Voretigene neparvovec for inherited retinal dystrophy due to RPE65 mutations: a scoping review of eligibility and treatment challenges from clinical trials to real practice.

Biallelic mutations in the RPE65 gene affect nearly 8% of Leber Congenital Amaurosis and 2% of Retinitis Pigmentosa cases. Voretigene neparvovec (VN) is the first gene therapy approach approved for their treatment. To date, real life experience has demonstrated functional improvements following VN treatment, which are consistent with the clinical trials outcomes. However, there is currently no consensus on the characteristics for eligibility for VN treatment. We reviewed relevant literature to explore whether recommendations on patient eligibility can be extrapolated following VN marketing. We screened 166 papers through six research questions, following scoping reviews methodology, to investigate: (1) the clinical and genetic features considered in VN treatment eligibility; (2) the psychophysical tests and imaging modalities used in the pre-treatment and follow-up; (3) the potential correlations between visual function and retinal structure that can be used to define treatment impact on disease progression; (4) retinal degeneration; (5) the most advanced testing modalities; and (6) the impact of surgical procedure on treatment outcomes. Current gaps concerning patients' eligibility in clinical settings, such as pre-treatment characteristics and outcomes are not consistently reported across the studies. No upper limit of retinal degeneration can be defined as the univocal factor in patient eligibility, although evidence suggested that the potential for function rescue is related to the preservation of photoreceptors before treatment. In general, paediatric patients retain more viable cells, present a less severe disease stage and show the highest potential for improvements, making them the most suitable candidates for treatment.

CORRELATION BETWEEN MICROPERIMETRY AND IMAGING IN EXTENSIVE MACULAR ATROPHY WITH PSEUDODRUSEN-LIKE APPEARANCE.

PURPOSE: To determine the correlation between microperimetry and imaging findings in extensive macular atrophy with pseudodrusen-like appearance (EMAP). METHODS: This cross-sectional, observational study included 44 consecutive patients with EMAP (88 eyes) and 30 healthy subjects (60 eyes). Both groups underwent visual acuity assessment, mesopic and scotopic microperimetry, fundus photography, autofluorescence, optical coherence tomography, and optical coherence tomography angiography. Retinal sensitivity was also subdivided in macular (0-4°) and paramacular areas (8-10°). Scotopic sensitivity loss was defined as the difference between scotopic and mesopic sensitivities for each tested point. Eyes with EMAP were further classified into the three stages described by Romano et al: 19 eyes in Stage 1, 31 in Stage 2, and 38 in Stage 3. RESULTS: Mesopic and scotopic retinal sensitivity were significantly reduced in patients with EMAP compared with controls, particularly in the macular area (all P < 0.001). Mesopic retinal sensitivity progressively declined in more advanced EMAP stages (all P < 0.01), but no scotopic differences were observed between Stages 2 and 3 ( P = 0.08). Remarkably, scotopic sensitivity loss was significantly higher in Stage 1 ( P < 0.05).On multivariate analysis, mesopic dysfunction was associated with larger atrophic areas ( P < 0.01), foveal involvement ( P = 0.03), and fibrosis ( P = 0.02). Conversely, no independent variable was associated with a reduced scotopic retinal sensitivity (all P > 0.05). CONCLUSION: The findings highlight that patients with EMAP suffer from a severe cone- and rod-mediated dysfunction on microperimetry. The predominant rod impairment in the early cases (Stage 1) emphasizes the importance of dark-adapted scotopic microperimetry as a clinical end point and suggests defective transportation across the RPE-Bruch membrane complex in its pathogenesis.

MULTIMODAL RETINAL IMAGING REVEALS NEW PATHOGENIC INSIGHTS IN CENTRAL AREOLAR CHOROIDAL DYSTROPHY: A CASE SERIES.

PURPOSE: To describe novel imaging findings in a family affected by central areolar choroidal dystrophy. METHODS: Case series with multimodal retinal imaging assessment. RESULTS: A 19-year-old asymptomatic woman was referred for bilateral macular defects of the retinal pigment epithelium. Blue-light autofluorescence of her right eye revealed a speckled pattern in the macular area with a ring of decreased autofluorescence using near-infrared autofluorescence. Multimodal assessment of her left eye disclosed a single parafoveal spot of decreased pigmentation that was clearly visible as hyperautofluorescent using blue-light autofluorescence and as hypoautofluorescent using near-infrared autofluorescence. Optical coherence tomography angiography revealed several tiny areas of flow voids in correspondence of the retinal pigment epithelium alterations of both eyes. Three family members were recently diagnosed with presumed age-related macular degeneration and demonstrated well-demarcated areas of retinal pigment epithelium atrophy surrounded by yellowish deposits and a hypopigmented halo. Next-generation genetic analysis for inherited macular dystrophies was performed on the index case and the affected family members and revealed a p.Arg172Gln missense mutation in PRPH2 gene, leading to the diagnosis of central areolar choroidal dystrophy. CONCLUSION: Multimodal imaging can reveal new pathogenic insights in central areolar choroidal dystrophy. Of notice, near-infrared autofluorescence and optical coherence tomography angiography are able to detect retinal pigment epithelium hypopigmentation and choriocapillaris rarefaction, respectively, since the earliest stages of the disease.

