Hereditary Retinal Dystrophies Research Articles

The spectrum of mutations in the patients presenting with ABCA4-associated Stargardt's disease in a Russian population

Introduction. Stargardt's disease is a hereditary retinal dystrophy characterized by the early manifestation and the progressive deterioration of visual acuity. The spectrum of mutations in the ABCA4 gene associated with this pathology in the Russian Federation has not been fully investigated. Aim. The objective of the present study was to elucidate the spectrum of mutations in the ABCA4 gene in the Russian patients presenting Stargardt's disease. Materials and methods. The study included a total of 38 unrelated patients at the age varying from 6 to 48 (mean 20 ± 8.9) years having the clinically confirmed diagnosis of Stargardt's disease. The search of mutations in DNA extracted from the peripheral blood lymphocytes of the patients was carried out with the use of a set of oligonucleotide primers (Ion Ampliseq Inherited Disease Panel; Life Technologies, USA). The Ion Torrent PGM Sequencer (Life Technologies, USA) was used for the parallel semiconductor sequencing of the gene-coding regions. All the patients underwent the standard ophthalmological examination, electroretinography, optical coherence tomography, and fundus autofluorescence. Results. We established the spectrum of mutations in the ABCA4 gene in the patients of a Russian population suffering from autosomal-recessive Stargardt's disease. We identified 45 alleles responsible for the development of this condition. 14 of them had been earlier described in the Russian patients while 19 were discovered for the first time in this country although they had been known to occur in other populations. Moreover, we described 12 novel heterozygous variations, viz. c.230T>A (rs61748527), c.4956T>G (rs61750561), c.2820>G (rs81749445). c.5226delT, c.2537A>T, c.57353T, c.893delG, c.702 insATC, c.3896T>G, c.1356delA, c.1341delGAT, and c.231insGAAAA. Discussion. The study has revealed the rather variable phenotype in the patients presenting with ABCA4-associated Stargardt's disease. A wide variety of mutations were shown to be responsible for the difference of the clinical picture of this condition in individual patients. The comparison of the genotypes and the phenotypes has demonstrated the differential effect of the concrete mutations. Conclusion. The spectrum of mutations in the patients presenting with ABCA4-associated Stargardt's disease in the surveyed Russian population is different from that in other populations. We have revealed 12 previously unknown mutations; moreover 19 mutations have been described for the first time in this country although they had been previously known to occur in other populations.

Genomic screening of ABCA4 and array CGH analysis underline the genetic variability of Greek patients with inherited retinal diseases

BackgroundRetinal dystrophies are a clinically and genetically heterogeneous group of disorders which affect more than two million people worldwide. The present study focused on the role of the ABCA4 gene in the pathogenesis of hereditary retinal dystrophies (autosomal recessive Stargardt disease, autosomal recessive cone-rod dystrophy, and autosomal recessive retinitis pigmentosa) in patients of Greek origin. Materials and methodsOur cohort included 26 unrelated patients and their first degree healthy relatives. The ABCA4 mutation screening involved Sanger sequencing of all exons and flanking regions. Evaluation of novel variants included sequencing of control samples, family segregation analysis and characterization by in silico prediction tools. Twenty five patients were also screened for copy number variations by array-comparative genomic hybridization. ResultsExcluding known disease-causing mutations and polymorphisms, two novel variants were identified in coding and non-coding regions of ABCA4. Array-CGH analysis revealed two partial deletions of USH2A and MYO3A in two patients with nonsyndromic autosomal recessive retinitis pigmentosa. ConclusionsThe ABCA4 mutation spectrum in Greek patients differs from other populations. Bioinformatic tools, segregation analysis along with clinical data from the patients seemed to be crucial for the evaluation of genetic variants and particularly for the discrimination between causative and non-causative variants.

Combining Zebrafish and Mouse Models to Test the Function of Deubiquitinating Enzyme (Dubs) Genes in Development: Role of USP45 in the Retina.

