Choroidal changes associated with Bruch membrane pathology in 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.

Subretinal autofluorescent deposits: A review and proposal for clinical classification

Subretinal autofluorescent deposits (SADs) may be found in the posterior pole, associated with very various conditions. These disorders usually present a typical pattern of autofluorescent lesions seen on short-wavelength fundus autofluorescence. We describe SADs according to their putative pathophysiological origin and also according to their clinical pattern, i.e., number, shape, and usual location. Five main putative pathophysiological origins of SADs were identified in disorders associated with an intrinsic impairment of phagocytosis and protein transportation, with excess of retinal pigment epithelium phagocytic capacity, with direct or indirect retinal pigment epithelium injury, and/or disorders associated with long-standing serous retinal detachment with mechanical separation between the retinal pigment epithelium and the photoreceptor outer segments. Clinically, however, they could be classified into eight subclasses of SADs, as observed on fundus autofluorescence as follows: single vitelliform macular lesion, multiple roundish or vitelliform lesions, multiple peripapillary lesions, flecked lesions, leopard-spot lesions, macular patterned lesions, patterned lesions located in the same area as the causal disorder, or nonpatterned lesions. Thus, if multimodal imaging may be required to diagnose the cause of SADs, the proposed classification based on noninvasive, widely available short-wavelength fundus autofluorescence could guide clinicians in making their diagnosis decision tree before considering the use of more invasive tools.

En-Face Optical Coherence Tomography Is Useful for Assessing Striated Lesions in Angioid Streaks: A Case Report

Angioid streaks are mainly characterized by radially striated lesions around the optical disc and result in severe vision loss when choroidal neovascularization (CNV) develops at the macula. The prediction of visual prognosis in cases with angioid streaks remains an unsolved problem. In this study, we report the usefulness of en-face optical coherence tomography (OCT) to assess the bilateral striated lesions in angioid streaks. A 59-year-old female who was previously diagnosed with angioid streaks complained of decreased visual acuity in her left eye. However, on en-face OCT, the striated lesions in the right eye with better vision were shown as thicker continuous lesions than those in the left eye. Twenty-four months after the initial visit, her right visual acuity was worse than her left. En-face OCT showed fine-striated lesions extending from those thicker lesions to the macular area in the right eye. The thicker striated lesions observed at the initial visit may be a risk factor for future CNV development and vision loss. The evaluation of lesion size using en-face OCT may be useful for predicting the visual prognosis in angioid streaks.

Choriocapillaris Flow Signal Impairment in Patients With Pseudoxanthoma Elasticum

Purpose

To quantify choriocapillaris flow alterations in patients with pseudoxanthoma elasticum (PXE) in pre-atrophic stages and its association with structural changes of the choroid and outer retina.

Methods

Thirty-two eyes of 21 patients with PXE and 35 healthy eyes of 35 controls were included. The density of choriocapillaris flow signal deficits (FDs) was quantified on 6 × 6-mm optical coherence tomography angiography (OCTA) images. Spectral-domain optical coherence tomography (SD-OCT) images were analyzed for thicknesses of the choroid and outer retinal microstructure and correlated with choriocapillaris FDs in the respective Early Treatment Diabetic Retinopathy Study subfield.

Results

The multivariable mixed model analysis for choriocapillaris FDs revealed significantly higher FDs associated with the group (PXE patients vs. controls +13.6; 95% confidence interval [CI] 9.87-17.3; P < 0.001), with increasing age (+0.22% per year; 95% CI 0.12-0.33; P < 0.001), and with retinal location (significantly higher FDs in nasal compared to temporal subfields). Choroidal thickness (CT) did not differ significantly between both groups (P = 0.078). The CT and choriocapillaris FDs were inversely correlated (-1.92 µm per %FDs; interquartile range -2.81 to -1.03; P < 0.001). Larger values of the choriocapillaris FDs were associated with significant thinning of the overlying photoreceptor layers (outer segments: -0.21 µm per %FDs, P < 0.001; inner segments: -0.12 µm per %FDs, P = 0.001; outer nuclear layer: -0.72 µm per %FDs; P < 0.001).

Conclusions

Patients with PXE display significant alterations of the choriocapillaris on OCTA even in pre-atrophic stages and in the absence of significant choroidal thinning. The analysis favors choriocapillaris FDs over choroidal thickness as a potential early outcome measure for future interventional trials in PXE. Further, increased FDs in nasal compared to temporal locations mirror the centrifugal spread of Bruch's membrane calcification in PXE.

