters λ. Model evaluation is performed on data collected for two longitudinal, prospective multi-center cohort studies on GA size progression.

Results

A transformation parameter of λ=0.45 yielded the best model fit regarding the Akaike information criterion (AIC). When hypertension and hypercholesterolemia were included as risk factors in the model, they showed an association with progression of GA size. The mean estimated age-of-onset in this model was 67.21±6.49 years.

Conclusions

We provide a comprehensive framework for modeling the course of uni- or bilateral GA size progression in longitudinal observational studies. Specifically, the model allows for age-of-onset estimation, identification of risk factors and prediction of future GA size. A square-root transformation of atrophy size is recommended before model fitting.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12874-021-01356-0).

Model Structure Uncertainty in the Characterization and Growth of Geographic Atrophy

Purpose

To identify the most suitable model for assessing the rate of growth of total geographic atrophy (GA) by analysis of model structure uncertainty.

Methods

Model structure uncertainty refers to unexplained variability arising from the choice of mathematical model and represents an example of epistemic uncertainty. In this study, we quantified this uncertainty to help identify a model most representative of GA progression. Fundus autofluorescence (FAF) images and GA progression data (i.e., total GA area estimation at each presentation) were acquired using Spectralis HRA+OCT instrumentation and RegionFinder software. Six regression models were evaluated. Models were compared using various statistical tests, [i.e., coefficient of determination (r²), uncertainty metric (U), and test of significance for the correlation coefficient, r], as well as adherence to expected physical and clinical assumptions of GA growth.

Results

Analysis was carried out for 81 GA-affected eyes, 531 FAF images (range: 3–17 images per eye), over median of 57 months (IQR: 42, 74), with a mean baseline lesion size of 2.62 ± 4.49 mm² (range: 0.11–20.69 mm²). The linear model proved to be the most representative of total GA growth, with lowest average uncertainty (original scale: U = 0.025, square root scale: U = 0.014), high average r² (original scale: 0.92, square root scale: 0.93), and applicability of the model was supported by a high correlation coefficient, r, with statistical significance (P = 0.01).

Conclusions

Statistical analysis of uncertainty suggests that the linear model provides an effective and practical representation of the rate and progression of total GA growth based on data from patient presentations in clinical settings.

Translational Relevance

Identification of correct model structure to characterize rate of growth of total GA in the retina using FAF images provides an objective metric for comparing interventions and charting GA progression in clinical presentations.

Foveal Sparing in Central Retinal Dystrophies

Purpose

To describe foveal sparing (FS) in central retinal dystrophies (RD).

Methods

Participants for this retrospective study were identified from the retinal dystrophy database of the Department of Ophthalmology at Radboud University Medical Center. FS was defined as an intact foveal structure surrounded by at least 180° of chorioretinal atrophy, and a best-corrected visual acuity (BCVA) of <1.0 logMAR (>20/200 Snellen). Eligible eyes were identified using fundus autofluorescence (FAF) images, and FS was confirmed using near-infrared reflectance (NIR) imaging and spectral-domain optical coherence tomography when available. Clinical and demographic data were extracted from medical records. We performed quantification of FS and chorioretinal atrophic areas using semiautomated software on fundus autofluorescence and NIR images. We calculated the chronologic change using eye-wise linear regression.

Results

We identified 36 patients (56 eyes) with FS. RDs included: Stargardt disease (STGD1;20 patients), central areolar choroidal dystrophy (CACD; 7 patients), mitochondrial retinal dystrophy (MRD; 6 patients), pseudo-Stargardt pattern dystrophy (PSPD; 3 patients). Median age at first presentation was 60 (interquartile range [IQR] 54-63) years. Median BCVA at first presentation ranged from 20/25 Snellen in STGD1, to 20/38 Snellen in MRD. Progression of the chorioretinal atrophic area ranged from 0.26 (0.25-0.28) mm/year in PSPD, to 0.14 (0.11-0.22) in CACD. Change in FS area over time was similar between the different dystrophies.

Conclusions

The presence of FS in different RDs suggests a disease-independent mechanism that prolongs the survival of the fovea. The associated preservation of BCVA is important for the individual prognosis and has implications for the design of therapeutic trials for RDs.

Assessment of Novel Genome-Wide Significant Gene Loci and Lesion Growth in Geographic Atrophy Secondary to Age-Related Macular Degeneration

Importance

Age-related macular degeneration (AMD) is a common threat to vision loss in individuals older than 50 years. While neovascular complications in AMD are treatable, there is currently no therapy for geographic atrophy secondary to AMD. Geographic atrophy lesion progression over time shows considerable interindividual variability, but little is known about prognostic factors.

Objective

To elucidate the contribution of common genetic variants to geographic atrophy lesion growth.

Design, Setting, and Participants

This pooled analysis combined 4 independent studies: the Fundus Autofluorescence Imaging in Age-Related Macular Degeneration (FAM) study, the Directional Spread in Geographic Atrophy (DSGA) study, the Age-Related Eye Disease Study (AREDS), and the Geographic Atrophy Treatment Evaluation (GATE) study. Each provided data for geographic atrophy lesion growth in specific designs. Patients with geographic atrophy secondary to AMD were recruited to these studies. Genotypes were retrieved through the database of Genotypes and Phenotypes (for AREDS) or generated at the Cologne Center for Genomics (for FAM, DSGA, and GATE).

Main Outcomes

The correlation between square root-transformed geographic atrophy growth rate and 7 596 219 genetic variants passing quality control was estimated using linear regression. The calculations were adjusted for known factors influencing geographic atrophy growth, such as the presence of bilateral geographic atrophy as well as the number of lesion spots and follow-up times.

