Vitelliform Macular Dystrophy Research Articles

Suppression of Choroidal Neovascularization in Mice by Subretinal Delivery of Multigenic Lentiviral Vectors Encoding Anti-Angiogenic MicroRNAs.

Lentivirus-based vectors have been used for the development of potent gene therapies. Here, application of a multigenic lentiviral vector (LV) producing multiple anti-angiogenic microRNAs following subretinal delivery in a laser-induced choroidal neovascularization (CNV) mouse model is presented. This versatile LV, carrying back-to-back RNApolII-driven expression cassettes, enables combined expression of microRNAs targeting vascular endothelial growth factor A (Vegfa) mRNA and fluorescent reporters. In addition, by including a vitelliform macular dystrophy 2 (VMD2) promoter, expression of microRNAs is restricted to the retinal pigment epithelial (RPE) cells. Six days post injection (PI), robust and widespread fluorescent signals of eGFP are already observed in the retina by funduscopy. The eGFP expression peaks at day 21 PI and persists with stable expression for at least 9 months. In parallel, prominent AsRED co-expression, encoded from the VMD2-driven microRNA expression cassette, is evident in retinal sections and flat-mounts, revealing RPE-specific expression of microRNAs. Furthermore, LV-delivered microRNAs targeting the Vegfa gene in RPE cells reduced the size of laser-induced CNV in mice 28 days PI, as a consequence of diminished VEGF levels, suggesting that LVs delivered locally are powerful tools in the development of gene therapy-based strategies for treatment of age-related macular degeneration.

Suppression of choroidal neovascularization in mice by subretinal delivery of multigenic lentiviral vectors encoding anti-angiogenic microRNAs

Lentivirus-based vectors have been used for the development of potent gene therapies. Here, we present application of a multigenic lentiviral vector (LV) producing multiple anti-angiogenic microRNAs following subretinal delivery in a laser-induced choroidal neovascularization (CNV) mouse model. This versatile LV, carrying back-to-back RNApolII-driven expression cassettes, enables combined expression of microRNAs targeting vascular endothelial growth factor A (Vegfa) mRNA, and fluorescent reporters. In addition, by including a vitelliform macular dystrophy 2 (VMD2) promoter, expression of microRNAs is restricted to the retinal pigment epithelial (RPE) cells. Already 6 days post injection (PI) robust and widespread fluorescent signals of eGFP are observed in the retina by fundoscopy. The eGFP expression peaks at day 21 PI and persists with stable expression for at least 9 months. In parallel, prominent AsRED co-expression, encoded from the VMD2-driven microRNA expression cassette, is evident in retinal sections and flat-mounts, revealing RPE-specific expression of microRNAs. Furthermore, LV-delivered microRNAs targeting the Vegfa gene in RPE cells reduced the size of laser-induced CNV in mice 28 days PI, as a consequence of diminished VEGF levels, suggesting that LVs delivered locally are powerful tools in the development of gene therapy-based strategies for treatment of age-related macular degeneration (AMD).

Clinical characteristics of adult-onset foveomacular vitelliform dystrophy

Adult-onset foveomacular vitelliform dystrophy (AFVD) is characterized by gradually loss of vision, subretinal vitelliform macular lesions and retinal pigment epithelium (RPE) atrophy. The electrooculogram (EOG) is usually normal or reduce slightly. On optical coherence tomography (OCT), there are vitelliform substance which deposited between the photoreceptor layer and the RPE layer, and thinner outer nuclear layer above these deposits. OCT angiography can show the superficial and deep retinal capillaries plexus (DCP) above the yolk-like deposits, the choroidal capillary blood flow is reduced and the DCP blood flow is increased near macular. On indocyanine green angiography (ICG), there is choroidal neovascularization under vitelliform substance at early stage and fluorescence leakage in the corresponding retinal region at late stage. There is no effective treatment for AFVD at present, monogenic gene therapy is the most worth looking forward to. Understanding AFVD clinical manifestations, multi-mode imaging features and new advances in treatment can provide a reference for diagnosis and treatment options Key words: Vitelliform macular dystrophy/diagnosis; Disease attributes; Review

Screening of BEST1 Gene in a Chinese Cohort With Best Vitelliform Macular Dystrophy or Autosomal Recessive Bestrophinopathy.

