SUBRETINAL DRUSENOID DEPOSIT IN AGE-RELATED MACULAR DEGENERATION: Histologic Insights Into Initiation, Progression to Atrophy, and Imaging

Reticular pseudodrusen: A critical phenotype in age-related macular degeneration

Reticular pseudodrusen (RPD), or subretinal drusenoid deposits (SDD), refer to distinct lesions that occur in the subretinal space. Over the past three decades, their presence in association with age-related macular degeneration (AMD) has become increasingly recognized, especially as RPD have become more easily distinguished with newer clinical imaging modalities. There is also an increasing appreciation that RPD appear to be a critical AMD phenotype, where understanding their pathogenesis will provide further insights into the processes driving vision loss in AMD. However, key barriers to understanding the current evidence related to the independent impact of RPD include the heterogeneity in defining their presence, and failure to account for the confounding impact of the concurrent presence and severity of AMD pathology. This review thus critically discusses the current evidence on the prevalence and clinical significance of RPD and proposes a clinical imaging definition of RPD that will help move the field forward in gathering further key knowledge about this critical phenotype. It also proposes a putative mechanism for RPD formation and how they may drive progression to vision loss in AMD, through examining current evidence and presenting novel findings from preclinical and clinical studies.

Retinal and Choroidal Pathologies in Aged BALB/c Mice Following Systemic Neonatal Murine Cytomegalovirus Infection

Although pathologies associated with acute virus infections have been extensively studied, the effects of long-term latent virus infections are less well understood. Human cytomegalovirus, which infects 50% to 80% of humans, is usually acquired during early life and persists in a latent state for the lifetime. The purpose of this study was to determine whether systemic murine cytomegalovirus (MCMV) infection acquired early in life disseminates to and becomes latent in the eye and if ocular MCMV can trigger in situ inflammation and occurrence of ocular pathology. This study found that neonatal infection of BALB/c mice with MCMV resulted in dissemination of virus to the eye, where it localized principally to choroidal endothelia and pericytes and less frequently to the retinal pigment epithelium (RPE) cells. MCMV underwent ocular latency, which was associated with expression of multiple virus genes and from which MCMV could be reactivated by immunosuppression. Latent ocular infection was associated with significant up-regulation of several inflammatory/angiogenic factors. Retinal and choroidal pathologies developed in a progressive manner, with deposits appearing at both basal and apical aspects of the RPE, RPE/choroidal atrophy, photoreceptor degeneration, and neovascularization. The pathologies induced by long-term ocular MCMV latency share features of previously described human ocular diseases, such as age-related macular degeneration.

Longitudinal choriocapillaris changes in the presence of reticular pseudodrusen

To determine longitudinal changes in choriocapillaris (CC) measures in eyes with reticular pseudodrusen (RPD) using optical coherence tomography angiography (OCTA). In this observational prospective study, 20 patients with exclusively RPD and no other alteration due to age-related macular degeneration were included. Eight RPD patients were re-examined at 5-year follow-up. Multimodal imaging was performed at baseline and at 5-year follow-up. OCTA CC images were analyzed for number, size and total area of flow deficits (FD), mean signal intensity, signal intensity standard deviation and kurtosis of signal intensity distribution in the ring area between a circle of 4 mm diameter and a circle of 6 mm diameter and in the superior ring quadrant. Area affected by RPD increased from 19.36 ± 8.39 mm² at baseline to 37.77 ± 9.03 mm² at 5-year follow-up. At baseline, percent of CC FD area was greater in RPD eyes (quadrant: p < 0.001; ring: p < 0.001) compared to controls. Besides, RPD eyes revealed a lower mean intensity signal (quadrant: p < 0.001; ring: p < 0.001). Evaluation of CC parameters suggested significant group × time interaction effects for CC FD (p = 0.04) and mean intensity signal (p = 0.004), in that RPD eyes presented increased CC FD and decreased mean intensity signal at follow-up. OCTA CC decorrelation signal further decreases in RPD patients over 5 years in both RPD-affected and RPD-unaffected macular areas.

Long-term retinal changes in progressive geographic atrophy

BACKGROUND

Age-related macular degeneration (AMD) is one of the leading causes of blindness with loss of retinal layers over long term. We aim to evaluate these changes in eyes with progressive non-exudative AMD with geographic atrophy (GA).

