Topographic Rod Recovery Profiles after a Prolonged Dark Adaptation in Subjects with Reticular Pseudodrusen

Reticular Pseudodrusen: Impact of Their Presence and Extent on Local Rod Function in Age-Related Macular Degeneration

Purpose

To understand the spatial relationship between local rod-mediated visual function and reticular pseudodrusen (RPD) in eyes with large drusen.

Design

Retrospective cross-sectional study.

Participants

One eye with large drusen (>125 μm) each from 91 individuals with intermediate age-related macular degeneration, with and without RPD.

Methods

All participants underwent dark adaptation testing using a dark-adapted chromatic perimeter, where visual sensitivities were measured over 30 minutes of dark adaptation after photobleach. The rod intercept time (RIT; a measure of dynamic rod function) and pointwise sensitivity difference (PWSD; a relative measure of rod- compared with cone-mediated function) was determined at multiple retinal locations, and their association with the overall (central 20° × 20° region) and local (2° diameter region centered on the location tested) extent of RPD and drusen (quantified using multimodal imaging) was examined.

Main Outcome Measures

Association between overall and local extent of RPD and drusen with RIT and PWSD at each retinal location tested.

Results

In a multivariable analysis, delayed RIT was associated with an increasing overall (P < 0.001), but not local (P = 0.884), extent of RPD. In contrast, the increasing local (P < 0.001), but not overall (P = 0.475), extent of drusen was associated with delayed RIT. Furthermore, only an increasing overall extent of RPD (P < 0.001) was associated with reduced PWSD (or worse rod compared with cone function), but not the local extent of RPD and drusen, or overall extent of drusen (P ≥ 0.344).

Conclusions

Local rod-mediated function was associated with the overall, rather than local, extent of RPD in eyes with large drusen, suggesting that there may be widespread pathologic changes in eyes with RPD that account for this.

Financial Disclosures

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

Deep Learning-Based Detection of Reticular Pseudodrusen in Age-Related Macular Degeneration on Optical Coherence Tomography

Reticular pseudodrusen (RPD) signify a critical phenotype driving vision loss in age-related macular degeneration (AMD). Their detection is paramount in the clinical management of those with AMD, yet they remain challenging to reliably identify. We thus developed a deep learning (DL) model to segment RPD from 9,800 optical coherence tomography B-scans, and this model produced RPD segmentations that had higher agreement with four retinal specialists (Dice similarity coefficient [DSC]=0·76 [95% confidence interval [CI] 0·71-0·81]) than the agreement amongst the specialists (DSC=0·68, 95% CI=0·63-0·73; p <0·001). In five external test datasets consisting of 1,017 eyes from 812 individuals, the DL model detected RPD with a similar level of performance as two retinal specialists (area-under-the-curve of 0·94 [95% CI=0·92-0·97], 0·95 [95% CI=0·92-0·97] and 0·96 [95% CI=0·94-0·98] respectively; p ≥0·32). This DL model enables the automatic detection and quantification of RPD with expert-level performance, which we have made publicly available.

En Face Optical Coherence Tomography Illustrates the Trizonal Distribution of Drusen and Subretinal Drusenoid Deposits in the Macula

PURPOSE

To analyze the topographic distribution of macular drusen and subretinal drusenoid deposits (SDDs) using single-capture en face spectral domain optical coherence tomography (SD-OCT) imaging.

DESIGN

Retrospective case series.

METHODS

Analysis of 33 eyes of 20 patients with evidence of SDDs. Structural en face OCT images were reconstructed using a 40-µm-thick slab positioned from 48 to 88 µm above the Bruch membrane. The Early Treatment of Diabetic Retinopathy Study (ETDRS) grid and a rod/cone density map were overlaid on the en face OCT images, and the distribution of different subtypes of SDDs and macular drusen were assessed.

RESULTS

A total of 31 eyes (94%) showed a trizonal distribution pattern of drusen and SDDs. Whereas small to large drusen tended to aggregate in the central circle, dot SDDs predominated in the inner ring and the inner portion of the outer ring of the ETDRS grid and ribbon SDDs localized to the outer ring and outside the ETDRS grid. Of note, drusen colocalized to the region of greatest cone density, whereas ribbon SDDs colocalized to the area of greatest rod density. The dot SDDs mapped to the intermediate region with mixed rod and cone representation.

