The Fate and Prognostic Implications of Hyperreflective Crystalline Deposits in Nonneovascular Age-Related Macular Degeneration

Rediscovering Age-Related Macular Degeneration with Swept-Source OCT Imaging: The 2022 Charles L. Schepens, MD, Lecture

PURPOSE

Swept-source OCT angiography (SS-OCTA) scans of eyes with age-related macular degeneration (AMD) were used to replace color, autofluorescence, infrared reflectance, and dye-based fundus angiographic imaging for the diagnosis and staging of AMD. Through the use of different algorithms with the SS-OCTA scans, both structural and angiographic information can be viewed and assessed using both cross sectional and en face imaging strategies.

DESIGN

Presented at the 2022 Charles L. Schepens, MD, Lecture at the American Academy of Ophthalmology Retina Subspecialty Day, Chicago, Illinois, on September 30, 2022.

PARTICIPANTS

Patients with AMD.

METHODS

Review of published literature and ongoing clinical research using SS-OCTA imaging in AMD.

MAIN OUTCOME MEASURES

Swept-source OCT angiography imaging of AMD at different stages of disease progression.

RESULTS

Volumetric SS-OCTA dense raster scans were used to diagnose and stage both exudative and nonexudative AMD. In eyes with nonexudative AMD, a single SS-OCTA scan was used to detect and measure structural features in the macula such as the area and volume of both typical soft drusen and calcified drusen, the presence and location of hyperreflective foci, the presence of reticular pseudodrusen, also known as subretinal drusenoid deposits, the thickness of the outer retinal layer, the presence and thickness of basal laminar deposits, the presence and area of persistent choroidal hypertransmission defects, and the presence of treatment-naïve nonexudative macular neovascularization. In eyes with exudative AMD, the same SS-OCTA scan pattern was used to detect and measure the presence of macular fluid, the presence and type of macular neovascularization, and the response of exudation to treatment with vascular endothelial growth factor inhibitors. In addition, the same scan pattern was used to quantitate choriocapillaris (CC) perfusion, CC thickness, choroidal thickness, and the vascularity of the choroid.

CONCLUSIONS

Compared with using several different instruments to perform multimodal imaging, a single SS-OCTA scan provides a convenient, comfortable, and comprehensive approach for obtaining qualitative and quantitative anatomic and angiographic information to monitor the onset, progression, and response to therapies in both nonexudative and exudative AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Age-Related Macular Degeneration, a Mathematically Tractable Disease

A progression sequence for age-related macular degeneration onset may be determinable with consensus neuroanatomical nomenclature augmented by drusen biology and eye-tracked clinical imaging. This narrative review proposes to supplement the Early Treatment of Diabetic Retinopathy Study (sETDRS) grid with a ring to capture high rod densities. Published photoreceptor and retinal pigment epithelium (RPE) densities in flat mounted aged-normal donor eyes were recomputed for sETDRS rings including near-periphery rich in rods and cumulatively for circular fovea-centered regions. Literature was reviewed for tissue-level studies of aging outer retina, population-level epidemiology studies regionally assessing risk, vision studies regionally assessing rod-mediated dark adaptation (RMDA), and impact of atrophy on photopic visual acuity. The 3 mm-diameter xanthophyll-rich macula lutea is rod-dominant and loses rods in aging whereas cone and RPE numbers are relatively stable. Across layers, the largest aging effects are accumulation of lipids prominent in drusen, loss of choriocapillary coverage of Bruch's membrane, and loss of rods. Epidemiology shows maximal risk for drusen-related progression in the central subfield with only one third of this risk level in the inner ring. RMDA studies report greatest slowing at the perimeter of this high-risk area. Vision declines precipitously when the cone-rich central subfield is invaded by geographic atrophy. Lifelong sustenance of foveal cone vision within the macula lutea leads to vulnerability in late adulthood that especially impacts rods at its perimeter. Adherence to an sETDRS grid and outer retinal cell populations within it will help dissect mechanisms, prioritize research, and assist in selecting patients for emerging treatments.