Ubiquitination is a dynamic and reversible posttranslational modification. Much effort has been devoted to characterize the function of ubiquitin pathway genes in the cell context, but much less is known on their functional role in the development and maintenance of organs and tissues in the organism. In fact, several ubiquitin ligases and deubiquitinating enzymes (DUBs) are implicated in human pathological disorders, from cancer to neurodegeneration. The aim of our work is to explore the relevance of DUBs in retinal function in health and disease, particularly since some genes related to the ubiquitin or SUMO pathways cause retinal dystrophies, a group of rare diseases that affect 1:3000 individuals worldwide. We propose zebrafish as an extremely useful and informative genetic model to characterize the function of any particular gene in the retina, and thus complement the expression data from mouse. A preliminary characterization of gene expression in mouse retinas (RT-PCR and in situ hybridization) was performed to select particularly interesting genes, and we later replicated the experiments in zebrafish. As a proof of concept, we selected ups45 to be knocked down by morpholino injection in zebrafish embryos. Morphant phenotypic analysis showed moderate to severe eye morphological defects, with a defective formation of the retinal structures, therefore supporting the relevance of DUBs in the formation and differentiation of the vertebrate retina, and suggesting that genes encoding ubiquitin pathway enzymes are good candidates for causing hereditary retinal dystrophies.

Structural brain MRI studies in eye diseases: are they clinically relevant? A review of current findings.

Many eye diseases reduce visual acuity or are associated with visual field defects. Because of the well-defined retinotopic organization of the connections of the visual pathways, this may affect specific parts of the visual pathways and cortex, as a result of either deprivation or transsynaptic degeneration. For this reason, over the past several years, numerous structural magnetic resonance imaging (MRI) studies have examined the association of eye diseases with pathway and brain changes. Here, we review structural MRI studies performed in human patients with the eye diseases albinism, amblyopia, hereditary retinal dystrophies, age-related macular degeneration (AMD) and glaucoma. We focus on two main questions. First, what have these studies revealed? Second, what is the potential clinical relevance of their findings? We find that all the aforementioned eye diseases are indeed associated with structural changes in the visual pathways and brain. As such changes have been described in very different eye diseases, in our view the most parsimonious explanation is that these are caused by the loss of visual input and the subsequent deprivation of the visual pathways and brain regions, rather than by transsynaptic degeneration. Moreover, and of clinical relevance, for some of the diseases - in particular glaucoma and AMD - present results are compatible with the view that the eye disease is part of a more general neurological or neurodegenerative disorder that also affects the brain. Finally, establishing structural changes of the visual pathways has been relevant in the context of new therapeutic strategies to restore retinal function: it implies that restoring retinal function may not suffice to also effectively restore vision. Future structural MRI studies can contribute to (i) further establish relationships between ocular and neurological neurodegenerative disorders, (ii) investigate whether brain degeneration in eye diseases is reversible, (iii) evaluate the use of neuroprotective medication in ocular disease, (iv) determine optimal timing for retinal implant insertion and (v) establish structural MRI examination as a diagnostic tool in ophthalmology.

Progressive retinal atrophy in Shetland sheepdog is associated with a mutation in the CNGA1 gene.

Progressive retinal atrophy (PRA) is the collective name of a class of hereditary retinal dystrophies in the dog and is often described as the equivalent of retinitis pigmentosa in humans. PRA is characterized by visual impairment due to degeneration of the photoreceptors in the retina, usually leading to blindness. PRA has been reported in dogs from more than 100 breeds and can be genetically heterogeneous both between and within breeds. The disease can be subdivided by age at onset and rate of progression. Using genome-wide association with 15 Shetland Sheepdog (Sheltie) cases and 14 controls, we identified a novel PRA locus on CFA13 (Praw =8.55×10(-7) , Pgenome =1.7×10(-4) ). CNGA1, which is known to be involved in human cases of retinitis pigmentosa, was located within the associated region and was considered a likely candidate gene. Sequencing of this gene identified a 4-bp deletion in exon 9 (c.1752_1755delAACT), leading to a frameshift and a premature stop codon. The study indicated genetic heterogeneity as the mutation was present in all PRA-affected individuals in one large family of Shelties, whereas some other cases in the studied Sheltie population were not associated with this CNGA1 mutation. To our knowledge, this is the first report of a mutation in CNGA1 causing PRA in dogs.

Identification of Genetic Defects in 33 Probands with Stargardt Disease by WES-Based Bioinformatics Gene Panel Analysis.

