Classification of abnormal fundus autofluorescence patterns in the junctional zone of geographic atrophy in patients with age related macular degeneration

American Society of Retina Specialists Clinical Practice Guidelines on Multimodal Imaging for Retinal Disease

Purpose: Advancements in retinal imaging have augmented our understanding of the pathology and structure-function relationships of retinal disease. No single diagnostic test is sufficient; rather, diagnostic and management strategies increasingly involve the synthesis of multiple imaging modalities. Methods: This literature review and editorial offer practical clinical guidelines for how the retina specialist can use multimodal imaging to manage retinal conditions. Results: Various imaging modalities offer information on different aspects of retinal structure and function. For example, optical coherence tomography (OCT) and B-scan ultrasonography can provide insights into the microstructural anatomy; fluorescein angiography (FA), indocyanine green angiography (ICGA), and OCT angiography (OCTA) can reveal vascular integrity and perfusion status; and near-infrared reflectance and fundus autofluorescence (FAF) can characterize molecular components within tissues. Managing retinal vascular diseases often includes fundus photography, OCT, OCTA, and FA to evaluate for macular edema, retinal ischemia, and the secondary complications of neovascularization (NV). OCT and FAF play a key role in diagnosing and treating maculopathies. FA, OCTA, and ICGA can help identify macular NV, posterior uveitis, and choroidal venous insufficiency, which guides treatment strategies. Finally, OCT and B-scan ultrasonography can help with preoperative planning and prognostication in vitreoretinal surgical conditions. Conclusions: Today, the retina specialist has access to numerous retinal imaging modalities that can augment the clinical examination to help diagnose and manage retinal conditions. Understanding the capabilities and limitations of each modality is critical to maximizing its clinical utility.

Discovery of Nonretinoid Inhibitors of CRBP1: Structural and Dynamic Insights for Ligand-Binding Mechanisms

The dysregulation of retinoid metabolism has been linked to prevalent ocular diseases including age-related macular degeneration and Stargardt disease. Modulating retinoid metabolism through pharmacological approaches holds promise for the treatment of these eye diseases. Cellular retinol-binding protein 1 (CRBP1) is the primary transporter of all-trans-retinol (atROL) in the eye, and its inhibition has recently been shown to protect mouse retinas from light-induced retinal damage. In this report, we employed high-throughput screening to identify new chemical scaffolds for competitive, nonretinoid inhibitors of CRBP1. To understand the mechanisms of interaction between CRBP1 and these inhibitors, we solved high-resolution X-ray crystal structures of the protein in complex with six selected compounds. By combining protein crystallography with hydrogen/deuterium exchange mass spectrometry, we quantified the conformational changes in CRBP1 caused by different inhibitors and correlated their magnitude with apparent binding affinities. Furthermore, using molecular dynamic simulations, we provided evidence for the functional significance of the "closed" conformation of CRBP1 in retaining ligands within the binding pocket. Collectively, our study outlines the molecular foundations for understanding the mechanism of high-affinity interactions between small molecules and CRBPs, offering a framework for the rational design of improved inhibitors for this class of lipid-binding proteins.

Impact of Prophylactic Ranibizumab to Prevent Neovascular Age-Related Macular Degeneration on Eyes With Intermediate Age-Related Macular Degeneration

Purpose

The purpose of this study was to determine the impact of prophylactic ranibizumab (PR) injections given every 3 months in eyes with intermediate nonexudative age-related macular degeneration (AMD) on drusen volume, macular layer thicknesses, and progression of geographic atrophy (GA) area over 24 months in the PREVENT trial.

Methods

This post hoc analysis of the prospective PREVENT trial compared eyes with intermediate AMD randomized to PR versus sham injections to determine rates of conversion to neovascular AMD over 24 months. Drusen area and volume, macular thickness and volume, and retinal layer thicknesses were measured on spectral-domain optical coherence tomography images and analyzed. Masked grading of GA area and subretinal drusenoid deposits (SDDs) using fundus autofluorescence images was performed.

Results

There were no statistical differences in drusen area and volumes between groups, and similar reductions in central subfield thickness, mean cube thickness, cube volume, and retinal sublayer thickness from baseline to 24 months (P = 0.018 to < 0.001), with no statistical differences between groups in any of these anatomic parameters. These findings were not impacted by the presence or absence of SDD. Among the 9 eyes with GA in this study, mean GA growth rate from baseline to 24 months was 1.34 +/- 0.79 mm2/year after PR and 1.95 +/- 1.73 mm2/year in sham-treated eyes (P = 0.49), and similarly showed no statistical difference with square root transformation (P = 0.61).

Conclusions

Prophylactic ranibizumab given every 3 months did not appear to affect drusen volume, macular thinning, or GA progression in eyes with intermediate AMD.

Translational Relevance

This work investigates the impact of PR on progressive retinal degeneration in a clinical trial.

Retro-mode: a newer insight into dry age-related macular degeneration (AMD)

The purpose of this study is to study the role of retro-mode (RM) in early detection and to compare it with other preexisting available modalities on multimodal imaging system in dry AMD. A prospective observational cross-sectional study was done between November 2020 and October 2021 which included 409 eyes of 207 patients. For study purpose, eyes were divided into 3 groups according to the size and number of the drusen, viz, group 1: No AMD, group 2: early AMD and group 3: intermediate AMD which was further divided into 2 subgroups, viz, subgroup A: eyes with drusen size 63-125 μm and subgroup B: eyes with drusen size 125-250 μm. Patients with active or treated wet AMD, scarred choroidal neovascular membrane (CNVM), other maculopathies, other retinopathies, high myopia, trauma and glaucoma were excluded from the study. In cases of No AMD and early AMD, a number of drusens detected on RM were statistically not significant compared to fundus autofluorescence (FAF) and color photo (CF), but in intermediate AMD cases, it was statistically significant. While the area involved by drusens calculated by RM was statistically significant compared to both other modalities. When all modalities were compared with enhanced depth imaging-optical coherence tomography (EDI-OCT) at the choroid and chorio-capillary (CC) level and vessel density (VD) on optical coherence tomography angiography (OCTA) at the choroid, capillaries, deep retinal and superficial retinal plexus level; it was only RM which was found to be in sync with these proven modalities in terms of pattern and trend. In the present scenario, RM is found to be a better diagnostic modality in detecting early and a greater number of drusens with area of involvement than other existing modalities. Though superior, as found in this study, this mode cannot replace other modalities at present but only acts as a complementary investigation in early detection of this disease.

Geographic Atrophy Phenotypes in Subjects of Different Ethnicity: Asia-Pacific Ocular Imaging Society Work Group Report 3

OBJECTIVE

To characterize geographic atrophy (GA) and evaluate differences between Asians and non-Asians.

DESIGN

Multicenter, retrospective case series.

PARTICIPANTS

Subjects aged ≥ 50 years with GA secondary to age-related macular degeneration in the absence of neovascularization in the study eye and follow-up of ≥ 2 years.

METHODS

The GA lesion characterized at baseline and last follow-up based on multimodal imaging (fundus autofluorescence [FAF], near infrared [NIR], and spectral domain-OCT). Patients were grouped as either Asian or non-Asian.