METHODS

This retrospective study included patients with GA with a minimum of 4 years follow up. Retinal layers on spectral domain optical coherence tomography (SD-OCT) were segmented based on their reflectivity patterns using validated semi-automated segmentation algorithm. The thickness of the segmented retinal layers was measured. Horizontal length of GA at baseline and last follow-up were also measured. Regression analysis was performed to correlate changes in RPE layer thickness with other retinal layers and the length of GA on OCT.

RESULTS

A total of 351-line scans including 17 foveal scans showing presence of GA at final visit that is, a total of 2457 retinal layer bands were analyzed. Outer nuclear layer (ONL) (p = 0.02), outer segment layers (OSL) (p = 0.01), and retinal pigment epithelium (RPE) (p = 0.01) showed a statistically significant variation between baseline and final visit. Regression analysis showed the change in ONL (r = 0.72; p = 0.01) and OSL (r = 0.93, p < 0.01) correlated significantly with change in RPE thickness whereas rest of the layers failed to show significant correlation.

CONCLUSION

Outer retinal layers (ONL and OSL) show more significant and widespread changes in retinal thickness and correlated most significantly with RPE thickness changes in eyes with GA due to AMD. Assessment of various retinal layer bands can be used as surrogate quantitative parameters to study eyes with GA.

Age-Related Retinal Changes in Wild-Type C57BL/6J Mice Between 2 and 32 Months

Purpose

The purpose of this study was to extend our understanding of how aging affects normal retina function and morphology in wild-type C57BL/6J mice, by analyzing electrophysiological recordings and in vivo and post mortem anatomy.

Methods

Electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT), and confocal scanning laser ophthalmoscope (cSLO) in vivo images were obtained from mice between the ages of 2 and 32 months in four groups: group 1 (<0.5 years), group 2 (1.0-1.5 years), group 3 (1.5-2.0 years), and group 4 (>2.0 years). Afterward, mouse bodies and eyes were weighed. Eyes were stained with hematoxylin and eosin (H&E) and cell nuclei were quantified.

Results

With aging, mice showed a significant reduction in both a- and b-wave ERG amplitudes in scotopic and photopic conditions. Additionally, total retina and outer nuclear layer (ONL) thickness, as measured by SD-OCT images, were significantly reduced in older groups. The cSLO images showed an increase in auto-fluorescence at the photoreceptor-RPE interface as age increases. H&E cell nuclei quantification showed significant reduction in the ONL in older ages, but no differences in the inner nuclear layer (INL) or ganglion cell layer (GCL).

Conclusions

By using multiple age groups and extending the upper age limit of our animals to approximately 2.65 years (P970), we found that natural aging causes negative effects on retinal function and morphology in a gradual, rather than abrupt, process. Future studies should investigate the exact mechanisms that contribute to these gradual declines in order to discover pathways that could potentially serve as therapeutic targets.

Human RGR Gene and Associated Features of Age-Related Macular Degeneration in Models of Retina-Choriocapillaris Atrophy

Age-related macular degeneration (AMD) is a progressive eye disease and the most common cause of blindness among the elderly. AMD is characterized by early atrophy of the choriocapillaris and retinal pigment epithelium (RPE). Although AMD is a multifactorial disease with many environmental and genetic risk factors, a hallmark of the disease is the origination of extracellular deposits, or drusen, between the RPE and Bruch membrane. Human retinal G-protein-coupled receptor (RGR) gene generates an exon-skipping splice variant of RGR-opsin (RGR-d; NP_001012740) that is a persistent component of small and large drusen. Herein, the findings show that abnormal RGR proteins, including RGR-d, are pathogenic in an animal retina with degeneration of the choriocapillaris, RPE, and photoreceptors. A frameshift truncating mutation resulted in severe retinal degeneration with a continuous band of basal deposits along the Bruch membrane. RGR-d produced less severe disease with choriocapillaris and RPE atrophy, including focal accumulation of abnormal RGR-d protein at the basal boundary of the RPE. Degeneration of the choriocapillaris was marked by a decrease in endothelial CD31 protein and choriocapillaris breakdown at the ultrastructural level. Fundus lesions with patchy depigmentation were characteristic of old RGR-d mice. RGR-d was mislocalized in cultured cells and caused a strong cell growth defect. These results uphold the notion of a potential hidden link between AMD and a high-frequency RGR allele.

