Morphovascular changes after anti-VEGF intravitreal injection for a choroidal neovascularization secondary to COVID-19 infection in a pediatric patient.

Choroidal neovascularization (CNV) is a common pathologic lesion that occurs in various chorioretinopathy. Although the incidence of CNV is quite rare in children and adolescents, these lesions have a severe impact on visual acuity and quality of life over patients' lifetime. The management of CNV in pediatric patients is challenging, clear guidelines are limited due to a lack of randomized clinical trials. However, the more promising option is the use of vascular endothelial growth factor (VEGF) inhibitors. We reported a case of recurrent idiopathic choroidal neovascularization in a healthy pediatric patient after COVID 19 infection. Optical coherence tomography angiofraphy (OCTA) showed, in a non invasive way, a choroidal neovascularization at the posterior pole including macula and superior temporal arcade in the right eye, while the left eye was unaffected. In order to inactivate the neovascularization, intravitreal injections of anti-VEGF (Lucentis-Ranibizumab 0.3 mL) were performed in the right eye. Six months after the injections BCVA of the right eye was improved from 0.7 logMAR to 0.2 logMAR. OCT-A examination did not detect any signs of attivation of the preexistent neovascularization. It is reasonable to assert that Anti-VEGF could be the main treatment in case of choroidal neovascularization in young patients after COVID 19 infection due to the high chorioretinal level of VEGF-A described in these diseases.

Long-term effects of early/late-onset visual deprivation on macular and retinal nerve fibers layer structure: A pilot study.

BACKGROUND/AIMS: Tomographic analysis of macular and peripapillary retinal nerve fibers layer (RNFL) thickness in patients with history of congenital (CC) and developmental cataract (DC). METHODS: Analysis of macular and RNFL thickness using a spectral-domain optical coherence tomography was performed. Retinal layers thickness was measured using the internal segmentation software. Measurements of affected (unilateral and bilateral), contralateral eyes and control eyes were compared. RESULTS: Patients with history of CC or DC (n = 13 and 11 respectively) and 35 healthy control subjects were enrolled. Thicker inner and outer nuclear layers (INL, ONL) and thicker ONL were found when CC and DC group when compared to controls respectively. Bilateral CC showed the most relevant differences. Slight thickening of CC inner retinal layers were found when compared to DC. Increased superonasal RNFL thickness was found in CC group when compared to DC and controls. Thickening of RNFL of contralateral unaffected eyes of unilateral CC were found when compared to controls. CONCLUSION: Significant macular and RNFL thickness changes between CC, DC patients and controls that partially involve also contralateral unaffected eyes of unilateral congenital cataract were found. CC and DC groups show significant differences only in inner retinal layers thickness. Our data suggest that early visual deprivation may influence retinal arrangements occurring during development involving predominantly the outer nuclear layer and para/perifoveal inner retinal layers, and confirm that early treatment of CC allow to achieve better long-term visual outcome. Moreover functional and structural data support the hypothesis that unilateral amblyopia is not exclusively an unilateral issue.

Congenital isolated unilateral third nerve palsy in children: the diagnostic contribution of high-resolution MR imaging.

PURPOSE: To describe the neuroanatomical correlates of unilateral congenital isolated oculomotor palsy by means of high-resolution MRI. METHODS: Children with a clinical diagnosis of congenital isolated oculomotr palsy and with a high-resolution MRI acquisition targeted on the orbits and cranial nerves were selected and included in the study. An experienced pediatric neuroradiologist evaluated all the exams, assessing the integrity and morphology of extraocular muscles, oculomotor, trochlear and abducens nerves as well as optic nerves and globes. Clinical data and ophthalmologic evaluations were also collected. RESULTS: Six children (age range: 1-16 years; males: 3) were selected. All patients showed, on the affected side (left:right = 5:1), anomalies of the III nerve and extraocular muscles innervated by the pathological nerve. One patient had complete nerve agenesis, two patients showed a diffuse thinning of the nerve, from the brainstem to the orbit and 3 patients showed a distal thinning of the oculomotor nerve, starting at the level of the cavernous sinus. In all cases atrophy of corresponding muscles was noticed, but the involvement of the affected muscles varied with the nervous pattern of injury. CONCLUSIONS: High-resolution MRI represents a valuable tool for the diagnosis of III nerve anomalies in unilateral congenital IOP, showing different patterns of nerve involvement and muscular atrophy.