Optical coherence tomography biomarkers in early and intermediate age-related macular degeneration: A clinical guide

Advanced forms of age-related macular degeneration (AMD), characterised by atrophic and neovascular changes, are a leading cause of vision loss in the elderly population worldwide. Prior to the development of advanced AMD, a myriad of risk factors from the early and intermediate stages of AMD have been published in the scientific literature over the last years. The ability to precisely recognise structural and anatomical changes in the ageing macula, altogether with the understanding of the individual risk implications of each one of them is key for an accurate and personalised diagnostic assessment. The present review aims to summarise updated evidence of the relative risk conferred by diverse macular signs, commonly seen on optical coherence tomography, in terms of progression to geographic atrophy or macular neovascularization. This information may also serve as a basis for tailored follow-up monitoring visits.

Hyperlipidemia and lipid-lowering therapy in diabetic retinopathy (DR): A bibliometric study and visualization analysis in 1993-2023

Background

Diabetic retinopathy (DR) is a common complication in diabetic patients. DR is also a neurodegenerative disease. Patients with hyperglycemia, hyperlipidemia, and hypertension are vulnerable to retinopathy development. While the roles of blood glucose and blood pressure in the development of retinopathy have been extensively studied, the relationship between body fat and DR pathogenesis and the impact of lipid-reducing drugs on DR has just emerged as a research hotspot in DR study. We aim to visualize the contributions and cooperation of reporters, organizations, and nations, in addition to the research hotspots and trends in DR-related lipid research from 1993 to 2023, by bibliometric analysis.

Methods

We extracted all publications about DR-related lipid research from 1993 to 2023 from the Web of Science Core Collection, and bibliometric features were studied using VOSviewer and the CiteSpace program.

Results

1402 documents were retrieved. The number of studies has risen consistently for three decades, from an average of 16.8/year in the 1990s to 28.8/year in the 2000s, 64.5/year in 2010s, and reached 112/year in 2020-2022, confirming they are hot research topic in the field. These reports were from 93 nations/regions, with the USA, China, Japan, Australia, and England taking the leading positions. Diabetes Research and Clinical Practice was the journal that published the most studies, and Diabetes Care was the most quoted. We identified 6979 authors, with Wong TY having the most papers and being the most commonly co-cited. The most popular keyword, according to our research, is diabetic retinopathy. Oxidative stress, diabetic macular edema (DME), lipid peroxidation, and other topics have often been investigated.

Conclusion

DR-related lipid research is conducted mainly in North America, Asia, Oceania, and Europe. Much study has centered on the relationship between lipid-lowering therapy and DR pathogenesis. These studies strongly support using lipid-reducing medications (fenofibrate, statins, and omega-3 PUFAs), combined with hyperglycemia and hypertension therapy, to prevent and treat DR. However, the impact of fenofibrate or statin on retinopathy is not correlated with their action on blood lipid profiles. Thus, more randomized clinical trials with primary endpoints related to DR in T1D or T2D are merited. In addition, the lipid biomarker for DR (lipid aldehydes, ALEs, and cholesterol crystals), the action of lipid-reducing medicines on retinopathy, the mechanism of lipid-lowering medications preventing or curing DR, and ocular delivery of lipid-lowering drugs to diabetic patients are predicted as the research focus in the future in the DR-related lipid research field.

Cholesterol crystal formation is a unifying pathogenic mechanism in the development of diabetic retinopathy

AIMS/HYPOTHESIS

Hyper-reflective crystalline deposits found in retinal lesions have been suggested to predict the progression of diabetic retinopathy, but the nature of these structures remains unknown.

METHODS

Scanning electron microscopy and immunohistochemistry were used to identify cholesterol crystals (CCs) in human donor, pig and mouse tissue. The effects of CCs were analysed in bovine retinal endothelial cells in vitro and in db/db mice in vivo using quantitative RT-PCR, bulk RNA sequencing, and cell death and permeability assays. Cholesterol homeostasis was determined using 2H2O and 2H7-cholesterol.

