Macular cysts in retinal dystrophy:

Usher Syndrome on the Island of Ireland: A Genotype-Phenotype Review

Purpose

Usher syndrome (USH) is a genetically heterogeneous group of autosomal recessive (AR) syndromic inherited retinal degenerations (IRDs) representing 50% of deaf-blindness. All subtypes include retinitis pigmentosa, sensorineural hearing loss, and vestibular abnormalities. Thorough phenotyping may facilitate genetic diagnosis and intervention. Here we report the clinical/genetic features of an Irish USH cohort.

Methods

USH patients were selected from the Irish IRD registry (Target 5000). Patients were examined clinically (deep-phenotyping) and genetically using a 254 IRD-associated gene target capture sequencing panel, USH2A exon, and whole genome sequencing.

Results

The study identified 145 patients (24.1% USH1 [n = 35], 73.8% USH2 [n = 107], 1.4% USH3 [n = 2], and 0.7% USH4 [n = 1]). A genetic diagnosis was reached in 82.1%, the majority (80.7%) being MYO7A or USH2A genotypes. Mean visual acuity and visual field (VF) were 0.47 ± 0.58 LogMAR and 31.3° ± 32.8°, respectively, at a mean age of 43 years. Legal blindness criteria were met in 40.7%. Cataract was present in 77.4%. ADGRV1 genotypes had the most VF loss, whereas USH2A patients had greater myopia and CDH23 had the most astigmatism. Variants absent from gnomAD non-Finnish Europeans and ClinVar represented more than 20% of the variants identified and were detected in ADGRV1, ARSG, CDH23, MYO7A, and USH2A.

Conclusions

USH is a genetically diverse group of AR IRDs that have a profound impact on affected individuals and their families. The prevalence and phenotype/genotype characteristics of USH in Ireland have, as yet, gone unreported. Understanding the genotype of Irish USH patients may guide clinical and genetic characterization facilitating access to existing/novel therapeutics.

Cystoid macular oedema without leakage in fluorescein angiography: a literature review

Cystoid macular oedema (CMO), which is defined as a macular thickening and cystic changes due to accumulation of fluid, could be asymptomatic and only diagnosed using paraclinical techniques. Fluorescein angiography (FA) and optical coherence tomography (OCT) are useful in detecting CMO in clinical practice. Non-leaking CMO, also known as angiographically silent CMO, is referred to as cases of CMO without leakage in fluorescein angiography. This type of CMO has been reported in some retinal dystrophies, in cases of maculopathy as a side effect of certain drugs, and also in some systemic disorders. The exact mechanism and treatment options for this type of CMO are still not clear. This literature review aims to discuss different causes of non-leaking CMO, proposed mechanisms, and management options. Three sections including drugs, retinal dystrophies, and systemic disorders are discussed in this review.

STELLATE NONHEREDITARY IDIOPATHIC FOVEOMACULAR RETINOSCHISIS: NOVEL FINDINGS AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ANALYSIS

PURPOSE

To present novel findings in stellate nonhereditary idiopathic foveomacular retinoschisis, including the largest series of optical coherence tomography angiography findings to date.

METHODS

A retrospective case series with multimodal imaging was obtained and reviewed.

RESULTS

All three patients were women, aged 59-63. Two cases were unilateral, and one was bilateral. Vision ranged from 20/20 to 20/60 in the affected eyes. Peripheral retinoschisis was observed in all three patients. All patients were followed for a minimum of 1 year. In one case, progressive macular retinoschisis leading to foveal involvement was observed over two years, with an associated vision decline from 20/25 to 20/60. Attempted interventions included topical dorzolamide in all cases and intravitreal bevacizumab in one patient; however, no treatment effect was observed. The foveal avascular zone size was within normal limits (mean 280 µ m). In all stellate nonhereditary idiopathic foveomacular retinoschisis eyes, the retinoschisis cavities were nonvascular.

