The Progression of Stargardt Disease (ProgStar) as determined by spectral-domain optical coherence tomography over a 24-month period (ProgStar Report No. 19).

INTRODUCTION: To evaluate the progression of atrophy as determined by spectral-domain optical coherence tomography (SD-OCT) in patients with molecularly confirmed ABCA4-associated Stargardt disease type 1 (STGD1) over a 24-month period in a multicenter prospective cohort study. METHODS: SD-OCT images from 428 eyes of 236 patients were analyzed. Change of mean thickness (MT) and intact area were estimated after semi-automated segmentation for the following individual layers in the central subfield (CS), inner ring (IR) and outer ring (OR) of the ETDRS grid: retinal pigment epithelium (RPE), outer segments (OS), inner segments (IS), outer nuclear layer (ONL) inner retina (IR) and total retina (TR). RESULTS: Statistically significant decreases of all outer retinal layers (RPE, OS, IS, and ONL) could be observed over a 24-month period both in decline of mean retinal thickness and intact area (p<.0001, respectively); whereas the inner retina showed an increase of retinal thickness in the central subfield and inner ring and remained unchanged in the outer ring. CONCLUSIONS: Significant loss could be detected in outer retinal layers by SD-OCT over a 24-month period in patients with STGD1. Loss of thickness and/or intact area of such layers may serve as potential endpoints for clinical trials that aim to slow down the disease progression of STGD1.

Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.

Complications, Visual Acuity, and Refractive Error Three Years After Secondary Intraocular Lens implantation for Pediatric Aphakia.

OBJECTIVE: To report the cumulative incidence of complications and describe refractive error and visual acuity (VA) outcomes in children undergoing secondary intraocular lens (IOL) implantation following previous surgery for non-traumatic cataract. DESIGN: Pediatric cataract registry. PARTICIPANTS: 80 children (108 eyes: 60 bilateral, 48 unilateral) undergoing lensectomy at <13 years of age, followed by secondary IOL implantation at median age (range) of 2.7 (0.6 to 5.0) years for bilateral and 2.1 (0.5 to 6.4) for unilateral cases. METHODS: Annual data collection from medical record review through 5 years following lensectomy. MAIN OUTCOME MEASURES: Cumulative incidence of newly emergent complications following secondary IOL implantation; refractive error and VA by 5 years after lensectomy. RESULTS: Median (interquartile range [IQR]) follow-up following secondary IOL implantation was 2.5 years (0.8 to 3.3 years). A common complication following secondary IOL implantation was a glaucoma-related adverse event (GRAE: glaucoma or glaucoma suspect); the cumulative incidence was 17% (95% CI: 3%-29%) in bilateral and 12% (95% CI: 0%-23%) in unilateral cases. The cumulative incidence of surgery for visual axis opacification was 2% (95% CI: 0%-7%) for bilateral and 4% (95% CI: 0%-10%) for unilateral cases. Median prediction error (IQR) within 90 days of implantation was 0.88 D (-0.50 D to +3.00 D) less hyperopic than intended among 21 eyes for bilateral cases and 1.50 D (-0.25 D to +2.38 D) less among 19 unilateral cases. Median (IQR) spherical equivalent refractive error at 5 years (median 5.1 years of age) in eyes receiving a secondary IOL was +0.50 D (-2.38 D to +2.94 D) for 48 bilateral and +0.06 D (-2.25 D to +0.75 D) for 22 unilateral cases. Median (IQR) monocular VA at 5 years was 20/63 (20/50-20/100) for bilateral (n=42) and 20/400 (20/160-20/800) for unilateral (n=33) cases. CONCLUSIONS: Eyes with secondary IOL implantation have an ongoing risk of new glaucoma-related adverse events. Five years after lensectomy (approximately 2.5 years after secondary IOL implantation), average refractive error was less hyperopic than desired given the anticipated further myopic shift before refraction stabilizes.

BEST1 Variant Associated with an Atypical Macular and Peripheral Retinal Phenotype.