Stargardt disease (STGD) is the most common hereditary macular degeneration in juveniles, with loss of central vision occurring in the first or second decade of life. The aim of this study is to identify the genetic defects in 33 probands with Stargardt disease. Clinical data and genomic DNA were collected from 33 probands from unrelated families with STGD. Variants in coding genes were initially screened by whole exome sequencing. Candidate variants were selected from all known genes associated with hereditary retinal dystrophy and then confirmed by Sanger sequencing. Putative pathogenic variants were further validated in available family members and controls. Potential pathogenic mutations were identified in 19 of the 33 probands (57.6%). These mutations were all present in ABCA4, but not in the other four STGD-associated genes or in genes responsible for other retinal dystrophies. Of the 19 probands, ABCA4 mutations were homozygous in one proband and compound heterozygous in 18 probands, involving 28 variants (13 novel and 15 known). Analysis of normal controls and available family members in 12 of the 19 families further support the pathogenicity of these variants. Clinical manifestation of all probands met the diagnostic criteria of STGD. This study provides an overview of a genetic basis for STGD in Chinese patients. Mutations in ABCA4 are the most common cause of STGD in this cohort. Genetic defects in approximately 42.4% of STGD patients await identification in future studies.

495. In Vivo Evidence of trans-Splicing in a Humanized Mouse Model of Autosomal Dominant Retinitis Pigmentosa Induced By Mutation of the Rhodopsin Gene

The most frequent cause of retinitis pigmentosa (RP), a group of hereditary retinal dystrophies leading to blindness, is the occurrence of point mutations in the Rhodopsin (RHO) gene. Most of these mutations lead to gain of functions or dominant negative effects deleterious for photoreceptors, thus resulting in a dominant mode of transmission. Moreover, it has been shown that variations in RHO expression level are also deleterious for the retina. Gene transfer strategies modifying RHO mutations should therefore lead both to suppression of mutant protein expression and restoration of the normal one at a physiological level. Spliceosome-mediated RNA trans-splicing should in theory respect these constraints by repairing mutations at the pre-mRNA level. Using this technology, the expression level of the repaired mRNA will indeed depend solely on that of the gene endogenous promoter. To achieve this goal, this approach consists of introducing, by gene transfer, an exogenous RNA – called PTM, for Pre-Trans-splicing Molecule – able to bind the pre-mRNA and promote splicing in trans, leading to replacement of the mutant part of the RHO pre-mRNA.We engineered fourteen different RHO-PTMs able to repair any mutation in RHO exons 2, 3, 4 and 5, which differ only on their binding sequence to RHO pre-mRNA. To determine the efficiency of each PTM, we transiently co-transfected HEK293T cells with a plasmid encoding a PTM and another encoding the wild-type or mutant RHO. The maximum trans-splicing efficiency observed at the mRNA level was about 25%. We improved this efficiency to 40% by refinement of the PTM sequence, through reintroduction of an endogenous RHO intron in the cDNA part of the PTM. We then tested PTM at the protein level in a cellular model expressing RHO stably. While wild-type RHO was localized to the plasma membrane, mutant RHO was sequestrated in the cytoplasmic compartment. Using a flow-imaging methodology (ImageStreamX), we were able to precisely quantify this phenotype and showed that trans-splicing partially restored a correct localization of RHO in this cellular model. Thus, we constructed an AAV vector containing our best PTM to assess its activity in vivo in a humanized mouse model of rhodopsin mutation following subretinal injection. Using co-injection with an AAV-GFP and micro-dissection of the transduced part of the retina, we demonstrated that trans-splicing reached 30% at the RNA level, while it was not detectable in the untransduced part, or in animals that received a control PTM. This study demonstrates that trans-splicing may provide a therapeutic benefit in case of dominant mutations of the rhodopsin gene.

High Diagnostic Yield of Whole Exome Sequencing in Participants With Retinal Dystrophies in a Clinical Ophthalmology Setting

To assess the diagnostic yield and the practicality of implementing whole exome sequencing within a clinical ophthalmology setting. Evaluation of a diagnostic protocol. setting: Patient participants were enrolled during clinical appointments in a university-based ophthalmic genetics clinic. Twenty-six patients with a variety of presumed hereditary retinal dystrophies. Participants were offered whole exome sequencing in addition to clinically available sequencing gene panels between July 2012 and January 2013 to determine the molecular etiology of their retinal dystrophy. Diagnostic yield and acceptability of whole exome sequencing in patients with retinal disorders. Twenty-six of 29 eligible patients (∼90%) who were approached opted to undergo molecular testing. Each participant chose whole exome sequencing in addition to, or in lieu of, clinically available sequencing gene panels. Time to obtain informed consent was manageable in the clinical context. Whole exome sequencing successfully identified known pathogenic mutations or suspected deleterious variants in 57.7% of participants. Additionally, 1 participant had 2 autosomal dominant medically actionable incidental findings (unrelated to retinopathy) that were reported to enable the participant to take preventive action and reduce risk for future disease. In this study, we identified the molecular etiology for more than half of all participants. Additionally, we found that participants were widely accepting of whole exome sequencing and the possibility of being informed about medically actionable incidental findings.