RESULTS

We identified hyper-reflective crystalline deposits in human diabetic retina as CCs. Similarly, CCs were found in the retina of a diabetic mouse model and a high-cholesterol diet-fed pig model. Cell culture studies demonstrated that treatment of retinal cells with CCs can recapitulate all major pathogenic mechanisms leading to diabetic retinopathy, including inflammation, cell death and breakdown of the blood-retinal barrier. Fibrates, statins and α-cyclodextrin effectively dissolved CCs present in in vitro models of diabetic retinopathy, and prevented CC-induced endothelial pathology. Treatment of a diabetic mouse model with α-cyclodextrin reduced cholesterol levels and CC formation in the retina, and prevented diabetic retinopathy.

CONCLUSIONS/INTERPRETATION

We established that cholesterol accumulation and CC formation are a unifying pathogenic mechanism in the development of diabetic retinopathy.

Onion ring sign on spectral domain optical coherence tomography in diabetic macular edema: Its evolution and outcomes

PURPOSE

To report evolution and outcomes of hyperreflective crystalline deposit (HCD) on optical coherence tomography (OCT) in diabetic maculopathy (DM).

METHODS

Patients with DM showing HCD on OCT for the first time between June 2017 and May 2021 were included in the study. Demographic, ophthalmic and OCT features were documented and analysed. Factors leading to the development of HCD and its effect on the functional outcome were analysed and described in this study.

RESULTS

Sixty cases of HCD were identified in 45 (males -33; females - 12) patients for the first-time during the defined study period. Mean age of the eligible patients was 61.53 ± 8.19 years. Average duration of diabetes was 13.82 ± 7.38 years. Mean visual acuity of these patients was 0.902 ± 0.438 logMAR units (Snellen equivalent = 20/160). Patients with HCD showed subretinal hard exudates, were on anti-cholesterol medications (n = 36, 80%) and showed reduced visual acuity (20/160) if the HCD involved the fovea. The median time taken for the development of HCD was 28 months. Mean follow-up duration of the study was 26.19 ± 27.98 months. Persistence of HCD in all cases (n = 42, 100%) was noted at the last follow-up visit.

CONCLUSION

Horizontal, single or multi-layered HCDs on OCT in DM represent intraretinal or subretinal cholesterol crystal precipitates evolving from the hard exudates identical to the "onion ring sign" seen in neovascular AMD. HCDs or CCs depict deranged lipid metabolism, chronic vascular leakage and can lead to substantial visual impairment if the fovea gets involved.

Sequential structural and functional change in geographic atrophy on multimodal imaging in non-exudative age-related macular degeneration

PURPOSE

To investigate the temporal order of photoreceptor atrophy, retinal pigment epithelium (RPE) atrophy and visual acuity loss in patients with center-involving geographic atrophy (GA) in non-exudative age-related macular degeneration (neAMD).

METHODS

Forty eyes of 25 consecutive patients who eventually developed center-involving GA were investigated. Fundus autofluorescence (FAF) and infrared image coupled optical coherence tomography (OCT) were acquired at each visit. Development of RPE atrophy and photoreceptor atrophy was defined as abnormal hyper/hypo-fluorescence on FAF and photoreceptor loss on OCT over 50% of the vertical or horizontal diameters of the center 1 mm circle, respectively. Visual acuity loss was defined as worsening of more than 0.2 logMAR compared to baseline. Kaplan-Meier analyses was performed to compare the sequential order of these three events.

RESULTS

Mean age was 72.72 ± 8.63 years, and follow-up duration was 27.36 ± 17.22 months, with an average number of visits of 3.04 ± 1.54 during follow-up. GA progressed from photoreceptor atrophy on OCT, RPE atrophy on FAF, and then to vision loss (p < 0.001). The median survival time of photoreceptors preceded that of visual acuity by 16.3 months, and the median survival time of RPE preceded that of visual acuity by 7.0 months. At baseline, majority of eyes showed drusen only (57.5%), while the most common feature was incomplete RPE and outer retinal atrophy at 3-year follow-up (40.4%).