PURPOSE: Best vitelliform macular dystrophy (BVMD) is an inherited macular dystrophy associated with over 250 pathogenic variants of the Bestrophin-1 (BEST1) gene. While several of the types of lesions of BVMD are well-described, reports of phenotypic variations associated with rare genetic variants are limited. METHODS: Retrospective case-series performed in 2021 at a tertiary eye care center. PATIENTS: Three members of one family referred to a tertiary eye care clinic for evaluation of their autosomal dominant macular dystrophy. RESULTS: Study subjects presented with atypical findings of peripheral schisis-like lesions and atrophy with abnormal electroretinogram (ERG) in addition to typical macular lesions found in BVMD. Genetic analyses identified a heterozygous BEST1 c.227T>A, p.(Ile76Asn) pathogenic variant in all three subjects. CONCLUSIONS: This study represents the first report of the phenotype associated with the c.227T>A, p.(Ile76Asn) BEST1 variant, which - while mentioned twice in the literature - has not been previously described. The phenotype is unique, comprising features of typical BVMD with ERG and peripheral findings, suggestive of a panretinal dysfunction.

Indications for Systemic and Genetic Testing in Patients with Congenital Cataracts.

Congenital cataracts account for a significant proportion of blindness in children worldwide. They affect approximately 12-136 per 100,000 births worldwide. A genetic etiology is present in a large proportion of patients and can lead to isolated cataracts or those in the context of genetic multisystem disorders. We present two examples of genetically determined childhood cataracts and briefly review the work-up of such patients. Mutations in numerous genes have been identified that cause congenital cataracts, such as those encoding for crystallins, connexins and aquaporins, as well as some developmental regulatory proteins. Identifying the genetic or molecular etiology of congenital cataract is essential for identifying and better understanding the pathways leading to this disease, and for providing individualized genetic counseling and guiding treatment for possible associated systemic problems.

Neuropathy target esterase activity predicts retinopathy among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. PNPLA6 encodes Neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a clinical meta-analysis of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6 -associated clinical diagnoses unambiguously reclassified 10 variants as likely pathogenic and 36 variants as pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship and the generation of a preclinical animal model pave the way for therapeutic trials, using NTE as a biomarker.

Profiling of visual acuity and genotype correlations in RP2 patients: a cross-sectional comparative meta-analysis between carrier females and affected males.

BACKGROUND: X-linked retinitis pigmentosa (XLRP) is the most severe form of retinitis pigmentosa (RP) and accounts for 15-20% of all RP cases. In this study, we investigated the progression of visual acuity loss across age groups in female carriers and compared it to affected males. METHODS: A PubMed literature search was conducted, and RP2 cases were included based on specific inclusion criteria. Visual acuity (VA), refractive error spherical equivalent (SE), and retinal findings were recorded. Cross-sectional analyses investigated the relationship between VA and age in carrier females and affected males. Genotype-phenotype VA correlations were studied using t-tests. RESULTS: 35 carrier females and 28 affected males with confirmed RP2 mutations were collected from 13 studies. The mean age and logMAR VA of carrier females were 44.2 ± 17.4 years, and 0.5 ± 0.5, respectively. 78.8% of carrier females showed abnormal XLRP-related fundus findings and had significantly reduced VA compared to those with normal fundi (0.6 ± 0.5 vs. 0.1 ± 0.1; p = 0.03). Compared to affected males, no statistical correlation was found between logMAR VA and advancing age in carrier females (p = 0.75). Statistically significant linear correlations were found between logMAR VA and SE in each of carrier females (p = 0.01). There were no observed differences in logMAR VA based on mutation type (p = 0.97) or mutation location (p = 0.83). Anisometropia was observed in 38% of carrier females and 68% of affected males; these prevalence numbers are statistically significant between the two groups (1.7 ± 0.3 vs. 3.9 ± 10.9 dioptres; p = 0.03). CONCLUSIONS: RP2 carrier females generally maintain good VA throughout their lifetime, as opposed to affected males, whose vision progressively declines. Our study provides important VA prognostic data that is crucial for patient counseling.

Functional imaging of mitochondria in genetically confirmed retinal dystrophies using flavoprotein fluorescence.

