Reticular Pseudodrusen in Age-Related Macular Degeneration

Retinal Metabolic Profile on IMPG2 Deficiency Mice with Subretinal Lesions

The interphotoreceptor matrix (IPM) is the extracellular matrix between the photoreceptors and the retinal pigment epithelium (RPE). The IPM has two proteoglycans: the IPM proteoglycans 1 and 2 (IMPG1 and IMPG2, respectively). Patients with mutations on IMPG2 develop subretinal vitelliform lesions that affect vision. We previously created an IMPG2 knockout (KO) mice model that generates subretinal lesions similar to those found in humans. These subretinal lesions in IMPG2 KO mice retinas are, in part, composed of mislocalized IMPG1. In addition, IMPG2 KO mice show microscopic IMPG1 material accumulation between the RPE and the photoreceptor outer segments. In this work we discuss the possibility that material accumulation on IMPG2 KO mice retinas affects photoreceptor metabolism. To further investigate this idea, we used targeted metabolomics to profile retinal metabolome on IMPG2 KO mice. The metabolite set enrichment analysis showed reduced glutamate metabolism, urea cycle, and galactose metabolism suggesting affected energy metabolism in mice retinas of IMPG2 KO mice with subretinal lesion.

Plasma Biomarkers of Reticular Pseudodrusen and the Risk of Progression to Advanced Age-Related Macular Degeneration

Purpose

To determine, using an aptamer-based technology in patients with intermediate age-related macular degeneration (AMD), (1) if there is a difference in plasma levels of 4979 proteins in patients with and without reticular pseudodrusen (RPD), and (2) if plasma levels of proteins are related to time to conversion to advanced AMD.

Methods

Patients with intermediate AMD and RPD were identified from an AMD registry. Relative concentrations of each protein were log (base 2) transformed and compared between patients with and without RPD using linear regression. A Cox proportional hazards survival model was fit to each aptamer to quantify associations with time to conversion. A pathway analysis was conducted in converters versus non-converters using the Reactome database.

Results

Of the 109 intermediate AMD patients, 39 had bilateral RPD (36%). Two proteins, TCL1A and CNDP1, were lower in patients in the intermediate AMD group with RPD. Twenty-one patients converted to advanced AMD with a median time to conversion of 25.2 months (range, 2.3-48.5 months) and median follow-up time in non-converters of 26.4 months (range, 0.03-49.7 months). Several proteins (lysozyme C, TFF3, RNAS6, and SAP3) distinguished patients who converted from those who did not convert to advanced AMD. The top conversion pathways included tumor necrosis factors bind their physiological receptors, digestion and absorption, signaling by activin, and signaling by TGF-β family members.

Conclusions

We identified a protein signature related to RPD, as well as to conversion to advanced AMD. The pathway analysis suggests that dysfunction of critical systemic pathways may have links to conversion to advanced AMD.

Translational Relevance

Biomarkers identified in plasma likely reflect systemic alterations in protein expression in patients with intermediate AMD.

Multi-focal electro-retinogram response following sub-threshold nano-second laser intervention in age-related macular degeneration

IMPORTANCE

The effect of sub-threshold nano-second laser (SNL) treatment on retinal function remains unknown.

BACKGROUND

SNL treatment has been studied as a potential intervention in intermediate age-related macular degeneration (iAMD). This study investigated the longitudinal effect of SNL treatment on retinal function.

DESIGN

This was a sub-study of the LEAD trial; a 36-month, multi-centre, randomized and sham-controlled trial.

PARTICIPANTS

Subjects with iAMD.

METHODS

Eligible participants were assigned randomly to receive SNL or sham treatment to the study eye at 6-monthly visits. Multi-focal electro-retinography (mfERG) was performed at each study visit from a study site. The mfERG responses were grouped into three regions (central, middle and outer rings) and compared between the SNL and sham group.

MAIN OUTCOME MEASURES

mfERG P1 response amplitude and implicit time.

RESULTS

Data were collected from 50 subjects (26 in the SNL group, 24 in the sham group). At baseline, the P1 amplitudes of both the study eyes and the fellow eyes were similar between the groups at all rings. In the sham group, the P1 amplitude gradually decreased over time (P < .05). In the SNL group, there was an improvement in P1 amplitude which became statistically significant at the 36-month visit, detected in both the treated and fellow eyes at the central (P = .005) and middle ring (P = .007) but not at the outer ring (P = .070). No difference in P1 implicit time detected between the groups (P > .05).

