Longitudinal Study of Dark Adaptation as a Functional Outcome Measure for Age-Related Macular Degeneration

Topographic Measurement of the Subretinal Pigment Epithelium Space in Normal Aging and Age-Related Macular Degeneration Using High-Resolution OCT

Purpose

A micrometer scale hyporeflective band within the retinal pigment epithelium basal lamina - Bruch's membrane complex (RPE-BL-BrM) was topographically measured in aging and age-related macular degeneration (AMD).

Methods

In a prospective cross-sectional study, 90 normal eyes from 76 subjects (range = 23-90 years) and 53 dry AMD eyes from 47 subjects (range = 62-91 years) were enrolled. Isotropic volume raster scans over 6 mm × 6 mm (500 × 500 A-scans) were acquired using a high-resolution (2.7 µm axial resolution) spectral-domain optical coherence tomography (SD-OCT) prototype instrument. Six consecutive optical coherence tomography (OCT) volumes were computationally motion-corrected and fused to improve feature visibility. A boundary regression neural network was developed to measure hyporeflective band thickness. Topographic dependence was evaluated over a 6-mm-diameter Early Treatment Diabetic Retinopathy Study (ETDRS) grid.

Results

The hyporeflective band thickness map (median of 4.3 µm and 7.8 µm in normal and AMD eyes, respectively) is thicker below and radially symmetric around the fovea. In normal eyes, age-associated differences occur within 0.7 to 2.3 mm from the foveal center (P < 0.05). In AMD eyes, the hyporeflective band is hypothesized to be basal laminar deposits (BLamDs) and is thicker within the 3-mm ETDRS circle (P < 0.0002) compared with normal eyes. The inner ring is the most sensitive location to detect age versus AMD-associated changes within the RPE-BL-BrM. AMD eyes with subretinal drusenoid deposits (SDDs) have a significantly thicker hyporeflective band (P < 0.001) than those without SDDs.

Conclusions

The hyporeflective band is a quantifiable biomarker which differentiates AMD from aging. Longitudinal studies are warranted. The hyporeflective band may be a useful biomarker for risk stratification and disease progression.

Microperimetry and Structural Risk Factors on OCT in Intermediate Age-Related Macular Degeneration

PURPOSE

To determine the relationship between structural biomarkers on OCT that increase the risk of disease progression and microperimetric retinal sensitivity in patients with intermediate age-related macular degeneration (iAMD).

DESIGN

Prospective cross-sectional, observational study.

PARTICIPANTS

Forty-five eyes of 23 patients with iAMD.

METHODS

Patients underwent OCT and microperimetry. OCT scans were evaluated for the risk factors intraretinal hyperreflective foci (HRF), hyporeflectivity within drusenoid lesions (HRDL), subretinal drusenoid deposits, double-layer sign (DLS), and drusen volume. Microperimetric retinal sensitivity was analyzed with a 33-point grid covering the macula. With a novel method of determining what part of the retina corresponded to each microperimetry point, a Voronoi diagram was constructed, dividing the macula in cells consisting of the region nearer to each point than any other. The Voronoi diagram was superimposed on the OCT, making it possible to determine the point-to-point location of the OCT risk factors. Univariable and multivariable linear mixed-effect models were used for analysis.

MAIN OUTCOME MEASURES

Association between microperimetric retinal sensitivity and OCT risk factors at individual measuring points.

RESULTS

One thousand four hundred seventy-nine points of retinal sensitivity and corresponding structural area on OCT were included in this study. Retinal sensitivity was significantly decreased with presence of the OCT risk factors HRF, HRDL, DLS, and drusen volume (all P < 0.001) when analyzed with the univariable linear mixed-effect model. The multivariable model showed a significant decrease of retinal sensitivity with presence of HRF (P < 0.001), DLS (P = 0.025), and greater drusen volume (P < 0.001).

CONCLUSIONS

Presence of HRF, DLS, and greater drusen volume, all of which increase the risk of disease progression, is significantly and independently associated with decreased microperimetric retinal sensitivity in patients with iAMD.

FINANCIAL DISCLOSURE(S)

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

Local and Global Associations of Reticular Pseudodrusen in Age-Related Macular Degeneration

PURPOSE

To investigate the spatial distribution of reticular pseudodrusen (RPD) in eyes with age-related macular degeneration (AMD) and their correlation with functional measures, retinal thickness, and changes over time.

DESIGN

Longitudinal, cohort study.

PARTICIPANTS

Thirty-five participants with RPD and spectrum of AMD severity (including no AMD).

METHODS

Multimodal imaging was graded by a reading center, including evaluation of color fundus imaging to assess AMD severity scores. Reticular pseudodrusen presence on OCT volumes was confirmed on en face imaging and the RPD extent was contoured on infrared images. One study eye per participant underwent rod-mediated dark adaptation, measuring rod intercept time (RIT) at 5° and, if needed, 12° superior to the fovea.

MAIN OUTCOME MEASURES

The primary outcome was RIT and OCT thickness measures which were correlated with RPD area.

RESULTS

A total of 51 eyes had ≥ 1 visit with RPD detected (mean follow-up, 2.19 ± 2.04 years; range, 0-5 years), totaling 169 eye-based visits with RPD. Of the 51 eyes with RPD, 5 (9.8%) developed geographic atrophy and 17 (33.3%) progressed to neovascular AMD. Larger RPD areas were detected more frequently in AMD severity scores 6-7. Reticular pseudodrusen area within an eye generally increased over time. The lesion distribution showed a predilection for the superior retina, especially the outer superior subfield of the ETDRS grid, with the central subfield having least involvement. Reticular pseudodrusen area was inversely correlated with central subfield thickness and positively correlated with RIT at 5° (P = 0.001; r2 = 0.01) and 12° (P = 0.004; r2 = 0.01). Rod-mediated dark adaptation at 5° reached the test ceiling in > 85% of visits, irrespective of RPD lesion presence/absence at the test location. Retinal thickness decreased monotonically, with the central subfield demonstrating the greatest percentage change over 5 years (Δ = -5.47%).

CONCLUSIONS

In AMD, RPD involve predominantly the superior retina but can involve all ETDRS subfields and evolve over time. Eyes with RPD exhibit structural and functional impairments that can be measured beyond the boundaries of the RPD lesions, suggesting changes associated with RPD are associated with both local changes and a more widespread process.

FINANCIAL DISCLOSURES

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

Additional measures of macular function beyond visual acuity

PURPOSE

Visual function is a complex process in which external visual stimuli are interpreted. Patients with retinal diseases and prolonged follow-up times may experience changes in their visual function that are not detected by the standard visual acuity measure, as they are a result of other alterations in visual function. With the advancement of different methods to evaluate visual function, additional measurements have become available, and further standardization suggests that some methods may be promising for use in clinical trials or routine clinical practice. The objectives of this article are to review these additional measurements and to provide guidance on their application.

METHODS

The Vision Academy's membership of international retinal disease experts reviewed the literature and developed consensus recommendations for the application of additional measures of visual function in routine clinical practice or clinical trials.