Measuring the Contributions of Basal Laminar Deposit and Bruch's Membrane in Age-Related Macular Degeneration

Purpose

Basal laminar deposit (BLamD) is a consistent finding in age-related macular degeneration (AMD). We quantified BLamD thickness, appearance, and topography in eyes of aged donors with and without AMD and evaluated its relationship to other components of the retinal pigment epithelium-basal lamina/Bruch's membrane (RPE-BL-BrM) complex.

Methods

Donor eyes (n = 132) were classified as normal (n = 54), early to intermediate AMD (n = 24), geographic atrophy (GA; n = 13), and neovascular AMD (NV; n = 41). In high-resolution histology, we assessed RPE, BLamD, and BrM thicknesses and phenotypes at 3309 predefined locations in the central (foveal and perifovea) and superior (perifoveal) sections. Pre-mortem optical coherence tomography (OCT) imaging of a 90-year-old woman was compared to postmortem histopathology.

Results

In non-atrophic areas of AMD eyes, the RPE-BLamD is thick (normal = 13.7 µm, early-intermediate = 16.8 µm, GA = 17.4 µm, NV = 18.7 µm), because the BLamD is thick (normal = 0.3 µm, early-intermediate = 5.5 µm, GA = 4.1 µm, NV = 5.3 µm). RPE layer thickness is similar across these stages. Disease-associated variants of BLamD (thick, late, basal mounds) cluster subfoveally. A thick BLamD is visible on OCT as a hyporeflective split in the RPE-BL-BrM complex. BrM is thin (3.5 µm) in NV (normal = 4.2 µm, early to intermediate = 4.4 µm, and GA = 4.2 µm).

Conclusions

The RPE-BL-BrM complex is thick in AMD, driven by the accumulation and expansion of BLamD rather than expansion of either three-layer BrM, RPE-BL, or RPE. BLamD is clinically appreciable by OCT in some patients as a non-neovascular "split RPE-BL-BrM complex" or "double-layer sign." BLamD may contribute toward the formation and progression of high-risk drusen yet also exhibit protective properties.

Age-Related Macular Degeneration Revisited: From Pathology and Cellular Stress to Potential Therapies

Age-related macular degeneration (AMD) is a neurodegenerative disease of the aging retina, in which patients experience severe vision loss. Therapies available to patients are limited and are only effective in a sub-population of patients. Future comprehensive clinical care depends on identifying new therapeutic targets and adopting a multi-therapeutic approach. With this goal in mind, this review examines the fundamental concepts underlying the development and progression of AMD and re-evaluates the pathogenic pathways associated with the disease, focusing on the impact of injury at the cellular level, with the understanding that critical assessment of the literature may help pave the way to identifying disease-relevant targets. During this process, we elaborate on responses of AMD vulnerable cells, including photoreceptors, retinal pigment epithelial cells, microglia, and choroidal endothelial cells, based on in vitro and in vivo studies, to select stressful agents, and discuss current therapeutic developments in the field, targeting different aspects of AMD pathobiology.

Geographic Atrophy: Confocal Scanning Laser Ophthalmoscopy, Histology, and Inflammation in the Region of Expanding Lesions

Purpose

To describe the pathology of AMD in eyes with geographic atrophy (GA) using confocal scanning laser ophthalmoscopy (SLO) blue light autofluorescence (BAF), and near-infrared (IR) AF and to correlate it with the histology and immunohistochemistry analysis at the margins of the GA lesion.

Methods

Enucleated, fixed eyes from seventeen donors with GA were imaged and analyzed by BAF-SLO, IRAF-SLO, and by fundus macroscopy (FM). Tissue from the margins of the GA lesions was cut and processed for resin embedding and histology or cryosectioning and fluorescence in the green and far-red channels, and immunohistochemistry to assess markers of inflammation. Isolated DNA from donors was genotyped for single nucleotide polymorphisms (SNPs) previously shown to be risk factors for the development and progression of AMD.

Results

Around the leading edge of the GA lesions we observed hypertrophic RPE cells with cytoplasm filled with granules fluorescent both in the far-red and green-red channels; abundant microglia and macrophage; deposition of complement factor H (CFH) in Bruch's membrane (BM) and increased membrane attack complex (MAC) on RPE cells.

Conclusions

Fluorescence imaging of cryosections of RPE cells around the leading edge of the GA lesions suggest that IRAF-SLO visualizes mostly melanin-related compounds. In addition, medium-size GA atrophy displayed the most significant changes in inflammation markers.