CONCLUSIONS AND RELEVANCE

SNL treatment improved electro-physiological function. mfERG could be useful for monitoring AMD progression and evaluating the efficacy of SNL treatment.

Complement factors and reticular pseudodrusen in intermediate age-related macular degeneration staged by multimodal imaging

Objective

Systemic activation of the complement system in intermediate age-related macular degeneration (AMD) is understudied. Moreover, links between the presence of reticular pseudodrusen (RPD) and systemic complement dysregulation have not been studied. The aim of this study was to determine if there is a difference in plasma complement factor levels in intermediate AMD compared with controls, and if complement levels are related to the presence of RPD.

Methods and analysis

Levels of complement factors C1q (µg/mL), C4 (µg/mL), C2 (µg/mL), Mannose Binding Lectin (ng/mL), C4b (µg/mL), C3 (µg/mL), factor B (µg/mL), factor D (µg/mL), properdin (µg/mL), C3a (ng/mL), iC3b/C3b (ng/mL), Ba (ng/mL), factor H (µg/mL), factor I (µg/mL), C5 (µg/mL), C5a (pg/mL) and SC5b-9 (ng/mL) were measured in plasma.

Results

109 cases and 65 controls were included in the study. Thirty-nine (36%) cases had RPD. Significantly lower systemic levels of: C1q (OR 0.96, 95% CI 0.94 to 0.98), factor B (OR 0.98, 95% CI 0.96 to 0.99), iC3b/C3b (OR 0.97, 95% CI 0.95 to 0.98), factor H (OR 0.99, 95% CI 0.98 to 0.99), factor I (OR 0.83, 95% CI 0.77 to 0.89) and C5 (OR 0.94, 95% CI 0.90 to 0.98) were found in cases versus controls. Significantly elevated levels of: C2 (OR 1.29, 95% CI 1.07 to 1.59), C3a (OR 1.03, 95% CI 1.01 to 1.05) Ba (OR 1.03, 95% CI 1.01 to 1.05) and C5a (OR 1.04, 95% CI 1.02 to 1.07) were found in cases versus controls. Systemic levels of complement factors measured were not related to the presence of RPD.

Conclusions

Levels of several systemic complement pathway factors were found to be altered in intermediate AMD. Systemic levels of complement factors were not related to RPD.

Confocal infrared imaging with optical coherence tomography provides superior detection of a number of common macular lesions compared to colour fundus photography

PURPOSE

To compare diagnostic accuracy of confocal infrared reflectance (IR), with and without optical coherence tomography (OCT), to colour fundus photography (CFP) in the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA) Study.

METHODS

Cross-sectional observational study of participants in NICOLA. CFP, IR and IR/OCT of 640 eyes were graded for hard, soft and reticular pseudodrusen; geographic atrophy; choroidal neovascularisation; naevus; epiretinal membrane; and haemorrhages. Test characteristics (sensitivity and specificity) for each imaging modality with respect to each retinal feature were calculated.

RESULTS

With CFP as the reference standard, sensitivity of IR by itself ranged from 75% for RPD to 93.5% for hard drusen and specificity was above 90% for all features except hard drusen (71.7%). For IR combined with OCT, sensitivity ranged from 80% for choroidal neovascularisation to 96.5% for hard drusen. When IR alone was the reference standard, CFP sensitivity was high for naevi (97.5%) but reduced markedly for epiretinal membrane (48.5%). When the combination of IR and OCT was the reference standard, sensitivity for CFP was least for epiretinal membrane (31.5%), low for geographic atrophy and reticular pseudodrusen (77.8% and 76.2% respectively) and high for all other lesion types.

CONCLUSION

Our findings support the use of confocal IR with OCT as a screening tool for a variety of features of macular disease in community optometric practice.

IDENTIFYING FEATURES OF EARLY AND LATE AGE-RELATED MACULAR DEGENERATION: A Comparison of Multicolor Versus Traditional Color Fundus Photography

PURPOSE

To compare multicolor (MC) and traditional color fundus photography (CFP) in their ability to detect features of early and late age-related macular degeneration (AMD).

