Pigmentary abnormality without significant drusen as a risk factor for late age-related macular degeneration

Retinal Pigment Epithelium Curvature Can Predict Late Age-Related Macular Degeneration

Purpose

Outer retinal band integrity strongly predicts late age-related macular degeneration (AMD). However, it is often assessed subjectively as "continuity" using inconsistent definitions. Alternatively, "curvature" of the outer retinal bands is a quantitative metric that strongly correlates with AMD biomarkers and can screen for intermediate AMD. We evaluated the prognostic ability of retinal pigment epithelium (RPE) and ellipsoid zone (EZ) curvature for late AMD against outer retinal band continuity, pigmentary abnormalities, reticular pseudodrusen, and drusen volume.

Methods

Consecutive patients with intermediate AMD who progressed to late AMD (n = 17) or remained stable (n = 42) were recruited. RPE and EZ curvature were quantified as a ratio of their lengths over Bruch's membrane using the sinuosity method of assessing river curvature, where a ratio of ∼1 indicates no outer retinal pathology. RPE, EZ, and Bruch's membrane were manually segmented and their lengths automatically extracted. The primary outcomes were outer retinal sinuosity and the odds ratio of predicting late AMD.

Results

Mean follow-up time for progressors and nonprogressors was 4.4 and 3.6 years. RPE sinuosity was strongly associated with pigmentary abnormalities (P = 0.001) and drusen volume (P = 0.004) but not reticular pseudodrusen (P = 0.28). RPE sinuosity >1.03 was the strongest predictor of late AMD developing within 5 years (15 [2.9-75]) and across the study period (25 [2.3-282]). Drusen volume >0.03 mm3 was the strongest predictor of progression within 2 years (33 [2.5-426]), and RPD could not independently predict progression within any time frame.

Conclusions

RPE curvature is a promising, quantitative outer retinal biomarker that can prognosticate late AMD and potentially enhance prognostic models.

Predict and Protect: Evaluating the Double-Layer Sign in Age-Related Macular Degeneration

INTRODUCTION

Advanced age-related macular degeneration (AMD) is a major cause of vision loss. Therefore, there is interest in precursor lesions that may predict or prevent the onset of advanced AMD. One such lesion is a shallow separation of the retinal pigment epithelium (RPE) and Bruch's membrane (BM), which is described by various terms, including double-layer sign (DLS).

METHODS

In this article, we aim to examine and clarify the different terms referring to shallow separation of the RPE and BM. We also review current evidence on the outcomes associated with DLS: firstly, whether DLS is predictive of exudative neovascular AMD; and secondly, whether DLS has potential protective properties against geographic atrophy.

RESULTS

The range of terms used to describe a shallow separation of the RPE and BM reflects that DLS can present with different characteristics. While vascularised DLS appears to protect against atrophy but can progress to exudation, non-vascularised DLS is associated with an increased risk of atrophy. Optical coherence tomography (OCT) angiography (OCTA) is the principal method for identifying and differentiating various forms of DLS. If OCTA is unavailable or not practically possible, simplified classification of DLS as thick or thin, using OCT, enables the likelihood of vascularisation to be approximated. Research is ongoing to automate DLS detection by applying deep-learning algorithms to OCT scans.

CONCLUSIONS

The term DLS remains applicable for describing shallow separation of the RPE and BM. Detection and classification of this feature provides valuable information regarding the risk of progression to advanced AMD. However, the appearance of DLS and its value in predicting AMD progression can vary between patients. With further research, individualised risks can be confirmed to inform appropriate treatment.

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.

OCT Prognostic Biomarkers for Progression to Late Age-related Macular Degeneration: A Systematic Review and Meta-analysis

TOPIC

To evaluate which OCT prognostic biomarkers best predict the risk of progression from early/intermediate to late age-related macular degeneration (AMD).

CLINICAL RELEVANCE

Among > 100 OCT prognostic biomarkers for AMD, it is unclear which are the most relevant for clinicians and researchers to focus on. This review evaluated which OCT biomarkers confer the greatest magnitude of prediction for progression to late AMD.

METHODS

Study protocol was registered on PROSPERO (CRD42023400166). PubMed and Embase were searched from inception to March 2, 2023, and eligible studies assessed following the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was any quantified risk of progression from treatment-naive early/intermediate AMD to late AMD, including hazard ratios (HRs), odds ratios (ORs), and standardized mean differences (at baseline, between eyes with versus without progression), subgrouped by each OCT biomarker. Further meta-analyses were subgrouped by progression to geographic atrophy or neovascularization.