CONCLUSION

Dot and ribbon subtypes of SDDs and macular drusen show a characteristic trizonal distribution. The locations of these lesions colocalize according to the different densities of the cones and rods in the retina and may reflect varying pathophysiological activities of these photoreceptor subtypes.

Biomarkers for the Progression of Intermediate Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of severe vision loss worldwide, with a global prevalence that is predicted to substantially increase. Identifying early biomarkers indicative of progression risk will improve our ability to assess which patients are at greatest risk of progressing from intermediate AMD (iAMD) to vision-threatening late-stage AMD. This is key to ensuring individualized management and timely intervention before substantial structural damage. Some structural biomarkers suggestive of AMD progression risk are well established, such as changes seen on color fundus photography and more recently optical coherence tomography (drusen volume, pigmentary abnormalities). Emerging biomarkers identified through multimodal imaging, including reticular pseudodrusen, hyperreflective foci, and drusen sub-phenotypes, are being intensively explored as risk factors for progression towards late-stage disease. Other structural biomarkers merit further research, such as ellipsoid zone reflectivity and choriocapillaris flow features. The measures of visual function that best detect change in iAMD and correlate with risk of progression remain under intense investigation, with tests such as dark adaptometry and cone-specific contrast tests being explored. Evidence on blood and plasma markers is preliminary, but there are indications that changes in levels of C-reactive protein and high-density lipoprotein cholesterol may be used to stratify patients and predict risk. With further research, some of these biomarkers may be used to monitor progression. Emerging artificial intelligence methods may help evaluate and validate these biomarkers; however, until we have large and well-curated longitudinal data sets, using artificial intelligence effectively to inform clinical trial design and detect outcomes will remain challenging. This is an exciting area of intense research, and further work is needed to establish the most promising biomarkers for disease progression and their use in clinical care and future trials. Ultimately, a multimodal approach may yield the most accurate means of monitoring and predicting future progression towards vision-threatening, late-stage AMD.

Reticular Pseudodrusen: Interreader Agreement of Evaluation on OCT Imaging in Age-Related Macular Degeneration

Purpose

To determine the interreader agreement for reticular pseudodrusen (RPD) assessment on combined infrared reflectance (IR) and OCT imaging in the early stages of age-related macular degeneration across a range of different criteria to define their presence.

Design

Interreader agreement study.

Participants

Twelve readers from 6 reading centers.

Methods

All readers evaluated 100 eyes from individuals with bilateral large drusen for the following: (1) the presence of RPD across a range of different criteria and (2) the number of Stage 2 or 3 RPD lesions (from 0 to ≥ 5 lesions) on an entire OCT volume scan and on a selected OCT B-scan. Supportive information was available from the corresponding IR image.

Main Outcome Measures

Interreader agreement, as assessed by Gwet's first-order agreement coefficient (AC₁).

Results

When evaluating an entire OCT volume scan, there was substantial interreader agreement for the presence of any RPD, any or ≥ 5 Stage 2 or 3 lesions, and ≥ 5 definite lesions on en face IR images corresponding to Stage 2 or 3 lesions (AC₁ = 0.60-0.72). On selected OCT B-scans, there was also moderate-to-substantial agreement for the presence of any RPD, any or ≥ 5 Stage 2 or 3 lesions (AC₁ = 0.58-0.65) and increasing levels of agreement with increasing RPD stage (AC₁ = 0.08, 0.56, 0.78, and 0.99 for the presence of any Stage 1, 2, 3, and 4 lesions, respectively). There was substantial agreement regarding the number of Stage 2 or 3 lesions on an entire OCT volume scan (AC₁ = 0.68), but only fair agreement for this evaluation on selected B-scans (AC₁ = 0.30).

Conclusions

There was generally substantial or near-substantial-but not near-perfect-agreement for assessing the presence of RPD on entire OCT volume scans or selected B-scans across a range of differing RPD criteria. These findings underscore how interreader variability would likely contribute to the variability of findings related to the clinical associations of RPD. The low levels of agreement for assessing RPD number on OCT B-scans underscore the likely challenges of quantifying RPD extent with manual grading.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

LOW-DOSE SUPPLEMENTATION WITH RETINOL IMPROVES RETINAL FUNCTION IN EYES WITH AGE-RELATED MACULAR DEGENERATION BUT WITHOUT RETICULAR PSEUDODRUSEN

PURPOSE

The aim of this study was to determine the functional impact of oral vitamin A supplementation in patients with intermediate age-related macular degeneration with and without reticular pseudodrusen (RPD) demonstrating dysfunction in dark adaptation.