Biometrics, Impact, and Significance of Basal Linear Deposit and Subretinal Drusenoid Deposit in Age-Related Macular Degeneration

Purpose

Basal linear deposit (BLinD) is a thin layer of soft drusen material. To elucidate the biology of extracellular deposits conferring age-related macular degeneration (AMD) progression risk and inform multimodal clinical imaging based on optical coherence tomography (OCT), we examined lipid content and regional prevalence of BLinD, soft drusen, pre-BLinD, and subretinal drusenoid deposit (SDD) in AMD and non-AMD aged eyes. We estimated BLinD volume and illustrated its relation to type 1 macular neovascularization (MNV).

Methods

Donor eyes were classified as early to intermediate AMD (n = 25) and age-matched controls (n = 54). In high-resolution histology, we assessed BLinD/soft drusen thickness at 836 and 1716 locations in AMD and control eyes, respectively. BLinD volume was estimated using solid geometry in donor eyes, one clinically characterized.

Results

BLinD, drusen, type 1 MNV, and fluid occupy the sub-RPE-basal laminar space. BLinD volume in a 3-mm diameter circle may be as much as 0.0315 mm3. Osmophilic lipid was more concentrated in BLinD/drusen than SDD. In the fovea, BLinD/drusen was prevalent in AMD eyes; pre-BLinD was prevalent in control eyes. SDD was low in the fovea and high in perifovea, especially in AMD eyes.

Conclusions

Although invisible, BLinD may presage type 1 MNV. BLinD volume approaches the criterion OCT drusen volume of 0.03 mm3 for AMD progression risk. BLinD culminates years of subfoveal lipid accumulation. SDD is detected relatively late in life, with currently unknown precursors. Deposit topography suggests one outer retinal lipid recycling system serving specialized cone and rod physiology, and its dysregulation in AMD is due to impaired transfer to the circulation.

Longitudinal Analysis of Structural and Functional Changes in Presence of Reticular Pseudodrusen Associated With Age-Related Macular Degeneration

Purpose

To examine longitudinal changes of retinal thickness and retinal sensitivity in patients with intermediate age-related macular degeneration (iAMD) and predominantly reticular pseudodrusen (RPD).

Methods

At baseline 30 eyes of 25 iAMD patients underwent optical coherence tomography imaging, mesopic and scotopic fundus-controlled perimetry (FCP) with follow-up examinations at month 12 (20 eyes), 24 (12 eyes), and 36 (11 eyes). Thicknesses of different retinal layers and results of FCP testing (n = 56 stimuli) were spatially and longitudinally analyzed using linear mixed-effects models.

Results

At baseline, the thickness of the partial outer retinal layer (pORL, 70.21 vs. 77.47 µm) and both mesopic (16.60 vs. 18.72 dB) and scotopic (12.14 vs. 18.67 dB) retinal sensitivity were decreased in areas with RPD compared with unremarkable areas (P < 0.001). Over three years, mean change of pORL was −0.66 normative standard deviation (SD; i.e., z-score, P < 0.001) for regions with existing RPD, −0.40 SD (P < 0.001) for regions with new occurring RPD, and −0.17 SD (P = 0.041) in unremarkable regions. Decrease of scotopic and mesopic sensitivity over three years was more pronounced in areas with existing (−3.51 and −7.76 dB) and new occurring RPD (−2.06 and −5.97 dB). Structure-function analysis revealed that 1 SD decrease of pORL thickness was associated with a sensitivity reduction of 3.47 dB in scotopic and 0.79 dB in mesopic testing.

Conclusions

This study demonstrates progressive outer retinal degeneration and impairment of photoreceptor function in eyes with iAMD and RPD over three years. Preservation of outer retinal thickness and reduction of RPD formation may constitute meaningful surrogate endpoints in interventional trials on eyes with AMD and RPD aiming to slow outer retinal degeneration.

Association of plasma trace element levels with neovascular age-related macular degeneration