Cynomolgus monkey's choroid reference database derived from hybrid deep learning optical coherence tomography segmentation

Cynomolgus monkeys exhibit human-like features, such as a fovea, so they are often used in non-clinical research. Nevertheless, little is known about the natural variation of the choroidal thickness in relation to origin and sex. A combination of deep learning and a deterministic computer vision algorithm was applied for automatic segmentation of foveolar optical coherence tomography images in cynomolgus monkeys. The main evaluation parameters were choroidal thickness and surface area directed from the deepest point on OCT images within the fovea, marked as the nulla with regard to sex and origin. Reference choroid landmarks were set underneath the nulla and at 500 µm intervals laterally up to a distance of 2000 µm nasally and temporally, complemented by a sub-analysis of the central bouquet of cones. 203 animals contributed 374 eyes for a reference choroid database. The overall average central choroidal thickness was 193 µm with a coefficient of variation of 7.8%, and the overall mean surface area of the central bouquet temporally was 19,335 µm² and nasally was 19,283 µm². The choroidal thickness of the fovea appears relatively homogeneous between the sexes and the studied origins. However, considerable natural variation has been observed, which needs to be appreciated.

A case report: pseudoxanthoma elasticum diagnosed based on ocular angioid streaks and the curative effect of Conbercept treatment

Background

This article is a case report of pseudoxanthoma elasticum (PXE) which was diagnosed based on significant angioid streaks (AS) with choroidal neovascularization (CNV) and regain normal visual function by intravitreal injection with Conbercept.

Case presentation

A 51-year-old woman was referred to the Ophthalmology Department of Qingdao Municipal Hospital (Qingdao, China) on September 14, 2020 for metamorphopsia and loss of vision in the left eye in the preceding three days. Past history: high myopia for more than 30 years, best corrected visual acuity (BCVA) of both eyes was 1.0 (5 m Standard Logarithm Visual Acuity chart in decimal notations), hypertension for six years, and cerebral infarction two years ago, no history of ocular trauma or surgeries or similar patients in family was documented. We used methods for observation, including fundus examination, optical coherence tomography (OCT), fluorescein angiography combined with indocyanine green angiography (FFA + ICGA). Due to her symptoms and manifestations, along with the appearance of her neck skin, which resembled ‘chicken skin’, we speculated that she should be further examined at the Department of Dermatology by tissue paraffin section and molecular pathology analyses, and the diagnosis of PXE was then confirmed. After intravitreal injection with Conbercept (10 mg/ml, 0.2 ml, Chengdu Kanghong Biotechnologies Co., Ltd.; Chengdu, Sichuan, China) she regained her BCVA.

Conclusions

This patient regained her best corrected visual acuity through intravitreal injection with Conbercept. To the best of our knowledge, no publications are available on cases in which a vision loss and the normal visual function can be reverted by intravitreal injection with Conbercept. Although PXE is a disease with low incidence and thus no effective cure established, targeted symptomatic treatment can effectively retard the disease progression and improve visual function, such as intravitreal injection with Conbercept.

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.

Adaptive Optics Imaging in Patients Affected by Pseudoxanthoma Elasticum

PURPOSE

To describe the retinal findings of patients affected by pseudoxanthoma elasticum (PXE) using a multimodal imaging approach including flood-illumination adaptive optics ophthalmoscopy (AO).

DESIGN

Retrospective case series.

MATERIALS AND METHODS

Patients affected by PXE were retrospectively studied. Clinical data, color, infrared and autofluorescence fundus imaging, optical coherence tomographic scans, and AO examinations were collected. Furthermore, the photoreceptor count was assessed. PXE diagnosis was confirmed by a positive skin biopsy and/or genetic testing.

RESULTS

Twenty-one eyes of 18 patients (11 females and 7 males) were included in the study. In 3 patients, both eyes were studied. The mean age at examination was 37.7 ± 16.4 years (range 14-66) and the mean best-corrected visual acuity (BCVA) was 0.1 ± 0.2 logMAR (range 0-1). We identified 3 types of angioid streaks (AS) using AO: "crack," "band," and "hypopigmented." The first 2 were very similar and they differed in size; the third type showed specific clinical features. Comet lesions appeared as hyper-reflective round lesions on AO imaging. In all eyes, the cone mosaic appeared reduced inside the streaks compared to the neighboring areas (13,532.8 ± 1,366.5 cones/mm² vs 16,817.1 ± 1,263.0 cones/mm² respectively).