METHODS

Study design: Observational case series.

PARTICIPANTS

fundus images captured using standard CFP and MC imaging from 33 patients attending hospital clinics and 26 participants from the pilot phase of the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA). Systematic grading of early and late AMD features; (hard drusen, soft drusen, reticular pseudodrusen, pigment clumping, non-geographic atrophy hypopigmentation, atrophy, hemorrhage, and fibrosis) on CFP and MC.

RESULTS

There were 105 eyes with gradable images for comparison. Using CFP as the gold standard, sensitivity values for MC ranged from 100% for atrophy, non-geographic atrophy hypopigmentation, and fibrosis to 69.7% for pigment clumping. Specificity values were high: >80% for all features. On using MC as the comparator, CFP had lower sensitivity for the detection of early AMD features (27.8% for reticular drusen to 77.8% for non-geographic atrophy hypopigmention). Analysis of OCT in discrepant cases showed better agreement with MC for all AMD lesions, except hemorrhage and non-geographic atrophy hypopigmentation. For pigment clumping, CFP and MC were in equal agreement with OCT.

CONCLUSION

Multicolor retinal imaging allowed for improved detection and definition of AMD features.

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.

Macular atrophy in patients with long-term anti-VEGF treatment for neovascular age-related macular degeneration

PURPOSE

To identify the prevalence and progression of macular atrophy (MA) in neovascular age-related macular degeneration (AMD) patients under long-term anti-vascular endothelial growth factor (VEGF) therapy and to determine risk factors.

METHOD

This retrospective study included patients with neovascular AMD and ≥30 anti-VEGF injections. Macular atrophy (MA) was measured using near infrared and spectral-domain optical coherence tomography (SD-OCT). Yearly growth rate was estimated using square-root transformation to adjust for baseline area and allow for linearization of growth rate. Multiple regression with Akaike information criterion (AIC) as model selection criterion was used to estimate the influence of various parameters on MA area.

RESULTS

Forty-nine eyes (47 patients, mean age 77 ± 14) were included with a mean of 48 ± 13 intravitreal anti-VEGF injections (ranibizumab:37 ± 11, aflibercept:11 ± 6, mean number of injections/year 8 ± 2.1) over a mean treatment period of 6.2 ± 1.3 years (range 4-8.5). Mean best-corrected visual acuity improved from 57 ± 17 letters at baseline (= treatment start) to 60 ± 16 letters at last follow-up. The MA prevalence within and outside the choroidal neovascularization (CNV) border at initial measurement was 45% and increased to 74%. Mean MA area increased from 1.8 ± 2.7 mm² within and 0.5 ± 0.98 mm² outside the CNV boundary to 2.7 ± 3.4 mm² and 1.7 ± 1.8 mm² , respectively. Multivariate regression determined posterior vitreous detachment (PVD) and presence/development of intraretinal cysts (IRCs) as significant factors for total MA size (R² = 0.16, p = 0.02). Macular atrophy (MA) area outside the CNV border was best explained by the presence of reticular pseudodrusen (RPD) and IRC (R² = 0.24, p = 0.02).

CONCLUSION

A majority of patients show MA after long-term anti-VEGF treatment. Reticular pseudodrusen (RPD), IRC and PVD but not number of injections or treatment duration seem to be associated with the MA size.

Heritability of Choroidal Thickness in the Amish

PURPOSE

To evaluate the heritability of choroidal thickness and its relationship to age-related macular degeneration (AMD).

DESIGN

Cohort study.

PARTICIPANTS

Six hundred eighty-nine individuals from Amish families with early or intermediate AMD.

METHODS

Ocular coherence tomography was used to quantify choroidal thickness, and fundus photography was used to classify eyes into categories using a modified Clinical Age-Related Maculopathy Staging (CARMS) system. Repeatability and heritability of choroidal thickness and its phenotypic and genetic correlations with the AMD phenotype (CARMS category) were estimated using a generalized linear mixed model (GLMM) approach that accounted for relatedness, repeated measures (left and right eyes), and the effects of age, gender, and refraction.

MAIN OUTCOME MEASURES

Heritability of choroidal thickness and its phenotypic and genetic correlation with the AMD phenotype (CARMS category).