Low Vision Rehabilitation in Patients with Hereditary Retinal Dystrophy

Low Vision Rehabilitation in Patients with Hereditary Retinal Dystrophy

Gene therapy to treat inherited and complex retinal degenerative diseases

Gene therapy to treat inherited and complex retinal degenerative diseases

Novel GUCY2D Gene Mutations in Japanese Male Twins with Leber Congenital Amaurosis.

Purpose. Leber congenital amaurosis (LCA), a genetically and clinically heterogeneous disease, is the earliest onset retinitis pigmentosa (RP) and is the most severe of hereditary retinal dystrophies. This study was conducted to investigate genetic and clinical features of LCA in a set of Japanese male twins with LCA. Methods. To identify causative mutations, 74 genes known to cause RP or LCA were examined by targeted-next generation sequencing (NGS). Targeted-NGS was performed using a custom designed Agilent HaloPlex target enrichment kit with Illumina Miseq sequencer. Identified potential pathogenic mutations were confirmed using Sanger sequencing. Clinical analyses were based on ophthalmic examination, fundus photography, and electroretinography (ERG). Results. Compound heterozygous GUCY2D mutations of novel splicing mutation c.2113+2_2113+3insT and novel missense mutation p.L905P were detected in both twins. Their father and mother were heterozygous for c.2113+2_2113+3insT and p.L905P, respectively. The twins had phenotypic features similar to those previously reported in patients with GUCY2D mutations. This included early childhood onset of visual loss, nystagmus, unrecordable ERG, photophobia, and hyperopia. Conclusions. To the best of our knowledge, this is the first report of genetic and clinical features of Japanese LCA twins with GUCY2D mutation, which were detected using targeted-NGS.

Intravitreal Injection of Splice-switching Oligonucleotides to Manipulate Splicing in Retinal Cells.

Leber congenital amaurosis is a severe hereditary retinal dystrophy responsible for neonatal blindness. The most common disease-causing mutation (c.2991+1655A>G; 10–15%) creates a strong splice donor site that leads to insertion of a cryptic exon encoding a premature stop codon. Recently, we reported that splice-switching oligonucleotides (SSO) allow skipping of the mutant cryptic exon and the restoration of ciliation in fibroblasts of affected patients, supporting the feasibility of a SSO-mediated exon skipping strategy to correct the aberrant splicing. Here, we present data in the wild-type mouse, which demonstrate that intravitreal administration of 2'-OMePS-SSO allows selective alteration of Cep290 splicing in retinal cells, including photoreceptors as shown by successful alteration of Abca4 splicing using the same approach. We show that both SSOs and Cep290 skipped mRNA were detectable for at least 1 month and that intravitreal administration of oligonucleotides did not provoke any serious adverse event. These data suggest that intravitreal injections of SSO should be considered to bypass protein truncation resulting from the c.2991+1655A>G mutation as well as other truncating mutations in genes which like CEP290 or ABCA4 have a mRNA size that exceed cargo capacities of US Food and Drug Administration (FDA)-approved adeno-associated virus (AAV)-vectors, thus hampering gene augmentation therapy.

Lysosomal membrane permeabilization and autophagy blockade contribute to photoreceptor cell death in a mouse model of retinitis pigmentosa.

Retinitis pigmentosa is a group of hereditary retinal dystrophies that normally result in photoreceptor cell death and vision loss both in animal models and in affected patients. The rd10 mouse, which carries a missense mutation in the Pde6b gene, has been used to characterize the underlying pathophysiology and develop therapies for this devastating and incurable disease. Here we show that increased photoreceptor cell death in the rd10 mouse retina is associated with calcium overload and calpain activation, both of which are observed before the appearance of signs of cell degeneration. These changes are accompanied by an increase in the activity of the lysosomal protease cathepsin B in the cytoplasm of photoreceptor cells, and a reduced colocalization of cathepsin B with lysosomal markers, suggesting that lysosomal membrane permeabilization occurs before the peak of cell death. Moreover, expression of the autophagosomal marker LC3-II (lipidated form of LC3) is reduced and autophagy flux is blocked in rd10 retinas before the onset of photoreceptor cell death. Interestingly, we found that cell death is increased by the induction of autophagy with rapamycin and inhibited by calpain and cathepsin inhibitors, both ex vivo and in vivo. Taken together, these data suggest that calpain-mediated lysosomal membrane permeabilization underlies the lysosomal dysfunction and downregulation of autophagy associated with photoreceptor cell death.