BACKGROUND: Whether by indirect oxidative stress or direct genetic defect, various genetic retinal dystrophies involve mitochondrial stress. Mitochondrial flavoprotein fluorescence (FPF), reported as either average signal intensity or variability (heterogeneity), may serve as a direct, quantifiable marker of oxidative stress. MATERIALS AND METHODS: This observational study enrolled patients with genetically confirmed retinal dystrophies between January and December 2021. Patients with concomitant maculopathy and ocular hypertension were excluded. Patients were FPF imaged with OcuMet Beacon® third generation device during routine outpatient visit. RESULTS: The final analysis cohort included 242 images from 157 patients. Mean FPF intensity was significantly increased between age matched controls and patients with confirmed rod-cone dystrophy, Stargardt disease, Bardet-Biedl syndrome (BBS), and Mitochondrial ATP synthase mutation (P ≤ 0.007). Mean FPF heterogeneity was significantly increased between age matched controls and patients with confirmed rod-cone dystrophy, Stargardt disease, and BBS (P ≤ 0.011). FPF lesions were noted to correlate with Fundus Autofluorescence (FAF) lesions in diseases examined. CONCLUSIONS: FPF intensity and heterogeneity significantly increased in patients with retinal dystrophies. The correlation of FPF lesions with FAF lesions implies FPF may be a clinically useful biomarker in patients with IRDs.

This study found increases in flavoprotein fluorescence signal in patients with genetically confirmed inherited retinal dystrophies compared to age matched controls. Flavoprotein fluorescence signal correlated with fundus autofluorescence findings, suggesting clinical utility of novel signal.

Effective gene therapy of Stargardt disease with PEG-ECO/pGRK1-ABCA4-S/MAR nanoparticles.

Stargardt disease (STGD) is the most common form of inherited retinal genetic disorders and is often caused by mutations in ABCA4. Gene therapy has the promise to effectively treat monogenic retinal disorders. However, clinically approved adeno-associated virus (AAV) vectors do not have a loading capacity for large genes, such as ABCA4. Self-assembly nanoparticles composed of (1-aminoethyl)iminobis[N-(oleoylcysteinyl-1-amino-ethyl)propionamide (ECO; a multifunctional pH-sensitive/ionizable amino lipid) and plasmid DNA produce gene transfection comparable with or better than the AAV2 capsid. Stable PEG-ECO/pGRK1-ABCA4-S/MAR nanoparticles produce specific and prolonged expression of ABCA4 in the photoreceptors of Abca4 -/- mice and significantly inhibit accumulation of toxic A2E in the eye. Multiple subretinal injections enhance gene expression and therapeutic efficacy with an approximately 69% reduction in A2E accumulation in Abca4 -/- mice after 3 doses. Very mild inflammation was observed after multiple injections of the nanoparticles. PEG-ECO/pGRK1-ABCA4-S/MAR nanoparticles are a promising non-viral mediated gene therapy modality for STGD type 1 (STGD1).

TOPICAL CARBONIC ANHYDRASE INHIBITORS IN THE LONG-TERM TREATMENT OF JUVENILE X-LINKED RETINOSCHISIS.

PURPOSE: To describe the response to long-term topical dorzolamide treatment in patients with juvenile X-linked retinoschisis and cystic-like foveal lesions. METHODS: This was a retrospective interventional case series that included 18 eyes of 10 patients with genetically confirmed juvenile X-linked retinoschisis examined at the Cleveland Clinic Cole Eye Institute, a tertiary referral center, between 2005 and 2021. Patients were treated with topical 2% dorzolamide two to three times daily in both eyes. Two eyes were excluded because of retinal detachment. Primary outcome measures were logarithm of minimum angle of resolution visual acuity and optical coherence tomography based central subfield thickness. RESULTS: The mean follow-up was 8.38 years (SD, 3.41 years). The mean baseline and final central subfield thickness was 429.88 µ m (SD, 143.36 µ m) and 372.28 µ m, respectively (SD, 147.13 µ m, P = 0.10). The mean baseline and final logarithm of minimum angle of resolution visual acuity was 0.45 (SD, 0.17) and 0.34, respectively (SD, 0.22, P < 0.01). None of the patients experienced any side effects from topical dorzolamide. CONCLUSION: The study data support previous reports of improved visual acuity in X-linked retinoschisis patients on topical dorzolamide treatment. This is the longest follow-up for a series of juvenile X-linked retinoschisis patients treated with a topical carbonic anhydrase inhibitor to date. A large, prospective, randomized clinical trial is needed to provide stronger evidence regarding the efficacy of topical carbonic anhydrase inhibitors in juvenile X-linked retinoschisis.

