Drusen Ooze: A Novel Hypothesis in Geographic Atrophy

Geographic atrophy in Asia

PURPOSE

Geographic atrophy (GA) is a late-stage manifestation of age-related macular degeneration associated with vision loss. Differences between Asian and non-Asian populations with GA have been reported. It is essential to understand these differences because they may reflect variations in the natural history of the disease and its underlying pathophysiology, impacting resultant future treatment strategies and clinical trial designs.

METHODS

A non-systematic search for articles published up to November 22, 2023 was performed using PubMed. Reference lists from included articles were reviewed and relevant articles manually selected and included, as well as read for background information about the topic. Only articles in English were considered for inclusion in this narrative review.

RESULTS

Although the overall prevalence of GA appears to be low across Asia and shows a male predominance, regional variability is evident. Compared with White and other non-Asian populations, Asian populations typically have more distinct but fewer drusen overall (regardless of type), smaller GA lesion size at presentation, a thicker choroid, and lower rates of bilaterality. In both Asian and non-Asian populations, certain characteristics of GA may be associated with an increased risk of fast disease progression.

CONCLUSION

The characteristics of GA in Asian populations show some similarities as well as relevant differences compared with those in White and other non-Asian populations. A better understanding of the characteristics associated with GA subphenotypes and predictors of progression will help to optimize management strategies for Asian patients with GA and improve study designs for future interventional trials.

'EarlyAMDRate': A grading instrument for OCT-based assessment of early lesions caused by age-related macular degeneration

BACKGROUND AND OBJECTIVES

Long before any signs of age-related macular degeneration (AMD) become clinically noticeable, the disease starts with accumulation of deposits of extracellular debris and formation of lesions within the outermost layers of the retina. For a reliable imaging of lesions in these early stages, optical coherence tomography (OCT) turned out to be largely preferable to colour fundus photography. However, an adequate grading instrument for Early-AMD lesions within OCT data is missing in the literature as yet. The present paper aims to fill this gap.

METHODS

'EarlyAMDRate', an instrument for OCT-based grading of Early-AMD lesions, is presented and documented. It comprises a questionnaire assessing a given lesion with respect to its relative position and interaction with the surrounding retinal layers, its brightness, special properties and state of progression (if applicable). Furthermore, the grading procedure includes a graphical masking of the lesion within the OCT image.

RESULTS

For a consecutive sample of N = 100 Early-AMD patients, the 'EarlyAMDRate' grading instrument has been applied to leading OCT scans. Examples of masked lesions and processed grading questionnaires are provided. Both raw lesion diameters and cutting sizes follow a log-normal sample distribution.

CONCLUSIONS

'EarlyAMDRate' allows for unprecedented detail of description for single Early-AMD lesions which is adequate to the precision of underlying OCT imaging. The obtained grading information allows for a tracking of single lesions and their properties over time as well as for the generation of well-differentiated metric phenotypes for description of Early-AMD.

Spontaneous Soft Drusen Regression without Atrophy and the Drusen Ooze

OBJECTIVE

To determine the incidence of spontaneous soft drusen (SD) regression without atrophy (DRwoA) in patients with intermediate or atrophic age-related macular degeneration (AMD), evaluate associated events, and offer potential explanations.

DESIGN

A retrospective review of the imaging of a consecutive series of 640 eyes from 320 patients with AMD who had ≥2 years of follow-up.

SUBJECTS

Four hundred twenty-seven eyes from 262 patients with intermediate AMD or atrophic AMD and no present or past exudative AMD.

METHODS

Retinal imaging included infrared reflectance imaging, fundus autofluorescence, spectral-domain OCT, and color fundus photography.

MAIN OUTCOME MEASURES

The outcomes included drusen regression without atrophy with integrity of the retinal pigment epithelium (RPE) and repositioning over Bruch's membrane. In addition, drusen that would collapse with atrophy (DCwA) in the same area simultaneously were named "sentinel" DCwA. The outcomes also included the reversibility of features of incomplete RPE, outer retinal atrophy (iRORA), and the areas ("halos") of DRwoA around the "sentinel" drusen.

RESULTS

Among the 427 eyes, 53 events of DRwoA were found, representing 24.17% of the eyes with SD. In 50 cases (94.33%), a "sentinel" DCwA in the vicinity was found. In 58% of the cases, a well-identifiable halo of drusen disappearance around the "sentinel" DCwA was well visible.