MAIN OUTCOME MEASURES

Comparison of (1) phenotypes of GA lesions (size, foveal involvement, number of foci, drusen background, and choroid background) and (2) growth rates of GA.

RESULTS

A total of 144 patients (169 eyes) with distribution of 50.9% Asians and 49.1% non-Asians. The age and sex were similar between Asians and non-Asians (Asians: mean age, 77.2 ± 10.1 years, 47.9% female; non-Asians: mean age, 79.7 ± 8.4 years, 58.7% female). Asians exhibited thicker choroids (167 ± 74 versus [vs.] 134 ± 56 μm; P < 0.01) and lower prevalence of drusen (40.7% vs. 66.3%; P < 0.01). At baseline, the GA area was smaller in Asians vs. non-Asians (NIR, 3.7 ± 4.6 vs. 6.3 ± 6.8 mm²; P = 0.01: FAF, 2.4 ± 3.4 vs. 8.4 ± 9.6 mm²; P < 0.01). Asians had fewer GA foci (1.7 ± 1.3 vs. 2.7 ± 2.2; P < 0.01) compared to non-Asians. The proportion with diffused or banded FAF junctional zone pattern was similar between Asians and non-Asians (44.2% vs. 60.2%; P = 0.20). Asians had a slower GA lesion growth rate than non-Asians (NIR, 0.7 vs. 1.9 mm²/year; P < 0.01: FAF, 0.3 vs. 2.0 mm²/year; P < 0.01: NIR, 0.4 vs. 0.9 mm/year; P < 0.001 square root transformed: FAF, 0.3 vs. 1.0 mm/year; P < 0.001 square root transformed). The factors associated with GA lesion growth rate are (from the highest effect size) ethnicity, junctional zone FAF pattern, baseline GA area, and number of GA foci. Higher GA lesion growth rate was observed in both Asian and non-Asian subgroups, with drusen or lesion size and FAF patterns meeting inclusion criteria of recent therapeutic trials, but growth rate remained significantly slower in Asians. Eyes with baseline lesion ≥ 5 mm² showed the highest growth rate, and the difference between ethnicities was no longer significant (2.6 vs. 3.3 mm²/year; P = 0.09).

CONCLUSIONS

There are differences in GA lesion phenotype, associated features, and growth rate between Asians and non-Asian subjects.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Blue-light fundus autofluorescence imaging of pigment epithelial detachments

BACKGROUND

Pigment epithelial detachments (PEDs) occur in association with various chorioretinal diseases. With respect to the broad clinical spectrum of PEDs we describe fundus autofluorescence (FAF) characteristics of PEDs.

METHODS

Ninety-three eyes of 66 patients (mean age 71.9 ± 11.1) with uni- or bilateral PED ( ≥ 350 µm) were included in a retrospective cross-sectional study. PEDs were secondary to age-related macular degeneration (n = 79), central serous chorioretinopathy (n = 7), polypoidal choroidal vasculopathy (n = 2), pattern dystrophy (n = 3) or idiopathic PED (n = 2). FAF images were recorded using confocal scanning laser ophthalmoscopy (488 nm excitation wavelength, detection of emission >500 nm). Diagnosis of PED was confirmed using spectral-domain optical coherence tomography. A qualitative FAF grading system was established, and grading was performed by two independent readers.

RESULTS

PEDs showed highly variable characteristics on FAF imaging. FAF within the area of PED was found to be irregular/granular (n = 59, 63.4%), increased (n = 28, 30.1%), decreased (n = 3, 3.2 %), or normal (n = 3, 3.2%). Accompanying FAF changes included condensation of macular pigment (n = 67, 72.0%), focally increased FAF at the PED apex (n = 14, 15.1%) or elsewhere (n = 52, 55.9%), focally decreased FAF (n = 23, 24.7%), a cartwheel-like pattern (n = 10, 10.8%), a doughnut sign (n = 6, 6.5%), and a halo of decreased FAF encircling the PED (completely n = 20, 21.5% or incompletely n = 20, 21.5%).

CONCLUSIONS

PEDs show a variety of abnormal patterns on FAF imaging. These changes in FAF signals may be secondary to morphological and metabolic alterations within corresponding retinal layers and do not necessarily correspond with the underlying PED subtype or a specific pathology.

Optical Coherence Tomography Angiography: Clinical Utility and Future Directions

Purpose

This work aims to review the principles of optical coherence tomography angiography (OCTA), to survey its clinical utility, and to highlight the strengths of this technology as well as barriers to adoption.

Methods

A literature review with editorial discussion of the current applications for OCTA is presented.

Results

There have been recent advances in multiple domains in OCTA imaging, including devices, algorithms, and new observations pertaining to a range of pathologies. New devices have improved the scanning speed, signal-to-noise ratio, and spatial resolution and offer an increased field of view. New algorithms have been proposed to optimize image processing and reduce artifacts. Numerous studies employing OCTA have been published describing changes to the microvasculature in diabetic retinopathy, age-related macular degeneration, central serous chorioretinopathy, retinal vein occlusion, and uveitis.

Conclusions

OCTA provides noninvasive, high-resolution volumetric scans of the retinal and choroidal vasculature. OCTA can provide valuable data to augment traditional dye-based angiography in a range of chorioretinal diseases.

Evolving Patterns of Hyperfluorescent Fundus Autofluorescence Accompany Retinal Atrophy in the Rat and Mimic Atrophic Age-Related Macular Degeneration

Purpose

Complex two-dimensional (2D) patterns of hyperfluorescent short-wave fundus autofluorescence (FAF) at the border of geographic atrophy (GA) can predict its expansion in patients with late non-exudative “dry” AMD. However, preclinical models do not phenocopy this important feature of disease. We sought to describe the spatiotemporal changes in hyperfluorescent FAF patterns that occur following acute oxidative stress, potentially in association with GA expansion.

Methods

Sprague Dawley rats (n = 54) received systemic sodium iodate (25–45 mg/kg, n = 90 eyes) or saline (n = 18 eyes) and underwent serial full fundus imaging by confocal scanning laser ophthalmoscopy, including blue FAF and delayed near-infrared analysis. Composite images of the fundus were assembled, and the 2D patterns were described qualitatively and quantitatively. A subset of eyes underwent tissue analysis, and four underwent optical coherence tomography (OCT) imaging.

Results

Reproducibly changing, complex patterns of hyperfluorescent FAF emerge at the borders of toxin-induced damage; however, in the absence of GA expansion, they percolate inward within the region of retinal pigment epithelium loss, evolving, maturing, and senescing in situ over time. Unexpectedly, the late FAF patterns most closely resemble the diffuse tricking form of clinical disease. A five-stage classification system is presented.

Conclusions

Longitudinal, full-fundus imaging of outer retinal atrophy in the rat eye identifies evolving, complex patterns of hyperfluorescent FAF that phenocopy aspects of disease.

Translational Relevance

This work provides a novel tool to assess hyperfluorescent FAF in association with progressive retinal atrophy, a therapeutic target in late AMD.