Towards a Long-Read Sequencing Approach for the Molecular Diagnosis of RPGRORF15 Genetic Variants.

Sequencing of the low-complexity ORF15 exon of RPGR, a gene correlated with retinitis pigmentosa and cone dystrophy, is difficult to achieve with NGS and Sanger sequencing. False results could lead to the inaccurate annotation of genetic variants in dbSNP and ClinVar databases, tools on which HGMD and Ensembl rely, finally resulting in incorrect genetic variants interpretation. This paper aims to propose PacBio sequencing as a feasible method to correctly detect genetic variants in low-complexity regions, such as the ORF15 exon of RPGR, and interpret their pathogenicity by structural studies. Biological samples from 75 patients affected by retinitis pigmentosa or cone dystrophy were analyzed with NGS and repeated with PacBio. The results showed that NGS has a low coverage of the ORF15 region, while PacBio was able to sequence the region of interest and detect eight genetic variants, of which four are likely pathogenic. Furthermore, molecular modeling and dynamics of the RPGR Glu-Gly repeats binding to TTLL5 allowed for the structural evaluation of the variants, providing a way to predict their pathogenicity. Therefore, we propose PacBio sequencing as a standard procedure in diagnostic research for sequencing low-complexity regions such as RPGRORF15, aiding in the correct annotation of genetic variants in online databases.

Unveiling the Hidden: Early Manifestations of Extensive Macular Atrophy with Pseudodrusen-like appearance.

PURPOSE: To describe novel microperimetry and imaging findings in two patients affected by extensive macular atrophy with pseudodrusen-like appearance (EMAP) without signs of retinal pigment epithelium (RPE) atrophy. METHODS: Case series. Both patients underwent mesopic and dark-adapted two-color scotopic microperimetry, followed by multimodal imaging assessment including ultra-widefield photography, fundus autofluorescence (AF), high-resolution optical coherence tomography (Hi-Res OCT), OCT angiography and high-magnification module (HMM). RESULTS: Albeit normal visual acuity, both patients had a significant reduction of retinal sensitivity - especially under scotopic cyan conditions. One patient had macular pigment abnormalities, while the combination of blue and near-infrared AF modalities highlighted different patterns of pseudodrusen-like lesions.Of notice, Hi-Res OCT revealed a marked separation between the RPE and Bruch's membrane, containing a hyperreflective material with two different reflectivities. OCT angiography excluded the presence of macular neovascularization and documented several choriocapillaris flow voids. HMM images showed severe alteration of photoreceptors' mosaic in the perifovea. CONCLUSIONS: Our comprehensive assessment of two stage 1 EMAP patients revealed a predominant damage of perifoveal rods over areas of RPE-Bruch's membrane separation. These findings underscore the importance of basal laminar deposits in the initial stages of EMAP, contributing to a deeper understanding of its underlying mechanisms.

Clinical, Genotypic, and Imaging Characterization of the Spectrum of ABCA4 Retinopathies.