Main Outcomes and Measures

Slopes per allele, 95% CIs, and P values of genetic variants correlated with geographic atrophy lesion growth.

Results

A total of 935 patients (mean [SD] age, 74.7 [7.8] years; 547 female participants [59.0%]) were included. Two gene loci with conservative genome-wide significance were identified. Each minor allele of the genome-wide associated variants increased the geographic atrophy growth rate by a mean of about 15% or 0.05 mm per year. Gene prioritization within each locus suggests the protein arginine methyltransferase 6 gene (PRMT6; chromosome 1; slope, 0.046 [95% CI, 0.026-0.066]; P = 4.09 × 10-8) and the lanosterol synthase gene (LSS; chromosome 21; slope, 0.105 [95% CI, 0.068-0.143]; P = 4.07 × 10-7) as the most likely progression-associated genes.

Conclusions and Relevance

These data provide further insight into the genetic architecture of geographic atrophy lesion growth. Geographic atrophy is a clinical outcome with a high medical need for effective therapy. The genes PRMT6 and LSS are promising candidates for future studies aimed at understanding functional aspects of geographic atrophy progression and also for designing novel and targeted treatment options.

Emixustat Hydrochloride for Geographic Atrophy Secondary to Age-Related Macular Degeneration: A Randomized Clinical Trial

PURPOSE

To determine whether emixustat hydrochloride (emixustat) reduces the rate of enlargement of geographic atrophy (GA) compared with placebo in subjects with age-related macular degeneration (AMD) and to evaluate the safety and tolerability of emixustat over 24 months of treatment.

DESIGN

Multicenter, randomized, double-masked, placebo-controlled, phase 2b/3 clinical trial.

PARTICIPANTS

Patients with GA secondary to AMD, a visual acuity score of at least 35 letters, and GA with a total area of 1.25 to 18 mm² were enrolled.

METHODS

Subjects were randomized (1:1:1:1) to emixustat 2.5 mg, 5 mg, 10 mg, or placebo, administered orally once daily for 24 months. Visits included screening, baseline, and months 1, 2, 3, 6, 9, 12, 15, 18, 21, 24, and 25.

MAIN OUTCOME MEASURES

The primary efficacy end point was the mean annual growth rate of total GA area in the study eye, as measured by a central reading center using fundus autofluorescence (FAF) images. The change from baseline in normal luminance best-corrected visual acuity (NL-BCVA) was a secondary efficacy end point.

RESULTS

Of 508 randomized subjects, 320 completed the study. Demographics and baseline characteristics were comparable between treatment groups. On average, GA lesions in the study eye grew at a similar rate in each group (emixustat: 1.69 to 1.84 mm²/year; placebo: 1.69 mm²/year; P ≥ 0.81). Changes in NL-BCVA were also comparable between groups. Subjects with a larger low luminance deficit (LLD) at baseline (≥20 letters) demonstrated a more rapid growth of GA over 24 months. No relationship was observed between the risk-allele status of the AMD-associated single-nucleotide polymorphisms tested and the growth rate of GA. The most common adverse events in emixustat-treated subjects were delayed dark adaptation (55%), chromatopsia (18%), visual impairment (15%), and erythropsia (15%).

CONCLUSIONS

Emixustat did not reduce the growth rate of GA in AMD. The most common adverse events were ocular in nature and likely related to the drug's mechanism of action. Data gained from this study over a 2-year period add to the understanding of the natural history of GA and the baseline characteristics affecting the growth rate of GA.

Quantitative and Qualitative Features of Spectral-Domain Optical Coherence Tomography Provide Prognostic Indicators for Visual Acuity in Patients With Choroideremia

BACKGROUND AND OBJECTIVE

To identify qualitative and quantitative features of spectral-domain optical coherence tomography (SD-OCT) as prognostic indicators of visual acuity (VA) loss in patients with choroideremia (CHM).

PATIENTS AND METHODS

Retrospective study of 57 male patients with CHM. Central foveal thickness (CFT), subfoveal choroidal thickness (SCT), fundus autofluorescence area, and evidence of outer retinal and choroidal degeneration were analyzed by SD-OCT.

RESULTS

Best-corrected VA logMAR at baseline was associated with CFT at baseline (r = -0.47; P < .01), CFT at most recent follow-up (r = -0.27; P < .01), and SCT at baseline (r = -0.31; P < .01). Ellipsoid zone (EZ) rupture was associated with a higher CFT loss (r = 0.33; P < .01) and macular cystic spaces (MCS) with a reduction in VA over time (hazard risk = 0.48; P = .05).

CONCLUSION

Reduced CFT at baseline, EZ rupture, and MCS are poor prognostic indicators for VA outcome. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:711-716.].

Highly sensitive measurements of disease progression in rare disorders: Developing and validating a multimodal model of retinal degeneration in Stargardt disease

Background

Each inherited retinal disorder is rare, but together, they affect millions of people worldwide. No treatment is currently available for these blinding diseases, but promising new options—including gene therapy—are emerging. Arguably, the most prevalent retinal dystrophy is Stargardt disease. In each case, the specific combination of ABCA4 variants (> 900 identified to date) and modifying factors is virtually unique. It accounts for the vast phenotypic heterogeneity including variable rates of functional and structural progression, thereby potentially limiting the ability of phase I/II clinical trials to assess efficacy of novel therapies with few patients. To accommodate this problem, we developed and validated a sensitive and reliable composite clinical trial endpoint for disease progression based on structural measurements of retinal degeneration.