Postnatal microcephaly and retinal involvement expand the phenotype of RPL10-related disorder.

Hemizygous missense variants in the RPL10 gene encoding a ribosomal unit are responsible for an X-linked syndrome presenting with intellectual disability (ID), autism spectrum disorder, epilepsy, dysmorphic features, and multiple congenital anomalies. Among 15 individuals with RPL10-related disorder reported so far, only one patient had retinitis pigmentosa and microcephaly was observed in approximately half of the cases. By exome sequencing, three Italian and one Spanish male children, from three independent families, were found to carry the same hemizygous novel missense variant p.(Arg32Leu) in RPL10, inherited by their unaffected mother in all cases. The variant, not reported in gnomAD, is located in the 28S rRNA binding region, affecting an evolutionary conserved residue and predicted to disrupt the salt-bridge between Arg32 and Asp28. In addition to features consistent with RPL10-related disorder, all four boys had retinal degeneration and postnatal microcephaly. Pathogenic variants in genes responsible for inherited retinal degenerations were ruled out in all the probands. A novel missense RPL10 variant was detected in four probands with a recurrent phenotype including ID, dysmorphic features, progressive postnatal microcephaly, and retinal anomalies. The presented individuals suggest that retinopathy and postnatal microcephaly are clinical clues of RPL10-related disorder, and at least the retinal defect might be more specific for the p.(Arg32Leu) RPL10 variant, suggesting a specific genotype/phenotype correlation.

Optical coherence tomography angiography in healthy children: A comparison of macular structure.

PURPOSE: The purpose of the present study was to investigate the perfusion density (PD) of macular superficial (SCP) and deep capillary plexus (DCP), the size of foveal avascular zone (FAZ) and central macular thickness (CMT) in healthy children using optical coherence tomography angiography (OCT-A). PATIENTS AND METHODS: About 206 eyes of 111 children were analyzed. The correlation of gestational age (GA), birth weight (BW), age, sex, refractive errors, and visual acuity (VA) with OCT-A parameters were investigated. RESULTS: The mean PD of the fovea and the mean FAZ area of SCP were 17.1% (DS: 4.26) and 234.47 (DS: 106.39) µm2. The mean PD of the fovea and the mean FAZ area of DCP were 13.5% (DS: 5.23) and 298.32 (DS: 112.37) µm2. Superficial and deep FAZ areas were not correlated with sex, age, BW, refractive errors, or VA. FAZ area of SCP was correlated with foveal PD (r = -0.76) and with CMT (r = -0.68). FAZ area of DCP was correlated with foveal's PD (r = -0.61). There was no correlation between CMT and refractive errors. CONCLUSION: OCT-A may provide a non-invasive and reliable approach to evaluate macular perfusion in children. As the FAZ area, PD, and CMT change during the growth period, we performed established a reference range for different ages.

A case of retinal vascular involvement in a 6-year-old patient with Covid-19.

PURPOSE: This study evaluated fundus changes in a 6-year-old child who contracted Sars-CoV-2 without developing symptoms of the disease. MATERIALS AND METHODS: The patient underwent a complete ophthalmic evaluation, which included assessment of visual acuity with and without correction, extensive ophthalmological examination, cicloplegic refraction by retinoscopy and funduscopic examination, OCT, and angio-OCT examination. RESULTS: Fundoscopic examination in a young patient with previous Sars-CoV-2 infection showed marked vascular tortuosity, evident both at the posterior pole and retinal periphery, especially on the arterial vasculature, and cotton wool spots along the retinal vessels, highlightable also at OCT and angio-OCT examination. These alterations persist at a 6-month follow-up. CONCLUSIONS: In COVID-19 infection, even in asymptomatic pediatric patients, vasculitis develops also affecting the retinal vessels, appreciable on fundus examination. A thorough eye examination in all COVID-19 patients with close follow-up is therefore important. This is the first case report on retinal changes in a pediatric patient.

Reoperation in esotropic Duane retraction syndrome: Long-term motor outcome of superior rectus transposition.