Mutations in the BEST1 gene can cause Best vitelliform macular dystrophy (BVMD) and autosomal recessive bestrophinopathy (ARB). The aim of the current study was to establish the BEST1 mutation spectrum in Chinese patients with BVMD and ARB and to describe the phenotypic characteristics of patients carrying BEST1 mutations. A total of 37 probands with a clinical diagnosis of BVMD (17 patients) or ARB (20 patients) were recruited for genetic analysis; of these, only 5 probands had a family history. All probands underwent detailed ophthalmic examinations. All coding exons and exon-intron boundaries of the BEST1 gene were screened by PCR-based DNA sequencing. In silico programs were used to analyze the pathogenicity of all the variants. Genomic DNA rearrangements of the BEST1 gene were identified by real-time quantitative PCR (RQ-PCR). For patients with BVMD, single heterozygous BEST1 mutations were identified in 13 patients and compound heterozygous mutations were found in 3 patients. For patients with ARB, biallelic mutations were found in 13 probands and single mutant alleles in six patients. Overall, 36 disease-causing variants (20 novel mutations) of the BEST1 gene were identified, including 28 (77.8%) missense, 3 (8.3%) nonsense, 4 (11.1%) splicing effect, and 1 (2.8%) frameshift small duplication mutations. The mutation spectrum of the BEST1 gene in Chinese patients differed from those of Caucasian patients. Mutations that cause ARB differ from those that cause BVMD. BEST1 screening is important for precise diagnosis of BVMD or ARB.

Mutations in the Genes for Interphotoreceptor Matrix Proteoglycans, IMPG1 and IMPG2, in Patients with Vitelliform Macular Lesions.

A significant portion of patients diagnosed with vitelliform macular dystrophy (VMD) do not carry causative mutations in the classic VMD genes BEST1 or PRPH2. We therefore performed a mutational screen in a cohort of 106 BEST1/PRPH2-negative VMD patients in two genes encoding secreted interphotoreceptor matrix proteoglycans-1 and -2 (IMPG1 and IMPG2). We identified two novel mutations in IMPG1 in two simplex VMD cases with disease onset in their early childhood, a heterozygous p.(Leu238Pro) missense mutation and a homozygous c.807 + 5G > A splice site mutation. The latter induced partial skipping of exon 7 of IMPG1 in an in vitro splicing assay. Furthermore, we found heterozygous mutations including three stop [p.(Glu226*), p.(Ser522*), p.(Gln856*)] and five missense mutations [p.(Ala243Pro), p.(Gly1008Asp), p.(Phe1016Ser), p.(Tyr1042Cys), p.(Cys1077Phe)] in the IMPG2 gene, one of them, p.(Cys1077Phe), previously associated with VMD. Asymptomatic carriers of the p.(Ala243Pro) and p.(Cys1077Phe) mutations show subtle foveal irregularities that could characterize a subclinical stage of disease. Taken together, our results provide further evidence for an involvement of dominant and recessive mutations in IMPG1 and IMPG2 in VMD pathology. There is a remarkable similarity in the clinical appearance of mutation carriers, presenting with bilateral, central, dome-shaped foveal accumulation of yellowish material with preserved integrity of the retinal pigment epithelium (RPE). Clinical symptoms tend to be more severe for IMPG1 mutations.