Although the triggers causing angiogenesis in the context of neovascular age-related macular degeneration (nAMD) are not fully understood, oxidative stress is likely involved. Oxidative stress in the eye can occur through exposure of macular tissues to sunlight and local or systemic exposure to oxidative stressors associated with environmental or lifestyle factors. Because trace elements have been implicated as regulators of oxidative stress and cellular antioxidant defense mechanisms, we hypothesized that they may play a role as a risk factor, modifying the progression toward nAMD. Herein, we determined whether levels of human plasma trace elements are different in 236 individuals with nAMD compared to 236 age-matched controls without AMD. Plasma levels of 16 trace elements including arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, lead, antimony, selenium, vanadium and zinc were measured using inductively coupled plasma mass spectrometry. Associations of trace elements with demographic, environmental and lifestyle factors and AMD-associated genetic variants were assessed. Elevated levels of barium and cadmium and reduced levels of chromium were observed in nAMD patients compared to controls. Mean plasma concentrations of barium were 1.35 μg/L (standard deviation [SD] 0.71) in nAMD and 1.15 μg/L (SD 0.63) in controls (P = 0.001). Mean levels of chromium were 0.37 μg/L (SD 0.22) in nAMD and 0.46 μg/L (SD 0.34) in controls (P = 0.001). Median levels for cadmium, which were not normally distributed, were 0.016 μg/L (interquartile range [IQR] 0.001-0.026) in nAMD and 0.012 μg/L (IQR 0.001-0.022) in controls (P = 0.002). Comparison of the Spearman's correlation coefficients between nAMD patients and controls identified a difference in correlations for 8 trace elements. Cadmium levels were associated with the smoking status (P < 0.001), while barium levels showed a trend of association with the usage of antihypertensive drugs. None of the AMD-associated genetic variants were associated with any trace element levels. In conclusion, in this case-control study we detected elevated plasma levels of barium and cadmium and reduced plasma levels of chromium in nAMD patients. An imbalance in plasma trace elements, which is most likely driven by environmental and lifestyle factors, might have a role in the pathogenesis of AMD. These trace elements may be incorporated as biomarkers into models for prediction of disease risk and progression. Additionally, population-based preventive strategies to decrease Cd exposure, especially by the cessation of smoking, could potentially reduce the burden of nAMD. Future studies are warranted to investigate whether supplementation of Cr would have a beneficial effect on nAMD.

Subretinal Deposits in Pre-eclampsia and Malignant Hypertension: Implications for Age-Related Macular Degeneration

PURPOSE

To describe the incidence of subretinal deposits that are similar in structure and stage on OCT imaging to subretinal drusenoid deposits (SDDs) in age-related macular degeneration (AMD) in patients with hypertensive choroidopathy secondary to severe pre-eclampsia and malignant hypertension (MHT) and the implications of this ischemic choroidopathy for the pathophysiologic characteristics of SDDs in AMD.

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

Thirty-three pre-eclampsia patients and 25 MHT patients with serous retinal detachment (SRD) in at least 1 eye were included.

METHODS

Serial multimodal images, including enhanced depth imaging spectral-domain OCT of eyes with hypertensive choroidopathy secondary to pre-eclampsia and MHT, were reviewed at 2 time points, the acute phase (within 4 weeks of initial hypertensive insult) and the recovery phase (beyond 4 weeks).

MAIN OUTCOME MEASURES

Incidence of SDD-like lesions in patients with hypertensive choroidopathy secondary to pre-eclampsia and MHT.

RESULTS

Subretinal drusenoid deposit-like lesions were observed exclusively in eyes with SRD. Serous retinal detachment occurred in 87.87% of eyes of pre-eclampsia patients and in 94% of eyes of MHT patients. Subretinal drusenoid deposit-like lesions occurred in 28.57% of all eyes with SRD, in 32.76% of eyes with SRD from the pre-eclampsia group, and in 23.40% of eyes with SRD from the MHT group. Vascular imaging suggested underlying choroidal ischemia in all patients (12 eyes) in which it was performed.

CONCLUSIONS

Choroidal ischemia may be the underlying mechanism of SDD-like lesions in patients with pre-eclampsia and MHT choroidopathy. These findings potentially are of utmost importance in understanding the mechanism of the reticular macular disease subtype of AMD. Reticular macular disease is characterized by the known association of choroidal insufficiency and SDD, with choroidal insufficiency postulated, but not proven, to be causative. Pre-eclampsia and MHT choroidopathy seems to be a model for lesions similar to SDD in AMD developing based on choroidal insufficiency and, as such, may offer further insights into the pathoetiologic features of SDD in AMD.

Progression of Photoreceptor Degeneration in Geographic Atrophy Secondary to Age-related Macular Degeneration

Importance

Sensitive outcome measures for disease progression are needed for treatment trials in geographic atrophy (GA) secondary to age-related macular degeneration (AMD).

Objective

To quantify photoreceptor degeneration outside regions of GA in eyes with nonexudative AMD, to evaluate its association with future GA progression, and to characterize its spatio-temporal progression.

