Ultra-Widefield Imaging in Patients with Angioid Streaks Secondary to Pseudoxanthoma Elasticum

Pseudoxanthoma elasticum - Genetics, pathophysiology, and clinical presentation

Pseudoxanthoma elasticum (PXE) is an autosomal-recessively inherited multisystem disease. Mutations in the ABCC6-gene are causative, coding for a transmembrane transporter mainly expressed in hepatocytes, which promotes the efflux of adenosine triphosphate (ATP). This results in low levels of plasma inorganic pyrophosphate (PPi), a critical anti-mineralization factor. The clinical phenotype of PXE is characterized by the effects of elastic fiber calcification in the skin, the cardiovascular system, and the eyes. In the eyes, calcification of Bruch's membrane results in clinically visible lesions, including peau d'orange, angioid streaks, and comet tail lesions. Frequently, patients must be treated for secondary macular neovascularization. No effective therapy is available for treating the cause of PXE, but several promising approaches are emerging. Finding appropriate outcome measures remains a significant challenge for clinical trials in this slowly progressive disease. This review article provides an in-depth summary of the current understanding of PXE and its multi-systemic manifestations. The article offers a detailed overview of the ocular manifestations, including their morphological and functional consequences, as well as potential complications. Lastly, previous and future clinical trials of causative treatments for PXE are discussed.

Non-exudative choroidal and macular neovascularizations: An overview

Non-exudative choroidal and/or macular neovascularizations (NV) represent nowadays a common finding in different retinal disorders. The introduction of non-invasive techniques such as structural optical coherence tomography (OCT) and OCT angiography (OCTA) allowed for easy detection and follow-up of non-exudative NVs. Recognized as a distinct entity, these lesions demonstrate a high variability in terms of pathophysiology, morphology, and prognostic implications. In the absence of a consensus regarding correct classification of subtypes of non-exudative NVs, accurate management through strict follow-up strategies and prompt treatment is required. In this review we offer a comprehensive overview of the non-exudative NV spectrum in various retinal diseases aiming to provide a deeper insight into this clinical entity.

Prevalence, Features, and Outcomes of Type 1 Neovascularization in Eyes with Angioid Streaks

PURPOSE

This study aimed to delineate the characteristics, prevalence, and outcomes of neovascularization (NV), particularly aneurysmal type 1 NV, in patients with angioid streaks (AS) secondary to pseudoxanthoma elasticum (PXE), and to introduce a clinical classification based on multimodal imaging.

DESIGN

Retrospective longitudinal cohort study.

PARTICIPANTS

Eighty-five patients (168 eyes) with AS secondary to PXE at 2 tertiary referral centers.

METHODS

Data collection included demographic, medical, and ocular histories. Diagnostic methods comprised fundus photography, autofluorescence, indocyanine green angiography, OCT, and OCT angiography.

MAIN OUTCOME MEASURES

Prevalence of type 1 NV, visual acuity (VA), risk of exudation.

RESULTS

Type 1 NV was identified in 127 eyes (76%), with 85 of these (67%) showing exclusively type 1 NV. These lesions often originated around the disc, at sites of Bruch membrane dehiscences, and followed the path of AS, extending to the macula in 101 eyes (80%). Despite 65% of type 1 NV remaining nonexudative, 35% evolved into exudative over 5 years, and 11 eyes experienced midperipheral subretinal hemorrhages. Aneurysmal dilations, observed in 57% of eyes, substantially increased exudation risk (hazard ratio = 3.86, P = 0.02). Despite treatment, VA significantly deteriorated in exudative type 1 NV (P = 0.02). Type 2 NV, detected in 42 eyes (33%), often coexisted with type 1 NV and was associated with poorer visual outcomes and higher rates of macular atrophy. A classification of AS was developed, ranging from empty AS (stage 0, no NV) to advanced NV (stage 3, both type 1 and type 2 NV).

CONCLUSIONS

Type 1 NV predominates in AS. Although predominantly nonexudative, its progression correlates with substantial visual impairment, similar to the deficits observed with type 2 NV. Aneurysmal type 1 NV poses a significant exudation risk, underscoring the need for vigilant monitoring.