Reading Performance Improvements in Patients with Central Vision Loss without Age-Related Macular Degeneration after Undergoing Personalized Rehabilitation Training

ABSTRACTPurpose: To evaluate the efficacy of a reading rehabilitation program (RRP) in patients with central visual loss (CVL) and assess the impact of the RRP on the quality of life (QoL).Methods: The RRP included four in-office and 39 in-home training sessions over 6 weeks. Reading speed, duration, and font size were evaluated during each in-office session. The subjective perception of the QoL was assessed before and after the RRP using the short version of a questionnaire (World Health Organization Quality of Life). A control group who received advice about ocular conditions and low-vision aids also was included.Results: Seventeen patients with Stargardt’s disease (STGD), 11 with adult-onset foveomacular vitelliform dystrophy (AFVD), and eight with myopic macular degeneration (MMD) were included. The control group included five patients each with STGD, AFVD, and MMD. The respective mean corrected distance visual acuities (VAs) in patients with STGD, AFVD, MMD, and the control group were 0.57 ± 0.38, 0.51 ± 0.38, 0.49 ± 0.24, and 0.55 ± 0.25 logarithm of the minimum angle of resolution; the mean corrected near VAs were 0.89 ± 0.20, 1.08 ± 0.17, 0.99 ± 0.34, and 1.18 ± 0.37 (M notation) using low-vision aids. The reading speed, duration, and font size improved in all groups. The RRP groups obtained (p ≤ 0.01) greater improvements than the control group in each reading performance variable assessed. Patients with STGD obtained greater improvements in the subjective evaluation; the control group did not obtain noteworthy improvement in any domain.Conclusions: The RRP improved reading performance in patients with CVL and positively impacted the subjective perception of the QoL.

Two novel mutations in Best vitelliform macular dystrophy GONG

Two novel mutations in Best vitelliform macular dystrophy GONG

Juvenile Macular Degenerations

In this article, we review the following 3 common juvenile macular degenerations: Stargardt disease, X-linked retinoschisis, and Best vitelliform macular dystrophy. These are inherited disorders that typically present during childhood, when vision is still developing. They are sufficiently common that they should be included in the differential diagnosis of visual loss in pediatric patients. Diagnosis is secured by a combination of clinical findings, optical coherence tomography imaging, and genetic testing. Early diagnosis promotes optimal management. Although there is currently no definitive cure for these conditions, therapeutic modalities under investigation include pharmacologic treatment, gene therapy, and stem cell transplantation.

PHOTORECEPTOR INNER SEGMENT MORPHOLOGY IN BEST VITELLIFORM MACULAR DYSTROPHY.

To characterize outer retina structure in best vitelliform macular dystrophy (BVMD) and to determine the effect of macular lesions on overlying and adjacent photoreceptors. Five individuals with BVMD were followed prospectively with spectral domain optical coherence tomography and confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). The AOSLO cone photoreceptor mosaic images were obtained within and around retinal lesions. Cone density was measured inside and outside lesions. In 2 subjects, densities were compared with published measurements acquired ∼2.5 years before. One subject was imaged 3 times over a 5-month period. The AOSLO imaging demonstrated that photoreceptor morphology within BVMD retinal lesions was highly variable depending on the disease stage, with photoreceptor structure present even in advanced disease. The AOSLO imaging was repeatable even in severe disease over short-time and long-time intervals. Photoreceptor density was normal in retinal areas immediately adjacent to lesions and stable over ∼2.5 years. Mobile disk-like structures possibly representing subretinal macrophages were also observed. Combined confocal and nonconfocal split-detector AOSLO imaging reveals substantial variability within clinical lesions in all stages of BVMD. Longitudinal cellular photoreceptor imaging could prove a powerful tool for understanding disease progression and monitoring emerging therapeutic treatment response in inherited degenerations such as BVMD.

Adult onset Best’s macular dystrophy (VMD2) with unilateral presentation

Vitelliform macular dystrophy is an autosomal-dominant disease and has two clinical variants: Best's (VMD2) and adult onset vitelliform macular dystrophy (AOVMD). We report an atypical presentation of VMD2. A 50-year-old male presented with history of blurring of vision in left eye since two year. On fundus examination, left eye revealed a single, circular, yellow-opaque egg yolk-like macular lesion with no other abnormality. Fundus examination of right eye was unremarkable. Fundus fluoresceine angiography showed blocked fluorescence in the area of lesion. EOG-Arden ratios were found to be severely reduced bilaterally. OCT left eye showed sub-retinal hyperreflective echo. The age of onset and presentation can be highly variable in VMD2 and the vitelliform phase of VMD2 in elderly can be confused for adult onset vitelliform macular dystrophy(AOVMD). However, Arden ratio less than 1.5 is diagnostic of VMD2.