RESULTS

A total of 114 quantified OCT prognostic biomarkers were identified. With high GRADE certainty of evidence, the greatest magnitudes of prediction to late AMD belonged to: external limiting membrane abnormality (OR, 15.42 [7.63, 31.17]), ellipsoid zone abnormality (OR, 10.8 [4.58, 25.46]), interdigitation zone abnormality (OR, 7.68 [2.57, 23]), concurrent large drusen and reticular pseudodrusen (HR, 6.73 [1.35, 33.65], hyporeflective drusen cores (HR, 2.48 [1.8, 3.4]; OR 1.85 [1.29, 2.66]), intraretinal hyperreflective foci (IHRF; HR, 2.16 [0.92, 5.07]; OR 5.08 [3.26, 7.92]), and large drusen (HR, 2.01 [1.35, 2.99]); OR, 1.98 [1.27, 3.08]). There was greater risk of geographic atrophy for IHRF and hyporeflective drusen cores (P < 0.05), and neovascularization for ellipsoid zone abnormality (P < 0.05). Other OCT biomarkers such as drusenoid pigment epithelium detachment, shallow irregular retinal pigment epithelium elevations, and nascent geographic atrophy exhibited large magnitudes of risk but required further studies for validation.

CONCLUSION

This review synthesizes the 6 most relevant OCT prognostic biomarkers for AMD with greater predictive ability than large drusen alone, for clinicians and researchers to focus on. Further study is required to validate other biomarkers with less than high certainty of evidence, and assess how the copresence of biomarkers may affect risks.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Zinc Supplementation Induced Transcriptional Changes in Primary Human Retinal Pigment Epithelium: A Single-Cell RNA Sequencing Study to Understand Age-Related Macular Degeneration

Zinc supplementation has been shown to be beneficial to slow the progression of age-related macular degeneration (AMD). However, the molecular mechanism underpinning this benefit is not well understood. This study used single-cell RNA sequencing to identify transcriptomic changes induced by zinc supplementation. Human primary retinal pigment epithelial (RPE) cells could mature for up to 19 weeks. After 1 or 18 weeks in culture, we supplemented the culture medium with 125 µM added zinc for one week. RPE cells developed high transepithelial electrical resistance, extensive, but variable pigmentation, and deposited sub-RPE material similar to the hallmark lesions of AMD. Unsupervised cluster analysis of the combined transcriptome of the cells isolated after 2, 9, and 19 weeks in culture showed considerable heterogeneity. Clustering based on 234 pre-selected RPE-specific genes divided the cells into two distinct clusters, we defined as more and less differentiated cells. The proportion of more differentiated cells increased with time in culture, but appreciable numbers of cells remained less differentiated even at 19 weeks. Pseudotemporal ordering identified 537 genes that could be implicated in the dynamics of RPE cell differentiation (FDR < 0.05). Zinc treatment resulted in the differential expression of 281 of these genes (FDR < 0.05). These genes were associated with several biological pathways with modulation of ID1/ID3 transcriptional regulation. Overall, zinc had a multitude of effects on the RPE transcriptome, including several genes involved in pigmentation, complement regulation, mineralization, and cholesterol metabolism processes associated with AMD.

Characteristics of Retinal Pigment Epithelium Elevations Preceding Exudative Age-Related Macular Degeneration in Japanese

INTRODUCTION

Drusen and pigmentary abnormality are found as the hallmark to predict progression of age-related macular degeneration (AMD). In Asian populations, exudative AMD often appears in the absence of drusen but is rather accompanied by pigmentary abnormality. Recently, shallow irregular retinal pigment epithelium (RPE) elevations (SIRE) have been shown as a sign of subclinical nonexudative macular neovascularization. In this study, we aimed to investigate the characteristics of optical coherence tomography (OCT) findings including SIRE before the appearance of exudative AMD.

METHODS

We retrospectively reviewed 32 cases of exudative AMD that occurred in the fellow eye within the 5-year-observation period. Color fundus photography, OCT, and fluorescein/indocyanine-green angiography at the beginning of observation and at the time when exudative AMD appeared were examined to diagnose SIRE and the subtype of exudative AMD.

RESULTS

Exudative AMD was found in 19 eyes with large drusen and 13 eyes without large drusen. Mean sub-foveal choroidal thickness without large drusen was significantly thicker than that with large drusen (336 ± 109 and 220 ± 96 μm, respectively; mean ± SD). Six eyes with pachychoroid neovasculopathy, 4 eyes with type 1 macular neovascularization, and 3 eyes with PCV had occurred in the fellow eye without large drusen. Among those, 6 eyes had been accompanied by SIRE with a greatest transverse linear dimension of 1 mm or more at the beginning of observation period. Besides, small RPE elevations with a longest diameter of less than 1 mm had been observed in other 5 eyes. Three cases of polypoidal choroidal vasculopathy had originated from small RPE elevations. Moreover, pachyvessels, choriocapillaris thinning, or choroidal hyperpermeability were observed with SIRE or small RPE elevations.

CONCLUSIONS

There is a non-drusen type of exudative AMD that originates from small RPE elevations as well as SIRE.