AIM: The aim was to evaluate the long-term motor outcome of superior rectus transposition procedure in patients affected by unilateral esotropic Duane retraction syndrome with residual esotropia and anomalous head position. METHODS: A retrospective analysis of medical records of patients affected by esotropic Duane retraction syndrome who underwent superior rectus transposition procedure as reoperation for residual esotropia and/or residual anomalous head position. Amount of deviation, anomalous head position, duction limitation, globe retraction, presence of upshoot/downshoot, and vertical deviation were analyzed before and after superior rectus transposition procedure. RESULTS: Twenty patients were selected. All patients underwent unilateral medial rectus recession or bilateral medial rectus recession, for unilateral esotropic Duane retraction syndrome at least 2 years before superior rectus transposition reoperation. Mean age at surgery (superior rectus transposition) was 12 ± 6.8 years, and the follow-up period was 2.7 ± 0.6. Mean deviations at distance and near before surgery were 19.5 ± 5.7 and 15.2 ± 6.8, respectively. Two patients showed upshoot. Head turn was 11.4 ± 5.1°; abduction limitation was -2.6 ± 0.9. After superior rectus transposition, all patients showed an improvement of esotropia at distance and near (8.1 ± 5.7 and 5.1 ± 5.6, respectively; p < 0.05), anomalous head position (5.6 ± 3.9°; p < 0.05), and abduction limitation (-2.3 ± 0.8; p < 0.05). No statistically significant changes occurred in globe retraction. No adduction limitation, vertical deviation, and upshoot/downshoot were present after superior rectus transposition procedure. Results were stable during follow-up. CONCLUSION: Superior rectus transposition procedure is an effective procedure in esotropic Duane retraction syndrome patients who previously undergone unilateral/bilateral medial rectus recession, with residual esotropia and anomalous head position. It allows improvement of esotropia, head turn, and partial recovery of abduction in a significant percentage of patients (30%) with no vertical complications.

Optical coherence tomography angiography for the measurement of optic disc: Macular relationship.

INTRODUCTION: Fundus photography is the gold standard for assessing ocular torsion over the last 30 years. However, it is not a precise and reproducible tool during clinical practice. Optical coherence tomography angiography is characterized by precise identification of the macula and the optic disc, and it could be an effective method to easily calculate the angle of ocular torsion, compared to fundus photography. The aim of this study was to show whether any difference in the measurement and the accuracy of the angle of torsion between the head of the optic nerve and the fovea was present. METHODS: This is a prospective single-, referral-center study conducted at the San Giuseppe Hospital in Milan on 80 eyes of 40 adult patients, included in a random-sample way. Exclusion criteria were non-cooperation, higher refractive errors of ±3 diopters, retinal and optic disc pathologies, and ocular movement disorders. RESULTS: Patients' mean age was 54.3 ± 16.3 (range: 22-83) years. The angle measured by the fundus camera was 7.78° ± 3.04°, while the angle measured by the angiography was 7.09° ± 3.08° (p = .035). The mean interocular difference was 1.54° ± 3.42° for fundus photography and 0.5° ± 4.71° for angiography (p = .013). CONCLUSION: Optical coherence tomography angiography is a very useful, fast, precise, reproducible, and reliable technique in cooperative subjects, not inferior to the fundus camera and less prone to human error.

Novel USH1G homozygous variant underlying USH2-like phenotype of Usher syndrome.

PURPOSE: Usher syndrome (USH) is an autosomal recessive disorder characterized by congenital sensorineural hearing impairment and retinitis pigmentosa. Classification distinguishes three clinical types of which type I (USH1) is the most severe, with vestibular dysfunction as an added feature. To date, 15 genes and 3 loci have been identified with the USH1G gene being an uncommon cause of USH. We describe an atypical USH1G-related phenotype caused by a novel homozygous missense variation in a patient with profound hearing impairment and relatively mild retinitis pigmentosa, but no vestibular dysfunction. METHODS: A 26-year-old female patient with profound congenital sensorineural hearing loss, nyctalopia and retinitis pigmentosa was studied. Audiometric, vestibular and ophthalmologic examination was performed. A panel of 13 genes was tested by next-generation sequencing (NGS). RESULTS: While the hearing loss was confirmed to be profound, the vestibular function resulted normal. Although typical retinitis pigmentosa was present, the age at onset was unusually late for USH1 syndrome. A novel homozygous missense variation (c.1187T>A, p.Leu396Gln) in the USH1G gene has been identified as causing the disease in our patient. CONCLUSIONS: Genetic and phenotypic heterogeneity are very common in both isolated and syndromic retinal dystrophies and sensorineural hearing loss. Our findings widen the spectrum of USH allelic disorders and strength the concept that variants in genes that are classically known as underlying one specific clinical USH subtype might result in unexpected phenotypes.