CONCLUSION

In the progression of center-involving GA, photoreceptor atrophy on OCT and RPE atrophy on FAF precedes visual decline, and can act as biomarkers predicting future visual decline within the following years.

OCT Risk Factors for Development of Atrophy in Eyes with Intermediate Age-Related Macular Degeneration

PURPOSE

To determine the frequency of multiple OCT biomarkers of intermediate age-related macular degeneration (iAMD) and their relationship with the development of complete retinal pigment epithelium and outer retinal atrophy (cRORA) after 2 years.

DESIGN

Retrospective cohort study.

PARTICIPANTS

This retrospective analysis included 330 eyes of 330 consecutive patients with iAMD in ≥ 1 eye who had 24 months of follow-up data.

METHODS

Spectralis OCT volume scans (49 B-scans over 6 × 6 mm, automatic real time = 6, fovea-centered) at baseline were evaluated for the previously described iAMD biomarkers, including a high-central drusen volume (DV; ≥ 0.03 mm³), intraretinal hyper-reflective foci (IHRF), subretinal drusenoid deposits (SDDs), hypo-reflective drusen cores (hDCs), and a thin or thick (multilayered) double-layer sign (DLS). The age-related macular degeneration (AMD) status in the fellow eye was also assessed and classified as normal or early AMD, iAMD, exudative macular neovascularization, or cRORA.

MAIN OUTCOME MEASURES

Incidence of cRORA, odds ratio for demographics, and OCT features.

RESULTS

At month 24, 16.36% (54/330) of the iAMD eyes developed cRORA. Several baseline features, including high-central DV, IHRF, SDD, hDC, thin DLS, and cRORA in the fellow eye, were associated with a significantly greater risk for development of cRORA at 2 years. The odds ratio, 95% confidence interval, P value, and baseline frequencies of these biomarkers were DV (6.510, 2.467-17.176, P < 0.001, 49.1%), IHRF (12.763, 4.763-34.202, P < 0.001, 38.8%), SDD (2.307, 1.003-5.304, P = 0.049, 34.2%), hDC (3.012, 1.152-7.873, P = 0.024, 13.0%), thin DLS (4.517, 1.555-13.126, P = 0.006, 11.8%), and cRORA in the fellow eye (7.184, 1.938-26.623, P = 0.003, 8.2%).

CONCLUSIONS

In addition to the 4 previously reported factors that are present in a significant proportion of iAMD (DV, IHRF, hDC, and SDD), a thin DLS and cRORA in the fellow eye were associated with an increased risk of progression to cRORA over 2 years. These biomarkers may aid in prognostication, risk stratification, and selection of patients for clinical trials.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Differentiating drusen and drusenoid deposits subtypes on multimodal imaging and risk of advanced age-related macular degeneration

Drusen are extracellular material considered a precursor lesion to advanced age-related macular degeneration (AMD), located either on the retinal pigment epithelium (RPE) or the sub-RPE; they contain various proteins associated with inflammation and lipids. Previous studies suggest that the lifecycle of drusen varies depending on drusen type and size. In general, conventional drusen grow and aggregate/coalesce in the first stage, and in the second stage, they regress with or without showing RPE atrophy. The risk of advanced AMD also varies depending on the drusen and drusenoid deposit types' along with their size and RPE abnormalities. In eyes with macular neovascularization (MNV), specific drusen/drusenoid deposits are closely associated with the MNV subtype. Recently, pachychoroid-associated drusen (pachydrusen) were proposed and clinical findings regarding this entity have been accumulating, as more attention is focused on drusen as well as pachychoroid diseases. With the advance in imaging modalities, various modalities can show specific characteristics depending on drusen types. To assess the risk of advanced AMD, it is essential for physicians to have accurate clinical knowledge about each druse/drusenoid lesion and correctly evaluate its imaging characteristics using multimodal imaging. This review summarizes the latest clinical knowledge about each druse/drusenoid lesions and documents their imaging characteristics on multimodal imaging, allowing clinicians to better manage patients and stratify the risk of developing advanced AMD. The most representative cases are illustrated, which can be helpful in the differential diagnosis of drusen and drusenoid deposits.