Methods and findings

We used longitudinal data from early-onset Stargardt patients from the Netherlands (development cohort, n = 14) and the United Kingdom (external validation cohort, n = 18). The composite endpoint was derived from best-corrected visual acuity, fundus autofluorescence, and spectral-domain optical coherence tomography. Weighting optimization techniques excluded visual acuity from the composite endpoint. After optimization, the endpoint outperformed each univariable outcome, and showed an average progression of 0.41° retinal eccentricity per year (95% confidence interval, 0.30–0.52). Comparing with actual longitudinal values, the model accurately predicted progression (R², 0.904). These properties were largely preserved in the validation cohort (0.43°/year [0.33–0.53]; prediction: R², 0.872). We subsequently ran a two-year trial simulation with the composite endpoint, which detected a 25% decrease in disease progression with 80% statistical power using only 14 patients.

Conclusions

These results suggest that a multimodal endpoint, reflecting structural macular changes, provides a sensitive measurement of disease progression in Stargardt disease. It can be very useful in the evaluation of novel therapeutic modalities in rare disorders.

Modeling Visual Acuity in Geographic Atrophy Secondary to Age-Related Macular Degeneration

Purpose: To analyze and model visual acuity (VA) in geographic atrophy (GA) secondary to age-related macular degeneration (AMD). Methods: The course of VA was analyzed using Turnbull's estimator in 226 eyes with uni- or bilateral GA due to AMD (151 patients; mean age 74.0 ± 7.6 years; mean follow-up time 33.4 ± 23.4 months) from the natural history FAM (Fundus-Autofluorescence Imaging in AMD) study. The variables ‘age at baseline', ‘gender', ‘lesion size', ‘diagnosis of the fellow eye', ‘status of the fovea', ‘focality of the lesion' and ‘pattern' were evaluated for effects on predicting VA using linear mixed-effects models. Results: Mean VA at baseline was 0.6 (Snellen 20/80) ± 0.4 logMAR [range -0.1 to 1.8 (20/17 to hand motions)], showing an estimated mean increase of 0.181 (95% CI 0.152-0.210) and 0.256 (0.214-0.300) after 2 and 4 years of follow-up, respectively. The percentage of eyes with a loss of ≥3 lines was 34% by 2 years and 47% by 4 years. Linear mixed model analysis suggested that 65% of VA variability could be explained by the assessed predictor variables. The strongest effect was found for the ‘status of the fovea' (0.69 logMAR units between ‘definitively spared fovea' and ‘definitive foveal involvement', p < 0.001). The second strongest effect was identified for ‘total lesion size' (effects between 0.02 and 0.09 logMAR units for each mm depending on foveal involvement, p < 0.001, square root transformed values). Conclusions: These findings underscore the importance of GA lesion characteristics as these have the strongest impact on VA. Natural history data and modeling VA to other variables will be helpful for refining outcome parameters and estimating possible benefits of therapeutic interventions.

Genetic Association Analysis of Drusen Progression

PURPOSE

Age-related macular degeneration is a common form of vision loss affecting older adults. The etiology of AMD is multifactorial and is influenced by environmental and genetic risk factors. In this study, we examine how 19 common risk variants contribute to drusen progression, a hallmark of AMD pathogenesis.

METHODS

Exome chip data was made available through the International AMD Genomics Consortium (IAMDGC). Drusen quantification was carried out with color fundus photographs using an automated drusen detection and quantification algorithm. A genetic risk score (GRS) was calculated per subject by summing risk allele counts at 19 common genetic risk variants weighted by their respective effect sizes. Pathway analysis of drusen progression was carried out with the software package Pathway Analysis by Randomization Incorporating Structure.

RESULTS

We observed significant correlation with drusen baseline area and the GRS in the age-related eye disease study (AREDS) dataset (ρ = 0.175, P = 0.006). Measures of association were not statistically significant between drusen progression and the GRS (P = 0.54). Pathway analysis revealed the cell adhesion molecules pathway as the most highly significant pathway associated with drusen progression (corrected P = 0.02).

CONCLUSIONS

In this study, we explored the potential influence of known common AMD genetic risk factors on drusen progression. Our results from the GRS analysis showed association of increasing genetic burden (from 19 AMD associated loci) to baseline drusen load but not drusen progression in the AREDS dataset while pathway analysis suggests additional genetic contributors to AMD risk.

Geographic atrophy in patients with advanced dry age-related macular degeneration: current challenges and future prospects

Geographic atrophy (GA) of the retinal pigment epithelium (RPE) is a devastating complication of age-related macular degeneration (AMD). GA may be classified as drusen-related (drusen-associated GA) or neovascularization-related (neovascular-associated GA). Drusen-related GA remains a large public health concern due to the burden of blindness it produces, but pathophysiology of the condition is obscure and there are no proven treatment options. Genotyping, cell biology, and clinical imaging point to upregulation of parainflammatory pathways, oxidative stress, and choroidal sclerosis as contributors, among other factors. Onset and monitoring of progression is accomplished through clinical imaging instrumentation such as optical coherence tomography, photography, and autofluorescence, which are the tools most helpful in determining end points for clinical trials at present. A number of treatment approaches with diverse targets are in development at this time, some of which are in human clinical trials. Neovascular-associated GA is a consequence of RPE loss after development of neovascular AMD. The neovascular process leads to a plethora of cellular stresses such as ischemia, inflammation, and dramatic changes in cell environment that further taxes RPE cells already dysfunctional from drusen-associated changes. GA may therefore develop secondary to the neovascular process de novo or preexisting drusen-associated GA may continue to worsen with the development of neovascular AMD. Neovascular-associated GA is a prominent cause of continued vision loss in patients with otherwise successfully treated neovascular AMD. Clearly, treatment with vascular endothelial growth factor (VEGF) inhibitors early in the course of the neovascular disease is of great clinical benefit. However, there is a rationale and some suggestive evidence that anti-VEGF agents themselves could be toxic to RPE and enhance neovascular-associated GA. The increasing prevalence of legal blindness from this condition due to the aging of the general population lends urgency to the search for a therapy to ameliorate GA.