RESULTS

Phenotypic correlation between choroidal thickness and CARMS category was moderate (Spearman's rank correlation, r_s = -0.24; n = 1313 eyes) and significant (GLMM posterior mean, -4.27; 95% credible interval [CI], -7.88 to -0.79; P = 0.02) after controlling for relatedness, age, gender, and refraction. Eyes with advanced AMD had thinner choroids than eyes without AMD (posterior mean, -73.8; 95% CI, -94.7 to -54.6; P < 0.001; n = 1178 eyes). Choroidal thickness was highly repeatable within individuals (repeatability, 0.78; 95% CI, 0.68 to 0.89) and moderately heritable (heritability, 0.40; 95% CI, 0.14 to 0.51), but did not show significant genetic correlation with CARMS category, although the effect size was moderate (genetic correlation, -0.18; 95% CI, -0.49 to 0.16). Choroidal thickness also varied with age, gender, and refraction. The CARMS category showed moderate heritability (heritability, 0.49; 95% CI, 0.26 to 0.72).

CONCLUSIONS

We quantify the heritability of choroidal thickness for the first time, highlighting a heritable, quantitative trait that is measurable in all individuals regardless of AMD affection status, and moderately phenotypically correlated with AMD severity. Choroidal thickness therefore may capture variation not captured by the CARMS system. However, because the genetic correlation between choroidal thickness and AMD severity was not significant in our data set, genes associated with the 2 traits may not overlap substantially. Future studies should therefore test for genetic variation associated with choroidal thickness to determine the overlap in genetic basis with AMD.

Investigation of precursor lesions of polypoidal choroidal vasculopathy using contralateral eye findings

Purpose

The purpose was to investigate precursor lesions of polypoidal choroidal vasculopathy (PCV).

Methods

This cross-sectional study involved 276 unaffected contralateral eyes from unilateral PCV patients (Group 1), unilateral typical exudative age-related macular degeneration (AMD) patients (Group 2), and unilateral epiretinal membrane patients (Group 3) as age-matched controls. Grayish-yellow sub-retinal or sub-retinal-pigment-epithelial deposits larger than 63 μm in size with irregular but discrete margins were defined as drusen-like deposits (DLDs). The frequencies of DLDs, drusen, and pigmentary changes in each group were compared.

Results

DLDs larger than 125 μm in size were found more frequently in Group 1 (19.5 %) than in Groups 2 (3.4 %) and 3 (3.2 %) (p < 0.001). Soft drusen were discovered more frequently in Group 2 eyes than in Groups 1 and 3 (p < 0.001). Pigmentary changes were found more frequently in Groups 1 and 2 compared to Group 3. Compared with the other groups, Group 1 manifested a higher frequency of choroidal vascular hyperpermeability (p < 0.005) and thicker choroid (p < 0.001).

Conclusions

The precursor lesions of PCV are different from those of exudative AMD. DLDs larger than 125 μm and pigmentary changes may be early preclinical markers of PCV. Long-term longitudinal studies are warranted for validation.

Pseudodrusen in the Fellow Eye of Patients with Unilateral Neovascular Age-Related Macular Degeneration: A Meta-Analysis

Importance

The fellow eye of patients with unilateral neovascular age-related degeneration (nAMD) is at increased risk of developing late AMD. Several cohort studies have evaluated the prevalence of pseudodrusen and the association between pseudodrusen and late AMD in the fellow eye of patients with unilateral nAMD. However, these studies have limited sample sizes and their results are inconsistent.

Objective

To evaluate the prevalence rate of pseudodrusen, and the association between pseudodrusen and incidence of late AMD (nAMD and geographic atrophy (GA)) in the fellow eye of patients with unilateral nAMD.

Data Sources

The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched up to July 2015, as well as other systematic reviews.

Study Selection

All cohort studies for pseudodrusen with late AMD in the fellow eye of patients with unilateral nAMD.

Data Extraction and Synthesis

The numbers of patients with and without pseudodrusen at baseline and the numbers of incident nAMD and GA during follow up among patients with and without pseudodrusen were independently extracted by 2 authors. The results were pooled using random-effects meta-analysis. Heterogeneity was assessed using the I² test.

Main Outcome Measures

Prevalence rate of pseudodrusen, risk ratios (RRs) and their 95% confidence intervals (95% CIs) for associations between pseudodrusen and the incidence of nAMD and GA in the fellow eye.