CONCLUSION

Using AO imaging in PXE-related retinopathy, we were able to observe the presence of the photoreceptors within the angioid streaks, differentiate 3 types of angioid streaks, based on size and reflective features, and identify the very small crystalline bodies not identifiable using other retinal imaging techniques.

The Natural History of Bruch’s Membrane Calcification in Pseudoxanthoma Elasticum

Purpose

To describe the natural history of Bruch’s membrane (BM) calcification in patients with pseudoxanthoma elasticum (PXE).

Design

Retrospective cohort study.

Participants

Both eyes of 120 PXE patients younger than 50 years, 78 of whom had follow-up imaging after more than 1 year.

Methods

All patients underwent multimodal imaging, including color fundus photography, near-infrared reflectance (NIR) imaging, and late phase indocyanine green angiography (ICGA). We determined the distance from the optic disc to the central and temporal border of peau d’orange on NIR, expressed in horizontal optic disc diameter (ODD). The length of the longest angioid streak was classified into 5 zones.

Main Outcome Measures

Age-specific changes of peau d’orange, angioid streaks, and ICGA hypofluorescence as surrogate markers for the extent of BM calcification.

Results

In cross-sectional analysis, longer angioid streaks were associated with increasing age (P < 0.001 for trend). The temporal border of peau d’orange showed a weak association with increasing age (β = 0.02; 95% confidence interval [CI], 0.00–0.04), whereas the central border showed a strong association (β = 0.12; 95% CI, 0.09–0.15). Longitudinal analysis revealed a median shift of the central border to the periphery of 0.08 ODD per year (interquartile range [IQR], 0.00–0.17; P < 0.001). This shift was more pronounced in patients younger than 20 years (0.12 ODD per year [IQR, 0.08–0.28]) than in patients older than 40 years (0.07 ODD per year [IQR, –0.05 to 0.15]). The temporal border did not shift during follow-up (P = 0.69). New or growing angioid streaks were detected in 39 of 156 eyes (25%). The hypofluorescent area on ICGA was visible only in the fourth or fifth decade and correlated with longer angioid streaks.

Conclusions

In PXE patients, the speckled BM calcification slowly confluences during life. The location of the temporal border of peau d’orange remains rather constant, whereas the central border shifts to the periphery. This suggests the presence of a predetermined area for BM calcification. A larger ICGA hypofluorescent area correlates with older age and longer angioid streaks, which implies that it depends on the degree of BM calcification.

Contribution of OCT angiography in angioid streaks

PURPOSE

To study the appearance of angioid streaks (AS) in swept source optical coherence tomography angiography.

METHODS

Retrospective observational study of 16 patients (31 eyes) with various stages of AS. All included patients underwent complete ophthalmologic examinations including best-corrected visual acuity (BCVA), slit-lamp examination, indirect ophthalmoscopy and fundus photography. Swept source optical coherence tomography (SS-OCT), OCT angiography (OCT-A) and fluorescein angiography were also performed.

RESULTS

En face OCT detected hyper-reflective points in 65% of cases, with a choriocapillaris (CC) shadow on the corresponding OCT-A. Diffuse CC rarefaction was detected in 94%. In eyes without neovascular complications, streaks were visible as a hyposignal in the outer retina. An irregular vascular network (IVN) was detected in 80% of eyes. It filled the spaces between the AS and corresponded to flat elevation of the retinal pigmentary epithelium. Twenty-four eyes had choroidal neovascularization (CNV). CNV was type 1 in 8%, type 2 in 43%, mixed in 20% and unclassified in 29% because of a large scar. We found multiple sites of CNV in 8% of cases. CNV shape was tangled in 66% and in 2 eyes with newly diagnosed CNV. OCT-A showed a perilesional halo around new CNV. The morphology and configuration of neovascular network follow the IVN and the path of the AS and arises in proximity to sites of BM disruption.

CONCLUSION

OCT-A allows early detection and monitoring of AS and their neovascular complications. It shows CC rarefaction, IVN and a predominantly tangled shape of CNV. However, there are some limitations associated with difficulty in characterizing signs of CNV activity.