Complement Mediators in Development to Treat Age-Related Macular Degeneration

Over recent years, great attention has been paid to the role of the complement system in the pathogenesis of age-related macular degeneration (AMD). In particular, several studies have highlighted a link between AMD development and complement dysregulation, which can probably be explained as a complement cascade hyperactivation resulting from the presence of a series of risk factors such as aging; smoking; obesity; alcohol consumption; exposure to pesticides, industrial chemicals, or pollution; and other causes of oxidative stress. This hypothesis has been mainly supported by the presence of complement mediators as constituents of drusen, representing one of the earliest and most characteristic signs of retinal damage in AMD. Additionally, activated complement mediators and some complement regulators, such as vitronectin, have been found not only in the drusen and adjacent retinal areas but also in the peripheral blood of patients with AMD. Therefore, we aim to provide a review of recently studied complement factors to highlight their role in the pathogenesis of AMD and to evaluate new potential therapeutic strategies.

Impact of Baseline Characteristics on Geographic Atrophy Progression in the FILLY Trial Evaluating the Complement C3 Inhibitor Pegcetacoplan

PURPOSE

To evaluate the effect of select baseline characteristics on geographic atrophy (GA) progression in eyes receiving intravitreal pegcetacoplan or sham.

DESIGN

Phase 2 multicenter, randomized, single-masked, sham-controlled trial.

METHODS

Patients with GA received 15 mg pegcetacoplan monthly or every other month (EOM), or sham injection monthly or EOM for 12 months. Primary efficacy endpoint was change in GA lesion size (square root) from baseline. Post hoc analysis evaluated the effects of age; gender; lesion size, focality, and location (extrafoveal vs foveal); pseudodrusen status; best-corrected visual acuity (BCVA); and low-luminance deficit (LLD) on GA progression at Month 12.

RESULTS

Of 246 randomized patients, 192 with 12-month data were included in this analysis. Overall mean (standard deviation) change in lesion size (mm) was 0.26 (0.17) (P < .01), 0.27 (0.27) (P < .05), and 0.36 (0.21) in the monthly pegcetacoplan (n = 67), EOM pegcetacoplan (n = 58), and sham (n = 67) groups, respectively. In univariate analysis, patients with extrafoveal lesions (P < .001), BCVA ≥20/60 (P = .001), and larger LLD (P = .002) had greater mean changes in lesion size. Multivariate analysis confirmed significant association of extrafoveal lesions (P = .001) and larger LLD (P = .023) with GA progression. Monthly and EOM pegcetacoplan significantly reduced progression (P < .05) when controlling for these risk factors.

CONCLUSIONS

Extrafoveal lesions and larger LLD are potential risk factors for GA progression. Pegcetacoplan treatment significantly controlled GA progression even after accounting for these risk factors.

Impact of ocular and systemic risk factors on progression of geographic atrophy in age-related macular degeneration

BACKGROUND

Geographic atrophy (GA) corresponds to an end-stage form of age-related macular degeneration and the leading cause of irreversible vision loss. The aim of this study was to investigate the role of fundus autofluorescence (FAF) patterns surrounding GA, baseline GA size, the presence of reticular pseudodrusen (RPD), the condition of the fellow eye and the presence of systemic vascular diseases (diabetes, atherosclerosis, systemic hypertension) on the progression of GA due to age-related macular degeneration.

METHODS

Seventy-five eyes of 52 patients with GA were included into this retrospective study. Digital FAF images were achieved using scanning laser ophthalmoscopy. Areas of GA were measured with the Region Finder software program on an Heidelberg Retinal Angiograph 2. FAF patterns around GA were classified and the presence of RPD and systemic diseases were noted. The median follow-up of the patients was 2.6 years (interquartile range, 1-9.2).

RESULTS

The median progression rate of the banded pattern (median 0.97 mm²/year) was significantly higher than the other patterns (median 0.85 mm²/year) (p = 0.03). Eyes with RPD had a significantly higher progression rate (median 1.21 mm²/year) than those without RPD (median 0.79 mm²/year) (p = 0.007). The presence of systemic diseases was not related with lesion progression rates.

CONCLUSIONS

The results demonstrate that the banded pattern and the presence of RPD accelerate the progression of GA and function as predictive factors.

RECLASSIFICATION OF FUNDUS AUTOFLUORESCENCE PATTERNS SURROUNDING GEOGRAPHIC ATROPHY BASED ON PROGRESSION RATE: A Systematic Review and Meta-Analysis

PURPOSE

To reclassify fundus autofluorescence (FAF) patterns around geographic atrophy (GA) based on GA progression rates.

METHODS

MEDLINE, EMBASE, Cochrane Library, Clinicaltrials.gov, and PubMed were searched for studies reporting GA progression rates among different FAF patterns, such as "None," "Focal," "Banded," "Patchy," "Diffuse Nontrickling," and "Diffuse Trickling." The GA radius growth rate among different FAF patterns was compared, and a GA growth function for each group was derived. To account for the patients' different entry times, a horizontal translation factor was introduced to shift each data subset from "time after enrollment" to "duration of GA."

RESULTS

Seven studies with 496 eyes were included. Based on GA radius growth rates, the six FAF patterns were clustered into four groups with a high correlation coefficient within each group: Group 1, None, 0.061 mm/year (r = 0.996), Group 2, Focal, 0.105 mm/year (r = 0.987), Group 3, Banded, Patchy, and Diffuse Nontrickling, 0.149 mm/year (r = 0.993), and Group 4, "Diffuse Trickling, 0.245 mm/year (r = 0.997).

CONCLUSION

This meta-analysis suggested that the six FAF patterns can be coalesced into four groups based on lesion progression rates. Simplification of the reclassified FAF patterns may shed light on the GA natural history and assist in the design of clinical trials.

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.

Burden of Illness in Geographic Atrophy: A Study of Vision-Related Quality of Life and Health Care Resource Use

Purpose

To gain comprehensive information on the burden of illness due to geographic atrophy (GA).

Methods

This cross-sectional study with a retrospective chart review involved patients aged ≥70 years with physician-confirmed bilateral symptomatic GA due to age-related macular degeneration (GA group), as well as patients of similar age with no ophthalmic condition that in the opinion of the investigator affected visual function (non-GA group). Data relating to patients’ current disease status and sociodemographics were self-reported on patient questionnaires at study entry and extracted from patient charts. Historical data on health care resource utilization (HCRU) were also collected via patient questionnaires and retrospective chart review (GA group only). Overall vision-related functioning and quality of life (QoL) were compared between the GA and non-GA groups using the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25) composite and subscales, and change in vision over the past year was assessed using the Global Rating of Change Scale.

Results

Vision-related functioning and QoL were poorer in patients with vs without GA (n=137 vs 52), as demonstrated by significantly lower NEI-VFQ-25 composite score (mean, 53.1 vs 84.5 points, respectively; P<0.001), as well as lower subscale scores for near activities, distance activities, dependency, driving, social functioning, mental health, role difficulties, color vision, and peripheral vision. Substantially more patients with GA than without GA reported worsening in vision over the past year (82% vs 25%, respectively; odds ratio, 13.55; P<0.001). In the GA group, associated mean annual costs for direct ophthalmological resource use per patient amounted to €1772 (mostly for tests/procedures), and for indirect ophthalmological resource use, €410 (mostly for general practitioner visits).

Conclusion

Patients with GA experience a poorer level of vision-related function and QoL than their peers, especially in relation to driving. GA is also associated with notable HCRU/associated costs, mostly direct costs attributed to diagnostic tests/procedures.