Prognostic implications of imaging in atrophic macular degeneration and its use in clinical practice and clinical trial design

Clinical prognostic markers in atrophic age-related macular degeneration include the extent of existing atrophy, fundus autofluorescence (FAF) patterns and optical coherence tomography changes in the outer retina/retinal pigment epithelium interface. The prognostic implications of these findings may be used to determine not just the rate of disease progression but also influence the likelihood, magnitude and clinical relevance of therapy responses. FAF phenotypes have been extensively investigated; however, the pathophysiological mechanisms behind their appearance have not been fully elucidated. Optical coherence tomography imaging is additive to FAF imaging in atrophic age-related macular degeneration, allowing the visualization of detail not available through FAF imaging whilst also displaying subtle changes correlating with the FAF phenotypes themselves, thereby giving clues to their histological determinates. The developing understanding of these imaging modalities and consequent development of prognostically useful classification systems have widespread implication in clinical care and clinical trial design.

The genetics of age-related macular degeneration (AMD)--Novel targets for designing treatment options?

Age-related macular degeneration (AMD) is a progressive disease of the central retina and the main cause of legal blindness in industrialized countries. Risk to develop the disease is conferred by both individual as well as genetic factors with the latter being increasingly deciphered over the last decade. Therapeutically, striking advances have been made for the treatment of the neovascular form of late stage AMD while for the late stage atrophic form of the disease, which accounts for almost half of the visually impaired, there is currently no effective therapy on the market. This review highlights our current knowledge on the genetic architecture of early and late stage AMD and explores its potential for the discovery of novel, target-guided treatment options. We reflect on current clinical and experimental therapies for all forms of AMD and specifically note a persisting lack of efficacy for treatment in atrophic AMD. We further explore the current insight in AMD-associated genes and pathways and critically question whether this knowledge is suited to design novel treatment options. Specifically, we point out that known genetic factors associated with AMD govern the risk to develop disease and thus may not play a role in its severity or progression. Treatments based on such knowledge appear appropriate rather for prevention than treatment of manifest disease. As a consequence, future research in AMD needs to be greatly focused on approaches relevant to the patients and their medical needs.

Clinical and genetic factors associated with progression of geographic atrophy lesions in age-related macular degeneration

Worldwide, age-related macular degeneration (AMD) is a serious threat to vision loss in individuals over 50 years of age with a pooled prevalence of approximately 9%. For 2020, the number of people afflicted with this condition is estimated to reach 200 million. While AMD lesions presenting as geographic atrophy (GA) show high inter-individual variability, only little is known about prognostic factors. Here, we aimed to elucidate the contribution of clinical, demographic and genetic factors on GA progression. Analyzing the currently largest dataset on GA lesion growth (N = 388), our findings suggest a significant and independent contribution of three factors on GA lesion growth including at least two genetic factors (ARMS2_rs10490924 [P < 0.00088] and C3_rs2230199 [P < 0.00015]) as well as one clinical component (presence of GA in the fellow eye [P < 0.00023]). These correlations jointly explain up to 7.2% of the observed inter-individual variance in GA lesion progression and should be considered in strategy planning of interventional clinical trials aimed at evaluating novel treatment options in advanced GA due to AMD.

Directional Kinetics of Geographic Atrophy Progression in Age-Related Macular Degeneration with Foveal Sparing

PURPOSE

To describe the directional kinetics of the spread of geographic atrophy (GA) spread in eyes with age-related macular degeneration and foveal sparing.

DESIGN

Prospective, noninterventional natural history study: Fundus Autofluorescence Imaging in Age-Related Macular Degeneration (FAM; clinicaltrials.gov identifier, NCT00393692).

SUBJECTS

Participants of the FAM study exhibiting foveal sparing of GA.

METHODS

Eyes were examined longitudinally with fundus autofluorescence (FAF; excitation wavelength, 488 nm; emission wavelength, >500 nm) and near infrared (NIR) reflectance imaging (Spectralis HRA+OCT or HRA2; Heidelberg Engineering, Heidelberg, Germany). Areas of foveal sparing and GA were measured by 2 independent readers using a semiautomated software tool that allows for combined NIR reflectance and FAF image grading (RegionFinder; Heidelberg Engineering). A linear mixed effect model was used to model GA kinetics over time.

MAIN OUTCOME MEASURE

Change of GA lesion size over time (central vs. peripheral progression).

RESULTS

A total of 47 eyes of 36 patients (mean age, 73.8±7.5 years) met the inclusion criteria. Mean follow-up time was 25.2±16.9 months (range, 5.9-74.6 months). Interreader agreement for measurements of GA and foveal-sparing size were 0.995 and 0.946, respectively. Mean area progression of GA toward the periphery was 2.27±0.22 mm(2)/year and 0.25±0.03 mm(2)/year toward the center. Analysis of square root-transformed data revealed a 2.8-fold faster atrophy progression toward the periphery than toward the fovea. Faster atrophy progression toward the fovea correlated with faster progression toward the periphery in presence of marked interindividual differences.

CONCLUSIONS

The results demonstrate a significantly faster centrifugal than centripetal GA spread in eyes with GA and foveal sparing. Although the underlying pathomechanisms for differential GA progression remain unknown, local factors may be operative that protect the foveal retina-retinal pigment epithelial complex. Quantification of directional spread characteristics and modeling may be useful in the design of interventional clinical trials aiming to prolong foveal survival in eyes with GA.