RESULTS

Measures such as low-luminance visual acuity, contrast sensitivity, retinal fixation and microperimetry, and reading performance are measures which can complement visual acuity measurements to provide an assessment of overall visual function, including impact on patients' quality of life. Measures such as dark adaptation, color vision testing, binocular vision testing, visual recognition testing, and shape discrimination require further optimization and validation before they can be implemented in everyday clinical practice.

CONCLUSION

Additional measurements of visual function may help identify patients who could benefit from earlier diagnosis, detection of disease progression, and therapeutic intervention. New and additional functional clinical trial endpoints are required to fully understand the early stages of macular disease, its progression, and the response to treatment.

Evaluation of a mobile app for dark adaptation measurement in individuals with age-related macular degeneration

We present clinical evaluation of a mobile app for dark adaptation (DA) measurement in age-related macular degeneration (AMD) patients and in older adults (age > 50 years) without AMD or other retinal disorders (NV). The outcome measures were the area under dark adaptation curve (AUDAC) and the time for visual sensitivity to recover by 3 log units (TR). Larger AUDAC and TR values indicated worse DA response. The association of AUDAC with AMD was analyzed using linear regression, while time-to-event analysis was used for TR. 32 AMD patients (mean ± SD; age:72 ± 6.3 years, VA:0.09 ± 0.08 logMAR) and 25 NV subjects (mean ± sd; age:65 ± 8.7 years, VA:0.049 ± 0.07 logMAR) were measured with the app. Controlling for age, VA, and cataract severity, the AMD presence was significantly associated with higher AUDAC (β = 0.41, 95% CI 0.18-0.64, p = 0.001) and with slower sensitivity recovery (β = 0.32, 95% CI 0.15-0.69, p = 0.004). DA measurements with the app were highly correlated with those obtained with AdaptDx-an established clinical device (n = 18, ρ = 0.87, p < 0.001). AMD classification accuracy using the app was 72%, which was comparable to the 71% accuracy of AdaptDx. Our findings indicate that the mobile app provided reliable and clinically meaningful DA measurements that were strongly correlated with the current standard of care in AMD.

Reading Vision in Adults With Early and Intermediate Age-Related Macular Degeneration Under Mesopic and Photopic Conditions

Purpose

Reading is involved in various daily activities that operate under a wide range of luminance levels. Rod- and cone-mediated mesopic visual function is known to be impaired even in early/intermediate age-related macular degeneration (AMD). It remains unclear whether and to what extent mesopic reading is impaired in early/intermediate AMD. Here, we assessed differences in reading vision between photopic and mesopic conditions in early/intermediate AMD and compared their performance to those in older adults with normal macular health.

Methods

The study included 30 patients with early/intermediate AMD and 30 healthy controls. Reading performance was tested on the MNREAD iPad app under mesopic (2 cd/m2 with a neural-density filter) and photopic (220 cd/m2) conditions. Four reading indices-maximum reading speed (MRS), critical print size (CPS), reading acuity (RA), and reading accessibility index (ACC)-were obtained from the MNREAD test, yielding a function representing reading speed versus print size.

Results

Compared to photopic conditions, patients with AMD and healthy controls both exhibited noticeable decreases in reading vision under mesopic conditions (P < 0.001) despite normal photopic visual acuity. This decrease was more pronounced in AMD even after adjusting for age (P < 0.001): Under mesopic conditions, MRS and ACC decreased by 8 words per minute and 0.1, respectively; CPS and RA were enlarged by 0.27 and 0.24 logMAR, respectively.

Conclusions

Reading vision deteriorates under mesopic conditions compared to photopic conditions in early/intermediate AMD and is accentuated compared to this difference in healthy controls.

Translational Relevance

A mesopic reading test may provide a more sensitive and comprehensive assessment of a patient's reading impairment.

Choriocapillaris Impairment Is Associated With Delayed Rod-Mediated Dark Adaptation in Age-Related Macular Degeneration

Purpose

Progress toward treatment and prevention of age-related macular degeneration (AMD) requires imaging end points that relate to vision. We investigated choriocapillaris flow signal deficits (FD%) and visual function in eyes of individuals aged ≥60 years, with and without AMD.

Methods

One eye of each participant in the baseline visit of the Alabama Study on Early Age-Related Macular Degeneration 2 (ALSTAR2; NCT04112667) was studied. AMD presence and severity was determined using the Age-Related Eye Disease Study (AREDS) grading system. FD% was quantified using macular spectral domain optical coherence tomography angiography (OCTA) scans. Vision tests included rod-mediated dark adaptation (RMDA), best-corrected visual acuity, and contrast sensitivity (photopic and mesopic), and microperimetric light sensitivity (scotopic, mesopic, and photopic). Presence of subretinal drusenoid deposits (SDD) was determined using multimodal imaging.

Results

In 410 study eyes of 410 participants (mean [SD] age = 71.7 years [5.9]), FD% was higher in early AMD (mean [SD] = 54.0% [5.5], N = 122) and intermediate AMD (59.8% [7.4], N = 92), compared to normal (52.1% [5.3], N = 196) eyes. Among visual functions evaluated, RMDA showed the strongest association with FD% (r = 0.35, P < 0.0001), followed by contrast sensitivity (r = -0.22, P < 0.0001). Eyes with SDD had worse FD% (58.3% [7.4], N = 87), compared to eyes without SDD (53.4% [6.0], N = 323, P = < 0.0001).

Conclusions

Choriocapillaris FD% were associated with AMD severity and with impaired vision, especially RMDA. Reduced metabolic transport and exchange across the choriocapillaris-Bruch's membrane retinal pigment epithelium (RPE) complex, a causal factor for high-risk soft drusen formation, also may impair photoreceptor sustenance from the circulation. This includes retinoid resupply, essential to dynamic rod function.

Histology of type 3 macular neovascularization and microvascular anomalies in treated age-related macular degeneration: a case study

Purpose

To investigate intraretinal neovascularization and microvascular anomalies by correlating in vivo multimodal imaging with corresponding ex vivo histology in a single patient.

Design

A case study comprising clinical imaging from a community-based practice, and histologic analysis at a university-based research laboratory (clinicopathologic correlation).

Participants

A White woman in her 90s treated with numerous intravitreal anti-VEGF injections for bilateral type 3 macular neovascularization (MNV) secondary to age-related macular degeneration (AMD).

Methods

Clinical imaging comprised serial infrared reflectance, eye-tracked spectral-domain OCT, OCT angiography, and fluorescein angiography. Eye tracking, applied to the 2 preserved donor eyes, enabled the correlation of clinical imaging signatures with high-resolution histology and transmission electron microscopy.

Main Outcome Measures

Histologic/ultrastructural descriptions and diameters of vessels seen in clinical imaging.