PURPOSE: To investigate the clinical and genotypic differences in the spectrum of ABCA4-associated retinopathies (ABCA4Rs). DESIGN: Observational, cross sectional case series. PARTICIPANTS: Sixty-six patients (132 eyes) carrying biallelic ABCA4 variants. METHODS: Patients underwent visual acuity measurement and multimodal imaging. Clinical records were reviewed for age at onset, presenting symptoms, genetic variants, and electroretinogram (ERG). Each eye was assigned to a phenotype based on age at onset, imaging and ERG: cone dystrophy-bull's-eye maculopathy (CD-BEM, 40 eyes), cone-rod dystrophy (CRD, 12 eyes), Stargardt disease (SD, 28 eyes), late-onset SD (LO-SD, 38 eyes), and fundus flavimaculatus (14 eyes). Images were analyzed for: peripapillary sparing, retinal pigment epithelium (RPE) atrophy (definitely decreased autofluorescence, DDAF), flecks patterns using autofluorescence; type of atrophy according to Classification of Atrophy Meeting reports, macular and choroidal thickness on OCT; and choriocapillaris flow deficits on OCT angiography. MAIN OUTCOME MEASURES: Primary outcome was to report the demographic, genotypic, and imaging characteristics of the different ABCA4R phenotypes. Secondary objectives included the assessment of imaging biomarkers as outcome measures for clinical trials. RESULTS: Age at onset was lower in CRD (12 ± 8 years) and higher in patients with LO-SD (59 ± 9 years) (all P < 0.01). Central vision loss was a common presenting symptom in CD-BEM and SD, whereas patients with LO-SD primarily complained of difficult dark adaptation. Missense variants were more frequent in CD-BEM, and splice site in CRD and LO-SD (P < 0.05). Peripapillary sparing was absent in 3 eyes with LO-SD (8%). Cone dystrophy-bull's-eye maculopathy eyes typically had complete outer retinal atrophy alterations (98%), whereas CRD and SD eyes showed both complete outer retinal atrophy and complete RPE and outer retinal atrophy (cRORA) (71%-100%). Patients with LO-SD had larger areas of DDAF (100% cRORA) and of choriocapillaris flow deficits (all P < 0.01). Repeatability of DDAF measurements was low for some phenotypes (CD-BEM and CRD) and atrophic areas <7.5 mm2. Resorbed flecks were significantly associated with CRD and LO-SD (P < 0.01). CONCLUSIONS: This research provides a thorough evaluation of the spectrum of ABCA4R. Our findings suggest that certain phenotypes show preferential photoreceptor degeneration (e.g., CD-BEM), whereas others have substantial RPE and choriocapillaris alterations (e.g., LO-SD). We recommend that clinical trial end points take into consideration these imaging features to improve the interpretation of their results. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

NATURAL COURSE AND CLASSIFICATION OF EXTENSIVE MACULAR ATROPHY WITH PSEUDODRUSEN-LIKE APPEARANCE.

PURPOSE: To describe the imaging characteristics and topographic expansion of retinal pigment epithelium (RPE) and outer retinal atrophy in extensive macular atrophy with pseudodrusen-like appearance. METHODS: Three-year, prospective, observational study. Nine patients with extensive macular atrophy with pseudodrusen-like appearance (17 eyes; 6 women) with no other ocular conditions were annually examined; one eye was excluded because of macular neovascularization. Best-corrected visual acuity measurement, fundus photographs, blue-light autofluorescence, and optical coherence tomography were performed at each visit. Formation of atrophy was analyzed on optical coherence tomography at foveal and extrafoveal areas following the Classification of Atrophy Meeting recommendations. Spatial enlargement throughout four sectors was assessed on blue-light autofluorescence after placing an Early Treatment for Diabetic Retinopathy Study grid centered on the foveola. RESULTS: Mean age was 53.0 ± 2.1 years at baseline with a follow-up of 36.6 ± 0.7 months. Thinning of the outer nuclear layer and disruption of the ellipsoid zone initially appeared above areas of RPE-Bruch membrane separation and preceded RPE atrophy. Subfoveal fibrosis was seen in 65% of the eyes. Superior sector involvement was found in all patients at baseline and was significantly larger than the other sectors at any time point ( P < 0.001). Best-corrected visual acuity declined from 68.0 ± 15.7 letters to 44.8 ± 14.9 letters during the follow-up and was significantly associated with subfoveal atrophy ( P < 0.001) and fibrosis ( P = 0.02). CONCLUSION: Our findings suggest that primary alterations in patients with extensive macular atrophy with pseudodrusen-like appearance are present at the outer segment-RPE interface, with the superior Early Treatment for Diabetic Retinopathy Study sector being the most vulnerable, which progresses to extensive atrophy of the RPE and outer retinal layers. Accordingly, we propose a three-stage disease classification.

Optical Coherence Tomography-Based Choroidal Structural Analysis and Vascularity Index in Best Vitelliform Macular Dystrophy.