Disruption of Abcc6 Transporter in Zebrafish Causes Ocular Calcification and Cardiac Fibrosis

Pseudoxanthoma elasticum (PXE), caused by ABCC6/MRP6 mutation, is a heritable multisystem disorder in humans. The progressive clinical manifestations of PXE are accompanied by ectopic mineralization in various connective tissues. However, the pathomechanisms underlying the PXE multisystem disorder remains obscure, and effective treatment is currently available. In this study, we generated zebrafish abcc6a mutants using the transcription activator-like effector nuclease (TALEN) technique. In young adult zebrafish, abcc6a is expressed in the eyes, heart, intestine, and other tissues. abcc6a mutants exhibit extensive calcification in the ocular sclera and Bruch's membrane, recapitulating part of the PXE manifestations. Mutations in abcc6a upregulate extracellular matrix (ECM) genes, leading to fibrotic heart with reduced cardiomyocyte number. We found that abcc6a mutation reduced levels of both vitamin K and pyrophosphate (PPi) in the serum and diverse tissues. Vitamin K administration increased the gamma-glutamyl carboxylated form of matrix gla protein (cMGP), alleviating ectopic calcification and fibrosis in vertebrae, eyes, and hearts. Our findings contribute to a comprehensive understanding of PXE pathophysiology from zebrafish models.

Is arterial stiffness in the carotid artery associated with choroidal thinning in patients with pseudoxanthoma elasticum or controls?

PURPOSE

Patients with pseudoxanthoma elasticum (PXE) develop calcification of Bruch's membrane (BM) and choroidal thinning, as well as calcification of intracranial arteries, leading to arterial stiffness. We investigated whether arterial stiffness is associated with choroidal thinning in PXE patients, besides the presumed effect of BM calcification.

METHODS

Cross-sectional study with 75 PXE patients and 40 controls. Macular choroidal thickness was measured using optical coherence tomography scans. Functional magnetic resonance imaging was used to calculate the pulsatility index (PI) of the carotid siphon as a measure of arterial stiffness. Associations between PI and choroidal thickness were investigated using linear mixed effects models adjusted for age and ocular axial length. Furthermore, we investigated choroidal thickness in relation to the presence of retinal pigment epithelium (RPE) atrophy, its topographical distribution and age.

RESULTS

Median age was 58 years (IQR 53-66) in PXE patients and 62 years (IQR 56-67) in controls (p = 0.08). Pseudoxanthoma elasticum (PXE) patients had a thinner choroid than controls (138 μm versus 248 μm, p < 0.01). No association was observed between PI and choroidal thickness in PXE patients (β = -1.6, 95% CI -59.4 to 54.5) nor in controls (β =-47.6, 95% CI -129.7 to 31.9). In PXE patients, RPE atrophy was associated with a thinner choroid (p < 0.01). Also, the nasal choroid was thinner than the temporal choroid, and choroidal thickness already decreased with age in PXE eyes without RPE atrophy.

CONCLUSION

There was no independent association between measures of arterial stiffness and choroidal thinning in PXE patients and controls. Probably, changes in BM lead to choroidal thinning in PXE.

Quantifying the Separation Between the Retinal Pigment Epithelium and Bruch's Membrane using Optical Coherence Tomography in Patients with Inherited Macular Degeneration

Purpose

To describe and quantify Bruch's membrane (BM) and retinal pigment epithelium (RPE) separation using spectral-domain (SD) optical coherence tomography (OCT) in patients affected by inherited macular degenerations associated with BM thickening.

Methods

Patients with molecularly confirmed Sorsby fundus dystrophy (SFD), dominant drusen (DD), and late-onset retinal degeneration (L-ORD) were included in this retrospective study. Each disease was classed as early stage if subjects were asymptomatic, intermediate stage if they had nyctalopia alone, and late stage if they described loss of central vision. The main outcome was measurement of BM-RPE separation on SD-OCT. The BM-RPE separation measurements were compared against those in normal age-matched controls.

Results

Seventeen patients with SFD, 22 with DD, and eight with L-ORD were included. BM-RPE separation on SD-OCT demonstrated a high test-retest and interobserver reproducibility (intraclass correlation coefficients >0.9). BM-RPE separation was not identified in normal subjects. In SFD, there was greater BM-RPE separation in late-stage disease compared with intermediate-stage patients both at subfoveal (P < 0.05) and juxtafoveal (P < 0.01) locations. In DD, there was increased BM-RPE separation in late-stage disease compared with early stage at subfoveal (P < 0.001) and juxtafoveal (P < 0.05) topographies. There was no significant difference in BM-RPE separation between disease stages in L-ORD.