Design, Setting, and Participants

Monocenter cohort study (Directional Spread in Geographic Atrophy [NCT02051998]) and analysis of data from a normative data study at a tertiary referral center. One hundred fifty-eight eyes of 89 patients with a mean (SD) age of 77.7 (7.1) years, median area of GA of 8.87 mm2 (IQR, 4.09-15.60), and median follow-up of 1.1 years (IQR, 0.52-1.7 years), as well as 93 normal eyes from 93 participants.

Exposures

Longitudinal spectral-domain optical coherence tomography (SD-OCT) volume scans (121 B-scans across 30° × 25°) were segmented with a deep-learning pipeline and standardized in a pointwise manner with age-adjusted normal data (z scores). Outer nuclear layer (ONL), photoreceptor inner segment (IS), and outer segment (OS) thickness were quantified along evenly spaced contour lines surrounding GA lesions. Linear mixed models were applied to assess the association between photoreceptor-related imaging features and GA progression rates and characterize the pattern of photoreceptor degeneration over time.

Main Outcomes and Measures

Association of ONL thinning with follow-up time (after adjusting for age, retinal topography [z score], and distance to the GA boundary).

Results

The study included 158 eyes of 89 patients (51 women and 38 men) with a mean (SD) age of 77.7 (7.1) years. The fully automated B-scan segmentation was accurate (dice coefficient, 0.82; 95% CI, 0.80-0.85; compared with manual markings) and revealed a marked interpatient variability in photoreceptor degeneration. The ellipsoid zone (EZ) loss-to-GA boundary distance and OS thickness were prognostic for future progression rates. Outer nuclear layer and IS thinning over time was significant even when adjusting for age and proximity to the GA boundary (estimates of -0.16 μm/y; 95% CI, -0.30 to -0.02; and -0.17 μm/y; 95% CI, -0.26 to -0.09).

Conclusions and Relevance

Distinct and progressive alterations of photoreceptor laminae (exceeding GA spatially) were detectable and quantifiable. The degree of photoreceptor degeneration outside of regions of retinal pigment epithelium atrophy varied markedly between eyes and was associated with future GA progression. Macula-wide photoreceptor laminae thinning represents a potential candidate end point to monitor treatment effects beyond mere GA lesion size progression.

Progression of Unifocal versus Multifocal Geographic Atrophy in Age-Related Macular Degeneration: A Systematic Review and Meta-analysis

TOPIC

Determining the natural history of unifocal versus multifocal geographic atrophy (GA) secondary to nonexudative age-related macular degeneration.

CLINICAL RELEVANCE

The association between GA focality (i.e., unifocal vs. multifocal lesions) and enlargement rate is inconsistent in the literature. Some studies report a comparable growth rate between unifocal and multifocal GA, whereas others suggest the growth rate varies widely between the 2 groups.

METHODS

We searched 5 literature databases up to May 3, 2019, for studies that classified treatment-naïve GA patients based on lesion focality. We performed a random effects meta-analysis to determine the growth rates of GA. To account for different entry times among cohorts, we introduced a horizontal translation factor to the dataset of each cohort. Heterogeneity and study quality were assessed using the I2 statistic and Quality in Prognosis Studies tool, respectively. Publication bias was evaluated by funnel plots and the Egger test.

RESULTS

We included 12 studies with 3489 eyes from 3001 patients. After the introduction of translation factors, the effective radius of unifocal and multifocal GA enlarged linearly over approximately 7 years. The effective radius growth rate of multifocal GA (0.199±0.012 mm/year) was 46.3% higher than the growth rate of unifocal GA (0.136±0.008 mm/year; P < 0.001). Interestingly, unifocal and multifocal GA lesions with the same total baseline area grew at vastly different rates, with an estimated ratio of the growth rate as 1.46 (between 2 and 3). This difference disappeared after we accounted for different baseline total perimeters between unifocal and multifocal groups. The measured GA growth rate was consistent across studies using color fundus photography, fundus autofluorescence, or OCT (P = 0.35-0.99).

CONCLUSIONS

The effective radius of GA enlarges linearly and steadily over time in both unifocal and multifocal GA. The lesion focality is a significant prognostic factor for the GA effective radius growth rate. We propose that the growth rate of GA area is directly proportional to the total lesion perimeter (a measure of the number of retinal pigment epithelium cells exposed at the lesion border). Additional studies are needed to understand the cellular mechanisms underlying this relationship.