Optical coherence tomography in Best vitelliform macular dystrophy.

To analyze spectral-domain optical coherence tomography (SD-OCT)-specific findings in the different stages of vitelliform macular dystrophy (VMD). Thirty-seven patients were prospectively recruited. All the patients underwent a complete ophthalmologic examination, including best-corrected visual acuity (BCVA), biomicroscopy, and SD-OCT. The examined findings were vitelliform material, neurosensory detachment, intraretinal hyperreflective foci, and the status of external limiting membrane, ellipsoid zone, and retinal pigment epithelium. The primary outcome was the stratification of SD-OCT findings in each VMD stage. Secondary outcomes included the description of different characteristics related to intraretinal hyperreflective foci. Outer retinal layers were preserved almost exclusively in stage 1 (range 70%-100%), whereas their disruption and absence were typical of stages 2 to 4 (83%-100%) and stage 5 (67%-83%), respectively. Vitelliform material was found always in stages 2 and 3, 89% of stage 4, and rarely in stage 5 (33%). Neurosensory detachment was to some extent representative of stages 3 and 4 (80% and 72%, respectively) when compared with the other stages (p<0.001). Hyperreflective foci (16% of all eyes) demonstrated a progressive increase across stages 2 to 4, with slightly reduced figure in stage 5. These foci were located in the outer nuclear and plexiform layers, showed different sizes, and were not associated with a visual acuity reduction (p = 0.64). A progressive deterioration of the outer retinal layers was noticeable in more advanced stages of VMD. The reduction of vitelliform material from stage 3 to 4 was paralleled by an increased evidence of neurosensory detachment. Although showing different size and location, hyperreflective foci did not correlate with worse BCVA.

Optical Coherence Tomography Examination of the Retinal Pigment Epithelium in Best Vitelliform Macular Dystrophy

To describe the anatomic changes and natural history of vitelliform lesions in Best vitelliform macular dystrophy (BVMD) using spectral-domain optical coherence tomography (OCT). Prospective comparative case series. Twenty patients (40 eyes) with molecular confirmation of mutation in the BEST1 gene and 20 age-matched controls were included. Color fundus photographs, fundus autofluorescence, and spectral-domain OCT were obtained, and these findings were compared between the 2 groups. Fifteen of the 20 patients with Best disease had more than 1 visit, and the imaging studies from each visit were compared with each other over time. Evolution of visual acuity and clinical stage of BVMD correlated to OCT measurement parameters, including retinal pigment epithelium (RPE) thickness, central macular thickness, and integrity of the ellipsoid zone. Patients with BVMD demonstrated progressive disorganization and thinning of the submacular RPE on OCT when compared with normal controls. Concurrent with the appearance of "egg-yolk lesions," the OCT showed a cleft in the outer retina, creating an apical and basal separation of retinal layers. The apical complex of the vitelliform lesion eventually degenerated and flattened. Patients with such lesions nevertheless maintained reasonable visual acuity into the advanced vitelleruptive stages despite the disruption of normal anatomic changes. Our study suggests that in BVMD, subretinal vitelliform material accumulation leads to a clear separation of the outer retinal layers. The level at which this cleft forms is a topic of discussion andinterest, with the most likely levels of least resistance being the interdigitation zone or between the RPE and the Bruch's membrane. It is possible that RPE may continue to form a preserved photoreceptor-RPE complex that provides essential nutrients to the photoreceptors and in turn helps patients maintain better than expected visual acuity for years.

Bestrophin 1 and retinal disease.