Conclusions

BM-RPE separation is a novel, quantifiable phenotype in the three monogenic macular dystrophies studied, and may be an optical correlate of the histopathological thickening in BM that is known to occur. BM-RPE separation, as measured by OCT, varies with stage of disease in SFD and DD, but not in L-ORD.

Translational Relevance

SFD, DD, and L-ORD are associated with BM thickening. In this group of patients, OCT assessment of macular structure identifies a separation of the usually single, hyperreflective line thought to represent BM and the overlying RPE. This separation is a novel and quantifiable feature of disease staging in SFD and DD.

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.

Macular choroidal thickness in patients with pseudoxanthoma elasticum measured by enhanced-depth imaging spectral-domain optical coherence tomography

BACKGROUND/OBJECTIVES

To analyze macular choroidal thickness in patients with pseudoxanthoma elasticum (PXE) by enhanced depth imaging optical coherence tomography (EDI-OCT).

SUBJECTS/METHODS

This is a prospective cross-sectional study. Sixty-eight eyes of 34 patients with PXE and 68 normal eyes of 34 controls were included to study the macular area with enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). Eyes with PXE were classified in three groups: those without choroidal neovascularization (CNV) or chorioretinal macular atrophy macular (Group 1); those with active CNV (Group 2) and those with macular atrophy secondary to inactive CNV (Group 3).

RESULTS

Mean subfoveal choroidal thickness (CT) was 266.70 ± 46.93 µm in control group, 304.24 ± 65.52 µm in group 1, 198.55 ± 66.33 µm in group 2, and 119.45 ± 63.89 µm in group 3 (p = 0.00). Comparison between PXE subgroups showed that subfoveal CT was significantly decreased in group 2 and 3 compared to group 1 (p < 0.0001 for both groups). The CT in the different quadrants (superior, inferior, temporal and nasal) was significantly thinner in group 3, followed by group 2 and 1 in ascendant order. Group 1 showed significant increased thickness compared to the other groups.

CONCLUSION

To the best of our knowledge, this is the first report suggesting thicker macular choroid in patients with PXE without active or inactive CNV than in normal eyes. Initial changes in Bruch membrane (MB) and choroid, in addition to the increased oxidative stress, would lead to hyperpermeability of the choroid and alterations of the barrier BM-RPE causing a thick choroid in early stages.

The Fate and Prognostic Implications of Hyperreflective Crystalline Deposits in Nonneovascular Age-Related Macular Degeneration

Purpose

To explore patterns of disease progression in nonneovascular age-related macular degeneration (AMD) associated with hyperreflective crystalline deposits (HCDs) in the sub-retinal pigment epithelium-basal laminar space.

Methods

Retrospective review of medical records, multimodal imaging, and longitudinal eye-tracked near-infrared reflectance (NIR) and optical coherence tomography (OCT) spanning ≥2 years. NIR/OCT images were analyzed with ImageJ software to identify HCD morphology and location. Associated macular complications were reviewed from the time of HCD detection to the most recent follow-up, using NIR/OCT.

Results

Thirty-three eyes with HCDs from 33 patients (mean age: 72 ± 7.5 years) had 46.7 months (95% confidence limits: 33.7, 59.6) of serial eye-tracked NIR/OCT follow-up. Baseline best-corrected visual acuity (BCVA) was 0.44 logMAR (Snellen equivalent 20/55). At a mean of 11.3 months (3.1, 19.6) after HCD detection, 31/33 (93.9%) eyes had developed macular complications including de novo areas of complete retinal pigment epithelium and outer retinal atrophy (cRORA) in 21/33 (64%) eyes, enlargement of preexisting cRORA in 4/33 (12%) eyes, and incident macular neovascularization in 3/33 (9%) eyes. Movement and clearance of HCDs in 9/33 (27%) eyes was associated with enlargement of preexisting cRORA (r = 0.44, P = 0.02). BCVA at the last follow-up visit had decreased to 0.72 logMAR (20/105).

Conclusions

Eyes with nonneovascular AMD demonstrating HCDs are at risk for vision loss due to macular complications, particularly when movement and clearance of these structures appear on multimodal imaging. HCD reflectivity and dynamism may be amenable to automated recognition and analysis to assess cellular activity related to drusen end-stages.

Identification of hyperreflective foci in angioid streaks

AIMS

To assess hyperreflective foci (HF) number in angioid streaks (AS) by means of spectral-domain optical coherence tomography (SD-OCT).