INTRODUCTION: This study investigated choroidal structural changes on optical coherence tomography (OCT) using choroidal vascularity index (CVI) and choroidal thickness (CT) in patients with Best vitelliform macular dystrophy (BVMD). METHODS: This retrospective case control study included 78 patients with BVMD of different clinical stages and 242 age- and gender-matched healthy controls. Subfoveal OCT scans were analysed. Total choroidal area (TCA), luminal area (LA) and CT were measured after image segmentation and binarization. CVI, a novel marker for choroidal angioarchitecture, was defined as the ratio of LA to TCA. CVI and CT were compared between BVMD and control group, as well as among the BVMD subgroups. RESULTS: Mean CVI was lower in eyes with BVMD (65.0 ± 3.5%) compared to that in control eyes (67.5 ± 3.9%) and this was statistically significant (p < 0.0001). There was no significant difference in subfoveal CT between BVMD (302.88 ± 81.68 µm) and control (309.31 ± 65.46 µm) eyes (p = 0.4799). In the subgroup analysis, all stages of BVMD showed lower CVI compared to control while SFCT remained similar. Within the BVMD subgroups, CVI and subfoveal CT did not differ significantly and both were not shown to be associated with visual acuity. CONCLUSION: Decreased CVI was shown in eyes with BVMD compared to control eyes, while no significant difference in subfoveal CT was seen. CVI may be helpful in the understanding of choroidal pathology in BVMD.

Multimodal retinal imaging of m.3243A>G associated retinopathy.

Retro-mode illumination imaging can provide good visualization of chorio-retinal atrophy and of the retinal pigment epithelial alterations occurring in m.3243A > G associated retinopathy.

RPE65-Associated Retinopathies in the Italian Population: A Longitudinal Natural History Study.

Purpose: To investigate the course of inherited retinal degenerations (IRD) due to mutations in the RPE65 gene. Methods: This longitudinal multicentric retrospective chart-review study was designed to collect best corrected visual acuity (BCVA), Goldman visual field, optical coherence tomography (OCT), and electroretinography (ERG) measurements. The data, including imaging, were collected using an electronic clinical research form and were reviewed at a single center to improve consistency. Results: From an overall cohort of 60 Italian patients with RPE65-associated IRD, 43 patients (mean age, 27.8 ± 19.7 years) were included and showed a mean BCVA of 2.0 ± 1.0 logMAR. Time-to-event analysis revealed a median age of 33.8 years and 41.4 years to reach low vision and blindness based on BCVA, respectively. ERG (available for 34 patients) showed undetectable responses in most patients (26; 76.5%). OCT (available for 31 patients) revealed epiretinal membranes in five patients (16.1%). Central foveal thickness significantly decreased with age at a mean annual rate of -0.6%/y (P = 0.044). We identified 43 different variants in the RPE65 gene in the entire cohort. Nine variants were novel. Finally, to assess genotype-phenotype correlations, patients were stratified according to the number of RPE65 loss-of-function (LoF) alleles. Patients without LoF variants showed significantly (P < 0.05) better BCVA compared to patients with one or two LoF alleles. Conclusions: We described the natural course of RPE65-associated IRD in an Italian cohort showing for the first time a specific genotype-phenotype association. Our findings can contribute to a better management of RPE65-associated IRD patients.

Multimodal imaging of retinitis pigmentosa associated with Mainzer-Saldino syndrome.

Background: Syndromic ciliopathies have been variably linked to different retinal dystrophies. However, to date, few reports have characterized by means of multimodal imaging the retinal degeneration occurring in Mainzer-Saldino syndrome (MSS).Methods: Two siblings with history of kidney disease and other systemic abnormalities presented at our eye clinic in October 2017 complaining of night blindness and visual loss. They underwent a complete ophthalmologic examination including visual acuity (VA) assessment, optical coherence tomography (OCT) and blue-light autofluorescence (BAF). A screen for inherited retinal dystrophies was performed in this occasion.Results: At baseline, the youngest sister had slightly worse VA (20/30 vs. 20/20-25 Snellen equivalents). On fundoscopy, both siblings had severe thinning of the peripheral retina, attenuation of retinal vessels and widespread accumulation of pigmented deposits. Significant outer retinal atrophy with apparent foveal sparing was appreciable on OCT.During the 3 years of follow-up, vision remained overall stable in both patients whereas minimal progression of outer retinal atrophy was observed by means of OCT. Genetic analysis revealed compound heterozygosity in the IFT172 gene. Based on these findings, a diagnosis of retinitis pigmentosa (RP) associated with MSS was formulated.Conclusions: Our report describes the cases of two siblings affected by retinitis pigmentosa associated with MSS. Although both carrying the same mutations and a severe RP phenotype, the youngest sister had slightly more advanced retinal degeneration highlighting the remarkable variability related to the IFT172 retinopathy.

Progression of Atrophy and Visual Outcomes in Extensive Macular Atrophy with Pseudodrusen-like Appearance.