CONCLUSIONS

Drusen regression without atrophy is a frequently observed phenomenon linked to SD and almost invariably occurs near a "sentinel" DCwA. The coalescence of the drusen and the spatial and temporal association of the DRwoA and the DCwA strongly suggest that the drusen material of DRwoA escapes to a contiguous "sentinel" DCwA. Although the hypothesis of the disappearance of drusen material due to RPE death may explain the DCwA, it fails to account for DRwoA. Instead, the "drusen ooze" hypothesis, which posits the movement of drusen content to the subretinal space through RPE defects, may explain both the DCwA and the DRwoA. This hypothesis offers insights into the reversibility of iRORA features and suggests that therapies targeting drusen material removal before RPE disruptions could potentially prevent atrophy secondary to SD collapse.

FINANCIAL DISCLOSURE(S)

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

Assessment of optical coherence tomography biomarkers in patients with non-neovascular age-related macular degeneration (AMD) converting to exudative AMD according to the status of the fellow eye

OBJECTIVES

To compare optical coherence tomography (OCT) biomarkers in eyes converting from non-neovascular (nnAMD) to exudative age-related macular degeneration (eAMD) based on the status of fellow eye.

METHODS

Retrospective analysis of one year of pre-conversion data of fellow eyes of patients with nnAMD and eAMD which converted to eAMD, defined as converting eyes (CE) with fellow nnAMD and CE with fellow eAMD respectively. Demographics, best corrected visual acuity (BCVA), and OCT biomarkers including drusen type, iRORA/cRORA, subfoveal ellipsoid zone (SFEZ) disruption, central macular thickness (CMT), subfoveal choroidal thickness (SFCT), Haller vascular thickness (HVT) were evaluated. Chi-square and t-tests were employed, confidence interval of 95% and p < 0.05.

RESULTS

72 eyes of 72 patients were included: 31 CE with fellow nnAMD and 41 CE with fellow eAMD. Mean age was 81.8 ± 9.9 years, with 62.5% females. Subfoveal iRORA was more frequent in CE with fellow nnAMD (26%) compared to CE with fellow eAMD (6%) 44 weeks before conversion (p = 0.058). SFCT and HVT were higher in CE with fellow nnAMD compared to CE with fellow eAMD 19 weeks prior to conversion (213 ± 82 vs. 174 ± 63 µm, p = 0.052; 121 ± 44 vs. 104 ± 50 µm, p = 0.084 respectively). BCVA was significantly higher in CE with fellow eAMD compared to CE with fellow nnAMD every time frame (p < 0.05).

CONCLUSIONS

Although subtle distinctions, no significant differences were observed between the groups. Further research is needed to understand the influence of one eye's status on progression from nnAMD to eAMD in fellow eye.

Hyperreflective material in patients with non-neovascular pachychoroid disease

BACKGROUND

This study aimed to report eleven cases of non-neovascular pachychoroid disease with hyperreflective material (HRM) that occurred in Japanese patients.

METHODS

A retrospective review of data from eleven patients who had non-neovascular retinal pigment epithelium (RPE) protrusion with HRM in the neurosensory retina between March 2017 and June 2022 was conducted. Clinical examination, color fundus photography, fluorescein angiography, spectral-domain optical coherence tomography (SD-OCT), and OCT angiography data were analyzed. Main outcome measures were patient characteristics, changes in SD-OCT findings, and symptom outcomes.

RESULTS

All cases had RPE protrusion and HRM with dilated choroidal veins, which were characteristic of pachychoroid disease. However, none of the cases had macular neovascularization (MNV). In 9 eyes (81.8%), HRM improved spontaneously without intervention and resulted in alterations in RPE, referred to as pachychoroid pigment epitheliopathy (PPE) or focal choroidal excavation (FCE). In these cases, symptoms such as metamorphopsia and distortion improved without treatment. In the remaining two cases (18.2%), HRM still persisted during the follow-up period.

CONCLUSION

There are some cases of non-neovascular pachychoroid disorder with HRM, which might be a new entity of pachychoroid spectrum disease or an early stage of PPE or FCE. These cases should not be misdiagnosed as MNV, and careful observation is necessary.