METHODS

Five patients with intermediate age-related macular degeneration and without RPD (AMD group; mean ± SD age 78.0 ± 4.7 years) and seven with RPD (RPD group; age 74.1 ± 11.2 years) were supplemented with 16,000 IU of vitamin A palmitate for 8 weeks. Assessment at baseline, 4, 8, and 12 weeks included scotopic thresholds, dark adaptation, best-corrected and low luminance visual acuities, and the low-luminance quality of life questionnaire.

RESULTS

In the linear mixed model, rod intercept time improved significantly in the AMD group (mean [95% CI] change -1.1 minutes [-1.8; -0.5] after 4 weeks ( P < 0.001) and -2.2 min [-2.9 to -1.6] after 8 weeks of vitamin A supplementation ( P < 0.001). The dark adaptation cone plateau also significantly improved (i.e., more sensitive cone threshold) at 4 and 8 weeks ( P = 0.026 and P = 0.001). No other parameters improved in the AMD group, and there was no significant improvement in any parameter in the RPD group despite significantly elevated serum vitamin A levels measurable in both groups after supplementation ( P = 0.024 and P = 0.013).

CONCLUSION

Supplementation with 16,000 IU vitamin A, a lower dose than used in previous studies, partially overcomes the pathophysiologic functional changes in AMD eyes. The lack of improvement in the RPD group may indicate structural impediments to increasing vitamin A availability in these patients and/or may reflect the higher variability observed in the functional parameters for this group.

Age-related macular degeneration

Age-related macular degeneration is an increasingly important public health issue due to ageing populations and increased longevity. Age-related macular degeneration affects individuals older than 55 years and threatens high-acuity central vision required for important tasks such as reading, driving, and recognising faces. Advances in retinal imaging have identified biomarkers of progression to late age-related macular degeneration. New treatments for neovascular age-related macular degeneration offer potentially longer-lasting effects, and progress is being made towards a treatment for atrophic late age-related macular degeneration. An effective intervention to slow progression in the earlier stages of disease, or to prevent late age-related macular degeneration development remains elusive, and our understanding of underlying mechanistic pathways continues to evolve.

Reticular Pseudodrusen on the Risk of Progression in Intermediate Age-Related Macular Degeneration

PURPOSE

To examine the association between reticular pseudodrusen (RPD) and progression to late age-related macular degeneration (AMD) in individuals with intermediate AMD.

DESIGN

Prospective cohort study.

METHODS

Two hundred eighty eyes from 140 participants with bilateral large drusen underwent multimodal imaging (MMI), including optical coherence tomography (OCT), near-infrared reflectance (NIR), fundus autofluorescence, and color fundus photography (CFP), at 6-monthly intervals up over a 36-month follow-up period. The presence of RPD per eye was determined based on either a combined MMI criterion, or each individual imaging modality, and their extent measured on combined OCT and NIR imaging. The association between the presence of RPD on different imaging modalities, and their extent, with the development of late AMD (including OCT-defined atrophy) was evaluated.

RESULTS

The presence of RPD on MMI, or any of its individual modalities, at baseline was not significantly associated with an increased rate of developing late AMD, with or without adjusting for risk factors for AMD progression (age, drusen volume on OCT, and pigmentary abnormalities on CFP; all P ≥ 0.205). The extent of RPD present was also not significantly associated with an increased rate of developing late AMD, with or without adjustment for risk factors for AMD progression (both P ≥ 0.522).

CONCLUSIONS

In this cohort with bilateral large drusen, the presence of RPD was not significantly associated with an increased risk of developing late AMD. Additional longitudinal studies in all stages of AMD are needed to understand the implications of RPD on vision loss in this condition.

Exploring Reticular Pseudodrusen Extent and Impact on Mesopic Visual Sensitivity in Intermediate Age-Related Macular Degeneration

Purpose

To explore the impact of the extent of reticular pseudodrusen (RPD) on mesopic visual sensitivity in individuals with intermediate age-related macular degeneration (AMD).