CONCLUSION

Novel findings regarding stellate nonhereditary idiopathic foveomacular retinoschisis include the progressive nature of foveal involvement and the lack of response to topical dorzolamide and intravitreal bevacizumab. Foveal avascular zone was normal in all eyes, consistent with the relatively preserved vision in these cases. Retinoschisis cavities were nonvascular in all eyes, a finding which may give insight into the mechanism of this disease.

Non-vasogenic cystoid maculopathies

Besides cystoid macular edema due to a blood-retinal barrier breakdown, another type of macular cystoid spaces referred to as non-vasogenic cystoid maculopathies (NVCM) may be detected on optical coherence tomography but not on fluorescein angiography. Various causes may disrupt retinal cell cohesion or impair retinal pigment epithelium (RPE) and Müller cell functions in the maintenance of retinal dehydration, resulting in cystoid spaces formation. Tractional causes include vitreomacular traction, epiretinal membranes and myopic foveoschisis. Surgical treatment does not always allow cystoid space resorption. In inherited retinal dystrophies, cystoid spaces may be part of the disease as in X-linked retinoschisis or enhanced S-cone syndrome, or occur occasionally as in bestrophinopathies, retinitis pigmentosa and allied diseases, congenital microphthalmia, choroideremia, gyrate atrophy and Bietti crystalline dystrophy. In macular telangiectasia type 2, cystoid spaces and cavitations do not depend on the fluid leakage from telangiectasia. Various causes affecting RPE function may result in NVCM such as chronic central serous chorioretinopathy and paraneoplastic syndromes. Non-exudative age macular degeneration may also be complicated by intraretinal cystoid spaces in the absence of fluorescein leakage. In these diseases, cystoid spaces occur in a context of retinal cell loss. Various causes of optic atrophy, including open-angle glaucoma, result in microcystoid spaces in the inner nuclear layer due to a retrograde transsynaptic degeneration. Lastly, drug toxicity may also induce cystoid maculopathy. Identifying NVCM on multimodal imaging, including fluorescein angiography if needed, allows guiding the diagnosis of the causative disease and choosing adequate treatment when available.

Biallelic Heterozygous Mutations in Crumbs Homolog-1 Gene Associated With Macular Retinoschisis and Angle-Closure Glaucoma: A Case Report and Literature Review

Background

Mutations in the Crumbs homolog-1 (CRB1) gene are associated with a variety of retinal degenerations including Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP). It is also important to highlight atypical features to make proper diagnosis and treatment.

Case Presentation

We present the case of a 7-year-old girl with biallelic heterozygous CRB1 mutations. The clinical features include macular retinoschisis, Coats-like vasculopathy, short axial length, and angle-closure glaucoma (ACG). We also briefly review the current opinion on CRB1 mutation-related diseases.

Conclusion

CRB1 mutations could result in a combined manifestation in anterior and posterior segments. This case emphasizes the importance of genetic diagnosis for those young patients with complicated rare clinical features to call for a specific treatment and follow-up plan. It also highlights the crucial role of CRB1 in eyeball development.

AUTOSOMAL DOMINANT MÜLLER CELL SHEEN DYSTROPHY: Clinical, Histopathologic, and Genetic Assessment in an Extended Family With Long Follow-Up

BACKGROUND

Autosomal dominant Müller cell dystrophy is a rare condition we described in 1991. It is characterized by a striking sheen appearance on the retinal surface with progressive retinal changes leading to disorganization and atrophy with a decreased b-wave electroretinograms.

MATERIALS AND METHODS

We examined 45 members of a 4-generation family. Fifteen subjects from three generations were found with the disease, without gender predilection. Seven patients underwent ophthalmic examination including fundus examination, intravenous fluorescein angiogram, spectral-domain optical coherence tomography, and electroretinogram. Six patients have a 30-year follow-up. Histopathology examination was performed on eyes of the eldest patient. Whole exome sequencing was done in four affected subjects.