The Development of Macular Atrophy in Patients with Wet Age-Related Macular Degeneration Receiving Anti-VEGF Treatment

Age-related macular degeneration (AMD) is a leading cause of blindness. Late AMD can be classified into exudative (commonly known as wet AMD [wAMD]) or dry AMD, both of which may progress to macular atrophy (MA). MA causes irreversible vision loss and currently has no approved pharmacological treatment. The standard of care for wAMD is treatment with anti-vascular endothelial growth factors (VEGF). However, recent evidence suggests that anti-VEGF treatment may play a role in the development of MA. Therefore, it is important to identify risk factors for the development of MA in patients with wAMD. For example, excessive blockade of VEGF through intense use of anti-VEGF agents may accelerate the development of MA. Patients with type III macular neovascularisation (retinal angiomatous proliferation) have a particularly high risk of MA. These patients are characterised as having a pre-existing thin choroid (age-related choroidopathy), suggesting that the choroidal circulation is unable to respond to increased VEGF expression. Evidence suggests that subretinal fluid (possibly indicative of residual VEGF activity) may play a protective role. Patients receiving anti-VEGF agents must be assessed for overall risk of MA and there is an unmet medical need to prevent the development of MA without undertreating wAMD.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Drusen ooze: Predictor for progression of dry age-related macular degeneration

BACKGROUND

To evaluate natural history of drusen ooze and its role as a predictor for progression of dry age-related macular degeneration (AMD) longitudinally.

METHODS

Multi-centric retrospective observational case series of 72 eyes (72 patients) with dry AMD with a minimum follow-up of 4 years. Drusen types were identified on volume scans on optical coherence tomography (OCT) and were characterized for occurrence of drusen ooze at baseline until last visit. Drusen ooze was defined as hyperreflective dots overlying a collapsing drusen or pseudodrusen, or hyperreflective RPE above drusen or isoreflective dots at the level of outer nuclear layer. The consequent incidence of incomplete retinal pigment epithelium and outer retinal atrophy (iRORA), complete retinal pigment epithelium and outer retinal atrophy (cRORA), and neovascular AMD (nAMD) were evaluated statistically.

RESULTS

In total, 72 eyes with a mean follow-up of 68.89 (± 25.57 months) were studied. At presentation, 11 eyes (15.3%) had a single drusen type, whereas 61 eyes (84.7%) had mixed drusen. Reticular pseudodrusen were most common (84.7%) followed by soft drusen (66.6%). Drusen ooze was seen in 47 eyes (65.2%) at presentation. The presence of drusen ooze at baseline (p < 0.01) and baseline best corrected visual acuity (BCVA) (p = 0.04) significantly correlated with development of iRORA and cRORA. In total, 14 eyes progressed from iRORA to cRORA over a mean follow up of 29.14 (± 24.33) months. Odds of progression to iRORA or cRORA were 20.3 times greater for eyes with drusen ooze at baseline (95% C.I., 4.4-94.2).

CONCLUSIONS

In dry AMD, drusen ooze is a useful sign for predicting progression to iRORA and cRORA over time.

Early Detection of Incipient Retinal Pigment Epithelium Atrophy Overlying Drusen with Fundus Autofluorescence vs. Spectral Domain Optical Coherence Tomography

Purpose

This study aims to find out which tool, fundus autofluorescence (FAF) or spectral domain optical coherence tomography (SD-OCT), is more sensitive in detecting retinal pigment epithelium (RPE) demise overlying drusen and can, therefore, help predict geographic atrophy (GA) appearance in Age-Related Macular Degeneration (AMD).

Methods

A single-site, retrospective, observational, longitudinal study was conducted. Patients with intermediate AMD (iAMD) (large (>125 μm) or intermediate (63–125 μm) drusen with hyper/hypopigmentation) with a minimum follow-up of 18 months were included. Drusen with overlying incipient RPE atrophy were identified on SD-OCT defined as choroidal hypertransmission or nascent geographic atrophy (nGA). These selected drusen were, then, traced backwards in time to determine if incipient RPE atrophy overlying drusen was observed on FAF (well-demarcated region of absence of autofluorescence) before, simultaneously, or after having detected the first signs of incipient RPE atrophy on SD-OCT. The number of drusen in which signs of incipient RPE atrophy was detected earlier using FAF or SD-OCT was compared. The time elapsed from the identification with the more sensitive method to the other was recorded and analyzed.