Augmented vertical rectus transpositions: Intraoperative measurement of torsion following sequential muscle detachment.

INTRODUCTION: After vertical recti transposition surgery, a torsional change may occur. We hypothesized that step-by-step monitoring of the intraoperative torsional position of the eye can avoid any unexpected complications and identify critical moments of surgery that may have adverse effects. METHODS: Nine patients with sixth nerve palsy that underwent complete transposition of the superior (SR) and inferior rectus (IR) muscles to the lateral rectus muscle by means of the technique of augmented vertical recti transposition were prospectively included. The torsional position of the eye was recorded at eight stages of the procedure. RESULTS: We observed two distinct patterns of induced torsional deviation during partial disinsertion of a vertical rectus muscle depending on whether disinsertion began medially or laterally, after cutting about 3/4 of the muscle fibers: ¾ nasal disinsertion of the SR and ¾ temporal disinserton of the IR caused intorsion, ¾ temporal disinsertion of the SR and ¾ nasal disinsertion of the IR caused extorsion. Torsion improved after the vertical rectus was attached temporally to the sclera along the spiral of Tillaux with tying of the augmentation suture to the LR. The greatest change in torsion was from ¾ temporal disinsertion of the SR (5°extorsion), to reattachment along the spiral of Tillaux temporally (5°intorsion). CONCLUSION: The SR and IR have different torsional effects, which only appears when more than half of the fibers are detached. Augmented transposition does not cause any additional torsional effects. This intraoperative monitoring system can be used to detect unintended torsional complications, especially during transposition surgery.

Long-Term Effects of Botulinum Toxin in Large-Angle Infantile Esotropia.

PURPOSE: The purpose of this study is the motor outcome analysis of early Botulinum toxin (BT) treatment in patients affected by large-angle infantile esotropia (IE). PATIENTS AND METHODS: Retrospective analysis of 130 medical charts of IE patients who underwent BT injections between 2004 and 2019 was performed. All patients underwent BT injections within 13 months of age. RESULTS: Thirty patients, matching the inclusion criteria, were included in the study. Twenty-eight patients showing residual ET ≥25 PD (34.3±6.6 PD ranged from 25 to 50) underwent surgery. CONCLUSION: Our result after 1 Botulinum toxin injection showed a very low success rate (6.7%) at last follow-up (28.3±7.2 months). Our data would suggest one Botulinum toxin injection in children affected by large-angle infantile esotropia allows a significant reduction of deviation but does not avoid the need for surgical treatment.

Novel mutations in MFRP and PRSS56 are associated with posterior microphthalmos.

Background: Biallelic pathogenic variants in MFRP and PRSS56 genes can be responsible for nanophthalmos (NO) or posterior microphthalmos (PM). This study describes detailed clinical and molecular findings in a series of five patients affected by PM from four unrelated families.Materials and Methods: All patients underwent a complete ophthalmological and genetic evaluation. For proper and deep phenotyping a multimodal instrumental approach was used for all cases: B-scan ultrasound, spectral domain optical coherence tomography (SD-OCT), fundus retinal imaging and anterior segment data were obtained. Molecular analysis of PRSS56 and MFRP genes was performed with Next-Generation Sequencing (NGS) methodology and segregation analysis on parents and one affected sibling was performed with Sanger sequencing.Results: A very high hyperopia of +14.00D or more was the main refractive error and macular abnormalities were identified in all patients. Axial length ranged from 15.3 mm to 17.86 mm (mean 16.58 mm) and age at first presentation ranged from 6 to 36 months (mean 18 months). Anterior chamber depth was within normal values, according to age, while total axial length was severely reduced in all patients. All our patients met the diagnostic criteria for PM. Three patients, including a pair of siblings, carried compound heterozygous mutations in the PRSS56 gene; in the other two patients, one homozygous or two compound heterozygous mutations in the MFRP gene were detected.Conclusion: Our study describes four novel mutations in the PRSS56 gene and one in the MFRP gene in patients with non-syndromic posterior microphthalmos. Proper genotype-phenotype correlation and early diagnosis could lead to good functional results.