RESULTS

Findings include a decreased visual acuity, abnormal cellophane-like sheen of the vitreoretinal interface, a "plush" nerve fiber layer, and characteristic macular changes. Electroretinogram showed a selective b-wave diminution. Intravenous fluorescein angiogram presented perifoveal hyperfluorescence and capillary leakage. Spectral-domain optical coherence tomography revealed cavitations involving inner and later outer retinal layers with later disorganization. Histopathologic findings included Müller cell abnormalities with cystic disruption of inner retinal layers, pseudoexfoliation in anterior segment, and amyloidosis of extraocular vessels. Pedigree analysis suggests an autosomal dominant inheritance with late onset. DNA analysis demonstrated a previously undescribed heterozygous missense p.Glu109Val mutation in transthyretin.

CONCLUSION

To the best of our knowledge, this is the first family reported with this disorder. Our data support the hypothesis that autosomal dominant Müller cell dystrophy is a distinct retinal dystrophy affecting Müller cells. Mutations in transthyretin gene may manifest as a predominantly retinal disorder.

Inherited retinal diseases: Linking genes, disease-causing variants, and relevant therapeutic modalities

Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4,798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.

Childhood cone-rod dystrophy with macular cyst formation in ABCA4 mutation identified by serial spectral-domain optical coherence tomography

Cone-rod dystrophy (CORD) is a type of progressive hereditary retinal dystrophies that causes cone predominant photoreceptor degeneration characterized by wide genotypic and phenotypic heterogeneity. Macular cyst (MC) occurs very infrequently in the pediatric age group and has rarely been described in CORD. We report a case of young-onset CORD that was affected by an isolated ABCA4 mutation complicated by the development of MC. Through serial spectral-domain ocular coherence tomography MC has been observed to persist for 24 months before its resolution, followed by retinal thinning and macular atrophy with corresponding visual acuity decline. The formation of MC and visual acuity appeared to be directly correlated in ABCA4-related CORD and its manifestation is invaluable in predicting eventual visual loss. We further speculate that dysfunctional outer blood-retinal barrier may play a role in the pathophysiology of MC development in CORD.

Resolution of cystoid macular edema with topical carbonic anhydrase inhibitor in a patient with retinal dystrophy associated with Cohen syndrome

Background: Cohen Syndrome (CS) is an autosomal recessive multisystemic disorder characterized by various ophthalmologic findings, including retinal dystrophy and associated cystoid macular edema (CME), in which there was no known effective treatment approach.Material and Methods: We describe a CS patient with a homozygous c.62 T > G, p.(Leu21*) mutation in the VPS13B gene with a topical carbonic anhydrase inhibitor (CAI; brinzolamide %1, thrice daily) responding CME.Case Description: A seven-year-old girl with an established diagnosis of CS was referred with a primary complaint of nyctalopia. On ophthalmologic examination, bilateral decreased visual acuity and normal-appearing macula with mild optic disc pallor were present. However, the detailed evaluation revealed bilateral blunted foveal reflexes, barely visible foveal pigmentation, and slightly attenuated retinal vessels without any peripheral retinal pigmentary changes in dilated fundus examination, and CME on optical coherence tomography. Bilateral topical brinzolamide thrice daily was initiated for CME. Visual acuity increased, and CME was resolved except for minimal schisis at the inner nuclear layer level at the third-month follow-up visit and remained stable up to one-year follow-up. CME reappeared after five months of self-discontinuation of the patient's therapy but resolved again with treatment resumption.Conclusion: We report the first case of CME secondary to rod-cone dystrophy associated with CS showing improvement in anatomy and visual acuity with a topical CAI.

Novel clinical presentation of a CRX rod-cone dystrophy

We describe a novel clinical presentation of a CRX rod-cone dystrophy in a single family. Two boys ages 6 and 12 years presented with clinical and optical coherence tomography features suggestive of X-linked retinoschisis, but with optic nerve swelling without increased intracranial pressure. One patient had an electronegative electroretinogram (ERG) and the other had rod-cone dysfunction. Neither had retinoschisin (RS1) gene mutations. Biological mother and sister presented with retinal pigment epithelium (RPE) changes and abnormal cone-rod ERG responses. On further testing, next generation sequencing with array comparative genomic hybridisation showed a deletion in exon 4 of the CRX gene. Cystoid maculopathy in young male children can be difficult to distinguish from RS1-associated schisis. Phenotypic variants within a family must prompt a thorough retinal dystrophy evaluation even with electronegative ERG in the presenting child. This novel phenotype for CRX presents with optic nerve swelling and cystoid maculopathy in men, and RPE changes in women.