FINANCIAL DISCLOSURE(S)

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

Subretinal hyperreflective material in retinal and chorioretinal disorders: A comprehensive review

Subretinal hyperreflective material (SHRM) is a common and remarkable optical coherence tomography (OCT) biomarker whose importance is emerging in several retinal and chorioretinal diseases, including age-related macular degeneration, central serous chorioretinopathy, polypoidal choroidal vasculopathy, pathologic myopia, posterior uveitis, vitelliform lesions and macular dystrophies, and rarer disorders. Multimodal imaging, also thanks to the introduction of OCT angiography, allowed a deeper characterisation of SHRM components and its morphological changes after treatment, suggesting its usefulness in clinical practice. We discuss and summarize the nature, multimodal imaging characteristics, and prognostic and predictive significance of SHRM in the different retinal and choroidal disorders in which it has been described.

Bruch's Membrane Calcification in Pseudoxanthoma Elasticum: Comparing Histopathology and Clinical Imaging

Purpose

To investigate the histology of Bruch's membrane (BM) calcification in pseudoxanthoma elasticum (PXE) and correlate this to clinical retinal imaging.

Design

Experimental study with clinicopathological correlation.

Subjects and Controls

Six postmortem eyes from 4 PXE patients and 1 comparison eye from an anonymous donor without PXE. One of the eyes had a multimodal clinical image set for comparison.

Methods

Calcification was labeled with OsteSense 680RD, a fluorescent dye specific for hydroxyapatite, and visualized with confocal microscopy. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (SEM-EDX) and time-of-flight secondary ion mass spectrometry (TOF-SIMs) were used to analyze the elemental and ionic composition of different anatomical locations. Findings on cadaver tissues were compared with clinical imaging of 1 PXE patient.

Main Outcome Measures

The characteristics and topographical distribution of hydroxyapatite in BM in eyes with PXE were compared with the clinical manifestations of the disease.

Results

Analyses of whole-mount and sectioned PXE eyes revealed an extensive, confluent OsteoSense labeling in the central and midperipheral BM, transitioning to a speckled labeling in the midperiphery. These areas corresponded to hyperreflective and isoreflective zones on clinical imaging. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy and TOF-SIMs analyses identified these calcifications as hydroxyapatite in BM of PXE eyes. The confluent fluorescent appearance originates from heavily calcified fibrous structures of both the collagen and the elastic layers of BM. Calcification was also detected in an aged comparison eye, but this was markedly different from PXE eyes and presented as small snowflake-like deposits in the posterior pole.

Conclusions

Pseudoxanthoma elasticum eyes show extensive hydroxyapatite deposition in the inner and outer collagenous and elastic BM layers in the macula with a gradual change toward the midperiphery, which seems to correlate with the clinical phenotype. The snowflake-like calcification in BM of an aged comparison eye differed markedly from the extensive calcification in PXE.

Financial Disclosures

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

Subclinical Angioid Streaks with Pseudodrusen: A New Phenotype of Age-Related Macular Degeneration

INTRODUCTION

To describe subclinical angioid streaks (AS) as a frequent, peculiar age-related macular degeneration (AMD) phenotype, comparing features of eyes with subclinical AS with those of eyes with AMD without AS.

METHODS

This was a retrospective, observational study. Among a patient cohort with AMD, we selected patients without known causes for AS whose eyes showed signs of angioid streaks (AS) on structural optical coherence tomography (OCT) but not on fundus examination. Selected OCT features of AS were Bruch's membrane (BM) breaks and large BM dehiscences.

RESULTS

Among 543 eyes of 274 patients with AMD (mean ± standard deviation: 82 ± 7 years), 73 eyes of 46 patients (81 ± 7 years; p = 0.432) showed AS features on OCT (OCT AS) that were not visible on fundus examination. Estimated prevalence of subclinical age-related AS was 13.4% (95% confidence interval 10.3-16.3%) in this AMD population. Fifty-three eyes (73%) with AS features were affected by peripapillary atrophy, often with a "petaloid-like" pattern, similar to typical features of AS disease. Almost all cases (97%) presented reticular pseudodrusen (RPD), with (41%) or without (59%) drusen showing a significant difference in RPD prevalence in OCT AS eyes in comparison to AMD eyes without subclinical AS using generalized estimating equations (P < 0.001). Among the 73 subclinical AS cases, 71 were affected by late AMD (57 with macular neovascularization, 14 with geographic atrophy), showing a more advanced AMD stage in comparison with AMD eyes without subclinical AS (P < 0.001). The following OCT features were disclosed: BM breaks in 100% of cases and BM dehiscences in 37%.