Results

Six vascular lesions were histologically confirmed (type 3 MNV, n = 3; deep retinal age-related microvascular anomalies [DRAMAs], n = 3). Pyramidal (n = 2) or tangled (n = 1) morphologies of type 3 MNV originated at the deep capillary plexus (DCP) and extended posteriorly to approach without penetrating persistent basal laminar deposit. They did not enter the subretinal pigment epithelium (RPE)-basal laminar space or cross the Bruch membrane. Choroidal contributions were not found. The neovascular complexes included pericytes and nonfenestrated endothelial cells, within a collagenous sheath covered by dysmorphic RPE cells. Deep retinal age-related microvascular anomaly lesions extended posteriorly from the DCP into the Henle fiber and the outer nuclear layers without evidence of atrophy, exudation, or anti-VEGF responsiveness. Two DRAMAs lacked collagenous sheaths. External and internal diameters of type 3 MNV and DRAMA vessels were larger than comparison vessels in the index eyes and in aged normal and intermediate AMD eyes.

Conclusions

Type 3 MNV vessels reflect specializations of source capillaries and persist during anti-VEGF therapy. The collagenous sheath of type 3 MNV lesions may provide structural stabilization. If so, vascular characteristics may be useful in disease monitoring in addition to fluid and flow signal detection. Further investigation with longitudinal imaging before exudation onset will help determine if DRAMAs are part of the type 3 MNV progression sequence.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Visual outcomes of macula-involving rhegmatogenous retinal detachment in patients with and without age-related macular degeneration

BACKGROUND

The prognosis for patients with macula-off rhegmatogenous retinal detachment (RRD) and concomitant age-related macular degeneration (AMD) is not well known. The purpose of this study is to compare visual outcomes in macula-off RRD in eyes with AMD versus a group of comparison eyes without AMD.

METHODS

This was a retrospective chart review of 1149 patients. A total of 191 eyes met study criteria, 162 non-AMD eyes (controls), and 29 AMD eyes. The main outcome measure was postoperative visual acuity following pars plana vitrectomy (PPV), scleral buckle (SB), or combined PPV/SB in control eyes versus AMD eyes. This was compared using Fisher's exact test.

RESULTS

There was a statistically significant difference in postoperative visual acuity by AMD status, with those without AMD having a worse visual outcome overall (p = 0.0048). A similar percentage of AMD versus non-AMD eyes achieved vision better than 20/40. More patients in the non-AMD group achieved a final visual acuity between 20/40 and 20/200. Of patients with AMD, more had vision worse than 20/200 though 58% maintained functional vision (better than 20/200). Those without AMD had a higher frequency of Count Fingers (CF), Hand Motion (HM), Light Perception (LP), or No Light Perception (NLP) vision (p = 0.023).

CONCLUSIONS

Though postoperative visual acuity was worse overall in the non-AMD group with a higher frequency of patients having final vision of CF, HM, LP, or NLP, this is likely a function of the difference in sample size and composition between the two groups. Importantly, this study suggests AMD patients can expect similar outcomes to non-AMD patients after RRD repair. We conclude that AMD patients can achieve functional vision after RRD surgery, similar to those without AMD.

Evaluation of Cone- and Rod-Mediated Parameters in Dark Adaptation Testing as Outcome Measures in Age-Related Macular Degeneration

PURPOSE

To investigate the suitability of 6 rod- or cone-mediated dark adaptation (DA) parameters as outcome measures for clinical trials in age-related macular degeneration (AMD), including their retest reliability, association with age and disease severity, and measurable longitudinal change over time.

DESIGN

Prospective, longitudinal study (Clinicaltrials.gov: NCT01352975).

PARTICIPANTS

A total of 191 patients with AMD and older participants followed longitudinally over 5 years.

METHODS

Dark adaptation testing was performed using the AdaptDx dark adaptometer with a maximum test time of 40 minutes. A 2-part exponential-linear curve was fitted to obtain values for cone decay, cone plateau, time to rod-cone break, rod intercept time (RIT), rod adaptation rate (S2), and area under the curve. Intersession retest reliability was assessed in tests performed within 2 weeks using the Bland-Altman analysis. The relationship of DA parameters with age, AMD severity, and reticular pseudodrusen (RPD) presence was evaluated using linear mixed models.

MAIN OUTCOME MEASURES

Retest reliability, association with disease severity, and longitudinal change of 6 DA parameters.

RESULTS

A total of 1329 DA curves were analyzed. Rod intercept time was the parameter that showed the greatest reliability (intraclass correlation coefficient of 0.88) and greatest association with age, AMD severity, and RPD (marginal R² of 0.38), followed by the rod-mediated parameters area under the curve and rod-cone break. Cone plateau appeared constant at lower RIT values but increased with progressive rod dysfunction (RIT > 22.8 minutes) with a slope of 0.07 log units per 10 minutes RIT prolongation. Therefore, it might provide additional information in the advanced stages of AMD.

CONCLUSIONS

Age-related macular degeneration severity and RPD presence are each associated with large differences in multiple DA curve parameters. In addition, substantial differences in some parameters occur with age, even accounting for AMD severity and RPD status. This supports the 2-hit hypothesis of age and disease status on DA (and perhaps AMD pathophysiology itself). Of the DA parameters, RIT has the highest retest reliability, closest correlation with AMD severity and RPD, and largest longitudinal changes. This underscores the suitability of RIT as an outcome measure in clinical trials. The cone plateau increases only in advanced stages of kinetic rod dysfunction, indicating rod dysfunction preceding cone dysfunction and degeneration in the temporal sequence of pathology in AMD.

Assessment of the Classification of Age-Related Macular Degeneration Severity from the Northern Ireland Sensory Ageing Study Using a Measure of Dark Adaptation

Purpose

To assess the differences in rod-mediated dark adaptation (RMDA) between different grades of age-related macular degeneration (AMD) severity using an OCT-based criterion compared with those of AMD severity using the Beckman color fundus photography (CFP)-based classification and to assess the association between the presence of subretinal drusenoid deposits (SDDs) and RMDA at different grades of AMD severity using an OCT-based classification.

Design

Cross-sectional study.

Participants

Participants from the Northern Ireland Sensory Ageing study (Queen's University Belfast).

Methods

Complete RMDA (rod-intercept time [RIT]) data, CFP, and spectral-domain OCT images were extracted. Participants were stratified into 4 Beckman groups (omitting late-stage AMD) and 3 OCT-based groups. The presence and stage of SDDs were identified using OCT.

Main Outcome Measures

Rod-intercept time data (age-corrected).

Results

Data from 459 participants (median [interquartile range] age, 65 [59-71] years) were stratified by both the classifications. Subretinal drusenoid deposits were detected in 109 eyes. The median (interquartile range) RMDA for the Beckman classification (Beckman 0-3, with 3 being intermediate age-related macular degeneration [iAMD]) groups was 6.0 (4.5-8.7), 6.6 (4.7-10.5), 5.7 (4.4-7.4), and 13.2 (6-21.1) minutes, respectively. OCT classifications OCT0-OCT2 yielded different median (interquartile range) values: 5.8 (4.5-8.5), 8.4 (5.2-13.3), and 11.1 (5.3-20.1) minutes, respectively. After correcting for age, eyes in Beckman 3 (iAMD) had statistically significantly worse RMDA than eyes in the other Beckman groups (P ≤ 0.005 for all), with no statistically significant differences between the other Beckman groups. Similarly, after age correction, eyes in OCT2 had worse RMDA than eyes in OCT0 (P ≤ 0.001) and OCT1 (P < 0.01); however, there was no statistically significant difference between eyes in OCT0 and eyes in OCT1 (P = 0.195). The presence of SDDs was associated with worse RMDA in OCT2 (P < 0.01) but not in OCT1 (P = 0.285).