Choroidal Vascularity Features in Patients with Choroideremia and Cystoid Spaces

Cystoid spaces (CSs) are a common retinal finding in choroideremia (CHM) patients. The aim of this study was to analyze the vascular features of the choroid associated with the presence of CSs in patients with confirmed genetic diagnosis of CHM. A total of 33 patients (33 eyes) were enrolled in this retrospective cross-sectional study and divided into two groups based on the presence (17 eyes) or absence (16 eyes) of CSs. Choroidal features were evaluated on spectral-domain optical coherence tomography including subfoveal choroidal thickness (CT), total choroidal area (TCA), luminal choroidal area (LCA), and stromal choroidal area (SCA). The choroidal vascularity index (CVI) was then calculated in all study eyes. All structural choroidal parameters were calculated both on the entire length of the B-scan and in the central subfoveal 1500 μm. The average age was 37.3 ± 11.6 and 31.4 ± 16.7 years (p = 0.25) and mean logMAR best-corrected visual acuity was 0.11 ± 0.20 and 0.20 ± 0.57 (p = 0.54) in the CHM groups with and without CSs, respectively. There were no significant differences in subfoveal CT, and TCA, LCA, SCA, and CVI evaluated on either the entire scan or in the central 1500 μm (all p > 0.05). All choroidal vasculature parameters exhibited no significant differences between CHM eyes with and without CSs. Our results suggest that the choroid may not be involved in the development of CSs in patients with CHM.

Analysis of optical coherence angiography in cystoid macular oedema associated with gyrate atrophy

BACKGROUND

To evaluate the relationship between superficial, deep foveal avascular zone (FAZ) and foveal cyst areas in eyes with cystoid macular oedema (CMO) associated with gyrate atrophy of the choroid and retina (GA).

METHODS

This is a retrospective collaborative multicenter study of optical coherence tomography-angiography (OCTA) images in GA. Superficial and deep FAZ and foveal cyst were measured using Image J by two independent experts. Values were corrected for myopia magnification. These values were compared with age-matched controls from normative data.

RESULTS

Twenty-three eyes from 12 patients with GA and CMO were included in the study. The mean ± standard deviation age was 22 ± 19.7 years, mean Snellen spectacle-corrected visual acuity of 20/70 with mean myopia of 5.7 ± 4.1 dioptres. Qualitatively, no focal occlusion of superficial and deep capillary plexus was noted. Mean superficial FAZ area (0.484 ± 0.317 mm²), deep FAZ area (0.626 ± 0.452 mm²), and foveal cyst area (0.630 ± 0.503 mm²) were significantly larger than superficial and deep FAZ areas in controls of same age range (p < 0.001). Macular cyst area correlated with superficial FAZ area (R = 0.59; p = 0.0057) and more strongly with deep FAZ area (R = 0.69; p < 0.001).

CONCLUSIONS

The superficial and deep FAZ area in GA-associated CMO were noted to be significantly larger than in controls. It seems that RPE dysfunction leads to foveal cyst enlargement displacing the capillary plexus with resultant enlarged superficial and deep FAZ area.

Paradoxical response to carbonic anhydrase inhibitors in patients with intraretinal cystoid spaces

Background: Intraretinal cystoid spaces (IRCS) are fluid-filled spaces seen in some retinal dystrophies and often treated with carbonic anhydrase inhibitors. The purpose of this study is to report an unexpected bilateral improvement in the IRCS after discontinuation of therapy. Material and Methods: We identified from our records 23 patients with retinal dystrophy and IRCS who had been treated with topical and/or oral carbonic anhydrase inhibitors. All subjects had regular follow-up with OCT and previous genetic testing. Results: We identified four (17%) patients who experienced a bilateral and symmetrical paradoxical improvement in IRCS size and visual acuity after discontinuation of carbonic anhydrase inhibitors. Two were mutations in RS1, one in CLN3 and another in NR2E3. All patients were followed for at least three years (range 39-63 months). None had systemic abnormalities. Conclusions: Patients with IRCS may exhibit a paradoxical response after discontinuation of carbonic anhydrase inhibitors. Although the pathophysiology of these phenomena is unclear, stopping treatment may be an option in patients who cease to improve or get worse on treatment.