CONCLUSIONS

Subclinical AS in eyes with AMD is a peculiar phenotype of the disease, with features suggesting a primary involvement of Bruch's membrane and clinical similarities with mild, late-onset pseudoxanthoma elasticum.

Towards a better understanding of non-exudative choroidal and macular neovascularization

Non-exudative macular and choroidal neovascularization (MNV and CNV) usually refers to the entity of treatment-naïve type 1 neovascularization in the absence of associated signs of exudation. Histopathological studies, dating back in the early 70s, identified the presence of non-exudative MNV, but the first clinical report of this finding was in the late 90s using indocyanine green angiography in eyes with age-related macular degeneration (AMD). With more advanced retinal imaging, there has been an ever increasing appreciation of non-exudative MNV associated with AMD and CNV with other macular disorders. However, consensus regarding the exact definition and the clinical management of this entity is lacking. Furthermore, there may be variation in the imaging features and clinical course suggesting that a spectrum of disease may exist. Herein, we review the large body of published work that has provided a better understanding of non-exudative MNV and CNV in the last decade. The prevalence, multimodal imaging features, clinical course, and response to treatment are discussed to elucidate further key insights about this entity. Based on these observations, this review also proposes a new theory about the origin and course of different sub-types of non-exudative MNV/CNV which can have different etiologies and pathways according to the clinical context of disease.

Incidence and Risk Factors of Visual Impairment in Patients with Angioid Streaks and Macular Neovascularization

OBJECTIVE

To estimate the incidence and risk factors of visual impairment and complications in eyes with macular neovascularization (MNV) because of angioid streaks (ASs).

DESIGN

Longitudinal multicenter retrospective cohort study.

SUBJECTS

Patients with AS-associated MNV treated with anti-VEGF agents and a follow-up of > 3 months.

METHODS

Clinical and MNV characteristics were collected at baseline. Visual acuity (VA) values and the presence of atrophy or fibrosis were collected at each visit.

MAIN OUTCOME MEASURES

Rate of VA change over time and associated factors; the incidence rate of moderate-to-severe visual impairment (MSVI) and blindness and hazard ratio (HR) of candidate risk factors for MSVI; the incidence rate of fibrosis and macular atrophy.

RESULTS

Overall, 84 eyes of 66 patients (39 men, 58%) with a mean (standard deviation) age of 55.7 (13.8) years were followed for a mean (standard deviation) of 67.7 (48.5) months. The median number of anti-VEGF doses per eye was 13. The average rate (95% confidence interval [CI]) of visual loss was +0.04 (0.02-0.06) logarithm of the minimum angle of resolution/year (P < 0.001); the visual loss was faster in nonnaive eyes (P = 0.007) and those with better baseline VA (P < 0.001); it was slower in eyes with pattern dystrophy-like features (P = 0.04). The incidence rates (95% CI) of MSVI and blindness were 10.4 (6.88-15)/100-eye-years and 2.33 (1.12-4.29)/100-eye-years. A higher number of injections (HR [95% CI] = 0.45 [0.19-0.94] for receiving ≥ 13 injections vs. < 13; P = 0.03) was protective against MSVI. The incidence rates (95% CI) of fibrosis and macular atrophy were 24.1 (17.5-32.3)/100-eye-years and 14.3 (10.1-19.6)/100-eye-years.

CONCLUSIONS

Eyes with MNV-related AS had a high rate of visual impairment and propensity to macular fibrosis and atrophy. A higher number of injections yielded better chances of maintaining good VA, suggesting the need for intensive treatment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

The identification of activity of choroidal neovascularization complicating angioid streaks

OBJECTIVES

To inspect the inter-reader agreement of different diagnostic modalities in identifying choroidal neovascularization (CNV) activity secondary to angioid streaks (AS) and to analyze the prevalence of subretinal hyper-reflective material (SHRM) in active CNV.

METHODS

Retrospective study of patients with AS with active CNV; optical coherence tomography (OCT), OCT angiography (OCTA), fundus fluorescein angiography (FFA), and indocyanine green angiography (ICGA) from each patient were collected. Agreement between two readers using different diagnostic modalities is presented as free-marginal kappa (k) and 95% confidence interval (CI).