Mutations in the gene BEST1 are causally associated with as many as five clinically distinct retinal degenerative diseases, which are collectively referred to as the "bestrophinopathies". These five associated diseases are: Best vitelliform macular dystrophy, autosomal recessive bestrophinopathy, adult-onset vitelliform macular dystrophy, autosomal dominant vitreoretinochoroidopathy, and retinitis pigmentosa. The most common of these is Best vitelliform macular dystrophy. Bestrophin 1 (Best1), the protein encoded by the gene BEST1, has been the subject of a great deal of research since it was first identified nearly two decades ago. Today we know that Best1 functions as both a pentameric anion channel and a regulator of intracellular Ca2+ signaling. Best1 is an integral membrane protein which, within the eye, is uniquely expressed in the retinal pigment epithelium where it predominantly localizes to the basolateral plasma membrane. Within the brain, Best1 expression has been documented in both glial cells and astrocytes where it functions in both tonic GABA release and glutamate transport. The crystal structure of Best1 has revealed critical information about how Best1 functions as an ion channel and how Ca2+ regulates that function. Studies using animal models have led to critical insights into the physiological roles of Best1 and advances in stem cell technology have allowed for the development of patient-derived, "disease in a dish" models. In this article we review our knowledge of Best1 and discuss prospects for near-term clinical trials to test therapies for the bestrophinopathies, a currently incurable and untreatable set of diseases.

Bestrophinopathy: An RPE-photoreceptor interface disease.

Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.

Microperimetric evaluation in patients with adult-onset foveomacular vitelliform dystrophy.

Introduction:To compare mean best-corrected visual acuity (BCVA), retinal sensitivity (RS), and bivariate contour ellipse area (BCEA) in patients with adult-onset foveomacular vitelliform dystrophy (AOFVD) and healthy subjects (HSs), reporting also functional disease-related changes in the different stages of the AOFVD disease.Materials and Methods:In this observational cross-sectional study, a total of 19 patients (30 eyes; 12 female and 7 male) with AOFVD were enrolled, and 30 patients (30 eyes; 16 female and 14 male) were recruited as age-matched control group (74.36 ± 9.17 years vs. 71.83 ± 6.99 years respectively, P = 0.11). All patients underwent a complete ophthalmologic examination, fundus autofluorescence and fluorescein angiography, spectral-domain optical coherence tomography and microperimetry (MP)-1 analysis. The data collection included mean BCVA, mean RS measured by means of MP-1, BCEA, and central retinal thickness.Results:All the functional parameters (BCVA, RS, and BCEA) were significantly worse in AOFVD group than HS. Subgroup analysis showed that the most significant functional changes, quantified by mean BCVA, RS, and BCEA, were in the atrophic stage (P = 0.03, P = 0.01, and P = 0.001, respectively). All the functional parameters were well correlated in the different stages.Conclusions:This study further confirms the good visual prognosis in the AOFVD eyes. Fixation stability measurement using BCEA demonstrates good evaluation of visual performance integrating traditional functional parameters. It may also serve for further rehabilitative purposes in atrophic eyes.

Bilateral choroidal neovascularisation associated with adult‐onset foveomacular vitelliform dystrophy

Adult‐onset foveomacular vitelliform dystrophy (AFVD) is an increasingly well‐recognised maculopathy, originally described by Gass1974 as ‘peculiar foveomacular dystrophy’ and characterised by bila...

Optical coherence tomographic features and correlation with visual acuity in adult-onset foveal vitelliform dystrophy