Expanding the Clinical and Genetic Spectrum of RAB28-Related Cone-Rod Dystrophy: Pathogenicity of Novel Variants in Italian Families.

The small Ras-related GTPase Rab-28 is highly expressed in photoreceptor cells, where it possibly participates in membrane trafficking. To date, six alterations in the RAB28 gene have been associated with autosomal recessive cone-rod dystrophies. Confirmed variants include splicing variants, missense and nonsense mutations. Here, we present a thorough phenotypical and genotypical characterization of five individuals belonging to four Italian families, constituting the largest cohort of RAB28 patients reported in literature to date. All probands displayed similar clinical phenotype consisting of photophobia, decreased visual acuity, central outer retinal thinning, and impaired color vision. By sequencing the four probands, we identified: a novel homozygous splicing variant; two novel nonsense variants in homozygosis; a novel missense variant in compound heterozygous state with a previously reported nonsense variant. Exhaustive molecular dynamics simulations of the missense variant p.(Thr26Asn) in both its active and inactive states revealed an allosteric structural mechanism that impairs the binding of Mg2+, thus decreasing the affinity for GTP. The impaired GTP-GDP exchange ultimately locks Rab-28 in a GDP-bound inactive state. The loss-of-function mutation p.(Thr26Asn) was present in a compound heterozygosis with the nonsense variant p.(Arg137*), which does not cause mRNA-mediated decay, but is rather likely degraded due to its incomplete folding. The frameshift p.(Thr26Valfs4*) and nonsense p.(Leu13*) and p.(Trp107*) variants, if translated, would lack several key structural components necessary for the correct functioning of the encoded protein.

Pathogenicity of new BEST1 variants identified in Italian patients with best vitelliform macular dystrophy assessed by computational structural biology.

BACKGROUND: Best vitelliform macular dystrophy (BVMD) is an autosomal dominant macular degeneration. The typical central yellowish yolk-like lesion usually appears in childhood and gradually worsens. Most cases are caused by variants in the BEST1 gene which encodes bestrophin-1, an integral membrane protein found primarily in the retinal pigment epithelium. METHODS: Here we describe the spectrum of BEST1 variants identified in a cohort of 57 Italian patients analyzed by Sanger sequencing. In 13 cases, the study also included segregation analysis in affected and unaffected relatives. We used molecular mechanics to calculate two quantitative parameters related to calcium-activated chloride channel (CaCC composed of 5 BEST1 subunits) stability and calcium-dependent activation and related them to the potential pathogenicity of individual missense variants detected in the probands. RESULTS: Thirty-six out of 57 probands (63% positivity) and 16 out of 18 relatives proved positive to genetic testing. Family study confirmed the variable penetrance and expressivity of the disease. Six of the 27 genetic variants discovered were novel: p.(Val9Gly), p.(Ser108Arg), p.(Asn179Asp), p.(Trp182Arg), p.(Glu292Gln) and p.(Asn296Lys). All BEST1 variants were assessed in silico for potential pathogenicity. Our computational structural biology approach based on 3D model structure of the CaCC showed that individual amino acid replacements may affect channel shape, stability, activation, gating, selectivity and throughput, and possibly also other features, depending on where the individual mutated amino acid residues are located in the tertiary structure of BEST1. Statistically significant correlations between mean logMAR best-corrected visual acuity (BCVA), age and modulus of computed BEST1 dimerization energies, which reflect variations in the in CaCC stability due to amino acid changes, permitted us to assess the pathogenicity of individual BEST1 variants. CONCLUSIONS: Using this computational approach, we designed a method for estimating BCVA progression in patients with BEST1 variants.

Antioxidant Saffron and Central Retinal Function in ABCA4-Related Stargardt Macular Dystrophy.