A circulating microrna profile is associated with late-stage neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of severe vision impairment in Western populations over 55 years. A growing number of gene variants have been identified which are strongly associated with an altered risk to develop AMD. Nevertheless, gene-based biomarkers which could be dysregulated at defined stages of AMD may point toward key processes in disease mechanism and thus may support efforts to design novel treatment regimens for this blinding disorder. Circulating microRNAs (cmiRNAs) which are carried by nanosized exosomes or microvesicles in blood plasma or serum, have been recognized as valuable indicators for various age-related diseases. We therefore aimed to elucidate the role of cmiRNAs in AMD by genome-wide miRNA expression profiling and replication analyses in 147 controls and 129 neovascular AMD patients. We identified three microRNAs differentially secreted in neovascular (NV) AMD (hsa-mir-301-3p, p_corrected = 5.6*10⁻⁵, hsa-mir-361-5p, p_corrected = 8.0*10⁻⁴ and hsa-mir-424-5p, p_corrected = 9.6*10⁻³). A combined profile of the three miRNAs revealed an area under the curve (AUC) value of 0.727 and was highly associated with NV AMD (p = 1.2*10⁻⁸). To evaluate subtype-specificity, an additional 59 AMD cases with pure unilateral or bilateral geographic atrophy (GA) were analyzed for microRNAs hsa-mir-301-3p, hsa-mir-361-5p, and hsa-mir-424-5p. While we found no significant differences between GA AMD and controls neither individually nor for a combined microRNAs profile, hsa-mir-424-5p levels remained significantly higher in GA AMD when compared to NV (p_corrected<0.005). Pathway enrichment analysis on genes predicted to be regulated by microRNAs hsa-mir-301-3p, hsa-mir-361-5p, and hsa-mir-424-5p, suggests canonical TGFβ, mTOR and related pathways to be involved in NV AMD. In addition, knockdown of hsa-mir-361-5p resulted in increased neovascularization in an invitro angiogenesis assay.

A prospective longitudinal study of retinal structure and function in achromatopsia

PURPOSE

To longitudinally characterize retinal structure and function in achromatopsia (ACHM) in preparation for clinical gene therapy trials.

METHODS

Thirty-eight molecularly confirmed ACHM subjects underwent serial assessments, including spectral domain optical coherence tomography (SD-OCT), microperimetry, and fundus autofluorescence (FAF). Foveal structure on SD-OCT was graded and compared for evidence of progression, along with serial measurements of foveal total retinal thickness (FTRT) and outer nuclear layer (ONL) thickness. Fundus autofluorescence patterns were characterized and compared over time.

RESULTS

Mean follow-up was 19.5 months (age range at baseline, 6-52 years). Only 2 (5%) of 37 subjects demonstrated change in serial foveal SD-OCT scans. There was no statistically significant change over time in FTRT (P = 0.83), ONL thickness (P = 0.27), hyporeflective zone diameter (P = 0.42), visual acuity (P = 0.89), contrast sensitivity (P = 0.22), mean retinal sensitivity (P = 0.84), and fixation stability (P = 0.58). Three distinct FAF patterns were observed (n = 30): central increased FAF (n = 4), normal FAF (n = 11), and well-demarcated reduced FAF (n = 15); with the latter group displaying a slow increase in the area of reduced FAF of 0.03 mm(2) over 19.3 months (P = 0.002).

CONCLUSIONS

Previously published cross-sectional studies have described conflicting findings with respect to the age-dependency of progression. This study, which constitutes the largest and longest prospective longitudinal study of ACHM to date, suggests that although ACHM may be progressive, any such progression is slow and subtle in most patients, and does not correlate with age or genotype. We also describe the first serial assessment of FAF, which is highly variable between individuals, even of similar age and genotype.

Characteristics of incident geographic atrophy in the complications of age-related macular degeneration prevention trial

OBJECTIVE

To characterize the size, location, conformation, and features of incident geographic atrophy (GA) as detected by annual stereoscopic color photographs and fluorescein angiograms (FAs).

DESIGN

Retrospective cohort study within a larger clinical trial.

PARTICIPANTS

Patients with bilateral large drusen in whom GA developed during the course of the Complications of Age-related Macular Degeneration Prevention Trial (CAPT).

METHODS

Annual stereoscopic color photographs and FAs were reviewed from 114 CAPT patients in whom GA developed in the untreated eye during 5 to 6 years of follow-up. Geographic atrophy was defined according to the Revised GA Criteria for identifying early GA.(23) Color-optimized fundus photographs were viewed concurrently with the FAs during grading.

MAIN OUTCOME MEASURES

Size and distance from the fovea of individual GA lesions, number of areas of atrophy, and change in visual acuity (VA) when GA first developed in an eye.

RESULTS

At presentation, the median total GA area was 0.26 mm(2) (0.1 disc area). Geographic atrophy presented as a single lesion in 89 (78%) eyes. The median distance from the fovea was 395 μm. Twenty percent of incident GA lesions were subfoveal and an additional 18% were within 250 μm of the foveal center. Development of GA was associated with a mean decrease of 7 letters from the baseline VA level compared with 1 letter among matched early age-related macular degeneration eyes without GA. Geographic atrophy that formed in areas previously occupied by drusenoid pigment epithelial detachments on average were larger (0.53 vs. 0.20 mm(2); P = 0.0001), were more central (50 vs. 500 μm from the center of the fovea; P<0.0001), and were associated with significantly worse visual outcome (20/50 vs. 20/25; P = 0.0003) than GA with other drusen types as precursors.

CONCLUSIONS

Incident GA most often appears on color fundus photographs and FAs as a small, singular, parafoveal lesion, although a large minority of lesions are subfoveal or multifocal at initial detection. The characteristics of incident GA vary with precursor drusen types. These data can facilitate design of future clinical trials of therapies for GA.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

New grading criteria allow for earlier detection of geographic atrophy in clinical trials

PURPOSE

To evaluate new grading criteria for geographic atrophy (GA), as detected by annual stereoscopic color fundus photographs and fluorescein angiograms, and to assess whether application of the revised criteria provides earlier identification of GA than previous criteria involving only color fundus photography.