Sub-retinal pigment epithelium tubules in non-neovascular age-related macular degeneration

To describe a novel optical coherence tomography (OCT) signature resembling sub-retinal pigment epithelium (RPE) tubules (SRT) in non-neovascular age-related macular degeneration (AMD). Patients suffering from non-neovascular AMD with complete medical records and multimodal imaging were retrospectively revised in three different tertiary care centers. Multimodal imaging included color fundus photograph, spectral-domain OCT (Spectralis, Heidelberg Engineering, Germany), fundus autofluorescence, OCT angiography (RTVue XR Avanti, Optovue, Inc., Fremont, CA). A total of 7 eyes of 7 patients with drusenoid pigment epithelium detachment (PED) were consecutively analyzed. The sub-RPE tubules appeared as ovoidal structures with a hyperreflective contour and hyporeflective interior appreciable in the sub-RPE-basal lamina (BL) space on OCT B-scan. The anatomical location of the sub-RPE formations was lying above the Bruch's membrane in 5/7 cases (71.4%) or floating in the sub-RPE-BL space in 2/7 cases (28.6%). En-face OCTA revealed a curvilinear tubulation-like structure corresponding to SRT without flow signal. Sub-RPE tubules represent a newly identified OCT signature observed in eyes with drusenoid PED. The presumed origin may include a variant of calcified structure or alternatively activated RPE cells with some residual BL or basal laminar deposits attracted to BrM for craving oxygen.

Characterization of West African Crystalline Macular Dystrophy in the Ghanaian Population

OBJECTIVE/PURPOSE

West African Crystalline Maculopathy (WACM) is characterized by the presence of macular hyper-refractile crystal-like deposits. Although the underlying pathophysiology has not been elucidated, a few biological drivers have been proposed. We analysed a large WACM case series to gain a more robust understanding of its features and etiology.

DESIGN

Prospective, Cross-sectional cohort study.

SUBJECTS/PARTICIPANTS

Participants with WACM were selected from the large cohort recruited into the Ghana Age-Related Macular Degeneration Study (Ghana AMD Study).

METHODS

Demographic and detailed medical histories, full ophthalmic examinations, digital colour fundus photographs and optical coherence tomography (OCT) images were obtained. All WACM cases were evaluated by three retina experts. Crystal numbers, location, and distribution were determined. Associations between WACM and Caucasian AMD risk variants were assessed using Firth's bias-reduced logistic regression, including age and gender as covariates.

MAIN OUTCOME MEASURES

Phenotypic features of, and genetic associations with, WACM.

RESULTS

WACM was identified in 106 eyes of 53 participants: 22 were bilateral and 24 unilateral. Grading for AMD was not possible in one eye of seven WACM participants; therefore, laterality was not assessed in these subjects. Thirty-eight participants were female, and 14 male; gender was unrecorded for one participant. Mean age was 68.4 years (range 45-101). OCT demonstrated typical WACM crystals, which were more easily identified at high contrast and predominantly located at the inner limiting membrane (ILM). In eyes with co-pathology, crystals localised deeper in the inner retina with wider retinal distribution over co-pathology lesions. There was no age or gender association. A significant association was observed between the complement factor H (CFH) 402H risk variant and WACM.

CONCLUSION

This study confirms localization of crystals adjacent to the ILM, and distribution over lesions in eyes with co-pathology. Evaluation of OCT images under high contrast allows improved identification. WACM may be associated with the CFH-CFHR5 AMD-risk locus identified amongst Caucasians; however, it is also possible that combination of crystals and the CFH 402H allele increases the risk for developing late AMD. Further analyses using larger sample sizes are warranted to identify causalities between genotype and WACM phenotype.