Nonleaking cystoid macular edema in Cohen syndrome

An 11-year-old girl with a history of neutropenia, developmental delay, hypotonia, and intellectual disability was diagnosed with Cohen syndrome after genetic testing discovered homozygous mutation in the VPS13B gene. She was referred to a retinal specialist with a chief complaint of decreased peripheral vision. On examination, decreased visual acuity, pigmentary changes, and nonleaking cystoid macular edema were present in both eyes.

Novel clinical findings in autosomal recessive NR2E3-related retinal dystrophy

PURPOSE

To evaluate the clinical phenotype of autosomal recessive NR2E3-related retinal dystrophy.

METHODS

We retrospectively studied 11 patients carrying out at least 2 NR2E3 mutations; they had undergone comprehensive ophthalmological examination, fundus photography, optical coherence tomography, electrophysiological testing, and visual field at the Regional Reference Center for Hereditary Retinal Degenerations of the Eye Clinic in Florence.

RESULTS

Five females and six males with a diagnosis of NR2E3-related retinal dystrophy were included in the study. All patients complained of nyctalopia. Visual acuity ranged from 0.00 logMAR to hand motion. Two patients presented bull's eye maculopathy, and one of these was characterized by a triple hyper-autofluorescent ring at the fundus autofluorescence examination. Three patients showed small yellowish dots and spots at the mid-periphery. One patient was characterized by widespread subretinal drusenoid deposits (SDD) at the posterior pole. Four patients showed vitreous abnormalities. Optical coherence tomography (OCT) examinations detected variable degrees of abnormal retinal lamination and schitic changes. Seven patients were compound heterozygous and four were homozygous for mutations in NR2E3.

CONCLUSIONS

Our study confirmed high variable phenotype in autosomal recessive NR2E3-related retinal dystrophy. Bull's eye maculopathy, subretinal drusenoid deposits, and foveal hypoplasia represent novel clinical findings in NR2E3-related retinal dystrophy. Macular involvement was detectable in all the patients, and the abnormal foveal avascular zone (FAZ) supports the role of NR2E3 in retinal development.

Quantitative and Qualitative Features of Spectral-Domain Optical Coherence Tomography Provide Prognostic Indicators for Visual Acuity in Patients With Choroideremia

BACKGROUND AND OBJECTIVE

To identify qualitative and quantitative features of spectral-domain optical coherence tomography (SD-OCT) as prognostic indicators of visual acuity (VA) loss in patients with choroideremia (CHM).

PATIENTS AND METHODS

Retrospective study of 57 male patients with CHM. Central foveal thickness (CFT), subfoveal choroidal thickness (SCT), fundus autofluorescence area, and evidence of outer retinal and choroidal degeneration were analyzed by SD-OCT.

RESULTS

Best-corrected VA logMAR at baseline was associated with CFT at baseline (r = -0.47; P < .01), CFT at most recent follow-up (r = -0.27; P < .01), and SCT at baseline (r = -0.31; P < .01). Ellipsoid zone (EZ) rupture was associated with a higher CFT loss (r = 0.33; P < .01) and macular cystic spaces (MCS) with a reduction in VA over time (hazard risk = 0.48; P = .05).

CONCLUSION

Reduced CFT at baseline, EZ rupture, and MCS are poor prognostic indicators for VA outcome. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:711-716.].