RESULTS

This study included 19 eyes of 12 patients with active CNV (5 naive and 14 previously treated). Agreement among readers on CNV activity was excellent for OCT (k =0.88; 95% CI 0.71-1.00), good for FFA (k = 0.70; 95% CI 0.46-0.94) and ICGA (k = 0.58; 95% CI 0.31-0.84), and poor using OCTA (k = 0.39; 95% CI 0.11-0.68). SHRM was the most common OCT finding associated with active CNV (100%); fuzzy borders were present in 53% of SHRM cases at baseline.

CONCLUSIONS

Identification of CNV activity in AS is challenging; OCT was the best modality to inspect active CNV. The identification of SHRM contributed to recognizing active CNV. Further studies are needed to assess the role of SHRM in anticipating prognosis and guiding treatment of CNV secondary to AS.

Fundus Autofluorescence and Clinical Applications

Fundus autofluorescence (FAF) has allowed in vivo mapping of retinal metabolic derangements and structural changes not possible with conventional color imaging. Incident light is absorbed by molecules in the fundus, which are excited and in turn emit photons of specific wavelengths that are captured and processed by a sensor to create a metabolic map of the fundus. Studies on the growing number of FAF platforms has shown each may be suited to certain clinical scenarios. Scanning laser ophthalmoscopes, fundus cameras, and modifications of these each have benefits and drawbacks that must be considered before and after imaging to properly interpret the images. Emerging clinical evidence has demonstrated the usefulness of FAF in diagnosis and management of an increasing number of chorioretinal conditions, such as age-related macular degeneration, central serous chorioretinopathy, retinal drug toxicities, and inherited retinal degenerations such as retinitis pigmentosa and Stargardt disease. This article reviews commercial imaging platforms, imaging techniques, and clinical applications of FAF.

Phenotypic Features and Genetic Findings in a Cohort of Italian Pseudoxanthoma Elasticum Patients and Update of the Ophthalmologic Evaluation Score

BACKGROUND

Pseudoxanthoma elasticum (PXE) is a rare ectopic calcification genetic disease mainly caused by ABCC6 rare sequence variants. The clinical phenotype is characterized by typical dermatological, ophthalmological and cardiovascular manifestations, whose frequency and severity are differently reported in the literature.

METHODS

A retrospective study was performed on 377 PXE patients of Italian origin, clinically evaluated according to the Phenodex Index, who underwent ABCC6 biomolecular analyses. Moreover, 53 PXE patients were further characterized by in-depth ophthalmological examinations.

RESULTS

A total of 117 different ABCC6 rare sequence variants were detected as being spread through the whole gene. The severity of the clinical phenotype was dependent on age, but it was not influenced by gender or by the type of sequence variants. In-depth ophthalmological examinations focused on the incidences of coquille d'oeuf, comet lesions, pattern dystrophy-like lesions, optic disk drusen and posterior-pole atrophy. Conclusion: Given the large number of patients analyzed, we were able to better evaluate the occurrence of less frequent alterations (e.g., stroke, myocardial infarction, nephrolithiasis). A more detailed description of ophthalmological abnormalities allowed us to stratify patients and better evaluate disease progression, thus suggesting a further update of the PXE score system.

Non-exudative macular neovascularization in pseudoxanthoma elasticum

PURPOSE

To characterize morphological changes in the retina and to report the frequency and natural history of non-exudative macular neovascularization (MNV) in a cohort of pseudoxanthoma elasticum (PXE).

METHODS

A single-center, retrospective study was complemented by a cross-sectional examination. Consecutive patients with a definitive genetic and/or clinical diagnosis of PXE, visiting our department between January 2019 and December 2019, and with a minimum follow-up of 6 months were recruited. Baseline data were retrieved from each patient file. Additionally, a cross-sectional examination comprising color fundus photography, spectral-domain optical coherence tomography (SD-OCT), OCT-Angiography (OCT-A), and fundus autofluorescence was performed. The presence of typical PXE-related findings, as well as related complications, was multimodally evaluated. The prevalence and natural history of non-exudative MNV were assessed. All images were graded by two independent graders.

RESULTS

Forty-eight eyes from 24 patients (mean age 59.11 ± 18.14) with a median follow-up of 53.00 months were included. Angioid streaks and peau d'orange were observed in 46/48 and 42/48 eyes, while MNV was present in 75.00% of the cohort. The prevalence of non-exudative MNV was 33.33% (6/18). In the 2 eyes that developed exudation, time to conversion was 9.50 ± 4.95 months. No significant difference in visual acuity was found between eyes with non-exudative MNV and those with no signs of MNV.