Conclusions

Eyes with a structural definition of iAMD have delayed RMDA, regardless of whether a CFP- or OCT-based criterion is used. In this study, after correcting for age, the RMDA did not differ between groups of eyes defined to have early AMD or normal aging, regardless of the classification. The presence of SDDs has some effect on RMDA at different grades of AMD severity.

Hyperreflective Foci in Age-Related Macular Degeneration are Associated with Disease Severity and Functional Impairment

PURPOSE

To analyze presence of hyperreflective foci (HRF) across different age-related macular degeneration (AMD) severities and examine its correlation with other structural and functional AMD features.

DESIGN

Longitudinal, single-center, case-control study.

PARTICIPANTS

One hundred and fifty-eight participants aged > 50 years old with varying AMD severities (including no AMD).

METHODS

Color fundus imaging was used to assess AMD severity and hyperpigmentation (PGM) presence. Subretinal drusenoid deposits (SDD) and HRF were detected on OCT volumes. The correlations of HRF with additional AMD features were evaluated using linear and logistic mixed-effects models. One study eye per participant underwent dark adaptation (DA) testing to measure rod intercept time (RIT) for structure function associations. Eyes were followed longitudinally and changes in AMD severity and RIT were measured relative to HRF presence.

MAIN OUTCOME MEASURES

The primary outcome was presence of HRF, which was compared with presence of other AMD features and DA impairment.

RESULTS

One hundred and fifty-eight participants (median baseline age of 73.1 [interquartile range (IQR) = 66-79] years) contributing 1277 eye visits were included. Hyperreflective foci (HRF) were detected more frequently in higher AMD severities. Hyperreflective-foci presence was significantly associated with PGM presence (odds ratio 832.9, P < 0.001) and SDD presence (odds ratio 9.42, P = 0.017). Eyes with HRF demonstrated significantly longer DA (median 27.1 [IQR = 16-40] minutes) than those without HRF (13.5 [10-22] minutes) but less than eyes with SDD only (40 [28-40] minutes). Highest RIT values were found in eyes with both HRF and SDD (40.0 [40-40] minutes). Age and HRF explained a similar proportion of RIT variability as age and SDD. Eyes that developed HRF demonstrated baseline RITs closer to eyes with HRF at baseline, compared with eyes that never developed HRF (29.1 [16-40], 38.5 [22-40] versus 13.1 [10-22] minutes; Kruskal-Wallis P < 0.001).

CONCLUSIONS

The progressively increased presence of HRF in higher AMD severities, and its correlation with previously associated AMD biomarkers, suggests HRF is an important OCT feature adding to the understanding of disease progression. Hyperreflective foci presence was associated with delays in DA, indicating HRF is a marker for visual cycle impairment.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosure may be found after the references.

Area under the dark adaptation curve as a reliable alternate measure of dark adaptation response

PURPOSE

Quantification of dark adaptation (DA) response using the conventional rod intercept time (RIT) requires very long testing time and may not be measurable in the presence of impairments due to diseases such as age-related macular degeneration (AMD). The goal of this study was to investigate the advantages of using area under the DA curve (AUDAC) as an alternative to the conventional parameters to quantify DA response.

METHODS

Data on 136 eyes (AMD: 98, normal controls: 38) from an ongoing longitudinal study on AMD were used. DA was measured using the AdaptDx 20 min protocol. AUDAC was computed from the raw DA characteristic curve at different time points, including 6.5 min and 20 min (default). The presence of AMD in the given eye was predicted using a logistic regression model within the leave-one-out cross-validation framework, with DA response as the predictor while adjusting for age and gender. The DA response variable was either the AUDAC values computed at 6.5 min (AUDAC6.5) or at 20 min (AUDAC20) cut-off, or the conventional RIT.

RESULTS

AUDAC6.5 was strongly correlated with AUDAC20 (β=86, p<0.001, R2=0.87). The accuracy of predicting the presence of AMD using AUDAC20 was 76%, compared with 79% when using RIT, the current gold standard. In addition, when limiting AUDAC calculation to 6.5 min cut-off, the predictive accuracy of AUDAC6.5 was 80%.

CONCLUSIONS

AUDAC can be a valuable measure to quantify the overall DA response and can potentially facilitate shorter testing duration while maintaining diagnostic accuracy.

A Clinical and Preclinical Assessment of Clinical Trials for Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness for the elderly in high-income countries. Although multivitamin antioxidant nutrients can slow the progression of intermediate "dry" or nonneovascular AMD, no treatment can halt or reverse any stage of dry disease. Multiple biologic pathways have been implicated in AMD pathobiology, including the complement pathway. These pathways have been targeted by various approaches in clinical trials. To date, no treatment has reached their prespecified primary end point in 2 phase III trials, a requirement by the US Food and Drug Administration for a new drug approval. Here, we describe perspectives on the failures and possible successes of various clinical trials that will guide further investigation. These perspectives will also discuss clinical trial design issues to consider in future investigations, and how recent insights into AMD pathobiology might both provide additional explanation for trials not reaching the prespecified primary end points and offer direction for identifying prioritized treatment targets.

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.

Visual Dysfunction and Structural Correlates in Sorsby Fundus Dystrophy

PURPOSE

To elucidate morphological determinants of rod and cone dysfunction in Sorsby fundus dystrophy (SFD), and to systematically compare visual function tests for interventional trials.

DESIGN

Prospective cross-sectional study.

METHODS

Patients with SFD (n = 16) and controls (n = 20) underwent visual function testing (best-corrected visual acuity [BCVA] and low luminance visual acuity [LLVA], contrast sensitivity, mesopic and dark-adapted (DA) fundus-controlled perimetry [FCP], rod-mediated dark adaptation [RMDA]), and multimodal imaging. Vision-related quality of life was evaluated. FCP and RMDA thresholds were analyzed using mixed models and structure-function correlation using machine learning (ML). Longitudinal data of 1 patient with high-dose vitamin A supplementation were available.

RESULTS

Although photopic BCVA was normative in SFD, LLVA was impaired (0.30 LogMAR [0.20; 0.45] vs 0.20 LogMAR [0.03; 0.28], P < .05). Scotopic visual function exhibited a delayed rod-intercept time (21 minutes [12.15; 21] vs 4.05 minutes [3.22; 5.36], P < .001), and marked DA cyan mean sensitivity loss (-11.80 dB [-3.47; -19.85]), paralleled by a reduced vision-related quality of life. ML-based structure-function correlation allowed prediction of mesopic, DA cyan, and red sensitivity with high accuracy (cross-validated mean absolute error: 4.36, 7.77, and 5.31 dB, respectively), whereas RMDA could be slowed even in the absence of fundus alterations on multimodal imaging. After high-dose vitamin A supplementation, RMDA and DA thresholds improved markedly.