METHODS

Observational and cross-sectional study. Sixty-two eyes with AS and 62 controls underwent best-corrected visual acuity (BCVA), fundoscopy, and SD-OCT. HF were assessed on the horizontal scan of a six-line radial OCT, in the fovea (1500-μm diameter) and parafovea (500 μm external to the fovea), and sub-classified as retinal or choroidal, small or large. Eyes were distributed in one of four groups, as carrying foveal AS without choroidal neovascularization (CNV) (14 eyes), extra-foveal AS without CNV (14), active CNV (20), and inactive CNV (14). Primary outcome was HF assessment in AS. Secondary outcomes included their correlations with BCVA.

RESULTS

AS-affected eyes had higher HF numbers. Our sub-analysis revealed that patients with active CNV had a larger number of retinal and choroidal HF than all the other groups, whereas retinal and choroidal foci were significantly increased in inactive CNV only with respect to controls. Interestingly, patients with foveal AS showed HF number increase in the choroid and fovea. BCVA deterioration positively correlated with the total HF number found in the fovea and the choroid.

CONCLUSION

HF are significantly increased in patients with AS. Despite being especially evident in active CNV, the increasing number in eyes without CNV might suggest new pathogenetic aspects of the disease.

Reticular Pseudodrusen and Thin Choroid Are Associated With Angioid Streaks

BACKGROUND AND OBJECTIVE

To report the association of angioid streaks in patients with Pseudoxanthoma elasticum (PXE) with reticular pseudodrusen (RPD), thin choroid, and retinal pigment epithelium (RPE) atrophy using swept-source optical coherence tomography (SS-OCT) and short-wave autofluorescence (SWAF).

PATIENTS AND METHODS

Retrospective cross-sectional study. Records of consecutive patients with angioid streaks due to PXE, who presented with a decrease of vision due to choroidal neovascularization (CNV), were reviewed for best-corrected visual acuity, color fundus photographs, SS-OCT, SWAF, and red-free images with special emphasis on presence or absence of RPD, subfoveal choroidal thickness (SFCT), and RPE atrophy.

RESULTS

Sixteen eyes of eight patients with a mean age of 45.5 years ± 9.4 years were enrolled in the study. RPD were seen in 10 of the 16 eyes and were seen commonly along the superotemporal quadrant. Mean subfoveal thickness in study eyes (175.7 μm ± 37.2 μm) was significantly reduced when compared to controls (286.4 μm ± 40.8 μm). The mean SFCT was similar between the eyes with and without CNV. Four eyes had RPE atrophy in the macular area, whereas four eyes had peripapillary RPE atrophy.

CONCLUSIONS

Angioid streaks in PXE are associated with RPD, thin choroid, and RPE atrophy. These features occur at a younger age as compared to age-related macular degeneration and appear to be interrelated because of single pathophysiological mechanism. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:402-408.].

Carotid strain measurement in patients with pseudoxanthoma elasticum - Hint for a different pathomechanism?

Pseudoxanthoma Elasticum (PXE), caused by autosomal-recessive mutations in the ATP-binding cassette transporter (ABCC6) gene, is known for high prevalence of atherosclerosis. A novel method investigating elastic properties of arteries in atherosclerotic patients is vascular strain analysis. We compared 44 PXE patients with peripheral artery disease (PXE+PAD group) with 50 control patients, each 25 without (control group) and with PAD (PAD group). All participants underwent an angiological examination including ankle-brachial index (ABI) and were examined with speckle-tracking based vascular strain analysis of common carotid arteries, measuring radial displacement (r.Dis), radial velocity (r.Vel), radial strain (r.Str), circumferential strain (c.Str), radial strainrate (r.SR) and circumferential strainrate (c.SR). We found significant lower ABI in patients with PXE compared to all other groups (each p < 0.01). The vascular strain analysis resulted in significantly decreased values in the PAD group compared to PXE with PAD (each p ≤ 0.01) and controls without PAD (each p ≤ 0.05), whereas no significant difference could be found between PXE+PAD and controls without PAD. We found significant negative correlations between low strain values and a higher prevalence of PAD in non-PXE patients (r.Str r = -0.34; c.Str r = -0.35; r.SR: r = -0.51; c.SR: r = -0.53). In conclusion, PXE patients had similar values for arterial stiffness compared to controls without PAD in vascular strain analysis. In this group, arterial stiffness parameters were significantly higher compared to non-PXE PAD patients. It is worth to discuss whether PAD-like manifestations in PXE are a different kind of disease and might need another strategy in diagnostics and therapy.