METHODS

Annual fundus image sets from 114 CAPT patients who developed GA in the untreated eye during 5 to 6 years of follow-up were reassessed for the presence of GA, using revised grading criteria, in which GA was defined by (1) the presence of hyperfluorescence on fluorescein angiography; and (2) at least one other characteristic indicative of involution of the retinal pigment epithelium (i.e., sharp edges, excavation of the retina, or visible choroidal vessels on either color images or fluorescein angiograms). Reliability and time of initial detection of GA using the revised criteria were assessed.

RESULTS

The revised criteria are reliable (97.8% intragrader, 93.3% intergrader agreement) and accurate (false-positive rate, 0.8%) for detecting individual early GA lesions. Using this revised method, individual GA lesions were identified 1-year earlier on average than was possible with criteria used in previous CFP studies. The use of two imaging modalities was more sensitive in detecting GA and its features than either imaging modality alone (P ≤ 0.0001).

CONCLUSIONS

Early GA areas can be reliably identified when defining criteria are based on both color photographs and fluorescein angiograms. These methods can be used to investigate the natural history of GA earlier in the course of disease than previously possible and to facilitate the design of future clinical trials of treatments for GA. (ClinicalTrials.gov number, NCT00000167).

Fundus autofluorescence in geographic atrophy: a review

Fundus autofluorescence is a noninvasive imaging technology that provides information on the distribution of lipofuscin within the retinal pigment epithelial cell monolayer. Progressive accumulation of lipofuscin within retinal pigment epithelial cells is involved in the pathogenesis of geographic atrophy in age-related macular degeneration. This review contains an introduction to fundus autofluorescence, review of currently available imaging methods, and discussion of the role of autofluorescence imaging in geographic atrophy progression. The recent classification of geographic atrophy phenotypes by the Fundus Autofluorescence in Age-related Macular Degeneration Study (FAM) and the association of phenotype and atrophy progression are also summarized.

Progression of geographic atrophy in age-related macular degeneration imaged with spectral domain optical coherence tomography

PURPOSE

To determine the area and enlargement rate (ER) of geographic atrophy (GA) in patients with age-related macular degeneration (AMD) using the spectral domain optical coherence tomography (SD-OCT) fundus image.

DESIGN

Prospective, longitudinal, natural history study.

PARTICIPANTS

Eighty-six eyes of 64 patients with ≥6 months of follow-up.

METHODS

Patients with GA secondary to AMD were enrolled in this study. Macular scans were performed using the Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA). The areas of GA identified on the SD-OCT fundus images were quantified using a digitizing tablet. Reproducibility of these measurements was assessed and the ER of GA was calculated. The usefulness of performing square root transformations of the lesion area measurements was explored.

MAIN OUTCOME MEASURES

Enlargement rate of GA.

RESULTS

At baseline, 27% of eyes had a single area of GA. The mean total area at baseline was 4.59 mm(2) (1.8 disc areas [DA]). The mean follow-up time was 1.24 years. Reproducibility, as assessed with the intraclass correlation coefficient (ICC), was excellent on both the original area scale (ICC = 0.995) and the square root scale (ICC = 0.996). Intergrader differences were not an important source of variability in lesion size measurement (ICC = 0.999, 0.997). On average, the ER of GA per year was 1.2 mm(2) (0.47 DA; range, 0.01-3.62 mm(2)/year). The ER correlated with the initial area of GA (r = 0.45; P<0.001), but there were variable growth rates for any given baseline area. When the square root transformation of the lesion area measurements was used as a measure of lesion size, the ER (0.28 mm/yr) was not correlated with baseline size (r = -0.09; P = 0.40). In this cohort of lesions, no correlation was found between ER and length of follow-up. Square root transformation of the data helped to facilitate sample size estimates for controlled clinical trials involving GA.

CONCLUSIONS

The SD-OCT fundus image can be used to visualize and quantify GA. Advantages of this approach include the convenience and assurance of using a single imaging technique that permits simultaneous visualization of GA along with the loss of photoreceptors and the retinal pigment epithelium that should correlate with the loss of visual function.

Changes in retinal sensitivity in geographic atrophy progression as measured by microperimetry

PURPOSE

To characterize changes in macular sensitivity during geographic atrophy (GA) progression using microperimetry.

METHODS

Retinal sensitivity in the macular area was evaluated by microperimetry in 10 patients with bilateral GA, with adequate data obtained in 9 of 10 patients (n = 18 eyes). Patients had been enrolled in an interventional trial in which one eye had been randomized to treatment and the other eye observed. No treatment effect with regard to GA growth and microperimetric measurements was detected, and all eyes were analyzed. Microperimetric assessments of the central 20° of the macula were performed every 6 months over 24 months. Parameters analyzed included number of scotomatous points, mean retinal sensitivity of responding points, and fixation stability. Autofluorescence imaging and fundus photography were also obtained.

RESULTS

Microperimetric parameters demonstrated statistically significant changes as a function of time. Mean number of scotomatous points increased significantly with time (P = 0.004) at a rate of 4.4 points/year. Mean retinal sensitivities of all points, all responding points, and all perilesional points all decreased significantly with time (P < 0.003), as did fixation quality within the 2° and 4° circles (P < 0.002). The growth of GA lesion area was associated with the changes in the number of scotomatous points (P = 0.01) but not with changes in the other microperimetric parameters.