CONCLUSIONS

Patients with SFD exhibit severely impaired scotopic visual function even in the absence of funduscopic alterations on multimodal imaging. In contrast to BCVA, scotopic visual function tests are suitable to quantify dysfunction in the early stages. Improvement of scotopic dysfunction after (off-label) high-dose vitamin A intake, as observed in one patient in our study, is compatible with the hypothesized local deficiency of vitamin A secondary to Bruch's membrane alterations.

Scotopic microperimetry: evolution, applications and future directions

For many inherited and acquired retinal diseases, reduced night vision is a primary symptom. Despite this, the clinical testing options for spatially resolved scotopic vision have until recently been limited. Scotopic microperimetry is a relatively new visual function test that combines two-colour perimetry with fundus-controlled perimetry performed in scotopic luminance conditions. The technique enables spatially resolved mapping of central retinal sensitivity alongside the ability to distinguish between rod and cone photoreceptor sensitivities. Two companies produce commercially available scotopic microperimeters - Nidek (Nidek Technologies Srl, Padova, Italy) and CenterVue (CenterVue S.p.A., Padova, Italy). Scotopic microperimetry is a promising technology capable of detecting changes in retinal sensitivity before changes in other measures of visual function. Scotopic microperimetry is a promising functional biomarker that has the potential as a useful clinical trial outcome measure. This review summarises the evolution and applications of scotopic microperimetry, and discusses testing options, including testing grid selection, dark-adaptation time and threshold sensitivity analyses.

Plasma Metabolomic Profiles Associated with Three-Year Progression of Age-Related Macular Degeneration

Plasma metabolomic profiles have been shown to be associated with age-related macular degeneration (AMD) and its severity stages. However, all studies performed to date have been cross-sectional and have not assessed progression of AMD. This prospective, longitudinal, pilot study analyzes, for the first time, the association between plasma metabolomic profiles and progression of AMD over a 3-year period. At baseline and 3 years later, subjects with AMD (n = 108 eyes) and controls (n = 45 eyes) were imaged with color fundus photos for AMD staging and tested for retinal function with dark adaptation (DA). Fasting plasma samples were also collected for metabolomic profiling. AMD progression was considered present if AMD stage at 3 years was more advanced than at baseline (n = 26 eyes, 17%). Results showed that, of the metabolites measured at baseline, eight were associated with 3-year AMD progression (p < 0.01) and 19 (p < 0.01) with changes in DA. Additionally, changes in the levels (i.e., between 3 years and baseline) of 6 and 17 metabolites demonstrated significant associations (p < 0.01) with AMD progression and DA, respectively. In conclusion, plasma metabolomic profiles are associated with clinical and functional progression of AMD at 3 years. These findings contribute to our understanding of mechanisms of AMD progression and the identification of potential therapeutics for this blinding disease.

The role of dark adaptation in understanding early AMD

The main aim of the paper is to discuss current knowledge on how Age Related Macular Degeneration (AMD) affects Dark Adaptation (DA). The paper is divided into three parts. Firstly, we outline some of the molecular mechanisms that control DA. Secondly, we review the psychophysical issues and the corresponding analytical techniques. Finally, we characterise the link between slowed DA and the morphological abnormalities in early AMD. Historically, DA has been regarded as too cumbersome for widespread clinical application. Yet the technique is extremely useful; it is widely accepted that the psychophysically obtained slope of the second rod-mediated phase of the dark adaptation function is an accurate assay of photoreceptor pigment regeneration kinetics. Technological developments have prompted new ways of generating the DA curve, but analytical problems remain. A simple potential solution to these, based on the application of a novel fast mathematical algorithm, is presented. This allows the calculation of the parameters of the DA curve in real time. Improving current management of AMD will depend on identifying a satisfactory endpoint for evaluating future therapeutic strategies. This must be implemented before the onset of severe disease. Morphological changes progress too slowly to act as a satisfactory endpoint for new therapies whereas functional changes, such as those seen in DA, may have more potential in this regard. It is important to recognise, however, that the functional changes are not confined to rods and that building a mathematical model of the DA curve enables the separation of rod and cone dysfunction and allows more versatility in terms of the range of disease severity that can be monitored. Examples are presented that show how analysing the DA curve into its constituent components can improve our understanding of the morphological changes in early AMD.

Comparison of Visual Function Tests in Intermediate Age-Related Macular Degeneration

Purpose

Identifying the most sensitive functional measure in intermediate age-related macular degeneration (iAMD) could help select an appropriate test for monitoring disease progression and evaluating the efficacy of novel interventions for the early stages of AMD. The purpose of the study was to determine which commonly used visual function test is the most discriminatory when comparing individuals with iAMD to normal participants.

Methods

In this prospective observational study, iAMD cases and healthy controls underwent visual function testing (best corrected visual acuity (BCVA), low luminance visual acuity (LLVA), mesopic microperimetry, dark adaptation, and scotopic perimetry following photobleach), clinical eye examination, and multimodal retinal imaging in a single study visit. The data of each functional parameter were converted into z-score so that all the parameters had a common scale to allow a direct comparison between different functional parameters.

Results

Forty-eight subjects (23 normal control, 25 iAMD) participated. Although all five parameters showed a significant reduction in function in iAMD eyes compared to controls (P ≤ 0.003), the rod intercept time (RIT) detected the greatest reduction in function followed by the scotopic sensitivity, mesopic sensitivity, BCVA, and LLVA, with the absolute mean z-score of 4.5, 2.2, 1.0, 1.0, and 1.2, respectively.

Conclusions

Among the five visual function parameters commonly used, RIT is the most discriminatory functional parameter in the early stages of AMD.

Translational Relevance

The RIT could be considered for assessing visual function and evaluating efficacy of novel interventions aimed at improving retinal function in eyes with early stages of AMD.

BASELINE PREDICTORS ASSOCIATED WITH 3-YEAR CHANGES IN DARK ADAPTATION IN AGE-RELATED MACULAR DEGENERATION

PURPOSE

To assess the relationship between baseline age-related macular degeneration (AMD) and disease stage, as well as optical coherence tomography features seen in AMD, with 3-year changes in dark adaptation (DA).

METHODS

Prospective longitudinal study including patients with AMD and a comparison group (n = 42 eyes, 27 patients). At baseline and 3 years, we obtained color fundus photographs, spectral-domain optical coherence tomography, and rod-mediated DA (20 minutes protocol). Multilevel mixed-effect models were used for analyses, with changes in rod intercept time at 3 years as the primary outcome. As some eyes (n = 11) reached the DA testing ceiling value at baseline, we used 3-year changes in area under the DA curve as an additional outcome.