Cystoid macular changes on optical coherence tomography in a patient with maternally inherited diabetes and deafness (MIDD)-associated macular dystrophy

The clinical presentation and optical coherence tomography findings in a patient with maternally inherited diabetes and deafness (MIDD) are presented to highlight the presence of macular cystoid spaces in some patients with this disease. Typically, patients with MIDD demonstrate progression of a pigmentary maculopathy into areas of geographic macular atrophy. At the time of initial visit, the 30-year-old patient had large macular cystoid changes in addition to retinal pigmentary changes in both eyes. The cystoid changes responded to treatment with systemic immunosuppression and a topical carbonic anhydrase inhibitor (CAI), recurred when treated with topical CAI monotherapy, and finally resolved after an intravitreal triamcinolone acetonide injection. Over time, the retinal atrophy continued to progress, but the macular cysts did not recur. The patient received systemic immunosuppression for renal transplantation due to renal failure resulting from focal glomerulosclerosis. There was no evidence of diabetic retinopathy at any time during the five-and-a-half-year follow-up, and the patient retained good visual acuity in both eyes.

Dominant Retinitis Pigmentosa, p.Gly56Arg Mutation in NR2E3: Phenotype in a Large Cohort of 24 Cases

Importance

This research is the single largest NR2E3 genotype-phenotype correlation study performed to date in autosomal dominant Retinitis Pigmentosa.

Objective

The aim of this study is to analyse the frequency of the p.Gly56Arg mutation in NR2E3 for the largest cohort of autosomal dominant Retinitis Pigmentosa patients to date and its associated phenotype.

Patients and Methods

A cohort of 201 unrelated Spanish families affected by autosomal dominant Retinitis Pigmentosa. The p.Gly56Arg mutation in the NR2E3 (NM_014249.2) gene was analysed in 201 families. In the 24 cases where the mutation had been detected, a haplotype analysis linked to the p.Gly56Arg families was performed, using four extragenic polymorphic markers D15S967, D15S1050, D15S204 and D15S188. Phenotype study included presence and age of onset of night blindness, visual field loss and cataracts; and an ophthalmoscopic examination after pupillary dilation and electroretinogram for the 24 cases.

Results

Seven of the 201 analyzed families were positive for the p.Gly56Arg, leading to a prevalence of 3.5%. Clinical data were available for 24 subjects. Night blindness was the first noticeable symptom (mean 15.9 years). Visual field loss onset was variable (23.3 ± 11.9 years). Loss of visual acuity appeared late in the disease´s evolution. Most of the patients with cataracts (50%) presented it from the third decade of life. Fundus changes showed inter and intrafamiliar variability, but most of the patients showed typical RP changes and it was common to find macular affectation (47.4%). Electroretinogram was impaired from the beginning of the disease. Two families shared a common haplotype. Additionally, all patients shared a 104Kb region between D15S1050 and the NR2E3 gene.

Conclusions

This study highlights the importance of p.Gly56Arg in the NR2E3 gene as a common mutation associated with adRP, and provides new clues to its phenotype, which can allow for a better clinical management and genetic counselling of patients and their families.

Novel grading system for quantification of cystic macular lesions in Usher syndrome

BACKGROUND

To evaluate novel grading system used to quantify optical coherence tomography (OCT) scans for cystic macular lesions (CML) in Usher syndrome (USH) patients, focusing on CML associated alterations in MOY7A and USH2A mutations.

METHODS

Two readers evaluated 76 patients' (mean age 42 ± 14 years) data prospectively uploaded on Eurush database. OCT was used to obtain high quality cross-sectional images through the fovea. The CML was graded as none, mild, moderate or severe, depending on the following features set: subretinal fluid without clearly detectable CML boundaries; central macular thickness; largest diameter of CML; calculated mean of all detectable CML; total number of detectable CML; retinal layers affected by CML. Intra-and inter-grader reproducibility was evaluated.

RESULTS

CML were observed in 37 % of USH eyes, while 45 % were observed in MYO7A and 29 % in USH2A cases. Of those with CML: 52 % had mild, 22 % had moderate and 26 % had severe changes, respectively. CML were found in following retinal layers: 50 % inner nuclear layer, 44 % outer nuclear layer, 6 % retinal ganglion cell layer. For the inter-grader repeatability analysis, agreements rates for CML were 97 % and kappa statistics was 0.91 (95 % CI 0.83-0.99). For the intra-grader analysis, agreement rates for CML were 98 %, while kappa statistics was 0.96 (95 % CI 0.92-0.99).