CONCLUSIONS

Macular sensitivity and fixation quality undergo progressive change during the GA progression, reflecting alterations in macular function extending beyond the GA lesion proper. Microperimetric measurements may provide useful functional outcome measures for the clinical study of GA.

Treatment of geographic atrophy by the topical administration of OT-551: results of a phase II clinical trial

PURPOSE

To investigate the safety and preliminary efficacy of OT-551, a disubstituted hydroxylamine with antioxidant properties, for the treatment of geographic atrophy (GA), the advanced atrophic form of age-related macular degeneration (AMD).

METHODS

The study was a single-center, open-label phase II trial, enrolling 10 participants with bilateral GA. Topical 0.45% OT-551 was administered in one randomly assigned eye three times daily for 2 years. Safety measures were assessed by complete ophthalmic examination, fundus photography, and review of symptoms. The primary efficacy outcome measure was the change in best corrected visual acuity at 24 months. Secondary efficacy measures included changes in area of GA, contrast sensitivity, microperimetry measurements, and total drusen area from baseline.

RESULTS

Study drug was well tolerated and was associated with few adverse events. The mean change in BCVA at 2 years was +0.2 ± 13.3 letters in the study eyes and -11.3 ± 7.6 letters in fellow eyes (P = 0.0259). However, no statistically significant differences were found between the study and fellow eyes for all other secondary outcome measures.

CONCLUSIONS

OT-551 was well tolerated by study participants and was not associated with any serious adverse effects. Efficacy measurements in this small study indicate a possible effect in maintaining visual acuity. However, the absence of significant effects on other outcomes measures in this study suggests that OT-551, in the current concentration and mode of delivery, may have limited or no benefit as a treatment for GA (ClinicalTrials.gov number, NCT00306488).

CFH, C3 and ARMS2 are significant risk loci for susceptibility but not for disease progression of geographic atrophy due to AMD

Background

Age-related macular degeneration (AMD) is a prevalent cause of blindness in Western societies. Variants in the genes encoding complement factor H (CFH), complement component 3 (C3) and age-related maculopathy susceptibility 2 (ARMS2) have repeatedly been shown to confer significant risks for AMD; however, their role in disease progression and thus their potential relevance for interventional therapeutic approaches remains unknown.

Methodology/Principal Findings

Here, we analyzed association between variants in CFH, C3 and ARMS2 and disease progression of geographic atrophy (GA) due to AMD. A quantitative phenotype of disease progression was computed based on longitudinal observations by fundus autofluorescence imaging. In a subset of 99 cases with pure bilateral GA, variants in CFH (Y402H), C3 (R102G), and ARMS2 (A69S) are associated with disease (P = 1.6×10⁻⁹, 3.2×10⁻³, and P = 2.6×10⁻¹², respectively) when compared to 612 unrelated healthy control individuals. In cases, median progression rate of GA over a mean follow-up period of 3.0 years was 1.61 mm²/year with high concordance between fellow eyes. No association between the progression rate and any of the genetic risk variants at the three loci was observed (P>0.13).

Conclusions/Significance

This study confirms that variants at CFH, C3, and ARMS2 confer significant risks for GA due to AMD. In contrast, our data indicate no association of these variants with disease progression which may have important implications for future treatment strategies. Other, as yet unknown susceptibilities may influence disease progression.

Change in area of geographic atrophy in the Age-Related Eye Disease Study: AREDS report number 26

OBJECTIVE

To characterize progression of geographic atrophy (GA) associated with age-related macular degeneration in AREDS as measured by digitized fundus photographs.

METHODS

Fundus photographs from 181 of 4757 AREDS participants with a GA area of at least 0.5 disc areas at baseline or from participants who developed bilateral GA during follow-up were scanned, digitized, and evaluated longitudinally. Geographic atrophy area was determined using planimetry. Rates of progression from noncentral to central GA and of vision loss following development of central GA included the entire AREDS cohort.

RESULTS

Median initial lesion size was 4.3 mm(2). Average change in digital area of GA from baseline was 2.03 mm(2) (standard error of the mean, 0.24 mm(2)) at 1 year, 3.78 mm(2) (0.24 mm(2)) at 2 years, 5.93 mm(2) (0.34 mm(2)) at 3 years, and 1.78 mm(2) (0.086 mm(2)) per year overall. Median time to developing central GA after any GA diagnosis was 2.5 years (95% confidence interval, 2.0-3.0). Average visual acuity decreased by 3.7 letters at first documentation of central GA, and by 22 letters at year 5.

CONCLUSIONS

Growth of GA area can be reliably measured using standard fundus photographs that are digitized and subsequently graded at a reading center. Development of GA is associated with subsequent further growth of GA, development of central GA, and loss in central vision.

Fundus autofluorescence and progression of age-related macular degeneration

Fundus autofluorescence imaging is an imaging method that provides additional information compared to conventional imaging techniques. It permits to topographically map lipofuscin distribution of the retinal pigment epithelial cell monolayer. Excessive accumulation of lipofuscin granules in the lysosomal compartment of retinal pigment epithelium cells represents a common downstream pathogenetic pathway in various hereditary and complex retinal diseases including age-related macular degeneration (AMD). This comprehensive review contains an introduction in fundus autofluorescence imaging, including basic considerations, the origin of the signal, different imaging methods, and a brief overview of fundus autofluorescence findings in normal subjects. Furthermore, it summarizes cross-sectional and longitudinal fundus autofluorescence findings in patients with AMD, addresses the pathophysiological significance of increased fundus autofluorescence, and characterizes different fundus autofluorescence phenotypes as well as fundus autofluorescence alterations with disease progression.

The epidemiology of progression of pure geographic atrophy: the Beaver Dam Eye Study

PURPOSE

To examine the change in size and location of pure geographic atrophy (GA).

DESIGN

Population-based cohort study.