Optical coherence tomography predictors of progression of non-exudative age-related macular degeneration to advanced atrophic and exudative disease

PURPOSE

To study the natural history of optical coherence tomography (OCT) imaging-based findings seen in non-exudative age-related macular degeneration (neAMD) and model their relative likelihood in predicting development of incomplete retinal pigment epithelium and outer retinal atrophy (iRORA), complete retinal pigment epithelium and outer retinal atrophy (cRORA), and neovascular AMD (nAMD).

METHODS

Retrospective chart review was performed at two academic practices. Patients diagnosed with neAMD for whom yearly OCT scans were obtained for at least 4 consecutive years were included. Baseline demographic, visual acuity, AREDS staging, and OCT data were collected. OCTs were assessed for the presence or absence of eleven features previously individually associated with progression of neAMD, both at baseline, and on all subsequent follow-up scans. Likewise, charts were reviewed to assess visual acuity and staging of NEAMD at all follow-up visits. A multivariate regression analysis was constructed to determine predictors of iRORA, cRORA, and nAMD.

RESULTS

A total of 107 eyes of 88 patients were evaluated. Follow-up included yearly OCTs obtained over at least 4 consecutive years follow-up (range: 50-94 months). During the follow-up period, 17 eyes progressed to iRORA while 25 progressed to cRORA and 16 underwent conversion to nAMD. Predictors of conversion to iRORA and cRORA included integrity of the external limiting membrane (p = 0.02), the ellipsoid zone (p = 0.01), and the cone outer segment line (p = 0.003) and the presence of intraretinal hyporeflective spaces (p = 0.009), drusen ooze (p = 0.05), and drusen collapse (p = 0.001). OCT features predictive of conversion to nAMD included outer nuclear layer (ONL) loss (p = 0.01), presence of intraretinal (p = 0.001) and subretinal (p = 0.005) hyporeflective spaces, and drusen collapse (p = 0.003).

CONCLUSION

Of these multiple factors predictive of progression of neAMD, the OCT feature most strongly correlated to progression to iRORA/cRORA was drusen collapse, and the feature most predictive of conversion to nAMD was the presence of intraretinal hyporeflective spaces.

De-novo multilayering in fibrovascular pigment epithelial detachment

This study describes the occurrence of multilayered pigment-epithelial detachment (MLPED) as a De-novo phenomenon (DN-MLPED) and compare the features with multi-layering secondary to chronic anti-vascular endothelial growth factor (anti-VEGF) therapy (s-MLPED). We did a retrospective evaluation of spectral-domain optical coherence tomography (SD-OCT) features, treatment-profile, and visual-acuity (VA) outcomes in eyes with MLPED. Out of 17 eyes with MLPED, 7 eyes had DN-MLPED and 10 eyes had s-MLPED. There was no significant difference in baseline and final VA between the groups. At the final visit, no significant visual improvement was noted in both the groups, although a possible trend towards an improvement was seen in DN-MLPED eyes while the s-MLPED demonstrated a declining trend (DN-MLPED-LogMAR-BCVA: Baseline = 0.79 [∼ 20/123] ± 0.91; Final = 0.76 [∼ 20/115] ± 0.73; p = 0.87; s-MLPED-LogMAR BCVA: Baseline = 0.43 [∼ 20/54] ± 0.68; Final = 0.94 [∼ 20/174] ± 0.71; p = 0.06). Moreover, after presentation, the median number of injections in DN-MLPED eyes were significantly lower compared to s-MLPED eyes (DN-MLPED:4; s-MLPED:12; p = 0.03) (Median follow-up: DN-MLPED = 26 months; s-MLPED = 54 months; p = 0.15). Subretinal hyperreflective-material (SHRM) deposition heralded the onset of multilayering and was seen to progress in all DN-PED eyes and 1/4 eyes of s-MLPED. To conclude, MLPED is a unique form of cicatrizing fibrovascular-PED which can evolve denovo too. Long-standing disease with intermittent or low-grade activity can potentially explain this unique phenomenon. With fewer anti-VEGF therapy, the de-novo MLPED eyes show more visual stability as compared to s-MLPED eyes.