RESULTS

Baseline AMD, AMD stage, and hyperreflective foci on optical coherence tomography were associated with larger changes in rod intercept time at 3 years. When change in area under the DA curve was used as an outcome, in addition to these features, the presence of retinal atrophy and drusenoid pigment epithelial detachment had significant associations. New subretinal drusenoid deposits at 3 years were also associated with more pronounced changes in rod intercept time and area under the DA curve.

CONCLUSION

Specific optical coherence tomography features are associated with DA impairments over time, which supports that structural changes predict functional loss over 3 years.

Vision through Healthy Aging Eyes

As life expectancy grows, so too will the number of people adversely affected by age. Although it is acknowledged that many conditions and diseases are associated with age, this mini-review will present a current update of the various visual changes that generally occur in healthy individuals disregarding the possible effects of illness. These alterations influence how the world is perceived and in turn can affect efficiency or the ability to perform ordinary daily tasks such as driving or reading. The most common physical developments include a decreased pupil size and retinal luminance as well as changes both in intercellular and intracellular connections within the retina along the pathway to the visual cortex and within the visual cortex. The quantity and the physical location of retinal cells including photoreceptors, ganglion and bipolar retinal cells are modified. The clarity of intraocular organs, such as the intraocular lens, decreases. These all result in common visual manifestations that include reduced visual acuity, dry eyes, motility changes, a contraction of the visual field, presbyopia, reduced contrast sensitivity, slow dark adaptation, recovery from glare, variation in color vision and a decreased visual processing speed. Highlighting these prevalent issues as well as current and possible future innovations will assist providers to formulate treatments and thereby conserve maximum independence and mobility in the modern mature population.

Impact of low luminance conditions on quality of life for the visually impaired: development of the Low Luminance Questionnaire Japanese version

PURPOSE

This study aimed to develop a Japanese version of the Low Luminance Questionnaire (LLQ-J) and to evaluate its reliability and validity.

STUDY DESIGN

Cross-sectional study.

METHODS

LLQ-J was developed by standardized methods. A total of 101 patients comprising 55 with age-related macular degeneration, 25 with glaucoma, 15 with regressed proliferative diabetic retinopathy, and 6 with retinitis pigmentosa were included in this study. The patients completed the LLQ-J and Japanese version of the visual function Questionnaire-25 (VFQ-25). Using the LLQ-J data, floor and ceiling effects were computed. To examine internal consistency, some patients completed the LLQ-J a second time 2-4 weeks later and the data were analyzed for Cronbach's alpha and intra-class correlation coefficients (ICCs). Best-corrected visual acuity (BCVA) and low luminance visual acuity (LLVA) were measured, and low-luminance deficit (LLD) was calculated. Criterion validity was also tested.

RESULTS

No ceiling or floor effects were present in the LLQ-J data. Cronbach's alfa was 0.88, and ICCs were higher than 0.70 for all subscales. Moderate to high correlation was observed between LLQ-J and VFQ-25 (p < 0.01), confirming concurrent validity. "General dim lighting" and "Peripheral vision" were significantly associated with LLVA in the better eye (p < 0.05). "Mobility", "General dim lighting" and "Peripheral vision" were significantly associated with LLD (p < 0.05). "Emotional distress" was significantly associated with BCVA in the worse eye (p < 0.05). No subscales were associated with BCVA of the better eye.

CONCLUSIONS

The LLQ-J is a valid and reliable questionnaire for assessing QOL under low luminance conditions.

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.

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

PURPOSE

To clarify the role of subretinal drusenoid deposits (SDD; pseudodrusen) in the progression of age-related macular degeneration through high-resolution histology.

METHODS

In 33 eyes of 32 donors (early age-related macular degeneration, n = 15; geographic atrophy, n = 9; neovascular age-related macular degeneration, n = 7; unremarkable, n = 2), and 2 eyes of 2 donors with in vivo multimodal imaging including optical coherence tomography, examples of SDD contacting photoreceptors were assessed.

RESULTS

Subretinal drusenoid deposits were granular extracellular deposits at the apical retinal pigment epithelium (RPE); the smallest were 4-µm wide. Outer segment (OS) fragments and RPE organelles appeared in some larger deposits. A continuum of photoreceptor degeneration included OS disruption, intrusion into inner segments, and disturbance of neurosensory retina. In a transition to outer retinal atrophy, SDD appeared to shrink, OS disappeared, inner segment shortened, and the outer nuclear layer thinned and became gliotic. Stage 1 SDD on optical coherence tomography correlated with displaced OS. Confluent and disintegrating Stage 2 to 3 SDD on optical coherence tomography and dot pseudodrusen by color fundus photography correlated with confluent deposits and ectopic RPE.

CONCLUSION

Subretinal drusenoid deposits may start at the RPE as granular, extracellular deposits. Photoreceptor OS, RPE organelles, and cell bodies may appear in some advanced deposits. A progression to atrophy associated with deposit diminution was confirmed. Findings support a biogenesis hypothesis of outer retinal lipid cycling.

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.

Full-field electroretinography in age-related macular degeneration: an overall retinal response

PURPOSE

Age-related macular degeneration (AMD) is generally considered a disease of the macula. However, recent studies show peripheral retinal lesions are prevalent in patients with AMD, indicative of a disease process that is more widespread. Full-field electroretinography (ffERG) measures an electrical response, not only from the macula, but from the entire retina. We wanted to study the ffERG response in eyes with AMD.

METHODS

We performed full-field electroretinography (RETI-port/scan 21, Roland, Berlin) in 13 patients with early AMD, 25 patients with late AMD and 24 individuals without vitreoretinal disease as a control group. Dawson-Trick-Litzkow fibre electrodes were used. Statistical analysis was performed and a p-value <0.05 was considered significant.

RESULTS

After adjusting for multiple comparisons, both the light-adapted 3.0 a-wave implicit time (p < 0.001) and 30-Hertz flicker peak time (p = 0.012) showed significant difference between patients with late AMD and individuals without vitreoretinal disease. There was a significant difference in the light-adapted 3.0 a-wave implicit time (p = 0.011) between patients with early AMD and the control group, but the difference in 30 Hz flicker peak time was not significant (p = 0.256).

CONCLUSION

The difference in cone function measured by light-adapted 3.0 a-wave implicit time and 30-Hertz flicker peak time in early and late AMD when compared to healthy controls suggests a more diminished overall response when AMD has reached later stages.

Relationship Between Choriocapillaris Flow and Scotopic Microperimetry in Early and Intermediate Age-related Macular Degeneration

PURPOSE

To evaluate the correlation between choriocapillaris (CC) flow alterations and scotopic macular sensitivity (sMS) in patients with early and intermediate age-related macular degeneration (AMD).

DESIGN

Prospective cross-sectional study.