Results

One hundred and thirty-three drusen in 22 eyes of 22 patients were included. Of these, 112 (84.2%) drusen showed choroidal hypertransmission and 21(15.8%) nGA. Early signs of atrophy overlying drusen were found simultaneously on SD-OCT and FAF in 52 cases (39.1%, 95% CI 30.8–47.9%), earliest on FAF in 51 (38.3%, 95% CI 30.0–47.2%) and first on SD-OCT in 30 (22.6%, 95% CI 15.8–30.6%; p < 0.05). Statistically significant differences were found between both techniques (p=0.005), with FAF detecting it earlier than SD-OCT. When RPE atrophy was found first on FAF, the median time to diagnosis with SD-OCT was 6.6 months (95% CI 5.5 to 8.6), while if detection occurred earlier on SD-OCT, the median time until identification with FAF was 12.6 months (95% CI 6.0 to 23.4; p=0.0003).

Conclusions

In iAMD cases in which early atrophy overlying drusen is not detected simultaneously in FAF and SD-OCT, FAF was significantly more sensitive. Nevertheless, a multimodal approach is recommended and required to evaluate these patients.

Non-neovascular age-related macular degeneration with subretinal fluid

PURPOSE

To evaluate the various patterns of subretinal fluid (SRF) in eyes with age-related macular degeneration (AMD) in the absence of macular neovascularisation (MNV) and to assess the long-term outcomes in these eyes.

METHODS

This retrospective study included only eyes with non-neovascular AMD and associated SRF. Eyes with evidence of MNV were excluded. Spectral-domain optical coherence tomography (SD-OCT) was obtained at baseline and at follow-up, and qualitative and quantitative SD-OCT analysis of macular drusen including drusenoid pigment epithelial detachment (PED) and associated SRF was performed to determine anatomic outcomes.

RESULTS

Forty-five eyes (45 patients) were included in this analysis. Mean duration of follow-up was 49.7±36.7 months. SRF exhibited three different morphologies: crest of fluid over the apex of the drusenoid PED, pocket of fluid at the angle of a large druse or in the crypt of confluent drusen or drape of low-lying fluid over confluent drusen. Twenty-seven (60%) of the 45 eyes with fluid displayed collapse of the associated druse or drusenoid PED and 24 (53%) of the 45 eyes developed evidence of complete or incomplete retinal pigment epithelial and outer retinal atrophy.

CONCLUSION

Non-neovascular AMD with SRF is an important clinical entity to recognise to avoid unnecessary anti-vascular endothelial growth factor therapy. Clinicians should be aware that SRF can be associated with drusen or drusenoid PED in the absence of MNV and may be the result of retinal pigment epithelial (RPE) decompensation and RPE pump failure.

Quantifying Retinal Pigment Epithelium Dysmorphia and Loss of Histologic Autofluorescence in Age-Related Macular Degeneration

Purpose

Lipofuscin and melanolipofuscin organelles in retinal pigment epithelium (RPE) cells are signal sources for clinical fundus autofluorescence (AF). To elucidate the subcellular basis of AF imaging, we identified, characterized, and quantified the frequency of RPE morphology and AF phenotypes in donor eyes with age-related macular degeneration (AMD).

Methods

In 25 RPE-Bruch's membrane flat mounts from 25 eyes, we analyzed 0.4-μm z-stack epifluorescence images of RPE stained with phalloidin for actin cytoskeleton. Using a custom ImageJ plugin, we classified cells selected in a systematic unbiased fashion in six phenotypes representing increasing degrees of pathology. For each cell, area, AF intensity, and number of Voronoi neighbors were compared with phenotype 1 (uniform AF, polygonal morphology) via generalized estimating equations. We also analyzed each cell's neighborhood.

Results

In 29,323 cells, compared with phenotype 1, all other phenotypes, in order of increasing pathology, had significantly larger area, reduced AF, and more variable number of neighbors. Neighborhood area and AF showed similar, but subtler, trends. Cells with highly autofluorescent granule aggregates are no more autofluorescent than others and are in fact lower overall in AF. Pre-aggregates were found in phenotype 1. Phenotype 2, which exhibited degranulation despite normal cytoskeleton, was the most numerous nonhealthy phenotype (16.23%).

Conclusions

Despite aggregation of granules that created hyperAF aggregates within cells, overall AF on a per cell basis decreased with increasing severity of dysmorphia (abnormal shape). Data motivate further development of subcellular resolution in clinical fundus AF imaging and inform an ongoing reexamination of the role of lipofuscin in AMD.