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.

Visible-light optical coherence tomography-based multimodal system for quantitative fundus autofluorescence imaging

IMPACT STATEMENT

Quantitative fundus autofluorescence imaging with simultaneous visible-light optical coherence tomography-based multimodal technology has potential significant impact on the diagnosis and monitoring the progression of retinal diseases.

CLASSIFICATION AND QUANTITATIVE ANALYSIS OF GEOGRAPHIC ATROPHY JUNCTIONAL ZONE USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

The junctional zone at the border of areas of geographic atrophy (GA) in eyes with nonneovascular age-related macular degeneration is an important target region for future therapeutic strategies. The goal of this study was to perform a detailed classification and quantitative characterization of the junctional zone using spectral domain optical coherence tomography.

METHODS

Spectral domain optical coherence tomography volume cube scans (Spectralis OCT, 1024 × 37, Automatic Real Time > 9) were obtained from 15 eyes of 11 patients with GA because of nonneovascular age-related macular degeneration. Volume optical coherence tomography data were imported into previously described validated grading software (3D-OCTOR), and manual segmentation of the retinal pigment epithelium (RPE) and photoreceptor layers was performed on all B-scans (total of 555). Retinal pigment epithelium and photoreceptor defect maps were produced for each case. The borders of the photoreceptor defect area and RPE defect area were delineated individually on separate annotation layers. The two outlines were then superimposed to compare the areas of overlap and nonoverlap. The perimeter of the RPE defect area was calculated by the software in pixels. The superimposed outline of the photoreceptor defect area and the RPE defect area was scrutinized to classify the overlap configuration of the junctional zone into one of three categories: Type 0, exact correspondence between the edge of the RPE defect and photoreceptor defect; Type 1, loss of photoreceptors outside and beyond the edge of the RPE defect; Type 2, preservation of photoreceptors beyond the edge of the RPE defect. The relative proportion of the various border configurations was expressed as a percentage of the perimeter of the RPE defect. Each configuration was then classified into four subgroups according to irregularity of the RPE band and the presence of debris.

RESULTS

Fifteen eyes of 11 patients (mean age: 79.3 ± 4.3 years; range: 79-94 years) were included in this study. Seventeen GA lesions were analyzed. Two hundred and thirty-two B-scans were found to pass through the GA lesions, yielding 612 individual GA borders which were separately analyzed and classified. The mean area of the RPE defect was 4.0 ± 4.4 mm, which was significantly smaller than that of the photoreceptor defect which measured 4.4 ± 4.1 mm (paired t test, P = 0.037). On average, 18.0 ± 9.6% (range, 2.3-36.6%) of the junctional zone was of the Type 0 configuration, 57.3 ± 19.0% (range, 21.3-96.8%) was Type 1, and 24.7 ± 18.0% (range, 0.9-64.4%) was Type 2. Type 1 was more prevalent than Type 0 and 2 (analysis of variance, P = 0.000). Debris was present at the margin of the defect in 24.3% (149 of 612) of all assessed junctional zones; 20.0% (14 of 70) of Type 0 junctions, 28.7% (120 of 418) of Type 1, and 12.1% (15 of 124) of Type 2. Debris was more common in Type 1 than Type 2 junctions (P < 0.001). Retinal pigment epithelial irregularity was present at the margin of the defect in 34.8% (213 of 612) of all assessed junctional zones; 52.9% (37 of 70) of Type 0 junctions, 38.0% (159 of 418) of Type 1, and 13.7% (17 of 124) of Type 2. Retinal pigment epithelial irregularity was present more often at Type 0 and Type 1 than at Type 2 junctions (P < 0.001 for both).

CONCLUSION

The size of the optical coherence tomography-visible RPE and photoreceptor defect in GA lesions differ significantly. There were significant areas where the photoreceptor outer segments were preserved despite the absence of visible RPE cells, and also areas of photoreceptor outer segment loss despite apparent RPE preservation. These findings have implications for development of therapeutic strategies, particularly cell-replacement approaches.

EVALUATION OF PATCHY ATROPHY SECONDARY TO HIGH MYOPIA BY SEMIAUTOMATED SOFTWARE FOR FUNDUS AUTOFLUORESCENCE ANALYSIS

PURPOSE

To evaluate the progression of patchy atrophy in high myopia using semiautomated software for fundus autofluorescence (FAF) analysis.

METHODS

The medical records and multimodal imaging of 21 consecutive highly myopic patients with macular chorioretinal patchy atrophy (PA) were retrospectively analyzed. All patients underwent repeated fundus autofluorescence and spectral domain optical coherence tomography over at least 12 months. Color fundus photography was also performed in a subset of patients. Total atrophy area was measured on FAF images using Region Finder semiautomated software embedded in Spectralis (Heidelberg Engineering, Heidelberg, Germany) at baseline and during follow-up visits. Region Finder was compared with manually measured PA on FAF images.

RESULTS

Twenty-two eyes of 21 patients (14 women, 7 men; mean age 62.8 + 13.0 years, range 32-84 years) were included. Mean PA area using Region Finder was 2.77 ± 2.91 SD mm at baseline, 3.12 ± 2.68 mm at Month 6, 3.43 ± 2.68 mm at Month 12, and 3.73 ± 2.74 mm at Month 18 (overall P < 0.005); this accounts for PA progression rate of 0.821 mm/year. Atrophy progression was significantly greater among eyes with larger PA compared with smaller baseline PA at Months 6, 12, and 18. There was no statistically significant difference between semiautomated Region Finder PA area and manually measured PA area on FAF images.

CONCLUSION

Fundus autofluorescence analysis by Region Finder semiautomated software provides accurate measurements of lesion area and allows us to quantify the progression of PA in high myopia. In our series, PA enlarged significantly over at least 12 months, and its progression seemed to be related to the lesion size at baseline.

Comparison of short-wavelength blue-light autofluorescence and conventional blue-light autofluorescence in geographic atrophy

BACKGROUND/AIMS

To systematically compare the intermodality and inter-reader agreement for two blue-light confocal fundus autofluorescence (FAF) systems.

METHODS

Thirty eyes (21 patients) with a diagnosis of geographic atrophy (GA) were enrolled. Eyes were imaged using two confocal blue-light FAF devices: (1) Spectralis device with a 488 nm excitation wavelength (488-FAF); (2) EIDON device with 450 nm excitation wavelength and the capability for 'colour' FAF imaging including both the individual red and green components of the emission spectrum. Furthermore, a third imaging modality (450-RF image) isolating and highlighting the red emission fluorescence component (REFC) was obtained and graded. Each image was graded by two readers to assess inter-reader variability and a single image for each modality was used to assess the intermodality variability.

RESULTS

The 95% coefficient of repeatability (1.35 mm2 for the 488-FAF-based grading, 8.13 mm2 for the 450-FAF-based grading and 1.08 mm2 for the 450-RF-based grading), the coefficient of variation (1.11 for 488-FAF, 2.05 for 450-FAF, 0.92 for 450-RF) and the intraclass correlation coefficient (0.994 for 488-FAF, 0.711 for 450-FAF, 0.997 for 450-RF) indicated that 450-FAF-based and 450-RF-based grading have the lowest and highest inter-reader agreements, respectively. The GA area was larger for 488-FAF images (median (IQR) 2.1 mm2 (0.8-6.4 mm2)) than for 450-FAF images (median (IQR) 1.0 mm2 (0.3-4.3 mm2); p<0.0001). There was no significant difference in lesion area measurement between 488-FAF-based and 450-RF-based grading (median (IQR) 2.6 mm2 (0.8-6.8 mm2); p=1.0).