METHODS

We acquired 2 3 × 3 mm and 2 6 × 6 mm swept-source optical coherence tomography angiography (OCTA) images of 1 eye of consecutive early or intermediate AMD patients at the Doheny UCLA Eye Centers. After 30 minutes of dark adaptation, the same eye underwent scotopic microperimetry with an 18-degree-wide grid (52 stimuli) centered on the fovea. The 2 en face CC angiograms obtained from each scan pattern were compensated for signal loss and averaged. The main outcome measures were correlation between percentages of flow deficits (FD_3mm and FD_6mm) and sMS in the central 10° (MS₁₀) and the overall pattern (MS₁₈).

RESULTS

Thirty eyes of 30 patients were enrolled, with 14 (46.7%) having subretinal drusenoid deposits (SDD). In the averaged OCTA scans, the FD_3mm was 12.56% ± 2.41% while the FD_6mm was 9.33% ± 1.84%. The mean MS₁₀ and MS₁₈ were 13.84 ± 5.89 dB and 14.64 ± 5.21 dB, respectively. For the MS_10, the multivariate regression analysis showed a significant association only with FD_3mm (β: -0.628, P < .001) while the MS₁₈ was significantly correlated with both SDD (β: -0.32, P = .047) and FD_6mm (β: -0.473, P = .005).

CONCLUSIONS

Our study reports a significant correlation between the CC flow impairment and the sMS in eyes with early or intermediate AMD. If replicated in future longitudinal studies, the choriocapillaris FD may prove to be a useful parameter for evaluating the functional status and prognosis of these eyes.

Exploring a Structural Basis for Delayed Rod-Mediated Dark Adaptation in Age-Related Macular Degeneration Via Deep Learning

Purpose

Delayed rod-mediated dark adaptation (RMDA) is a functional biomarker for incipient age-related macular degeneration (AMD). We used anatomically restricted spectral domain optical coherence tomography (SD-OCT) imaging data to localize de novo imaging features associated with and to test hypotheses about delayed RMDA.

Methods

Rod intercept time (RIT) was measured in participants with and without AMD at 5 degrees from the fovea, and macular SD-OCT images were obtained. A deep learning model was trained with anatomically restricted information using a single representative B-scan through the fovea of each eye. Mean-occlusion masking was utilized to isolate the relevant imaging features.

Results

The model identified hyporeflective outer retinal bands on macular SD-OCT associated with delayed RMDA. The validation mean standard error (MSE) registered to the foveal B-scan localized the lowest error to 0.5 mm temporal to the fovea center, within an overall low-error region across the rod-free zone and adjoining parafovea. Mean absolute error (MAE) on the test set was 4.71 minutes (8.8% of the dynamic range).

Conclusions

We report a novel framework for imaging biomarker discovery using deep learning and demonstrate its ability to identify and localize a previously undescribed biomarker in retinal imaging. The hyporeflective outer retinal bands in central macula on SD-OCT demonstrate a structural basis for dysfunctional rod vision that correlates to published histopathologic findings.

Translational Relevance

This agnostic approach to anatomic biomarker discovery strengthens the rationale for RMDA as an outcome measure in early AMD clinical trials, and also expands the utility of deep learning beyond automated diagnosis to fundamental discovery.

Relationship of Topographic Distribution of Geographic Atrophy to Visual Acuity in Nonexudative Age-Related Macular Degeneration

PURPOSE

To investigate the topographic distribution of geographic atrophy (GA) and to identify an anatomic endpoint that correlates with visual acuity (VA) in eyes with GA.

DESIGN

Retrospective analysis of a multicenter, prospective, randomized controlled trial.

PARTICIPANTS

The Age-Related Eye Disease Study participants with GA secondary to nonexudative age-related macular degeneration.

METHODS

We manually delineated GA on 1654 fundus photographs of 365 eyes. We measured GA areas in 9 subfields on the Early Treatment Diabetic Retinopathy Study (ETDRS) grid and correlated them with VA via a mixed-effects model. We determined the optimal diameter for the central zone by varying the diameter from 0 to 10 mm until the highest r² between GA area in the central zone and VA was achieved. We estimated the VA decline rate over 8 years using a linear mixed model.

MAIN OUTCOME MEASURES

Geographic atrophy area in macular subfields and VA.

RESULTS

The percentage of area affected by GA declined as a function of retinal eccentricity. GA area was higher in the temporal than the nasal region (1.30 ± 1.75 mm² vs. 1.10 ± 1.62 mm²; P = 0.005) and in the superior than the inferior region (1.26 ± 1.73 mm² vs. 1.03 ± 1.53 mm²; P < 0.001). Total GA area correlated poorly with VA (r² = 0.07). Among GA areas in 9 subfields, only GA area in the central zone was associated independently with VA (P < 0.001). We determined 1 mm as the optimal diameter for the central zone in which GA area correlated best with VA (r² = 0.45). On average, full GA coverage of the central 1-mm diameter zone corresponded to 34.8 letters' decline in VA. The VA decline rate was comparable between eyes with initial noncentral and central GA before GA covered the entire central 1-mm diameter zone (2.7 letters/year vs. 2.8 letters/year; P = 0.94).

CONCLUSIONS

The prevalence of GA varies significantly across different macular regions. Although total GA area was associated poorly with VA, GA area in the central 1-mm diameter zone was correlated significantly with VA and may serve as a surrogate endpoint in clinical trials.

Drusenoid pigment epithelial detachment volume is associated with a decrease in best-corrected visual acuity and central retinal thickness: the Norwegian Pigment Epithelial Detachment Study (NORPED) report no. 1

PURPOSE

To investigate the association of drusenoid pigment epithelial detachment (DPED) volume and change in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) during the growth phase of large DPEDs.

METHODS

Patients from an ongoing prospective observational study, the Norwegian Pigment Epithelial Detachment Study (NORPED), with 1 year of follow-up and DPEDs ≥1000 µm in diameter, examined with the Heidelberg Spectralis HRA-OCT were included. Patients with DPEDs in the regression phase were excluded. Multicolour, near-infrared reflectance, optical coherence tomography (OCT) and OCT angiography images were obtained every 6 months. Fluorescein angiography and indocyanine green angiography were performed at baseline and yearly to exclude choroidal neovascularization (CNV).

RESULTS

Forty-four patients and 66 eyes were included. In the statistical model for BCVA, every 1.0 mm³ increase in DPED volume led to a decrease in BCVA of 4.0 ETDRS letters (95% CI, -7.0 to -1.0, p = 0.008). A decrease in BCVA was significantly associated with older patient age, the presence of acquired vitelliform lesions and subfoveal location of the DPEDs. In the model for CRT, every 1.0 mm³ increase in DPED volume led to a decrease in CRT of 26.7 µm (95% CI, -44.4 to -9.0, p = 0.003). Two eyes had progression of geographic atrophy and none developed CNV.

CONCLUSION

The increasing volume of DPEDs during the growth phase is associated with a decrease in BCVA and CRT. The subfoveal location of DPEDs and the presence of acquired vitelliform lesions appear to be associated with a further reduction in BCVA.

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.