The landscape of submicroscopic structural variants at the OPN1LW/OPN1MW gene cluster on Xq28 underlying blue cone monochromacy.

Blue cone monochromacy (BCM) is an X-linked retinal disorder characterized by low vision, photoaversion, and poor color discrimination. BCM is due to the lack of long-wavelength-sensitive and middle-wavelength-sensitive cone photoreceptor function and caused by mutations in the OPN1LW/OPN1MW gene cluster on Xq28. Here, we investigated the prevalence and the landscape of submicroscopic structural variants (SVs) at single-base resolution in BCM patients. We found that about one-third (n = 73) of the 213 molecularly confirmed BCM families carry an SV, most commonly deletions restricted to the OPN1LW/OPN1MW gene cluster. The structure and precise breakpoints of the SVs were resolved in all but one of the 73 families. Twenty-two families-all from the United States-showed the same SV, and we confirmed a common ancestry of this mutation. In total, 42 distinct SVs were identified, including 40 previously unreported SVs, thereby quadrupling the number of precisely mapped SVs underlying BCM. Notably, there was no "region of overlap" among these SVs. However, 90% of SVs encompass the upstream locus control region, an essential enhancer element. Its minimal functional extent based on deletion mapping in patients was refined to 358 bp. Breakpoint analyses suggest diverse mechanisms underlying SV formation as well as in one case the gene conversion-based exchange of a 142-bp deletion between opsin genes. Using parsimonious assumptions, we reconstructed the composition and copy number of the OPN1LW/OPN1MW gene cluster prior to the mutation event and found evidence that large gene arrays may be predisposed to the occurrence of SVs at this locus.

Severe retinal complications in Knobloch Syndrome - Three siblings without clinically apparent occipital defects and a review of the literature.

BACKGROUND: Knobloch syndrome results from recessive mutations in COL18A1 and is characterized by retinopathy and occipital scalp, brain and skull defects. METHODS AND MATERIALS: We report three siblings, born to consanguineous parents, two of whom with genetically confirmed Knobloch syndrome due to a homozygous pathogenic variant c.4054_4055del; p.Leu1352Valfs*72 in COL18A1. RESULTS: With the lack of classic occipital findings, an initial diagnosis of familial exudative vitreoretinopathy was entertained in these siblings because of the history of retinal detachments, retinal pigmentary changes and abnormal vitreous. The diagnosis of Knobloch syndrome was eventually made through molecular genetic testing using an extensive panel. In one patient presenting with acute retinal detachment and posteriorly dislocated intraocular lens implant, reattachment surgery was successful in stabilizing vision. CONCLUSION: The clinical diagnosis of Knobloch syndrome can be difficult to reach in the absence of the typical occipital scalp defects. A careful medical history, detailed clinical examination and molecular genetic testing will reveal the correct diagnosis of Knobloch syndrome in atypical cases.

Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia.

Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by impaired color discrimination, low visual acuity, photosensitivity, and nystagmus. To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade. CNGA3 encodes the CNGA3 subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors and is one of the major disease-associated genes for ACHM. Herein, we provide a comprehensive overview of the CNGA3 variant spectrum in a cohort of 1060 genetically confirmed ACHM patients, 385 (36.3%) of these carrying "likely disease-causing" variants in CNGA3. Compiling our own genetic data with those reported in the literature and in public databases, we further extend the CNGA3 variant spectrum to a total of 316 variants, 244 of which we interpreted as "likely disease-causing" according to ACMG/AMP criteria. We report 48 novel "likely disease-causing" variants, 24 of which are missense substitutions underlining the predominant role of this mutation class in the CNGA3 variant spectrum. In addition, we provide extensive in silico analyses and summarize reported functional data of previously analyzed missense, nonsense and splicing variants to further advance the pathogenicity assessment of the identified variants.

Ocular Findings in a Patient With KAT6A Mutation.