CONCLUSION

The isolation of the REFC from the 450-FAF images allowed for a reproducible quantification of GA. This assessment had good comparability with that obtained with 488-FAF images.

Accuracy of fundus autofluorescence imaging for the diagnosis and monitoring of retinal conditions: a systematic review

BACKGROUND

Natural fluorescence in the eye may be increased or decreased by diseases that affect the retina. Imaging methods based on confocal scanning laser ophthalmoscopy (cSLO) can detect this 'fundus autofluorescence' (FAF) by illuminating the retina using a specific light 'excitation wavelength'. FAF imaging could assist the diagnosis or monitoring of retinal conditions. However, the accuracy of the method for diagnosis or monitoring is unclear.

OBJECTIVE

To conduct a systematic review to determine the accuracy of FAF imaging using cSLO for the diagnosis or monitoring of retinal conditions, including monitoring of response to therapy.

DATA SOURCES

Electronic bibliographic databases; scrutiny of reference lists of included studies and relevant systematic reviews; and searches of internet pages of relevant organisations, meetings and trial registries. Databases included MEDLINE, EMBASE, The Cochrane Library, Web of Science and the Medion database of diagnostic accuracy studies. Searches covered 1990 to November 2014 and were limited to the English language.

REVIEW METHODS

References were screened for relevance using prespecified inclusion criteria to capture a broad range of retinal conditions. Two reviewers assessed titles and abstracts independently. Full-text versions of relevant records were retrieved and screened by one reviewer and checked by a second. Data were extracted and critically appraised using the Quality Assessment of Diagnostic Accuracy Studies criteria (QUADAS) for assessing risk of bias in test accuracy studies by one reviewer and checked by a second. At all stages any reviewer disagreement was resolved through discussion or arbitration by a third reviewer.

RESULTS

Eight primary research studies have investigated the diagnostic accuracy of FAF imaging in retinal conditions: choroidal neovascularisation (one study), reticular pseudodrusen (three studies), cystoid macular oedema (two studies) and diabetic macular oedema (two studies). Sensitivity of FAF imaging using an excitation wavelength of 488 nm was generally high (range 81-100%), but was lower (55% and 32%) in two studies using longer excitation wavelengths (514 nm and 790 nm, respectively). Specificity ranged from 34% to 100%. However, owing to limitations of the data, none of the studies provide conclusive evidence of the diagnostic accuracy of FAF imaging.

LIMITATIONS

No studies on the accuracy of FAF imaging for monitoring the progression of retinal conditions or response to therapy were identified. Owing to study heterogeneity, pooling of diagnostic outcomes in meta-analysis was not conducted. All included studies had high risk of bias. In most studies the patient spectrum was not reflective of those who would present in clinical practice and no studies adequately reported how FAF images were interpreted.

CONCLUSIONS

Although already in use in clinical practice, it is unclear whether or not FAF imaging is accurate, and whether or not it is applied and interpreted consistently for the diagnosis and/or monitoring of retinal conditions. Well-designed prospective primary research studies, which conform to the paradigm of diagnostic test accuracy assessment, are required to investigate the accuracy of FAF imaging in diagnosis and monitoring of inherited retinal dystrophies, early age-related macular degeneration, geographic atrophy and central serous chorioretinopathy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014014997.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Fundus Autofluorescence in Age-related Macular Degeneration

: Fundus autofluorescence (FAF) provides detailed insight into the health of the retinal pigment epithelium (RPE). This is highly valuable in age-related macular degeneration (AMD) as RPE damage is a hallmark of the disease. The purpose of this paper is to critically appraise current clinical descriptions regarding the appearance of AMD using FAF and to integrate these findings into a chair-side reference. A wide variety of FAF patterns have been described in AMD, which is consistent with the clinical heterogeneity of the disease. In particular, FAF imaging in early to intermediate AMD has the capacity to reveal RPE alterations in areas that appear normal on funduscopy, which aids in the stratification of cases and may have visually significant prognostic implications. It can assist in differential diagnoses and also represents a reliable, sensitive method for distinguishing reticular pseudodrusen. FAF is especially valuable in the detection, evaluation, and monitoring of geographic atrophy and has been used as an endpoint in clinical trials. In neovascular AMD, FAF reveals distinct patterns of classic choroidal neovascularization noninvasively and may be especially useful for determining which eyes are likely to benefit from therapeutic intervention. FAF represents a rapid, effective, noninvasive imaging method that has been underutilized, and incorporation into the routine assessment of AMD cases should be considered. However, the practicing clinician should also be aware of the limitations of the modality, such as in the detection of foveal involvement and in the distinction of phenotypes (hypo-autofluorescent drusen from small areas of geographic atrophy).

Recent developments in age-related macular degeneration: a review

Background

Visual impairment in elderly people is a considerable health problem that significantly affects quality of life of millions worldwide. The magnitude of this issue is becoming more evident with an aging population and an increasing number of older individuals.

Objective

The objective of this article was to review the clinical and pathological aspects of age-related macular degeneration (AMD), diagnostic tools, and therapeutic modalities presently available or underway for both atrophic and wet forms of the disease.

Methods

An online review of the PubMed database was performed, searching for the key words. The search was limited to articles published since 1980 to date.

Results

Several risk factors have been linked to AMD, such as age (>60 years), lifestyle (smoking and diet), and family history. Although the pathogenesis of AMD remains unclear, genetic factors have been implicated in the condition. Treatment for atrophic AMD is mainly close observation, coupled with nutritional supplements such as zinc and antioxidants, whereas treatment of wet AMD is based on targeting choroidal neovascular membranes.

Conclusion

Identification of modifiable risk factors would improve the possibilities of preventing the progression of AMD. The role of anti-vascular endothelial growth factor (anti-VEGF) agents has transformed the therapeutic approach of the potentially blinding disease “wet AMD” into a more favorable outcome.

Quantitative Characteristics of Spectral-Domain Optical Coherence Tomography in Corresponding Areas of Increased Autofluorescence at the Margin of Geographic Atrophy in Patients With Age-Related Macular Degeneration

BACKGROUND AND OBJECTIVE

To evaluate the spectral-domain optical coherence tomography (SD-OCT) characteristics of the junctional zone corresponding to areas of increased autofluorescence (IAF) at the margin of geographic atrophy (GA) in patients with age-related macular degeneration (AMD).

PATIENTS AND METHODS

SD-OCT and fundus autofluorescence (FAF) images from untreated eyes with GA available from archived studies at Doheny Image Reading Center were evaluated. Areas of definite decreased autofluorescence (DDAF) corresponding to GA, and areas of IAF at the margins of the GA were manually segmented. Eyes with evidence of IAF were selected. Following manual registration of FAF and OCT data, areas of IAF and normal fluorescence were correlated with OCT features at these locations.