CONCLUSION

We have shown that non-exudative MNV is a frequent finding in PXE but the majority of eyes did not develop exudation during follow-up. Our results are a clear evidence of the utility of OCT-A in the management of PXE.

Comparison Between Ultra-Widefield Pseudocolor Imaging and Indirect Ophthalmoscopy in the Detection of Peripheral Retinal Lesions

BACKGROUND AND OBJECTIVE

To systematically compare the intermodality and inter-rater agreement for indirect ophthalmoscopy and ultra-widefield (UWF) imaging in detecting peripheral retinal lesions predisposing to retinal rhegmatogenous detachment.

PATIENTS AND METHODS

In this prospective, observational, cross-sectional study, patients with a previous diagnosis of peripheral retinal lesions were enrolled. UWF pseudocolor imaging and dilated fundus examination were obtained.

RESULTS

Thirty-seven eyes (20 patients, 12 females) were enrolled. The level of inter-rater agreement was excellent in both the ophthalmoscopy-based and UWF-based assessment. The overall agreement in the UWF-based assessment was found to be Kappa = 0.874 (P < .0001). The UWF-based evaluation was demonstrated to have a sensitivity of 89.2% in detecting peripheral retinal lesions. In the sectorial analysis, the UWF-based reading had a lower sensitivity in the inferior sector.

CONCLUSION

The identification of peripheral retinal lesions with UWF imaging allowed for an accurate and reproducible assessment. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:544-549.].

Pattern dystrophy-like changes and coquille d'oeuf atrophy in elderly patients affected by pseudoxanthoma elasticum

PURPOSE

To evaluate the retinal features of elderly patients affected by pseudoxanthoma elasticum (PXE).

MATERIALS AND METHODS

This is a retrospective case series of 62 eyes of 31 elderly PXE patients (age > 50 years). Clinical data, ultra-widefield fundus imaging (color, red-free (RF), infra-red imaging (IR), fundus autofluorescence (FAF)), and OCT examinations were collected. Diagnosis was confirmed by genetic testing or skin biopsy.

RESULTS

Thirty-one patients (10 males and 21 females (mean age 61.3 years, range 50-74 years)) were included in our study. Visual acuity ranged from 20/20 Snellen equivalent to 20/200. The mean follow-up was 66.4 ± 20.7 months (range 10-88). Pattern dystrophy-like changes (PD) (52 eyes of 26 patients, 83.8%) and atrophy resembling the "diffuse trickling" pattern described in geographic atrophy were present in the majority of patients. Twenty-three eyes of 12 patients (67.6%) had peripapillary atrophy, 9 eyes of 5 patients (26.4%) macular atrophy, 6 eyes of 3 patients (17.6%) displayed posterior pole atrophy and in 6 eyes of 3 patients (17.6%), atrophy could be detected beyond the vascular arcades (mid-peripheral atrophy). End-stage atrophy covered the entire area indicated as "coquille d'oeuf" (eggshell). Choroidal neovascularization occurred in 49 eyes of 26 patients (94.2%) with PD and in 6 eyes of 3 patients (60%) without PD. Genetic examinations were available for 29 patients (29/31, 93.5%).

CONCLUSIONS

The elderly PXE patients were characterized by pattern dystrophy-like changes with more or less extensive atrophy, progressive over time, which in some cases affected the whole area of the coquille d'oeuf during the course of the disease.

Advances in imaging of uveitis

Advances in multimodal imaging have significantly contributed to the management of many uveitis diseases in recent years. The most significant developments include the use of optical coherence tomography to obtain a more accurate and reproducible assessment of ocular inflammation, the application of optical coherence tomography angiography in choroiditis and retinal vasculitis, new possibilities for studying vitritis with ultrawide field imaging, and the most recent applications of fundus autofluorescence in uveitis. In this review, we provide an overview of the most significant advances in multimodal imaging of uveitis achieved in recent years.

Peripheral Linear Streaks in Pseudoxanthoma Elasticum

The authors report a case of unilateral curvilinear streaks occurring in a patient with pseudoxanthoma elasticum. These represent a previously unreported finding in this disease, as usually found in inflammatory or infective conditions. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e292-e295.].