CONCLUSIONS

The novel grading system is a reproducible tool for grading OCT images in USH complicated by CML, and potentially could be used for objective tracking of macular pathology in clinical therapy trials.

The cost of genetic testing for ocular disease: who pays?

PURPOSE OF REVIEW

To facilitate ophthalmologists' understanding on the cost of genetic testing in ocular disease, the complexities of insurance coverage and its impact on the availability of testing.

RECENT FINDINGS

Many insurance carriers address coverage for genetic testing in written clinical policies. They provide criteria for medically necessary testing. These policies mostly cover testing for individuals who are symptomatic and in whom testing will have a direct impact on medical treatment. In cases in which no treatments are currently available, other than research trials, patients may have difficulty in getting insurance coverage for genetic testing.

SUMMARY

Genetic testing for inherited eye diseases can be costly but has many benefits to patient care, including confirmation of a diagnosis, insight into prognostic information, and identification of associated health risks, inheritance patterns, and possible current and future treatments. As gene therapy advances progress, the availability for treatment in ocular diseases, coverage for genetic testing by third-party payers could increase on the basis of current clinical policies.

Molecular analysis and phenotypic study in 14 Chinese families with Bietti crystalline dystrophy

Purpose

To investigate the clinical features and cytochrome P450 family 4 subfamily V polypeptide 2 (CYP4V2) gene mutations in 14 Chinese families with Bietti crystalline dystrophy (BCD).

Methods

Seventeen patients from 14 unrelated Chinese families with BCD were recruited for complete clinical ophthalmic examination and genetic study. The 11 exons of CYP4V2 were amplified from genomic DNA of all patients and their family members by polymerase chain reaction (PCR) and then sequenced. Exons of TIMP3 were also sequenced in BCD patient associated with choroidal neovascularization (CNV). One hundred and seventy unrelated healthy Chinese subjects were screened for mutations in CYP4V2.

Results

All 17 patients with BCD had mutations in CYP4V2; one of these mutations was novel (c.219T>A, p.F73L) and four other mutations had been reported. The p.F73L mutation was a commonly detected mutation in our study (seven out of 34 alleles), either in the homozygous state or in the heterozygous state. Among the patients, considerable phenotypic variability was detected, both within and between families. Screening of TIMP3 did not find any mutation in the BCD patient associated with CNV.

Conclusion

The novel CYP4V2 c.219T>A (p.F73L) mutation may be another recurrent mutation in Chinese patients with BCD. Our study expands the mutation spectrum of CYP4V2 and characterizes novel genotype–phenotype associations in Chinese patients with BCD.

Outer retinal tubulation in degenerative retinal disorders

PURPOSE

To demonstrate outer retinal tubulation (ORT) in various degenerative retinal disorders.

METHODS

This was a retrospective review of the multimodal imaging of 29 eyes of 15 patients with various retinal dystrophies and inflammatory maculopathies manifesting ORT. The morphologic features of ORT and its evolution over time were analyzed using spectral-domain optical coherence tomography data.

RESULTS

Outer retinal tubulation was identified as round or ovoid structures with hyperreflective borders in pattern dystrophy (six eyes), acute zonal occult outer retinopathy (five eyes), retinitis pigmentosa (four eyes), Stargardt disease (four eyes), gyrate atrophy (two eyes), choroideremia (two eyes), and various other degenerative conditions. These structures appeared to develop from the invagination of photoreceptors at the junction of intact and atrophic outer retina. During follow-up, the number and distribution of ORT largely remained stable. As zones of atrophy enlarged, the frequency of ORT appeared to increase. The ORT structures were found in <10% of patients with retinitis pigmentosa, Stargardt disease, or pattern dystrophy.

CONCLUSION

Outer retinal tubulation is found in various degenerative retinal disorders that share in common damage to the outer retina and/or retinal pigment epithelium. The presence of ORT may be an indicator of underlying disease stage and severity.