RESULTS

Thirty eyes were included. The mean retinal pigment epithelium (RPE) thickness in areas of IAF was 40.6 µm ± 7.69 µm, compared to 28.8 µm ± 7.09 µm in normal adjacent areas (P < .001).

CONCLUSION

Regions of IAF at the junctional zone of GA lesions appear to correspond to thickening of the presumed RPE band on OCT. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:523-527.].

VISUALIZING RETINAL PIGMENT EPITHELIUM PHENOTYPES IN THE TRANSITION TO GEOGRAPHIC ATROPHY IN AGE-RELATED MACULAR DEGENERATION

PURPOSE

To inform the interpretation of clinical optical coherence tomography and fundus autofluorescence imaging in geographic atrophy (GA) of age-related macular degeneration by determining the distribution of retinal pigment epithelium (RPE) phenotypes in the transition from health to atrophy in donor eyes.

METHODS

In RPE-Bruch membrane flat mounts of two GA eyes, the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histological sections of 13 GA eyes, RPE phenotypes were assessed at ±500 and ±100 μm from the descent of the external limiting membrane (ELM) toward Bruch membrane. The ELM descent was defined as curved, reflected, or oblique in shape. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE plus BLamD were measured.

RESULTS

A border of atrophy that can be precisely delimited is the ELM descent, as opposed to the termination of the RPE layer itself, because of dissociated RPE in the atrophic area. Approaching the ELM descent, the percentage of abnormal RPE morphologies increases, the percentage of age-normal cells decreases, overall RPE thickens, and BLamD does not thin. The combination of RPE plus BLamD is 19.7% thicker at -100 μm from the ELM descent than that at -500 μm (23.1 ± 10.7 μm vs. 19.3 ± 8.2 μm; P = 0.05).

CONCLUSION

The distribution of RPE phenotypes at the GA transition supports the idea that these morphologies represent defined stages of a degeneration sequence. The idea that RPE dysmorphia including rounding and stacking helps explain variable autofluorescence patterns in GA is supported. The ELM descent and RPE plus BLamD thickness profile may have utility as spectral domain optical coherence tomography metrics in clinical trials.

Fundus autofluorescence applications in retinal imaging

Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications.

Confocal scanning laser ophthalmoscopy versus modified conventional fundus camera for fundus autofluorescence

INTRODUCTION

Fundus autofluorescence (FAF) is a noninvasive imaging method to detect fundus endogenous fluorophores, mainly lipofuscin located in the retinal pigment epithelium (RPE). The FAF provides information about lipofuscin distribution and RPE health, and consequently an increased accumulation of lipofuscin has been correlated with ageing and development of certain retinal conditions. Areas covered: An exhaustive literature search in MEDLINE (via OVID) and PUBMED for articles related to ocular FAF in retinal diseases and different devices used for acquiring FAF imaging was conducted. Expert commentary: This review aims to show an overview about autofluorescence in the RPE and the main devices used for acquiring these FAF images. The knowledge of differences in the optical principles, acquisition images and the image post-processing between confocal scanning laser ophthalmoscopy and modified conventional fundus camera will improve the FAF images interpretation when are used as a complementary diagnosis and monitoring tool of retinal diseases.

Semiautomatic Segmentation of Rim Area Focal Hyperautofluorescence Predicts Progression of Geographic Atrophy Due to Dry Age-Related Macular Degeneration

Purpose

To develop image analysis software usable by nonexpert graders to segment geographic atrophy (GA) from dry AMD and to quantify rim area focal hyperautofluorescence (RAFH) surrounding GA on fundus autofluorescence (FAF) images. To compare the GA progression predictions based on RAFH with those of a validated qualitative classification system.

Methods

Retrospective analysis of serial FAF images from 49 eyes of 30 subjects with GA was performed using MATLAB-based software (MathWorks, Natick, MA, USA). Correlation between RAFH and progression of GA was analyzed using Spearman correlation. Comparisons of lesion growth rate between RAFH tertiles used generalized estimating equations and Kruskal-Wallis testing. Interobserver variability in lesion size, growth rate and RAFH were compared between two expert and one nonexpert grader using Bland-Altman statistics.

Results

Rim area focal hyperautofluorescence was positively correlated with GA progression rate (ρ = 0.49, P < 0.001). Subjects in the middle or highest RAFH tertile were at greater risk of progression (P = 0.005 and P = 0.001, respectively). Mean difference in RAFH was 0.012 between expert and −0.005 to 0.017 between expert and nonexperts. Mean difference in lesion size (mm²) was 0.11 between expert and −0.29 to 0.41 between expert and nonexperts. Mean difference in lesion growth rate (mm²/mo) was 0.0098 between expert and −0.027 to 0.037 between expert and nonexperts. Risk stratification based on RAFH tertile was 96% identical across all graders.

Conclusions

Our semiautomated image analysis software facilitates stratification of progression risk based on RAFH and enabled a nonexpert grader with minimal training to obtain results comparable to expert graders. Predictions based on RAFH were similar to those of a validated qualitative classification system.

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.

Natural History of Geographic Atrophy Progression Secondary to Age-Related Macular Degeneration (Geographic Atrophy Progression Study)

PURPOSE

The Geographic Atrophy Progression (GAP) study was designed to assess the rate of geographic atrophy (GA) progression and to identify prognostic factors by measuring the enlargement of the atrophic lesions using fundus autofluorescence (FAF) and color fundus photography (CFP).

DESIGN

Prospective, multicenter, noninterventional natural history study.

PARTICIPANTS

A total of 603 participants were enrolled in the study; 413 of those had gradable lesion data from FAF or CFP, and 321 had gradable lesion data from both FAF and CFP.

METHODS

Atrophic lesion areas were measured by FAF and CFP to assess lesion progression over time. Lesion size assessments and best-corrected visual acuity (BCVA) were conducted at screening/baseline (day 0) and at 3 follow-up visits: month 6, month 12, and month 18 (or early exit).

MAIN OUTCOME MEASURES

The GA lesion progression rate in disease subgroups and mean change from baseline visual acuity.

RESULTS

Mean (standard error) lesion size changes from baseline, determined by FAF and CFP, respectively, were 0.88 (0.1) and 0.78 (0.1) mm(2) at 6 months, 1.85 (0.1) and 1.57 (0.1) mm(2) at 12 months, and 3.14 (0.4) and 3.17 (0.5) mm(2) at 18 months. The mean change in lesion size from baseline to month 12 was significantly greater in participants who had eyes with multifocal atrophic spots compared with those with unifocal spots (P < 0.001) and those with extrafoveal lesions compared with those with foveal lesions (P = 0.001). The mean (standard deviation) decrease in visual acuity was 6.2 ± 15.6 letters for patients with image data available. Atrophic lesions with a diffuse (mean 0.95 mm(2)) or banded (mean 1.01 mm(2)) FAF pattern grew more rapidly by month 6 compared with those with the "none" (mean, 0.13 mm(2)) and focal (mean, 0.36 mm(2)) FAF patterns.

CONCLUSIONS

Although differences were observed in mean lesion size measurements using FAF imaging compared with CFP, the measurements were highly correlated with one another. Significant differences were found in lesion progression rates in participants stratified by hyperfluorescence pattern subtype. This large GA natural history study provides a strong foundation for future clinical trials.