Functionally validated imaging endpoints in the Alabama study on early age-related macular degeneration 2 (ALSTAR2): design and methods

Background

Age-related macular degeneration (AMD), a leading cause of irreversible vision impairment in the United States and globally, is a disease of the photoreceptor support system involving the retinal pigment epithelium (RPE), Bruch’s membrane, and the choriocapillaris in the setting of characteristic extracellular deposits between outer retinal cells and their blood supply. Research has clearly documented the selective vulnerability of rod photoreceptors and rod-mediated (scotopic) vision in early AMD, including delayed rod-mediated dark adaptation (RMDA) and impaired rod-mediated light and pattern sensitivity. The unifying hypothesis of the Alabama Study on Early Macular Degeneration (ALSTAR2) is that early AMD is a disease of micronutrient deficiency and vascular insufficiency, due to detectable structural changes in the retinoid re-supply route from the choriocapillaris to the photoreceptors. Functionally this is manifest as delayed rod-mediated dark adaptation and eventually as rod-mediated visual dysfunction in general.

Methods

A cohort of 480 older adults either in normal macular health or with early AMD will be enrolled and followed for 3 years to examine cross-sectional and longitudinal associations between structural and functional characteristics of AMD. Using spectral domain optical coherence tomography, the association between (1) subretinal drusenoid deposits and drusen, (2) RPE cell bodies, and (3) the choriocapillaris’ vascular density and rod- and cone-mediated vision will be examined. An accurate map and timeline of structure-function relationships in aging and early AMD gained from ALSTAR2, especially the critical transition from aging to disease, will identify major characteristics relevant to future treatments and preventative measures.

Discussion

A major barrier to developing treatments and prevention strategies for early AMD is a limited understanding of the temporal interrelationships among structural and functional characteristics while transitioning from aging to early AMD. ALSTAR2 will enable the development of functionally valid, structural biomarkers for early AMD, suitable for use in forthcoming clinical trials as endpoint/outcome measures. The comprehensive dataset will also allow hypothesis-testing for mechanisms that underlie the transition from aging to AMD, one of which is a newly developed Center-Surround model of cone resilience and rod vulnerability.

Trial registration

ClinicalTrials.gov Identifier NCT04112667, October 7, 2019.

Hyperreflective Foci and Specks Are Associated with Delayed Rod-Mediated Dark Adaptation in Nonneovascular Age-Related Macular Degeneration

PURPOSE

Hyperreflective foci (HRF) are OCT biomarkers for the progression of nonneovascular age-related macular degeneration (AMD) attributed to anteriorly migrated retinal pigment epithelial cells. We examined associations between rod- and cone-mediated vision and HRF plus smaller hyperreflective specks (HRS); we identified a histologic candidate for HRS.

DESIGN

Cross-sectional study and histologic survey.

PARTICIPANTS

Patients with healthy maculae (n = 34), early AMD (n = 26), and intermediate AMD (n = 41).

METHODS

AMD severity was determined by color fundus photography. In OCT scans, HRF and HRS were counted manually. Vision tests probed cones (best-corrected visual acuity [VA], contrast sensitivity), mixed cones and rods (low-luminance VA, low-luminance deficit, mesopic light sensitivity), or rods (scotopic light sensitivity, rod-mediated dark adaptation [RMDA]). An online AMD histopathologic resource was reviewed.

MAIN OUTCOME MEASURES

Vision in eyes assessed for HRF and HRS; histologic candidate for HRS.

RESULTS

In 101 eyes of 101 patients, HRF and HRS were identified in 25 and 95 eyes, respectively, with good reliability. Hyperreflective foci were present but sparse in healthy eyes, infrequent in early AMD eyes, and frequent but highly variable among intermediate AMD eyes (mean±standard deviation [SD] number per eye, 0.1 ± 0.2, 0.2 ± 0.5, and 1.9 ± 3.4 for healthy, early AMD, and intermediate AMD eyes, respectively). Hyperreflective specks outnumbered HRF in all groups (mean±SD, 4.5 ± 3.2, 6.3 ± 5.8, and 19.4 ± 22.4, respectively). Delayed RMDA was associated strongly with more HRF and HRS (P < 0.0001). Hyperreflective foci also were associated with worse low-luminance VA (P = 0.0117). Hyperreflective specks were associated with worse contrast sensitivity (P = 0.0278), low-luminance VA (P = 0.0010), low-luminance deficit (P = 0.0031), and mesopic (P = 0.0018) and scotopic (P < 0.0001) sensitivity. By histologic analysis, cone lipofuscin was found in outer retinal layers of 25% of healthy aged eyes.

CONCLUSIONS

Hyperreflective foci and HRS are markers of cellular activity associated with visual dysfunction, especially delayed RMDA, an AMD risk indicator assessing efficiency of retinoid resupply. Hyperreflective specks may represent lipofuscin translocating inwardly within cones. HRF and HRS may serve as structural end points in clinical trials targeting AMD stages earlier than atrophy expansion. These results should be confirmed in a larger sample.

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.

Peripheral Retinal Lesions in Eyes with Age-Related Macular Degeneration Using Ultra-Widefield Imaging: A Systematic Review with Meta-analyses

TOPIC

Age-related macular degeneration (AMD) is highly prevalent among the elderly. We systematically reviewed the literature to provide an overview of ultra-widefield imaging (UWFI) of peripheral retinal lesions in AMD.

CLINICAL RELEVANCE

Information regarding retinal characteristics and prevalence of AMD is based mainly on studies using color photography of the central retina, where early and potentially severe manifestations of the disease are found. However, this approach has the effect of neglecting the periphery. Studies using UWFI provide new evidence to show that clinical features associated with AMD are not exclusive to the area of the macula.

METHODS

Eligible studies had to detect lesions of the peripheral retina (based on the original definition of a standard macular grid, with the addition of 2 zones classed as peripheral) using UWFI in eyes with AMD. Ultra-widefield imaging included pseudocolor photography, fundus autofluorescence, fluorescein angiography, and indocyanine green angiography. Eligibility was restricted to human participants and studies written in English. We searched the bibliographic databases PubMed, the Cochrane Library, EMBASE, and the Web of Science on March 27, 2018. We calculated the prevalence of peripheral findings in eyes with AMD and performed similar meta-analyses on the healthy control group. A random-effects model was used because of possible study heterogeneity.

RESULTS

Twelve studies were eligible for the review, which included 3261 or more eyes. Studies were clinic based, apart from 1 study that was a random population sample of individuals 62 years of age or older. Studies were cross-sectional in nature, apart from 1 case-control study. The peripheral lesions most commonly observed were drusen, atrophy, and changes to the retinal pigment epithelium. In eyes with AMD, peripheral lesions were found in 82.7% of eyes (confidence interval, 78.4%-86.7%) compared with 33.3% of healthy eyes (confidence interval, 28.3%-38.5%).

CONCLUSIONS

Peripheral changes were found to be highly prevalent in eyes with AMD, supporting the claim that the disease is panretinal and not macula only. The clinical significance of peripheral lesions in AMD remains incompletely understood, and therefore, further UWFI studies are recommended.