Imaging of Age-Related Macular Degeneration by Adaptive Optics Scanning Laser Ophthalmoscopy in Eyes With Aged Lenses or Intraocular Lenses

Purpose

To assess the performance of adaptive optics scanning laser ophthalmoscopy (AOSLO) in a large sample of eyes with or without age-related macular degeneration (AMD) and with cataracts or intraocular lenses (IOLs).

Methods

Patients with various degrees of AMD and age-similar normal subjects underwent fundus photography. Cataract severity and IOL clarity were assessed by fundus reflex photographs. In phakic eyes, lenticular opacity was graded as nuclear, cortical, or posterior subcapsular cataract. In eyes with IOLs, lens clarity was assessed by posterior capsule opacification (PCO). Quality of AOSLO images of the macular photoreceptor mosaic was classified as good, adequate or inadequate by human graders in a subjective assessment of cone visibility.

Results

A total of 159 eyes in 80 subjects (41 males, 39 females, aged 72.5 ± 11.5 years, 16 normals) were examined. Seventy-nine eyes had IOLs, and 80 eyes were phakic. AOSLO produced good images in 91 eyes (57%), adequate images in eight eyes (5%), and inadequate images in 27 eyes (17%). AOSLO did not acquire images in 33 eyes (21%), because of dense lenticular opacity, widespread PCO, or problems specific to individual subjects.

Conclusions

AOSLO images considered at least Adequate or better for visualizing cone photoreceptors were acquired from 62% of study eyes.

Translational Relevance

AOSLO can be used as an additional imaging modality to investigate the structure of cone photoreceptors in research on visual function in AMD and in clinical trials involving older patients.

MTOR-initiated metabolic switch and degeneration in the retinal pigment epithelium

The retinal pigment epithelium (RPE) is a particularly vulnerable tissue to age-dependent degeneration. Over the life span, the RPE develops an expanded endo-lysosomal compartment to maintain the high efficiency of phagocytosis and degradation of photoreceptor outer segments (POS) necessary for photoreceptor survival. As the assembly and activation of the mechanistic target of rapamycin complex 1 (mTORC1) occur on the lysosome surface, increased lysosome mass with aging leads to higher mTORC1 activity. The functional consequences of hyperactive mTORC1 in the RPE are unclear. In the current study, we used integrated high-resolution metabolomic and genomic approaches to examine mice with RPE-specific deletion of the tuberous sclerosis 1 (Tsc1) gene which encodes an upstream suppressor of mTORC1. Our data show that RPE cells with constitutively high mTORC1 activity were reprogramed to be hyperactive in glucose and lipid metabolism. Lipolysis was suppressed, mitochondrial carnitine shuttle was inhibited, while genes involved in fatty acid (FA) biosynthesis were upregulated. The metabolic changes occurred prior to structural changes of RPE and retinal degeneration. These findings have revealed cellular events and intrinsic mechanisms that contribute to lipid accumulation in the RPE cells during aging and age-related degeneration.

Recognizing Atrophy and Mixed-Type Neovascularization in Age-Related Macular Degeneration Via Clinicopathologic Correlation

Purpose

We explored via multimodal imaging and histology an eye with mixed-types 1 and 2 macular neovascularization (MNV) and complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA) in age-related macular degeneration.

Methods

An 82-year-old white man was followed 7 years by optical coherence tomography and treated with intravitreal anti-vascular endothelial growth factor for 3 years. At the last clinic visit, visual acuity was stable at 20/50. Two months later the patient died, and eyes were preserved at 8.33 hours after death. Submicrometer epoxy resin sections of osmicated tissue were stained with toluidine blue and evaluated by oil immersion microscopy.

Results

A shallow irregular RPE elevation on optical coherence tomography correlated with type 1 MNV with fibrocellular scar and neocapillaries (close to RPE), at a density similar to underlying native choriocapillaris (0.37 vs. 0.42). Type 2 MNV covered the native RPE and was enveloped at the margins by RPE, without neocapillaries. Native RPE cells transdifferentiated from age-normal to melanotic and entered type 1 MNV and choroid. Some photoreceptors persisted over MNV. The cRORA initiated at a collapsed druse, expanded during follow-up, and exhibited low choriocapillaris density (0.05).

Conclusions

An eye with maintained vision on 3 years of anti-vascular endothelial growth factor therapy had type 1 MNV sustaining RPE. Type 2 MNV enveloped by RPE was visible in optical coherence tomography and histology. Persistence of photoreceptors and RPE over MNV contrasted with drusen-associated cRORA.