Investigating the choriocapillaris and choroidal vasculature with new optical coherence tomography technologies

The body of knowledge of in vivo investigation of the choroid has been markedly enhanced by recent technological advances in optical coherence tomography (OCT). New insights elucidating the morphological features of the choriocapillaris and choroidal vasculature, in both physiological and pathological conditions, indicate that the choroid plays a pivotal role in many posterior segment diseases. In this article, a review of the histological characteristics of the choroid, which must be considered for the proper interpretation of in vivo imaging, is followed by a comprehensive discussion of fundamental principles of the current state-of-the-art in OCT, including cross-sectional OCT, en face OCT, and OCT angiography using both spectral domain OCT and swept source OCT technologies. A detailed review of the tomographic features of the choroid in the normal eye is followed by relevant findings in prevalent chorioretinal diseases, focusing on major causes of vision loss such as typical early and advanced age-related macular degeneration, polypoidal choroidal vasculopathy, central serous chorioretinopathy, pachychoroid spectrum disorders, diabetic choroidopathy, and myopia.

Retinal Pigment Epithelium Tears: Risk Factors, Mechanism and Therapeutic Monitoring

Tears of the retinal pigment epithelium (RPE) are most commonly associated with vascularised RPE detachment due to age-related macular degeneration (AMD), and they usually involve a deleterious loss in visual acuity. Recent studies suggest an increase in RPE tear incidences since the introduction of anti-vascular endothelial growth factor (anti-VEGF) therapies as well as a temporal association between the tear event and the intravitreal injection. As the number of AMD patients and the number of administered anti-VEGF injections increase, both the challenge of RPE tear prevention and the treatment after RPE tear formation have become more important. At the same time, the evolution of retinal imaging has significantly contributed to a better understanding of RPE tear development in recent years. This review summarises the current knowledge on RPE tear development, predictive factors, and treatment strategies before and after RPE tear formation.

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.

Modeling of in vivo acousto-optic two-photon imaging of the retina in the human eye

Our aim is to establish a novel combined acousto-optical method for in vivo imaging of the human retina with the two-photon microscope. In this paper we present modeling results based on eye model samples constructed with parameters measured on patients. We used effectively the potential of the electronic compensation offered by the acousto-optic lenses to avoid the use of adaptive optical correction. Simulation predicted lateral resolution between 1.6 µm and 3 µm on the retina. This technology allows the visualization of single cells and promises real time measuring of neural activity in individual neurons, neural segments and cell assemblies with 30-100 µs temporal and subcellular spatial resolution.

Fundus Autofluorescence and RPE Lipofuscin in Age-Related Macular Degeneration

Genes that increase susceptibility to age-related macular degeneration (AMD) have been identified; however, since many individuals carrying these risk alleles do not develop disease, other contributors are involved. One additional factor, long implicated in the pathogenesis of AMD, is the lipofuscin of retinal pigment epithelium (RPE). The fluorophores that constitute RPE lipofuscin also serve as a source of autofluorescence (AF) that can be imaged by confocal laser ophthalmoscopy. The AF originating from lipofuscin is excited by the delivery of short wavelength (SW) light. A second autofluorescence is emitted from the melanin of RPE (and choroid) upon near-infrared (NIR-AF) excitation. SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized. Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility. To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

Effect of photodynamic therapy on short-wavelength fundus autofluorescence in eyes with acute central serous chorioretinopathy

PURPOSE

To evaluate short-wavelength FAF as a parameter of retinal pigment epithelium function in eyes with acute symptomatic central serous chorioretinopathy after indocyanine green angiography-guided verteporfin photodynamic therapy with half-fluence rate.

METHODS

A retrospective review over a period of 1 year of short-wavelength FAF images of 15 consecutive patients treated with half-fluence rate (25 J/cm) indocyanine green angiography-guided verteporfin photodynamic therapy due to acute symptomatic central serous chorioretinopathy was performed. Short-wavelength (488 nm) FAF gray values were evaluated with a confocal scanning laser ophthalmoscope at a 350-μm diameter and a 1,200-μm diameter circle centered on the fovea. The change in short-wavelength (488 nm) FAF gray values for the 2 circles was evaluated by calculating the differences of respective values between the first month after treatment and the 3, 6, 9, and 12 months follow-up.

RESULTS

Mean differences (95% confidence interval) in short-wavelength (488 nm) FAF gray values of the 350-μm and 1,200-μm diameter circle between the 1-month and the 3-month (n = 15) follow-up were -0.03 (-0.11 to 0.05) (P = 0.46) and -0.03 (-0.17 to 0.10) (P = 0.6). Respective differences between the 1 month and the 6 (n = 15), 9 (n = 14), and 12 months (n = 13) of follow-up were -0.03 (-0.11 to 0.05) (P = 0.42) and -0.04 (-0.16 to 0.08) (P = 0.5); -0.05 (-0.12 to 0.03) (P = 0.23) and -0.06 (-0.18 to 0.07) (P = 0.33); -0.03 (-0.12 to 0.07) (P = 0.57) and -0.07 (-0.20 to 0.05) (P = 0.22).

CONCLUSION

Half-fluence rate (25 J/cm) indocyanine green angiography-guided verteporfin photodynamic therapy did not significantly affect short-wavelength FAF at a 350-μm diameter and a 1,200-μm diameter circle in eyes with resolved acute symptomatic central serous chorioretinopathy throughout 12 months of follow-up.

Significance of the hyperautofluorescent ring associated with choroidal neovascularisation in eyes undergoing anti-VEGF therapy for wet age-related macular degeneration

AIM

To characterise the presence of a hyperautofluorescent (HAF) ring associated with choroidal neovascularisation (CNV) complex in patients with wet age-related macular degeneration (AMD).

METHODS

Fundus autofluorescence images and spectral-domain optical coherence tomography (OCT) scans from 362 eyes with wet AMD were reviewed. The presence and size of an HAF ring associated with the CNV complex was evaluated. A subgroup of 64 treatment-naive eyes with new-onset CNV was studied to analyse the relationship between pretreatment OCT characteristics and the presence of the HAF ring.

RESULTS

An HAF ring was present in 38% of the entire cohort of eyes and in 39% of treatment-naive eyes. The presence of the HAF ring was significantly correlated with the extent of baseline subretinal fluid (SRF) on OCT (p=0.0113), the number of antivascular endothelial growth factor (VEGF) injections (p=0.0439) and the number of treatment cycles (p=0.0154). Eyes with an HAF ring were more likely to have disruption of the ellipsoid zone line once the SRF was resolved compared with eyes without an HAF ring (p=0.0002). In multivariate analysis, the best predictors for HAF ring were the baseline area of SRF (p=0.0449) and the number of anti-VEGF treatments received (p=0.0568).

CONCLUSIONS

Nearly 40% of wet AMD eyes had an HAF ring. In treatment-naive eyes, the HAF ring had a significant association with SRF and was found as early as the baseline measurement and as long as 18 months after beginning treatment, persisting for up to 6 years after the initial diagnosis. Its association with baseline SRF and disruption of the ellipsoid zone line of the photoreceptors on OCT could indicate continuous stress on the outer retinal structures after exposure to prolonged SRF and/or transmitted autofluorescence from loss of the photoreceptors overlying the retinal pigment epithelium.