KAT6A mutations are associated with intellectual disability, speech delays, dysmorphic facial features, and strabismus. However, detailed ocular findings of such patients have not yet been published. In this case report, the authors present a patient with a KAT6A mutation and optic nerve malformation. [J Pediatr Ophthalmol Strabismus. 2021;58(3):e9-e11.].

Mitochondrial DNA A3243G variant-associated retinopathy: a meta-analysis of the clinical course of visual acuity and correlation with systemic manifestations.

PURPOSE: The mitochondrial DNA A3243G (m.3243A>G) variant causes a wide spectrum of phenotypes, with pigmentary retinopathy as the most common ocular finding. We undertook this meta-analysis to investigate the clinical course of visual acuity (VA) in patients with m.3243A>G variant and provide key clinical correlations with systemic manifestations. METHODS: A PubMed literature search was performed and studies were selected after satisfying pre-set inclusion criteria. Demographic and clinical data, including retinal findings and systemic manifestations were recorded. Cross-sectional and linear regression analyses were used to investigate the relationship between VA and age, as well as between the age at diagnosis of retinopathy and the mean ages at diagnosis of sensorineural hearing loss or diabetes. The age and prevalence of systemic manifestations among patients with and without retinopathy were studied using t-tests and Mann-Whitney U-tests (performed on binarized data). Likelihood ratios were computed. RESULTS: The mean VA (average of both eyes) of 90 patients (72.2% female; 65/90) were collected from 18 studies published between 1990 and 2018. The baseline mean age was 45.2 years (range 17 to 92). The mean logMAR VA was 0.10 (- 0.12 to 1.39). There was a statistically significant linear correlation between the logMAR VA and age (p = .008). The VA of patients less than or equal to 50 years of age was significantly better than that of patients older than 50 years (0.06 vs.0.18 logMAR, p = .002). 67 patients (74.4%) showed a characteristic pigmentary retinopathy with a mean age at diagnosis of 47.9 years (17 to 92) and VA of 0.14 logMAR (- 0.12 to 1.24). Age at diagnosis of retinopathy was linearly correlated with age at diagnosis of hearing loss or diabetes (p < .001). Patients with retinopathy were more likely to have hearing loss (83.6% vs. 56.5%, p = .03) or diabetes (56.7% vs. 17.4%, p = .001) than those without retinopathy. Those with both hearing loss and diabetes had an earlier onset of retinopathy than those without (46.4 vs. 60.4 years, p = .01). Patients without both hearing loss and diabetes were 5.3-fold less likely to develop a retinopathy. CONCLUSIONS: Patients with m.3243A>G variant pigmentary retinopathy maintain highly functional VA until around the fifth decade of life, after which significant visual decline ensues. Patients without hearing loss and diabetes have a lower likelihood of exhibiting a retinopathy, which tends to appear about one decade after hearing loss and diabetes are diagnosed.

Mitochondrial DNA A3243G variant-associated retinopathy: Current perspectives and clinical implications.

Cellular function and survival are critically dependent on the proper functionality of the mitochondrion. Neurodegenerative cellular processes including cellular adenosine triphosphate production, intermediary metabolism control, and apoptosis regulation are all mitochondrially mediated. The A to G transition at position 3243 in the mitochondrial MTTL1 gene that encodes for the leucine transfer RNA (m.3243A>G) causes a variety of diseases, including maternally inherited loss of hearing and diabetes syndrome (MIDD), mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS). Ophthalmological findings-including posterior sub-capsular cataract, ptosis, external ophthalmoplegia, and pigmentary retinopathy- have all been associated with the m.3243A>G variant. Pigmentary retinopathy is, however, the most common ocular finding, occurring in 38% to 86% of cases. To date, little is known about the pathogenesis, natural history, and heteroplasmic and phenotypic correlations of m.3243A>G-associated pigmentary retinopathy. We summarize the current understanding of mitochondrial genetics and pathogenesis of some associated diseases. We then review the pathophysiology, histology, clinical features, treatment, and important ocular and systemic phenotypic manifestations of m.3243A>G variant associated retinopathy. Mitochondrial diseases require a multidisciplinary team approach to ensure effective treatment, regular follow-up, and accurate genetic counseling.