Methods

In total, 570 eyes from 285 participants with bilateral large drusen underwent microperimetry testing to assess the visual sensitivity of the central 3.6-mm region and multimodal imaging to determine the extent of RPD in the central 20° × 20° region (at the eye level). Mean visual sensitivity within five sectors in the central 3.6-mm region sampled on microperimetry and the extent of RPD in these sectors were derived. Linear mixed models were used to examine the association between the extent of RPD on overall mean visual sensitivity and sector-based mean sensitivity.

Results

An increasing extent of RPD at the eye level and within sectors was associated with a significant reduction in overall and sector-based mean sensitivity, respectively (P < 0.001 for both). However, when both RPD parameters were considered together in a multivariable model, only an increasing extent of RPD at the eye level (P < 0.001) and not within each sector (P = 0.178) was independently associated with reduced sector-based mean sensitivity.

Conclusions

Mesopic visual sensitivity is generally reduced in eyes with large drusen and coexistent RPD compared to eyes without RPD, with greater reductions with an increasing extent of RPD. However, reduced sector-based visual sensitivities are explained by the overall extent of RPD present, rather than their extent within the sector itself. These findings suggest that there are generalized pathogenic changes in eyes with RPD accounting for the observed mesopic visual dysfunction.

Scotopic Contour Deformation Detection Reveals Early Rod Dysfunction in Age-Related Macular Degeneration With and Without Reticular Pseudodrusen

Purpose

The purpose of this study was to investigate scotopic contour deformation detection (sCDD), and its structural determinants, in participants with intermediate age-related macular degeneration (iAMD) with or without reticular pseudodrusen (RPD).

Methods

Forty-one participants (aged 58–89 years), including 9 with iAMD and RPD, 16 with iAMD only, and 16 controls, underwent functional testing. The sCDD was evaluated with radial frequency arcs presented at 4 loci: ±4 degrees and 8 degrees vertical eccentricity. Scotopic thresholds and dark adaptation (DA) were measured at the same loci. Retinal layers of spectral domain optical coherence tomography (SD-OCT) volume scans were segmented. To establish the concurrent validity of the functional test, we evaluated the fraction of variability in sCDD thresholds explained by SD-OCT data.

Results

The iAMD group had significantly worse sCDD thresholds compared with controls (8 degrees inferior retina: P = 0.004 and the 4 degrees loci: P < 0.02 for both). Elevated sCDD thresholds were observed in iAMD and RPD eyes at loci with normal scotopic thresholds; the opposite was rarely encountered. Elevated sCDD thresholds were also observed in iAMD eyes with normal DA. Elevated sCDD thresholds were associated with increased age and presence of late AMD in the fellow eye. The optimal machine learning model predicted 16% of variability (cross-validated R²) in sCDD thresholds at 8 degrees.

Discussion

A novel scotopic contour deformation task can provide unique information about rod dysfunction in participants with iAMD and RPD not observed with structural and other functional assessments. Rod dysfunction observed with scotopic contour deformation testing was associated with factors linked to risk of AMD progression.

Dark Adaptation and Its Role in Age-Related Macular Degeneration

Dark adaptation (DA) refers to the slow recovery of visual sensitivity in darkness following exposure to intense or prolonged illumination, which bleaches a significant amount of the rhodopsin. This natural process also offers an opportunity to understand cellular function in the outer retina and evaluate for presence of disease. How our eyes adapt to darkness can be a key indicator of retinal health, which can be altered in the presence of certain diseases, such as age-related macular degeneration (AMD). A specific focus on clinical aspects of DA measurement and its significance to furthering our understanding of AMD has revealed essential findings underlying the pathobiology of the disease. The process of dark adaptation involves phototransduction taking place mainly between the photoreceptor outer segments and the retinal pigment epithelial (RPE) layer. DA occurs over a large range of luminance and is modulated by both cone and rod photoreceptors. In the photopic ranges, rods are saturated and cone cells adapt to the high luminance levels. However, under scotopic ranges, cones are unable to respond to the dim luminance and rods modulate the responses to lower levels of light as they can respond to even a single photon. Since the cone visual cycle is also based on the Muller cells, measuring the impairment in rod-based dark adaptation is thought to be particularly relevant to diseases such as AMD, which involves both photoreceptors and RPE. Dark adaptation parameters are metrics derived from curve-fitting dark adaptation sensitivities over time and can represent specific cellular function. Parameters such as the cone-rod break (CRB) and rod intercept time (RIT) are particularly sensitive to changes in the outer retina. There is some structural and functional continuum between normal aging and the AMD pathology. Many studies have shown an increase of the rod intercept time (RIT), i.e., delays in rod-mediated DA in AMD patients with increasing disease severity determined by increased drusen grade, pigment changes and the presence of subretinal drusenoid deposits (SDD) and association with certain morphological features in the peripheral retina. Specifications of spatial testing location, repeatability of the testing, ease and availability of the testing device in clinical settings, and test duration in elderly population are also important. We provide a detailed overview in light of all these factors.