A longitudinal comparison of spectral-domain optical coherence tomography and fundus autofluorescence in geographic atrophy

PURPOSE

To identify reliable criteria based on spectral-domain optical coherence tomography (SD OCT) to monitor disease progression in geographic atrophy attributable to age-related macular degeneration (AMD) compared with lesion size determination based on fundus autofluorescence (FAF).

DESIGN

Prospective longitudinal observational study.

METHODS

setting: Institutional. study population: A total of 48 eyes in 24 patients with geographic atrophy. observation procedures: Eyes with geographic atrophy were included and examined at baseline and at months 3, 6, 9, and 12. At each study visit best-corrected visual acuity (BCVA), FAF, and SD OCT imaging were performed. FAF images were analyzed using the region overlay device. Planimetric measurements in SD OCT, including alterations or loss of outer retinal layers and the RPE, as well as choroidal signal enhancement, were performed with the OCT Toolkit. main outcome measures: Areas of interest in patients with geographic atrophy measured from baseline to month 12 by SD OCT compared with the area of atrophy measured by FAF.

RESULTS

Geographic atrophy lesion size increased from 8.88 mm² to 11.22 mm² based on quantitative FAF evaluation. Linear regression analysis demonstrated that results similar to FAF planimetry for determining lesion progression can be obtained by measuring the areas of outer plexiform layer thinning (adjusted R(2) = 0.93), external limiting membrane loss (adjusted R(2) = 0.89), or choroidal signal enhancement (R(2) = 0.93) by SD OCT.

CONCLUSIONS

SD OCT allows morphologic markers of disease progression to be identified in geographic atrophy and may improve understanding of the pathophysiology of atrophic AMD.

Clinical applications of age-related macular degeneration genetics

Understanding genetic causes of age-related macular degeneration (AMD) will eventually yield effective discoveries and improvements in predictive/prognostic methods. These include, but are not limited to, reliable disease prediction (screening for increased discrimination of clinical risk), differential classification of AMD subtypes with biomarkers (development of risk-linked molecular taxonomies), selection of optimal preventive and therapeutic interventions (guided by a biologically meaningful understanding of treatment response), and drug dosing. In this review, we discuss clinical applications informed by key findings in AMD genetics, and provide commentary on leveraging extant and forthcoming evidence to improve AMD risk prediction, AMD classification, and knowledge on the genetic basis of drug activity and toxicity. Advances in translating AMD genetics findings for AMD risk prediction require development of a genetics-based causality for AMD incidence and progression. Molecular subtyping of AMD phenotypes requires a set of dynamic biomarkers presenting prognostic value; although these have yet to be identified, the formation of multidisciplinary teams and their participation in large-scale consortia may yield promising results. Drugs targeting complement and vascular endothelial growth factor (VEGF) systems are under evaluation, and forthcoming work on rare variants and noncoding DNA in AMD pathogenesis will likely reveal biochemical pathways enriched with AMD-associated genetic variants. Pharmacologic targets in these pathways may inform a rational and effective therapeutic approach to preventing and treating this sight-threatening disease.

Geographic atrophy progression in eyes with age-related macular degeneration: role of fundus autofluorescence patterns, fellow eye and baseline atrophy area

BACKGROUND/OBJECTIVE

To evaluate if fundus autofluorescence (FAF) patterns around geographic atrophy (GA) and the status of the fellow eye have an impact on GA progression.

METHODS

We included 54 eyes of 35 patients with GA. Areas of GA were quantified by RegionFinder software.

RESULTS

GA progression rates in eyes with a diffuse trickling pattern (median 1.42 mm(2)/year) were significantly higher than in normal eyes (median 0.22 mm(2)/year) and eyes with other diffuse FAF patterns (median 0.46 mm(2)/year). Eyes with a banded pattern had a significantly higher progression rate (median 0.81 mm(2)/year) than those without any FAF abnormalities (p = 0.038). The group with baseline total atrophy of the eyes <1 disk area (DA; median 0.42 mm(2)) had an inverse relation with GA progression compared to the groups with baseline atrophy >1 DA (p < 0.05).

CONCLUSION

Diffuse trickling and banded patterns may have an impact on GA progression and may serve as prognostic factors.

Fundus autofluorescence imaging: Fundamentals and clinical relevance

Fundus autofluorescence (FAF), a relatively new imaging modality, focuses on the fluorescent properties of pigments in the retina to generate images that help us view various disease processes from a different perspective. It aids us in the understanding of the pathophysiology of different retinal disorders. Recently, FAF imaging is being used commonly to help us in the diagnosis, prognosis as well as in determining the treatment response of various retinal disorders. It generates an image based on the distribution pattern of a fluorescent pigment called lipofuscin. Knowing the distribution pattern of lipofuscin in the normal retina is key to understanding an FAF image representing a retinal pathology. Like most other imaging modalities, FAF comes with its own limitations, taking steps to overcome these limitations will be of utmost importance in using this imaging modality to its fullest potential.

Multiple A2E treatments lead to melanization of rod outer segment-challenged ARPE-19 cells

PURPOSE

Daily phagocytosis of outer segments (OSs) and retinoid recycling by the RPE lead to the accumulation of storage bodies in the RPE containing autofluorescent lipofuscin, which consists of lipids and bisretinoids such as A2E and its oxidation products. Accumulation of A2E and its oxidation products is implicated in the pathogenesis of several retinal degenerative diseases. However, A2E accumulates in the RPE during normal aging. In this study, we used a cell model to determine the homeostatic mechanisms of RPE cells in response to A2E accumulation.

METHODS

To distinguish between pathologic and normal responses of the RPE to A2E accumulation, we treated established ARPE-19 cells (cultured for 3 weeks after reaching confluence) with low micromolar amounts of A2E for several weeks. We compared the lysosomal function, lysosomal pH, degree of OS digestion, and melanization of the treated cells to untreated control cells in response to a challenge of purified rod OSs (ROSs). A2E was analyzed with high-performance liquid chromatography (HPLC); and A2E and melanin were identified with mass spectrometry.

RESULTS

We found that post-confluent ARPE-19 cells took up and accumulated A2E under dim light conditions. Spectral analysis of the HPLC separations and mass spectrometry showed that A2E-fed cells contained A2E and oxidized A2E (furan-A2E). A2E accumulation led to a modest increase (up to 0.25 unit) in lysosomal pH in these cells. The specific activity of cathepsin D and lysosomal acid phosphatase was reduced in the A2E-treated cells, but ROS degradation was not impaired. We found that, upon challenge with ROSs, melanin pigment was induced in the lysosomal fraction of the A2E-treated ARPE-19 cells. Thus, the ARPE-19 cells responded to the A2E treatment and ROS challenge by producing a melanin-containing lysosome fraction. We speculate that this prevents them from becoming impaired in OS processing.

CONCLUSIONS

We used a modified ARPE-19 cell model in which melanization was elicited as a response to chronic accumulation of A2E. We found that although A2E treatment led, as has been previously reported, to modest lysosomal alkalinization and lysosomal impairment of ARPE-19 cells, a potential homeostatic mechanism may involve production of a special type of lysosomes containing melanin.