LOCATING AND CHARACTERIZING ANGIOID STREAKS WITH EN FACE OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To characterize angioid streaks (AS) with en face optical coherence tomography (OCT).

METHODS

Case report of a patient with myopia presenting with choroidal neovascularization secondary to AS. Swept-source en face OCT ability to image the streaks was compared with spectral-domain and swept-source B-scans as well as color and red-free pictures. A 48-year-old man with myopia presented with sudden central visual loss. Choroidal neovascularization secondary to AS was diagnosed and intraocular anti-vascular endothelial growth factor given with clinical and OCT features improvement.

RESULTS

Angioid streaks were visualized as less dark than the overlying retinal and the underlying choroidal vasculature. En face OCT located the changes at the level of Bruch membrane. An AS was found to be interrupted by the choroidal neovascularization, what was not captured by other modalities.

CONCLUSION

En face OCT allows to assess the extent of changes in Bruch membrane and their spatial relationship to choroidal neovascularization.

CHOROIDAL ALTERATIONS IN ABCA4-RELATED RETINOPATHY

PURPOSE

To investigate choroidal alterations in ABCA4-related retinopathy.

METHODS

Mean choroidal thickness and subfoveal choroidal thickness were measured in the right eyes of 40 patients with ABCA4-related retinopathy using enhanced-depth imaging optical coherence tomography. The right eyes of 65 age-matched healthy subjects were used for comparison.

RESULTS

Compared with controls, patients with ABCA4-related retinopathy revealed a reduced subfoveal choroidal thickness ([mean ± SEM] 347 ± 10 μm vs. 302 ± 12 μm; P = 0.006) and mean choroidal thickness (315 ± 9 μm vs. 275 ± 10 μm; P = 0.005). This difference was mainly due to choroidal thinning in eyes with reduced photopic and/or scotopic amplitudes on full-field electroretinography. Atrophy of the retinal pigment epithelium (RPE) was associated with a thinner choroid compared with eyes without RPE atrophy (subfoveal choroidal thickness: 277 ± 17 μm vs. 341 ± 16 μm; mean choroidal thickness: 252 ± 13 μm vs. 313 ± 13 μm; both, P ≤ 0.001), but choroidal thinning was not restricted to the area of RPE atrophy. Choroidal thickness was similar to controls when RPE atrophy and functional loss were limited to the central retina. There was no association between visual acuity and choroidal thickness.

CONCLUSION

The results indicate choroidal alterations in widespread ABCA4-related retinopathy, especially when associated with atrophy of the RPE. The absence of focal choroidal thinning in areas of RPE atrophy is suggestive for a diffusible factor from the RPE sustaining the choroidal structure.

Pseudoxanthoma Elasticum - Also a Lung Disease? The Respiratory Affection of Patients with Pseudoxanthoma Elasticum

BACKGROUND

Pseudoxanthoma elasticum (PXE) is an autosomal-recessive mineralisation disorder caused by loss of function mutations in the ABCC6 Gen. Histological findings and data of an autopsy of a PXE-patient suggest a possible pulmonal calcification. So far, there exists no clinical data whether PXE patients actually are at high risk of developing pulmonary disorder.

METHODS

In a cross-sectional study, 35 PXE patients and 15 healthy controls underwent a pulmonary function testing, including spirometry, body plethysmography and carbon monoxide diffusing test. Additionally, PXE patients completed a COPD-Assessment-Test (CAT).

RESULTS

We observed in PXE patients normal values for predicted vital capacity (VC%; 96.0±13.0%), predicted total lung capacity (TLC%; 98.2±12.0%) and predicted forced expiration volume (FEV1%; 102.5±15.6%), whereas compared to healthy controls the PXE group showed significant diminished values for carbon monoxide diffusing capacity (DLCO, 7.2 ±1.4mmol/min/kPa vs. 8.6 ±1.5 mmol/min/kPa; p = 0.008) and predicted carbon monoxide diffusing capacity (DLCO%; 79.7±11.5% vs. 87.2±6.6%; p = 0.008). 11/35 (31.4%) PXE patients showed pathological DLCO% values under 75% (68.5%±5.4%).

CONCLUSION

PXE patients demonstrated a regular lung function testing, but nevertheless they had impaired CO diffusing parameters, which might be associated with a preclinical state of an interstitial lung disease and a risk for restrictive ventilation disorders.