Full-field Electroretinography Changes Associated with Age-related Macular Degeneration: A Systematic Review with Meta-Analyses

BACKGROUND

To systematically review the literature and to perform meta-analyses on full-field electroretinography (ffERG) between healthy controls and age-related macular degeneration (AMD) to map the extent of retinal dysfunction.

SUMMARY

We systematically searched 11 databases on 3 March 2021. Eligible studies had to measure retinal function using ffERG in eyes with AMD and in healthy controls. We extracted data on a-wave and b-wave function in dark- and light-adapted ffERG, and calculated summary estimates on differences between eyes with AMD and controls using weighted mean differences (WMD). Subgroup analyses were made for early and late AMD. Six studies (n=481 eyes) were eligible for review (301 with any AMD, 180 controls). For dark-adapted data, any AMD was associated with reduced a-wave amplitude (WMD: -17.16 µV; 95% CI: -31.79 to -2.52 µV; P=0.02) and b-wave amplitude (WMD: -28.70 µV; 95% CI: -51.40 to -6.01 µV; P=0.01). For light-adapted data, any AMD was associated with longer a-wave implicit time (WMD: 0.92 ms; 95% CI: 0.12 to 1.72 ms; P=0.02), reduced b-wave amplitude (WMD: -13.26 µV; 95% CI: -18.64 to -7.88 µV; P<0.0001), and longer b-wave implicit time (WMD: 0.69 ms; 95% CI: 0.30 to 1.08 ms; P=0.0006). Subgroup analyses found that these changes were only statistically significant in eyes with late AMD, not early AMD. Key messages: Reduced retinal function on ffERG is present in eyes with AMD, in particular those with late AMD. These findings suggest that AMD is a pan-retinal disease with AMD-associated photoreceptor dysfunction beyond the macula.

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.

Scotopic thresholds on dark-adapted chromatic perimetry in healthy aging and age-related macular degeneration

To evaluate the effect of aging, intra- and intersession repeatability and regional scotopic sensitivities in healthy and age-related macular degeneration (AMD) eyes. Intra- and intersession agreement and effect of age was measured in healthy individuals. The mean sensitivity (MS) and pointwise retinal sensitivities (PWS) within the central 24° with 505 nm (cyan) and 625 nm (red) stimuli were evaluated in 50 individuals (11 healthy and 39 AMD eyes). The overall intra- and intersession had excellent reliability (intraclass correlation coefficient, ICC > 0.90) and tests were highly correlated (Spearman r_s = 0.75-0.86). Eyes with subretinal drusenoid deposit (SDD) had reduced PWS centrally, particularly at inferior and nasal retinal locations compared with controls and intermediate AMD (iAMD) without SDD. There was no difference in MS or PWS at any retinal location between iAMD without SDD and healthy individuals nor between iAMD with SDD and non-foveal atrophic AMD groups. Eyes with SDD have reduced rod function compared to iAMD without SDD and healthy eyes, but similar to eyes with non-foveal atrophy. Our results highlight rod dysfunction is not directly correlated with drusen load and SDD location.

Are Current Methods of Measuring Dark Adaptation Effective in Detecting the Onset and Progression of Age-Related Macular Degeneration? A Systematic Literature Review

INTRODUCTION

Dark adaptation (DA) has been proposed as a possible functional biomarker for age-related macular degeneration (AMD). In this systematic review we aim to evaluate current methodology used to assess DA in people with AMD, the evidence of precision in detecting the onset and progression of AMD, and the relationship between DA and other functional and structural measures.