Results

Five cohort studies (N = 677 patients) from 8 countries across 4 continents were included. The pooled prevalence rate of pseudodrusen in the fellow eye was 48.1% (95% Cl: 36.7–59.5%, I² = 87%). Pseudodrusen were associated with an increased risk of nAMD (RR = 1.54, 95% Cl: 1.10–2.16, I² = 42%), GA (RR = 4.70, 95% Cl: 1.22–18.1, I² = 64%), and late AMD (RR = 2.03, 95% Cl: 1.35–3.06, I² = 60%).

Conclusions

For patients with unilateral nAMD, pseudodrusen were present in about half of the fellow eyes. The presence of pseudodrusen was associated with a 1.5 times higher risk of developing nAMD, a 4.7 times higher risk of developing GA, and a 2 times higher risk of developing late AMD. Pseudodrusen should be considered in evaluating the risk of late AMD development; however, due to considerable heterogeneity across these studies, a larger study is needed to validate these findings.

Widefield En Face Optical Coherence Tomography Imaging of Subretinal Drusenoid Deposits

BACKGROUND AND OBJECTIVE

To determine whether subretinal drusenoid deposits (SDD) can be detected on widefield en face slab images derived from spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) volume scans.

PATIENTS AND METHODS

Retrospective study of patients with dry age-related macular degeneration (AMD) enrolled prospectively in an OCT imaging study using SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec, Dublin, CA) with a central wavelength of 840 nm, and a prototype 100-kHz SS-OCT instrument (Carl Zeiss Meditec) with a central wavelength of 1,050 nm. Seven en face slabs were evaluated with thicknesses from 20 to 55 µm and positioned at distances up to 55 µm above the retinal pigment epithelium (RPE). A montage of 6 × 6 mm SD-OCT en face images of the posterior pole from each patient was compared with a 9 × 12 mm SS-OCT single en face slab image and with color, autofluorescence, and infrared reflectance images.

RESULTS

A total of 160 patients (256 eyes) underwent scanning with both OCT instruments; 57 patients (95 eyes) also underwent multimodal fundus imaging. Of 95 eyes, 32 (34%) were diagnosed with reticular pseudodrusen (RPD) using multimodal imaging. All eyes with RPD demonstrated a pattern of SDD on widefield en face OCT similar to that observed for RPD. The en face slab image that consistently identified SDD was the 20-µm thick slab with boundaries from 35 to 55 µm above the RPE.

CONCLUSION

Widefield en face slab imaging with SD-OCT and SS-OCT can detect SDD and could replace multimodal imaging for the diagnosis of RPD in the future.

Prevalence of Reticular Pseudodrusen in Eyes with Newly Presenting Neovascular Age-Related Macular Degeneration

Purpose

To use multimodal imaging to evaluate the prevalence of reticular pseudodrusen (RPD) in eyes with newly presenting neovascular age-related macular degeneration (nAMD) in a UK population and explore associations with RPD and angiographic subtypes of nAMD.

Methods

A retrospective review of all spectral-domain optical coherence tomography, color fundus photographs, red-free and blue channel images, and fundus fluorescein angiograms of 202 consecutive patients who presented to a rapid access macular clinic over a 4-year period was performed. All images were graded by at least 2 ophthalmologists for the presence of RPD and choroidal neovascular membrane (CNV) subtypes.

Results

A total of 231 consecutive eyes were studied, of which 131 (56.7%) were in women. Of these, 51 eyes with CNV (22.1%) had identifiable RPD, with one or more imaging methods in that eye. A total of 30.3% of patients with newly presenting CNV in either or both eyes had identifiable RPD. The RPD were bilateral in 85.4% of patients and were identified more commonly in women than men (72.5% vs 27.5%), a difference that reached statistical significance (p = 0.011). No association between RPD and any particular CNV subtype was demonstrated, including for retinal angiomatous proliferations (RAP).

Conclusions

Reticular pseudodrusen have a high prevalence in eyes presenting with nAMD (22.1%), although at rates much lower than that of conventional drusen. They are largely a bilateral finding, occurring more frequently in women. Unlike other previous reports, we found no difference in their occurrence between the different subtypes of CNV including RAPs.