Automated macular choroidal thickness measurement by swept-source optical coherence tomography in pseudoxanthoma elasticum

Introduction

Pseudoxanthoma elasticum (PXE) typically involves elastic fibers in blood vessels and Bruch membrane. Our purpose was to analyze retinal and choroidal macular thickness in patients with angioid streaks due PXE compared with a control group.

Methods

Best-corrected visual acuity (BCVA), axial length (AL), and macular swept-source optical coherence tomography were obtained. Automated segmentations of the retina and the choroid were used to obtain the corresponding thickness values. An age, gender and AL matched control group was used to compare the thickness values.

Results

Twelve eyes of 6 patients were included. The mean BCVA was 0.68 ± 0.29 versus 1.0 in controls (p < 0.001). The mean macular retinal thickness was thinner in eyes with PXE (p = 0.038). Only patients with choroidal neovascularization (NV) showed statistically significant differences in the mean macular choroidal thickness (p = 0.008).

Conclusions

The present study shows that choroidal thickness may be thinner in eyes with NV due to angioid streaks in PXE compared with healthy eyes analyzed by an automated segmentation of the choroid. Further studies are warranted in order to assess the importance of this choroidal changes in the pathogenesis of retinal disturbances related to PXE and its influence in long-term follow-up.

Assessment of Choroidal Microstructure and Subfoveal Thickness Change in Eyes With Different Stages of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a major cause of irreversible blindness. Choroidal structural changes seem to be inevitable in AMD pathogenesis. Our study revealed associated choroidal microstructural changes in AMD eyes.The aim of the study was to compare choroidal microstructural changes in eyes with AMD of different stages.The study was a retrospective, cross-sectional case series.The participants comprised of 32 age-matched normal eyes as controls, and 26 fellow uninvolved eyes of intermediate/late AMD, 29 of early AMD, 28 of intermediate AMD, and 39 of late AMD.All subjects underwent comprehensive ophthalmologic examination. The choroid images, including subfoveal choroidal thickness, percentage of Sattler layer area, and en face images of the choroid, were obtained using spectral-domain optical coherence tomography.The main outcome measures were subfoveal choroidal thickness changes, percentage of Sattler layer area changes, and en face images of the choroid in AMD eyes.One hundred fifty-four eyes of 96 individuals with mean age of 67.1±9.2 years were included. The mean subfoveal choroidal thickness was 295.4 ± 56.8 μm in age-matched normal eyes, 306.7 ± 68.4 μm in fellow uninvolved eyes with AMD, 293.8 ± 80.4 μm in early AMD, 215.6 ± 80.4 μm in intermediate AMD, and 200.4 ± 66.6 μm in late AMD (F = 14.2, all P < 0.001). Choroidal thickness was greater in early AMD eyes than in intermediate/late AMD eyes (P < 0.001). Mean percentage of Sattler layer area in each group showed a similar tendency. Microstructure of the choroid showed reduced vascular density of Sattler layer areas in late AMD eyes compared with normal eyes.Decreasing subfoveal choroidal thickness and percentage of Sattler layer area were demonstrated in the progression of AMD. The choroidal change was related to atrophy of the microstructural changes of underlying capillaries and medium-sized vessels.

The ABCC6 Transporter as a Paradigm for Networking from an Orphan Disease to Complex Disorders

The knowledge on the genetic etiology of complex disorders largely results from the study of rare monogenic disorders. Often these common and rare diseases show phenotypic overlap, though monogenic diseases generally have a more extreme symptomatology. ABCC6, the gene responsible for pseudoxanthoma elasticum, an autosomal recessive ectopic mineralization disorder, can be considered a paradigm gene with relevance that reaches far beyond this enigmatic orphan disease. Indeed, common traits such as chronic kidney disease or cardiovascular disorders have been linked to the ABCC6 gene. While during the last decade the awareness of the wide ramifications of ABCC6 has increased significantly, the gene itself and the transmembrane transporter it encodes have not unveiled all of the mysteries that surround them. To gain more insights, multiple approaches are being used including next-generation sequencing, computational methods, and various "omics" technologies. Much effort is made to place the vast amount of data that is gathered in an integrated system-biological network; the involvement of ABCC6 in common disorders provides a good view on the wide implications and potential of such a network. In this review, we summarize the network approaches used to study ABCC6 and the role of this gene in several complex diseases.