Purpose: To report visual outcomes and rate of retinal pigment epithelium (RPE) atrophy progression in patients with extensive macular atrophy with pseudodrusen-like appearance (EMAP). Design: Retrospective, observational study. Participants: Patients with EMAP and symptom onset before 55 years of age, at least 12 months of follow-up using Spectralis blue-light fundus autofluorescence (BAF) and OCT and with no other ocular or systemic conditions. Methods: Best-corrected visual acuity (BCVA), BAF, and OCT images were reviewed at baseline and at each annual visit until the last available follow-up. Atrophy was measured by 2 graders using the region finder software on Heidelberg Explorer and confirmed using OCT scans covering the entire atrophic lesion. The following imaging biomarkers were analyzed at each visit: foveal atrophy, vitreomacular traction, outer retinal tubulations, choroidal caverns and subfoveal choroidal thickness, border autofluorescence pattern (hyper-autofluorescent or iso-autofluorescent), and border irregularity as expressed by circularity index (CI). Main Outcome Measures: Primary outcomes were annual rate of atrophy enlargement and BCVA loss in EMAP patients. Secondary outcomes included the assessment of potential factors able to predict disease progression. Results: Thirty-six eyes from 18 patients with EMAP (6 men [33%]; mean age at symptom onset, 48.1 ± 1.7 years) were included. Mean follow-up lasted 32.8 ± 14.3 months. RPE atrophy increased from 10.8 ± 6.3 mm2 at baseline to 18.1 ± 8.3 mm2 at the end of follow-up, with a rate of 2.91 ± 1.09 mm2/year. Faster progression was associated with smaller CI at baseline (P = 0.02) and with iso-autofluorescent lesion borders (P = 0.01). Visual acuity declined progressively at a rate of 7.4 ± 5.8 letters per year, with 57% of eyes showing vision of 20/200 Snellen or worse at the 4-year follow-up. Worse visual outcomes were observed in patients with early foveal involvement at baseline (P = 0.02). Conclusions: Patients affected by EMAP present a rapid expansion of RPE atrophy that is comparable with the diffuse-trickling form of geographic atrophy. More irregular and iso-autofluorescent lesion borders seem to predict faster progression. Our findings may provide relevant information for patient counseling and future interventional approaches to select the best candidates and proper clinical outcomes.

RPGR-Related X-Linked Retinitis Pigmentosa Carriers with a Severe "Male Pattern".

BACKGROUND: X-linked retinitis pigmentosa (XLRP) due to mutations in the RPGR gene is a very severe form of RP, resulting in rapid disease progression and retinal dysfunction. Female carriers do not usually report symptoms. However, it has reported that carriers of XLRP can have a significant visual and retinal impairment. OBJECTIVES: To report a detailed description of 3 cases of severely affected females who presented with a "male" phenotype and have posed challenges at diagnosis, due to the apparent autosomal dominant family history. METHOD: Autofluorescence imaging (AF), colour imaging and optical coherence tomography (OCT) were performed. Confirmation of the genetic mutation was obtained by Sanger genetic sequencing. In 1 patient an X-inactivation analysis was performed to detect the X-inactivation ratio, as the percentage of cells tested in which each allele is active. RESULTS: All the patients started suffering from night blindness in early childhood. Colour, fundus AF and OCT images showed the typical pattern of degeneration reported in men. One patient underwent retina implant surgery due to the severe atrophy. CONCLUSIONS: This is a small selection of females with a severe phenotype that do not differ from the typical male phenotype. In our opinion gene therapy surgery should be warranted in this scenario.

Initial results from a first-in-human gene therapy trial on X-linked retinitis pigmentosa caused by mutations in RPGR.

Retinal gene therapy has shown great promise in treating retinitis pigmentosa (RP), a primary photoreceptor degeneration that leads to severe sight loss in young people. In the present study, we report the first-in-human phase 1/2, dose-escalation clinical trial for X-linked RP caused by mutations in the RP GTPase regulator (RPGR) gene in 18 patients over up to 6 months of follow-up (https://clinicaltrials.gov/: NCT03116113). The primary outcome of the study was safety, and secondary outcomes included visual acuity, microperimetry and central retinal thickness. Apart from steroid-responsive subretinal inflammation in patients at the higher doses, there were no notable safety concerns after subretinal delivery of an adeno-associated viral vector encoding codon-optimized human RPGR (AAV8-coRPGR), meeting the pre-specified primary endpoint. Visual field improvements beginning at 1 month and maintained to the last point of follow-up were observed in six patients.