METHODS

MEDLINE, EMBASE, CINAHL, AMED, PsycINFO, PsycARTICLES were searched for studies published between January 2006 and January 2020 that assessed DA in people with AMD. Details of eligible studies including study design, characteristics of study population and outcomes were recorded. All included studies underwent quality appraisal using approved critical appraisal tools. This systematic review follows PRISMA guidelines (PROSPERO registration number: CRD42019129486).

RESULTS

Forty-eight studies were eligible for inclusion, reporting a variety of instruments and protocols to assess different DA parameters. Twenty of these studies used the AdaptDx (MacuLogix, Hummelstown, PA, USA) instrument and assessed rod-intercept time (RIT). Most of these reported that RIT was delayed in people with AMD and this delay worsened with AMD severity. Four studies, involving 533 participants, reported estimates of diagnostic performance of AdaptDx to separate people with AMD from visually healthy controls. DA has been compared to other measures of visual function, patient-reported outcome measures (PROMs) and structural measures. Ten studies specifically considered evidence that the presence of certain structural abnormalities was associated with impaired DA in AMD.

CONCLUSIONS

This systematic review indicates overwhelming evidence of reasonable quality for an association between impaired DA and AMD. Data on the repeatability and reproducibility of DA measurement are sparse. There is evidence that structural abnormalities such as reticular drusen are associated with prolongation of DA time. Fewer studies have explored an association between DA and other measures of visual function or PROMs. We found no studies that had compared DA with performance-based measures.

Fundus-controlled perimetry (microperimetry): Application as outcome measure in clinical trials

Fundus-controlled perimetry (FCP, also called 'microperimetry') allows for spatially-resolved mapping of visual sensitivity and measurement of fixation stability, both in clinical practice as well as research. The accurate spatial characterization of visual function enabled by FCP can provide insightful information about disease severity and progression not reflected by best-corrected visual acuity in a large range of disorders. This is especially important for monitoring of retinal diseases that initially spare the central retina in earlier disease stages. Improved intra- and inter-session retest-variability through fundus-tracking and precise point-wise follow-up examinations even in patients with unstable fixation represent key advantages of these technique. The design of disease-specific test patterns and protocols reduces the burden of extensive and time-consuming FCP testing, permitting a more meaningful and focused application. Recent developments also allow for photoreceptor-specific testing through implementation of dark-adapted chromatic and photopic testing. A detailed understanding of the variety of available devices and test settings is a key prerequisite for the design and optimization of FCP protocols in future natural history studies and clinical trials. Accordingly, this review describes the theoretical and technical background of FCP, its prior application in clinical and research settings, data that qualify the application of FCP as an outcome measure in clinical trials as well as ongoing and future developments.

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.

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.

Longitudinal Assessment of Rod Function in Intermediate Age-Related Macular Degeneration With and Without Reticular Pseudodrusen

Purpose

To evaluate rod function longitudinally in intermediate age-related macular degeneration subjects with reticular pseudodrusen (RPD) and without RPD (AMD).

Methods

Retinal sensitivities (505 and 625 nm) during dark adaptation, at 14 locations within the central 12° macula were obtained after photobleaching at baseline and 12-month visits. Pointwise sensitivity differences between both stimuli were used to assess static rod function, while rod intercept time (RIT) and rod recovery rate (RRR) were used to evaluate dynamic function. Changes in function over time were compared between groups.

Results

A total of 23 controls, 12 AMD, and 13 RPD cases were followed-up. At baseline, the RPD group had significantly worst static and dynamic rod function compared to AMD and control groups. Static function in AMD was similar to controls. Static and dynamic function across the central 12° was consistent in controls; however, it was most impaired at 4° compared to 12° eccentricity in disease groups. Over 12 months, no AMD cases progressed clinically and static function in AMD improved (P ≤ 0.04), but remained unchanged in control and RPD groups (P ≥ 0.17). The RRR for control and RPD groups remained stable, while the AMD group deteriorated, but only at 12° (P = 0.02). The RIT was stable in AMD (P = 0.75) and RPD (P = 0.71) groups but improved in the control group (P = 0.002).

Conclusions

A decrease in RRR was detected over 12 months at 12° eccentricity in the AMD group. Evaluating changes in rod function requires testing at multiple locations including the peripheral macula.