Spontaneously resolving macular cyst in an infant

The purpose of this study is to describe transient macular cysts in an infant and correlate their occurrence with normal development events. A newborn Caucasian girl presented with a protruding corneal mass in her left eye at birth. She underwent a complete ophthalmic examination. A keratinized staphylomatous malformation involving the entire cornea and precluding further visualization of the anterior and posterior segment was observed in the left eye. Spectral domain optical coherence tomography (SD-OCT) of the right eye performed when the child was approximately 6-week-old had revealed an unexpected finding of macular cysts involving the inner nuclear and outer retinal layers. Corneal transplant in the left eye was performed a month later. Ocular examination under anesthesia just prior to surgery revealed normal intraocular pressure, anterior segment and retina in the right eye. SD-OCT was normal in both eyes and showed complete resolution of the cysts in the right eye. The patient had not been on any medications at that time. Although clinical retinal examination might be unremarkable, SD-OCT may reveal cystic spaces in the macula. In the absence of conditions known to be associated with macular edema, transient macular cysts may arise due to a developmental incompetence of the blood-retinal barrier or may represent transient spaces created during normal migration of retinal cells. Further study is warranted to delineate the entity of transient macular cysts in infancy.

Childhood cone-rod dystrophy with macular cystic degeneration from recessive CRB1 mutation

PURPOSE

To describe three siblings with childhood cone-rod dystrophy and macular cystic degeneration in a family with apparently variable phenotypes of CRB1-related recessive retinal dystrophy.

METHODS

Ophthalmologic examination (including electroretinography (ERG), ocular coherence tomography (OCT), and intravenous fluorescein angiography when possible) and homozygosity analysis guided candidate gene testing.

RESULTS

When the proband was evaluated at 7 years old for progressive visual loss, fundus exam was unremarkable (including no macular thickening clinically or by OCT) but ERG revealed cone-rod dysfunction with an electronegative waveform. Four years later repeat examination was significant for bilateral macular cystic degeneration and immediate family members were evaluated. Both the older sister (15 years old) and the younger brother (7 years old) had cone-rod dystrophy with macular cystic degeneration. Both the father (45 years old) and mother (35 years old) had had early adult-onset nyctalopia with later eventual loss of central vision; examination revealed dystrophic retinas with mostly peripheral clumped and/or nummular pigment and macular atrophy. ERG for both the older sister and younger brother confirmed cone-rod dysfunction (without an electronegative waveform) and was non-recordable for both the parents. Homozygosity analysis guided candidate gene analysis and confirmatory Sanger sequencing for the family uncovered a homozygous CRB1 mutation (c.80G > T [p.Cys27Phe]) in affected family members.

CONCLUSIONS

The phenotypic spectrum of recessive CRB1 mutation includes childhood cone-rod dystrophy with macular cystic degeneration and the associated ERG can be electronegative.

Topical dorzolamide treatment of macular cysts in the enhanced S-cone syndrome patient

Purpose

The purpose of the study was to evaluate the efficacy of a topical form of a carbonic anhydrase inhibitor (dorzolamide) on the foveal function and thickness in the eye of a patient with enhanced S-cone syndrome (ESCS) associated with macular cysts.

Methods

Twenty-eight-year-old Polish man with ESCS and macular cysts appearance in the right eye was treated 3 times daily with 2.0 % dorzolamide drops for the period time equal to 6 months. Monthly controls included: best corrected distance visual acuity (BCDVA-logMAR), foveal thickness (optical coherence tomography, OCT) and foveal function (multi-focal electroretinography, mfERG).

Results

Before treatment, BCDVA in the right eye was equal to 0.26 logMAR, improved to 0.1 logMAR during the first 3 months and remained stable for the next 3 months. After 6 months, foveal thickness decreased (from 482 to 224 μm) and foveal function improved (the amplitude of P1-wave density increased from 34.8 to 107.3 nV/deg²) and was between the ranges of normal values. Implicit time of P1-wave remained prolonged.

Conclusions

The results of our short-term study suggest potential efficacy of topical dorzolamide treatment in ESCS patients with macular cysts.