Retinal oxidative damage, associated with an ATP-binding cassette, sub-family A, member 4, also known as ABCA4 gene mutation, has been implicated as a major underlying mechanism for Stargardt disease/fundus flavimaculatus (STG/FF). Recent findings indicate that saffron carotenoid constituents crocins and crocetin may counteract retinal oxidative damage, inflammation and protect retinal cells from apoptosis. This pilot study aimed to evaluate central retinal function following saffron supplementation in STG/FF patients carrying ABCA4 mutations. METHODS: in a randomized, double-blind, placebo-controlled study (clinicaltrials.gov: NCT01278277), 31 patients with ABCA4-related STG/FF and a visual acuity >0.25 were randomly assigned to assume oral saffron (20 mg) or placebo over a six month period and then reverted to P or S for a further six month period. Full ophthalmic examinations, as well as central 18° focal electroretinogram (fERG) recordings, were performed at baseline and after six months of either saffron or placebo. The fERG fundamental harmonic component was isolated by Fourier analysis. Main outcome measures were fERG amplitude (in µV) and phase (in degrees). The secondary outcome measure was visual acuity. RESULTS: supplement was well tolerated by all patients throughout follow-up. After saffron, fERG amplitude was unchanged; after placebo, amplitude tended to decrease from baseline (mean change: -0.18 log µV, p < 0.05). Reverting the treatments, amplitude did not change significantly. fERG phase and visual acuity were unchanged throughout follow-up. CONCLUSIONS: short-term saffron supplementation was well tolerated and had no detrimental effects on the electroretinographic responses of the central retina and visual acuity. The current findings warrant further long-term clinical trials to assess the efficacy of saffron supplementation in slowing down the progression of central retinal dysfunction in ABCA4-related STG/FF.

Paralog Studies Augment Gene Discovery: DDX and DHX Genes.

Members of a paralogous gene family in which variation in one gene is known to cause disease are eight times more likely to also be associated with human disease. Recent studies have elucidated DHX30 and DDX3X as genes for which pathogenic variant alleles are involved in neurodevelopmental disorders. We hypothesized that variants in paralogous genes encoding members of the DExD/H-box RNA helicase superfamily might also underlie developmental delay and/or intellectual disability (DD and/or ID) disease phenotypes. Here we describe 15 unrelated individuals who have DD and/or ID, central nervous system (CNS) dysfunction, vertebral anomalies, and dysmorphic features and were found to have probably damaging variants in DExD/H-box RNA helicase genes. In addition, these individuals exhibit a variety of other tissue and organ system involvement including ocular, outer ear, hearing, cardiac, and kidney tissues. Five individuals with homozygous (one), compound-heterozygous (two), or de novo (two) missense variants in DHX37 were identified by exome sequencing. We identified ten total individuals with missense variants in three other DDX/DHX paralogs: DHX16 (four individuals), DDX54 (three individuals), and DHX34 (three individuals). Most identified variants are rare, predicted to be damaging, and occur at conserved amino acid residues. Taken together, these 15 individuals implicate the DExD/H-box helicases in both dominantly and recessively inherited neurodevelopmental phenotypes and highlight the potential for more than one disease mechanism underlying these disorders.

Long-term development of refractive error in refractive, nonrefractive and partially accommodative esotropia.

Accommodative esotropia (AE) is a convergent deviation due to an excess of the convergence linked to the innervational stimulus for accommodation and it is usually associated to the presence of hyperopia. The development of hyperopia over time has been widely described but the lack of comparative analysis among accommodative esotropia subtypes, does not allow to verify the existence of different developmental patterns. In this study we aimed to describe the long term changes of refractive error in patients affected by accommodative esotropia as a function of the strabismus type: refractive (RAE), non-refractive (NRAE) and partially accommodative esotropia (PAE). The medical records of 66 patients (24 RAE, 22 PAE, 20 NRAE), who wore the full correction of their cycloplegic refraction error during the entire follow up period, were retrospectively reviewed. Mean outcome was the analysis of the variations, among groups, of refractive error over time; differences between mild (≤3.00D) and high (≥5.00D) hyperopia, effects of amblyopia and relationship with AC/A ratio were also investigated. All patients were followed up from approximately 4 years of age to 20, with mean follow up of 16.06±0.29 years. Our results described similar non-linear trend of refractive error development among groups. The initial increase of hyperopia (up to 7-8 years) was followed by a decreasing trend persisting up to adulthood (approximately 20 years of age). During this period, spherical equivalent decreased at a lower mean annual rate in patients affected by RAE (-0.07D) compared to other groups (NRAE -0.11D, p = 0.003 and PAE 0.13D, p = 0.002). In all groups, however, significant amount of hyperopia was found at last examination; indeed the observed difference in SE values from baseline to the end of follow up, was not significant (RAE: +0.27D, 95% C.I. -0.49 to +1.04D, p = 0.472; PAE: -0.69D, 95% C.I. -1.67 to +0.28D, p = 0.154; NRAE: -0.39D, 95% C.I. -1.11 to +0.34D, p = 0.278). AC/A ratio, amblyopia and amount of initial hyperopia appeared to have no significant role in longitudinal change of the refractive error. In conclusion, this study provides a complete overview, from childhood to adulthood, of refractive error development in different form of accommodative esotropia.