Near-Infrared Reflectance Imaging in Retinal Diseases Affecting Young Patients

Near-infrared reflectance (NIR) is a noninvasive, contactless, and rapid in vivo imaging technique for visualizing subretinal alterations in the photoreceptor layer, retinal pigment epithelium, and choroid. The present report describes the application of this imaging method in retinal and choroidal pathologies affecting young patients where scarce cooperation, poor fixation, and intense glare sensation can result in a challenging clinical examination. A literature search of the MEDLINE database was performed using the terms "near-infrared reflectance" and "spectral-domain optical coherence tomography." Articles were selected if they described the diagnostic use of NIR in children or young adults. Of 700 publications, 42 manuscripts published between 2005 and 2020 were inherent to children or young adults and were considered in this narrative literature review. The first disease category is the phakomatoses where NIR is essential in visualizing choroidal alterations recognized as cardinal biomarkers in neurofibromatosis type 1, microvascular retinal alterations, and retinal astrocytic hamartomas. Another diagnostic application is the accurate visualization of crystals of various nature, including the glistening crystals that characterize Bietti crystalline dystrophy. Acute macular neuropathy and paracentral acute middle maculopathy represent a further disease category with young adulthood onset where NIR is not only diagnostic but also essential to monitor disease progression. A further interesting clinical application is to facilitate the detection of laser-induced maculopathy where funduscopic examination can be normal or subnormal. In conclusion, NIR imaging has a noninterchangeable role in diagnosing certain retinal diseases, especially in children and young adults where there is scarce collaboration and a lack of evident clinical findings. Moreover, this technique can reveal unique retinal and choroidal biomarkers highly specific to rare conditions.

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

Introduction

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

Materials and Methods

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

Results

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

Conclusions

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

Imaging Features Associated with Progression to Geographic Atrophy in Age-Related Macular Degeneration: Classification of Atrophy Meeting Report 5

PURPOSE

To provide an image-based description of retinal features associated with risk for development of geographic atrophy (GA) in eyes with age-related macular degeneration (AMD), as visualized with multimodal imaging anchored by structural OCT.

DESIGN

Consensus meeting.

PARTICIPANTS

International group that included those with expertise in imaging and AMD basic science and histology, and those with Reading Center experience in AMD clinical trials.

METHODS

As part of the Classification of Atrophy Meeting program, an international group of experts analyzed and discussed retinal multimodal imaging features in eyes with AMD associated with GA, risk of progression to GA, or both. Attendees undertook premeeting grading exercises that were reviewed during the meeting sessions. Meeting presentations illustrated established and investigational multimodal imaging features and associated histologic features. Each of these different features were then discussed openly by the entire group to arrive at consensus definitions. These definitions were applied to 40 additional images that were graded independently by attendees to refine the consensus definitions and descriptions further.

RESULTS

Consensus was reached on images with descriptors for 12 features. These features included components of outer retinal atrophy (e.g., ellipsoid zone disruption), components of complete retinal pigment epithelium (RPE) and outer retinal atrophy (e.g., RPE perturbation with associated hypotransmission or hypertransmission), features frequently seen in eyes with atrophy (e.g., refractile drusen), and features conferring risk for atrophy development (e.g., hyperreflective foci, drusen, and subretinal drusenoid deposits).

CONCLUSIONS

An international consensus on terms and descriptions was reached on multimodal imaging features associated GA and with risk for GA progression in eyes with AMD. We believe this information will be useful to clinicians who manage patients with AMD, researchers who study AMD disease interventions and pathogenesis, and those who design clinical trials for therapies targeting earlier AMD stages than GA expansion.