The research status of preclinical animal experiments of gene therapy for Leber congenital amaurosis

Leber congenital amaurosis （LCA） is extremely severe hereditary retinal dystrophy, because it leads to congenital bilateral blindness in early childhood. With the development of molecular genetics and the therapeutic gene replacement technology, gene therapy clinical trials have obtained exciting results on the basis of relatively satisfied with preliminary clinical experimental results by adeno-associated virus （AAV） vector-mediated gene therapy in the past decade. These researching methods include intravitreal injection and subretinal space injection of gene vector, and the investigating indexes include evaluations of visual function and safety, such as immune reaction of the animals,ocular histopathological change,complications and bio-distribution of gene sequence. The preliminary success of the LCA17 ]I gene therapy will give some clues to the other inherited retinal diseases. This review focuses on the present status of pre-clinical animal experiments of its gene therapy. Key words: Leber congenital amaurosis; Gene therapy; RPE65 gene; Visual function; Safety

Molecular diagnostic testing by eyeGENE: analysis of patients with hereditary retinal dystrophy phenotypes involving central vision loss.

To analyze the genetic test results of probands referred to eyeGENE with a diagnosis of hereditary maculopathy. Patients with Best macular dystrophy (BMD), Doyne honeycomb retinal dystrophy (DHRD), Sorsby fundus dystrophy (SFD), or late-onset retinal degeneration (LORD) were screened for mutations in BEST1, EFEMP1, TIMP3, and CTRP5, respectively. Patients with pattern dystrophy (PD) were screened for mutations in PRPH2, BEST1, ELOVL4, CTRP5, and ABCA4; patients with cone-rod dystrophy (CRD) were screened for mutations in CRX, ABCA4, PRPH2, ELOVL4, and the c.2513G>A p.Arg838His variant in GUCY2D. Mutation analysis was performed by dideoxy sequencing. Impact of novel variants was evaluated using the computational tool PolyPhen. Among the 213 unrelated patients, 38 had BMD, 26 DHRD, 74 PD, 8 SFD, 6 LORD, and 54 CRD; six had both PD and BMD, and one had no specific clinical diagnosis. BEST1 variants were identified in 25 BMD patients, five with novel variants of unknown significance (VUS). Among the five patients with VUS, one was diagnosed with both BMD and PD. A novel EFEMP1 variant was identified in one DHRD patient. TIMP3 novel variants were found in two SFD patients, PRPH2 variants in 14 PD patients, ABCA4 variants in four PD patients, and p.Arg838His GUCY2D mutation in six patients diagnosed with dominant CRD; one patient additionally had a CRX VUS. ABCA4 mutations were identified in 15 patients with recessive CRD. Of the 213 samples, 55 patients (26%) had known causative mutations, and 13 (6%) patients had a VUS that was possibly pathogenic. Overall, selective screening for mutations in BEST1, PRPH2, and ABCA4 would likely yield the highest success rate in identifying the genetic basis for macular dystrophy phenotypes. Because of the overlap in phenotypes between BMD and PD, it would be beneficial to screen genes associated with both diseases.

Translational read-through as an alternative approach for ocular gene therapy of retinal dystrophies caused by in-frame nonsense mutations.

The eye has become an excellent target for gene therapy, and gene augmentation therapy of inherited retinal disorders has made major progress in recent years. Nevertheless, a recent study indicated that gene augmentation intervention might not stop the progression of retinal degeneration in patients. In addition, for many genes, viral-mediated gene augmentation is currently not feasible due to gene size and limited packaging capacity of viral vectors as well as expression of various heterogeneous isoforms of the target gene. Thus, alternative gene-based strategies to stop or delay the retinal degeneration are necessary. This review focuses on an alternative pharmacologic treatment strategy based on the usage of translational read-through inducing drugs (TRIDs) such as PTC124, aminoglycoside antibiotics, and designer aminoglycosides for overreading in-frame nonsense mutations. This strategy has emerged as an option for up to 30-50% of all cases of recessive hereditary retinal dystrophies. In-frame nonsense mutations are single-nucleotide alterations within the gene coding sequence resulting in a premature stop codon. Consequently, translation of such mutated genes leads to the synthesis of truncated proteins, which are unable to fulfill their physiologic functions. In this context, application of TRIDs facilitates the recoding of the premature termination codon into a sense codon, thus restoring syntheses of full-length proteins. So far, clinical trials for non-ocular diseases have been initiated for diverse TRIDs. Although the clinical outcome is not analyzed in detail, an excellent safety profile, namely for PTC124, was clearly demonstrated. Moreover, recent data demonstrated sustained read-through efficacies of nonsense mutations causing retinal degeneration, as manifested in the human Usher syndrome. In addition, a strong retinal biocompatibility for PTC124 and designer aminoglycosides has been demonstrated. In conclusion, recent progress emphasizes the potential of TRIDs as an alternative pharmacologic treatment strategy for treating nonsense mutation-based retinal disorders.