METHODS

Ninety-five persons with GA either at baseline or at the one of the three five-year follow-up examinations, or both, were identified. Using computer-assisted software, the lesion area and greatest linear dimension (GLD) were calculated. Thirty-two persons (53 multiple eye-visit pairs) were seen at multiple visits five years apart with GA in the same eye to evaluate changes in total area and GLD.

RESULTS

At the first occasion when pure GA was identified (n = 95), 45% had a single GA lesion, 18% had multifocal GA lesions, and 37% had a merged GA lesion. Of 53 eyes with multiple visits, the overall increase in atrophy was 6.4 mm(2) over a five-year period. The atrophy progressed to involve the foveal center in 47% of 19 eyes, and there was a mean decrease of 17 letters read correctly. Eyes with multifocal GA were most likely to have the area of atrophy increase (mean, 12 mm(2)), to have atrophy progress to the foveal center (83%), and to have a decrease in vision (mean, 22 letters), whereas eyes with a single GA lesion were least likely to have the area of atrophy increase (mean, 2 mm(2)), to have the lesion progress to the foveal center (22%), and to have a decrease in vision (mean, 10 letters).

CONCLUSIONS

These are the first population-based data describing the five-year change in eyes with pure GA. Information on progression of GA will be useful for clinical trials of new interventions for GA.

Fundus autofluorescence imaging: review and perspectives

Fundus autofluorescence (FAF) imaging is a novel imaging method that allows topographic mapping of lipofuscin distribution in the retinal pigment epithelium cell monolayer as well as of other fluorophores that may occur with disease in the outer retina and the subneurosensory space. Excessive accumulation of lipofuscin granules in the lysosomal compartment of retinal pigment epithelium cells represents a common downstream pathogenetic pathway in various hereditary and complex retinal diseases, including age-related macular degeneration. FAF imaging has been shown to be useful with regard to understanding of pathophysiologic mechanisms, diagnostics, phenotype-genotype correlation, identification of predictive markers for disease progression, and monitoring of novel therapies. FAF imaging gives information above and beyond that obtained by conventional imaging methods, such as fundus photography, fluorescein angiography, and optical coherence tomography. Its clinical value coupled with its simple, efficient, and noninvasive nature is increasingly appreciated. This review summarizes basic principles and FAF findings in various retinal diseases.

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

PURPOSE

To test if fundus autofluorescence (FAF) patterns around geographic atrophy (GA) have an impact on GA progression rates over time in atrophic age-related macular degeneration (AMD).

DESIGN

Prospective longitudinal multicenter natural history study.

METHODS

Standardized digital FAF images were obtained from 195 eyes of 129 patients with GA using confocal scanning laser ophthalmoscopy (excitation 488 nm, emission >500 nm). Areas of GA were quantified and patterns of abnormal FAF in the junctional zone were classified. Repeated FAF images were obtained over a median follow-up period of 1.80 years (interquartile range [IQR], 1.28 to 3.34).

RESULTS

Areas of GA (median, 7.04 mm(2) at baseline; IQR, 3.12 to 10.0) showed a median enlargement of 1.52 mm(2)/year (IQR, 0.81 to 2.33). Progression rates in eyes with the banded (median 1.81 mm(2)/year) and the diffuse FAF pattern (1.77 mm(2)/year) were significantly higher compared to eyes without FAF abnormalities (0.38 mm(2)/year) and focal FAF patterns (0.81 mm(2)/year, P < .0001). Within the group of the diffuse pattern, eyes with a diffuse trickling pattern could be identified that exhibited an even higher spread rate (median 3.02 mm(2)/year) compared to the other diffuse types (1.67 mm(2)/year, P = .001).

CONCLUSIONS

The results indicate that distinct phenotypic FAF patterns have an impact on disease progression in eyes with atrophic AMD and may therefore serve as prognostic determinants. The findings underscore the relevance of FAF imaging and the pathogenetic role of excessive retinal pigment epithelium (RPE) lipofuscin (LF) accumulation in GA. Natural history data and identification of high-risk characteristics will be helpful to design interventional studies aiming at slowing the spread of atrophy.

The long-term natural history of geographic atrophy from age-related macular degeneration: enlargement of atrophy and implications for interventional clinical trials

PURPOSE

To report the enlargement rate of geographic atrophy (GA) over time, its relationship to size of atrophy at baseline and to prior enlargement rate, and the implications for designing future treatment trials for GA.

DESIGN

Prospective natural history study of GA resulting from age-related macular degeneration.

PARTICIPANTS

Two hundred twelve eyes of 131 patients were included in the analysis.

METHODS

Annual follow-up included stereo color fundus photographs. The areas of GA were identified and measured, and the rate of enlargement of the atrophy was assessed. Sample sizes for clinical trials using systemic treatment and uniocular treatment were determined.

MAIN OUTCOME MEASURE

Rate of enlargement of the atrophy.

RESULTS

The median overall enlargement rate was 2.1 mm2/year (mean, 2.6 mm2/year). Eyes with larger areas of atrophy at baseline tended to have larger enlargement rates, but knowledge of prior rates of enlargement was the most significant factor in predicting subsequent enlargement rates. There was high concordance between the enlargement rates in the 2 eyes of patients with bilateral GA (correlation coefficient, 0.76). To detect a 25% reduction in enlargement rate for a systemic treatment (alpha, 0.05; power, 0.80; losses to follow-up, 15%), 153 patients each in a control and treatment group would be required for a trial with a 2-year follow-up period for each patient. For a uniocular treatment, 38 patients with bilateral GA would be required, with the untreated eye serving as a control for the treated eye.

CONCLUSIONS

Treatment trials for GA with an outcome variable of change in enlargement rate are feasible.