A novel p.(Glu111Val) missense mutation in GUCA1A associated with cone-rod dystrophy leads to impaired calcium sensing and perturbed second messenger homeostasis in photoreceptors.

Guanylate Cyclase-Activating Protein 1 (GCAP1) regulates the enzymatic activity of the photoreceptor guanylate cyclases (GC), leading to inhibition or activation of the cyclic guanosine monophosphate (cGMP) synthesis depending on its Ca2+- or Mg2+-loaded state. By genetically screening a family of patients diagnosed with cone-rod dystrophy, we identified a novel missense mutation with autosomal dominant inheritance pattern (c.332A>T; p.(Glu111Val); E111V from now on) in the GUCA1A gene coding for GCAP1. We performed a thorough biochemical and biophysical investigation of wild type (WT) and E111V human GCAP1 by heterologous expression and purification of the recombinant proteins. The E111V substitution disrupts the coordination of the Ca2+ ion in the high-affinity site (EF-hand 3, EF3), thus significantly decreasing the ability of GCAP1 to sense Ca2+ (∼80-fold higher Kdapp compared to WT). Both WT and E111V GCAP1 form dimers independently on the presence of cations, but the E111V Mg2+-bound form is prone to severe aggregation over time. Molecular dynamics simulations suggest a significantly increased flexibility of both the EF3 and EF4 cation binding loops for the Ca2+-bound form of E111V GCAP1, in line with the decreased affinity for Ca2+. In contrast, a more rigid backbone conformation is observed in the Mg2+-bound state compared to the WT, which results in higher thermal stability. Functional assays confirm that E111V GCAP1 interacts with the target GC with a similar apparent affinity (EC50); however, the mutant shifts the GC inhibition out of the physiological [Ca2+] (IC50E111V ∼10 µM), thereby leading to the aberrant constitutive synthesis of cGMP under conditions of dark-adapted photoreceptors.

Multimodal Imaging in Autosomal Dominant Cone-Rod Dystrophy Caused by Novel CRX Variant.

AIM: To characterize by multimodal approach the phenotype of patients from a 3 generations pedigree, affected by autosomal dominant cone-rod dystrophy (CRD), found to carry a novel pathogenic variant in the cone-rod homeobox-containing (CRX) gene. METHODS: Examination of the adult patients included the following tests: visual acuity, multicolour imaging, spectral domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF) and OCT angiography (OCT-A) recordings. In a 2.5-year-old child, cycloplegic refraction, fundoscopy, ocular motility evaluation and electrophysiological exams were performed. Next Generation Sequencing of patients' DNA has been carried out. RESULTS: A novel CRX pathogenic variant has been identified in our patients. The 2.5-year-old child in the third generation was found to have inherited the variant, with no clinical signs of the condition, but electroretinographic abnormalities in the scotopic component. In the adult patients, diffuse atrophy of the retinal pigment epithelium/photoreceptor complex in the macular region was evident at the OCT and FAF, while OCT-A showed choriocapillaris density reduction. CONCLUSIONS: Multimodal study allowed the characterization of a peculiar form of CRD. The novel pathogenic variant seems to have a different effect on the phenotype if compared with a previously described similar one, giving an insight into the pathogenic mechanism of CRX-related retinal dystrophies and offering valuable information that could lead to the development of possible future therapies.