Cell based therapies in retinal diseases

Background Degenerative retinal diseases, including age related macular degeneration, glaucoma, and hereditary retinal dystrophies are major causes of blindness. The principal defect in these diseases is cell loss which is amenable to both cell based neuroprotective and neuroregenerative therapies. To briefly review the lines of research and potential candidates for cell based therapies among retinal diseases.Methods: Review of current literature on stem cell therapies in retinal diseases.Results: As retinal degenerations progress slowly, they are potential candidates for neuroprotective treatments, one of the first being tested clinically is the cell capsule delivery of ciliary neurotrophic factor. Neuroregenerative therapies including stem cell transplantation, is still in its infancy and there are many hurdles to successful neural cell replacement from cell reproduction, to delivery, on sight survival and functional integration with adult tissue, which must still be overcome. The first clinical trials on stem cell replacement therapies have begun with embryonic stem cells being injected subretinally to remedy age related macular degeneration and hereditary retinal diseases. Epiretinal transplantation of neural progenitor cells and mesenchymal stem cells has so far not been very promising regarding integration of the transplanted cells with the mature retina.Conclusion: Treatment of the so far untreatable degenerative retinal diseases will hopefully be available in the near future with cell based therapies. Key words: Age related macular degeneration, Embryonic stem cells, Retinal degenerations, Retinal dystrophies, Mesenchymal stem cells, Neural stem cells.

Spezifische Gentherapie bei erblichen Netzhauterkrankungen – ein Update

Treatment possibilities based on specific gene therapy strategies have become reality for a small number of patients with hereditary retinal dystrophies and are currently under investigation in several clinical trials worldwide. The most advanced studies are for patients suffering from mutations in the RPE65 gene. In addition, studies are ongoing for patients with disease causing mutations in the MERTK, REP1, ABCA4, or Myosin7A gene. Depending on the size of the gene copy to be transferred, two vectors are currently used in clinical trials: vectors based on adeno-associated virus (AAV) or on lentivirus (equine infectious anaemia virus, EIAV). An important aspect of current research includes the capacity to objectively measure the treatment effect in patients, since this is currently limited. This article gives an overview of the current state of specific gene therapy for hereditary retinal dystrophies.

Causes of certifications for severe sight impairment (blind) and sight impairment (partial sight) in children in England and Wales

AimTo explore and describe trends in the principal disorders/conditions (‘cause’) for severe sight impairment (SSI) (blind) and sight impairment (SI) (partial sight) certification in children in England and Wales since...

The Prevalence of Macular Cysts in Patients with Clinical Cone-Rod Dystrophy Determined by Spectral-Domain Optical Coherence Tomography

ABSTRACTBackground: To determine the prevalance of macular cysts in patients with clinical cone-rod dystrophy (CORD) using spectral-domain optical coherence tomography (SD-OCT). If macular cysts could be demonstrated in such patients, they might benefit from treatment with a carbonic anhydrase inhibitor that has been shown to be effective for treating macular cysts in various night-blinding disorders.Material and Methods: Thirty-six CORD patients underwent a complete ophthalmic examination and an SD-OCT examination using two different systems. The presence of hypo-reflective lacunae was used to determine the presence of macular cysts.Results: The patients’ mean age was 42.9 ± 19.5 years (range 6–71 years). Mean BCVA was 1.09 ± 0.64 logMAR (range no light perception to 20/25 + 2 in the better-seeing eye). All the 72 eyes studied showed a variable degree of retinal thinning, disruption of what has been referred to as the inner segment ellipsoid and outer nuclear layer (ONL) thinning of the macula. None showed evidence of macular cysts on OCT testing.Conclusions: Although macular cysts are a common feature of various hereditary night-blinding retinal dystrophies, these were not identified in our cohort of CORD patients.