Translational Relevance

Vision during long-term anti-vascular endothelial growth factor treatment persists by MNV partially preserving outer retinal cells and by RPE enveloping type 2 MNV.

Lifecycles of Individual Subretinal Drusenoid Deposits and Evolution of Outer Retinal Atrophy in Age-Related Macular Degeneration

PURPOSE

To describe the progression and regression of individual subretinal drusenoid deposits (SDDs) and surrounding photoreceptors and retina in patients with age-related macular degeneration (AMD) over a 3.5-year period using multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO).

DESIGN

Longitudinal observational study.

PARTICIPANTS

Four patients with intermediate AMD.

METHODS

Six eyes of 4 patients with intermediate AMD each were imaged 4 times over 3.5 years. Five eyes of 3 patients showed only SDD and no drusen. Subretinal drusenoid deposit presence and progression were assessed by multimodal imaging and a 3-stage grading system based on spectral-domain (SD) OCT. Morphologic features and the fine structure of individual SDD lesions identified at baseline were examined by AOSLO at follow-up visits. Reflectivity of photoreceptors surrounding SDD were assessed with AOSLO and SD OCT.

MAIN OUTCOME MEASURES

Morphologic features, fine structure, and size of individual SDD lesions by AOSLO; photoreceptor integrity surrounding SDD via AOSLO and SD OCT; and retinal layer thicknesses via SD OCT.

RESULTS

Individual SDDs followed independent lifecycle trajectories, exhibiting growth, shrinkage, fusion, and disappearance. Alterations in shape, morphologic features, and internal structure were not obviously the result of the presence of invading phagocytes. Of 822 lesions across all stages examined at baseline, 566 (69%) grew, 123 (15%) shrank, 47 (6%) remained of similar size, 86 (11%) disappeared, and 5 (0.6%) reappeared after regression. A return of characteristic photoreceptor reflectivity in AOSLO (punctate) and in SD OCT (prominent ellipsoid zone) was observed after regression of some SDD in 5 eyes of 4 patients. All eyes exhibited thinning of photoreceptor layers, despite intact retinal pigment epithelium (RPE), to approximately 70% of baseline thicknesses, as well as poorly visible or undetectable outer retinal bands.

CONCLUSIONS

Adaptive optics scanning laser ophthalmoscopy and SD OCT imaging of individual SDDs over 3.5 years revealed independent trajectories of progression and regression, believed to reflect the activities of local outer retinal cells. Restoration of some photoreceptor reflectivity and intact RPE after SDD regression should be seen in the larger context of outer retinal atrophy, previously suggested as a new form of advanced AMD, and herein replicated.

Diet Mimicking "Fast Food" Causes Structural Changes to the Retina Relevant to Age-Related Macular Degeneration

Introduction: Metabolic syndrome is a disorder characterized by a constellation of findings including truncal obesity, elevated blood pressure, abnormal cholesterol levels, and high blood glucose. Recent evidence suggests that metabolic syndrome may be associated with increased risk of age-related macular degeneration (AMD) and other eye diseases. Recently, C57BL/6J wild-type mice fed with a "fast food" diet consisting of high fat, cholesterol, and fructose-supplemented water showed unique systemic pathology consistent with metabolic syndrome and nonalcoholic steatohepatitis. Additionally, these mice showed higher levels of fibrosis, inflammation, endoplasmic reticulum stress, and mitochondrial dysfunction compared to mice fed with only a high-fat diet alone. Since similar pathways are activated in AMD, we sought to determine whether mice fed a "fast food" diet exhibited retinal changes.Methods: 3-month-old wild-type mice were randomized to a standard chow (n = 11) or a "fast food" (n = 18) diet and fed for 9 months. At 1 year of age, tissues were collected and retinas were analyzed using transmission electron microscopy. Quantitative measures of Bruch's membrane thickness and retinal pigment epithelium (RPE) cell counts were performed.Results: "Fast food" fed mice showed ocular pathology relevant to various stages of AMD including basal laminar deposits, focal thickening of Bruch's membrane, and a significant loss of RPE cells.Discussion/conclusion: A wild-type mouse model of metabolic syndrome fed a "fast food" diet developed changes to the retina similar to some of the pathologic features seen in AMD. Further investigations into this and similar animal models as well as further epidemiological studies are needed to more clearly define the association between metabolic syndrome and AMD.