Age-related macular degeneration (AMD): More than meets the eye. The role of multimodal imaging in today's management of AMD-A review

Multimodal imaging (MMI) allows a more granular grading of age-related macular degeneration (AMD) disease severity, with many novel risk factors having been recently identified. With this imaging information, we are better able to counsel our patients with more accurate and individualized progression scenarios. MMI also allows identification of anatomical features that increase our understanding of disease processes involved in progression to late AMD. Treatment protocols for neovascular AMD (nAMD) depend largely on the optical coherence tomography (OCT) appearance to determine disease activity, which allows us to individualize treatment. In geographic atrophy (GA), new intervention trials require the ability to define the extent of GA, so that GA growth rate can be determined. This is achieved through fundus autofluorescence (FAF) imaging, which allows greater accuracy of border identification, as well as revealing FAF patterns predictive of growth rates. As we strive to bring interventions earlier in the disease course, OCT imaging provides an ability to identify the first signs of atrophy, which may serve as novel surrogate biomarkers for GA, thereby facilitating trials. In the future, the use of artificial intelligence (AI) to automatically identify relevant features on MMI could further enhance our ability to determine disease severity, predict progression and assist in identifying disease activity parameters to support clinical decision making when treating nAMD. Newer developments may allow frequent, remote capturing of images, reducing clinic visits, detecting progression and monitoring neovascular activity in-between clinic visits. Being aware of these new imaging insights in AMD, greatly enhance our clinical management of AMD.

Unique optical coherence tomographic features in age-related macular degeneration

Age-related macular degeneration is a major cause of blindness worldwide characterized by the presence of drusen and leading to retinal pigment epithelium and outer retinal changes in advanced stages. Approximately 10% of eyes with age-related macular degeneration develop neovascular complications and present with retinal or sub-retinal pigment epithelium exudation, hemorrhage, or both. Recent advances in imaging techniques, especially optical coherence tomography (OCT), help in early identification of disease and guide various treatment decisions; however, not all signs are suggestive of ongoing exudation or neovascular activity. Although uncommon, multiple OCT-based signs are reported that may be difficult to appreciate clinically. Prompt identification of these signs such as outer retinal tubulation, cystoid degeneration, or pseudocysts may avoid unnecessary interventions. Moreover, certain OCT-based features involving the choroid, such as prechoridal cleft and choroidal cavern, have also been found in eyes with age-related macular degeneration. We discuss these unique OCT-based signs, their pathogenesis, clinical relevance, and management.

Linear and planar reflection artifacts on swept-source and spectral-domain optical coherence tomography due to hyperreflective crystalline deposits

PURPOSE

To describe novel spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) linear and planar reflection artifacts produced by hyperreflective crystalline deposits (HCD).

METHODS

Imaging from 10 eyes with HCD producing linear and planar artifacts on OCT was retrospectively analyzed. All eyes had SD-OCT (Spectralis HRA + OCT, Heidelberg Engineering, Germany) and SS-OCT angiography (PLEX Elite 9000, Carl Zeiss Meditec, Inc., Dublin, CA) acquired on the same day. The horizontal extent of planar artifacts and the corresponding HCD on B-scans was measured using a digital caliper. Artifact features from HCD in eyes with non-neovascular age-related macular degeneration (AMD) were analyzed and compared to those seen in two eyes with the "onion sign," an OCT signature previously shown to represent cholesterol crystals (CC) in the sub-retinal pigment epithelium-basal laminar space of eyes with neovascular AMD. A third eye with the "onion sign" was imaged with dense B-scan (DB)-OCTA.

RESULTS

Ten eyes of ten patients (77.4 ± 8.7 years) with HCD were analyzed. On SS-OCTA, HCD produced linear artifacts of high signal intensity passing through the HCD and spanning the entire scan depth. On SD-OCT, HCD produced planar artifacts located anterior to both the retina and a hyporeflective space representing normal vitreous signal. The horizontal extent of the artifact did not differ significantly from the corresponding HCD on OCT B-scans (P = 0.62). The OCT artifacts produced by the "onion sign" appeared similar to those of HCD. The additional eye with neovascular AMD imaged with DB-OCTA was characterized by a single, vertical, linear false-flow signal crossing retinal layers.

CONCLUSIONS

To the authors' knowledge, this is the first description of SD- and SS-OCT/OCTA artifacts corresponding to both HCD and the "onion sign." These artifacts are likely due to highly reflective CC previously shown on histology to correspond to both of these OCT signatures.

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.