Purpose: The purpose of the study was to analyze the optical coherence tomographic (OCT) features of adult-onset foveal vitelliform dystrophy (AOFVD) using high-resolution spectral-domain (SD) OCT and to correlate each variable with visual acuity. Design: This was a retrospective, observational case series. Materials and Methods: Patients with a diagnosis of AOFVD based on clinical presentation, autofluorescence, and OCT were included in the study. SD-OCT images were analyzed. The vertical and horizontal basal dimensions of vitelliform material, the thickness of neurosensory retina (NSR) above the lesion, and the integrity of inner segment-outer segment (IS-OS) junction and external limiting membrane (ELM) were assessed, and each was correlated with best-corrected visual acuity. Results: Thirty-six eyes of 25 patients were included in the study. Mean age of patients was 65.39 ± 11.3 years. A weak positive correlation was noted between lesion dimensions and LogMAR visual acuity, but this was not statistically significant. A significant negative correlation was seen between thickness of NSR above the lesion and LogMAR visual acuity, indicating that as the overlying NSR became thinner, vision worsened. Although a worse visual acuity was noted in eyes with disrupted IS-OS junction and ELM, the result was not statistically significant. Conclusion: As the size of the vitelliform material increased, there was progressive thinning of overlying NSR which could lead to worsening of visual acuity.

Do We Still Need Electrophysiology in Ophthalmology?

Electrophysiological methods in clinical ophthalmology include the full-field electroretinogram (ERG) for assessment of outer and middle retinal layers, pattern ERG (PERG) for assessment of ganglion cell function, the electrooculogram (EOG) for assessment of retinal pigment epithelium function, as well as visual evoked potentials (VEP) for assessment of the visual pathway, including the optic nerve and visual cortex. Multifocal recording techniques for ERG and VEP are used for tests within selected areas of the visual field. Technical progress in ocular imaging, especially optical coherence tomography (OCT) and fundus autofluorescence (FAF), allows high-resolution imaging of subtle morphological changes of the retina and posterior fundus. Typical retinal diseases may then be diagnosed at an early stage, without conventional electrophysiological investigations (e.g. x-linked retinoschisis, Stargardt disease, vitelliform macular dystrophy). OCT outclasses electrophysiological methods in the quantification of optic atrophies. With newly developed optic techniques, peripheral retinal structures (wide angle optics) and subtle structures up to the photoreceptor level (adaptive optics) can be imaged with increasing quality. However, differentiation of central retinal disorders (e.g. macular dystrophy) from generalised retinal diseases requires electrophysiological diagnostic testing. The same applies to discrimination between different functional disorders in generalised retinal diseases (e.g. enhanced S-cone syndrome, congenital stationary night blindness, achromatopsia).

Choroidal neovascularization secondary to Best vitelliform macular dystrophy detected by optical coherence tomography angiography

Best vitelliform macular dystrophy (VMD) is a hereditary condition that causes childhood-onset macular dystrophy. In rare cases, VMD is accompanied by formation of a choroidal neovascular membrane (CNVM). We report a case of CNVM secondary to Best VMD in a 10-year-old boy that was detected using optical coherence tomography angiography, a new noninvasive diagnostic modality that detects motion contrast in repeated B-scans to identify blood flow within vessels.

Clinical and genetic heterogeneity in Slovenian patients with BEST disease.

To determine the spectrum of BEST1 mutations and to study the phenotype in Slovenian families with Best vitelliform macular dystrophy (BVMD) to identify genotype-phenotype correlations. Twenty patients from five families underwent the ophthalmological examination including electrooculogram (EOG; N=17), fundus autofluorescence imaging (N=16) and optical coherence tomography (N=14). Mutational screening was performed by direct DNA sequencing of the BEST1 gene. Mutation c.43G>C (p.Gly15Arg) was detected in three patients from family M presenting with different clinical stages of Best disease. Mutation c.313G>C (p.Arg105Gly) was found in families K, ST, S, B and was associated with incomplete clinical penetrance and variable retinal changes, including extramacular and multifocal lesions. In three patients from family K, an atypical form of BVMD was observed; there were additional peripheral lesions outside of the vascular arcades in addition to the typical macular lesions. Multiple alterations between the vitelliruptive and pseudohypopyon stages over a period of 11years were seen in one patient. Two previously unreported disease-associated variants in the BEST1 gene (p.Gly15Arg and p.Arg105Gly) were found in Slovenian patients with Best disease. Our data expand the mutation spectrum of the BEST1 gene and further support the broad phenotypic variability observed clinically and with optical coherence tomography (OCT) and AF imaging.