Tamaki Gekka

Subfoveal choroidal thickness in multiple evanescent white dot syndrome

Background:  Multiple evanescent white dot syndrome (MEWDS) is an inflammation of the choriocapillaris, which typically presents with unilateral vision loss and is characterised by the presence of multiple yellow‐white spots in the posterior pole to the midperipheral fundus. This study was conduced to evaluate subfoveal choroidal thickness between the acute and convalescent phases in two patients with MEWDS.

CYP4V2 Mutations in Two Japanese Patients with Bietti’s Crystalline Dystrophy

Bietti’s crystalline dystrophy (BCD) is an autosomal-recessive retinal dystrophy characterized by numerous glistening intraretinal dots scattered over the fundus, particularly in the posterior pole. The purpose of this study was to report mutations in the CYP4V2 gene (encoding a ubiquitously-expressed 525-amino acid sequence belonging to the CYP450 family) and to investigate the impact of the mutation on pre-mRNA splicing. DNA and RNA analyses were conducted using blood samples from two unrelated Japanese patients with BCD (a 46-year-old female and a 52-year-old male). In the female patient, a homozygous deletion/insertion mutation (g.IVS6–8_–1delc.802_810del/insGC) including the 3´-acceptor splice site was identified. Reverse transcription-PCR analysis revealed that the complete length of exon 7 (186 bp), is skipped, resulting in the in-frame deletion mutation (p.V268_E329del). Conversely, the male patient was a compound heterozygote for the deletion/insertion and novel nonsense (p.W340X) mutations. Clinically, the female patient had decreased visual acuity, constriction of visual fields, severely reduced amplitudes in both rod and cone electroretinograms (ERGs). Despite being 6 years older, the male patient presented with milder clinical manifestations having good visual acuity and substantial amplitudes in both rod and cone ERGs. Because the CYP4V2 truncated protein with the p.W340X mutation lacks 186 amino acids at the C-terminus, if expressed, it retains 62 amino acids encoded in exon 7, which are important for enzymatic activity. In the male patient, expression of both mutant alleles may compensate for the malfunction of each mutated protein and could explain why a milder form of BCD results from compound heterozygosity.

Compound heterozygous CNGA3 mutations (R436W, L633P) in a Japanese patient with congenital achromatopsia

Congenital achromatopsia is a stationary retinal disorder with autosomal recessive inheritance that is characterized by loss of color discrimination, low visual acuity, photophobia, and nystagmus. This disorder has been shown to be associated with CNGA3, CNGB3, and GNAT2 mutations, and the frequency of mutations in the CNGA3 gene (encoding alpha subunit of the cone-specific cGMP-gated cation channel) was 23-33% in European populations. The aim of this study was to test the hypothesis that CNGA3 mutations are also responsible for congenital achromatopsia in Japanese patients. DNA from venous blood samples from a total of 14 patients from 13 Japanese pedigrees was prepared. Mutation screening of the CNGA3 gene was performed using direct sequencing and PCR-single-strand conformation polymorphism analysis. Compound heterozygous missense mutations (p.R436W and p.L633P, the latter of which was novel) were identified in one patient only, a 22-year-old female. Neither of these two mutations was found in 150 Japanese control individuals. The patients parents and sister carried one of these mutations each but were not affected. No mutations in the CNGB3 or GNAT2 genes were identified in the patient. Clinically, best-corrected visual acuity was 0.1 in both eyes. No specific findings were obtained in funduscopy. Optical coherence topography revealed a normal foveal thickness but a 20% decrease in parafoveal thickness. Ganzfeld full-field electroretinograms (ERGs) showed normal responses in rod and mixed rod-plus-cone ERGs but no response in cone or 30-Hz flicker ERGs. Spectral sensitivity on a white background revealed a curve with only one peak at around 500 nm, which fits the absorption spectrum of human rhodopsin. L633, conserved among vertebrate orthologs of human CNGA3, is a hydrophobic residue forming part of the carboxy-terminal leucine zipper (CLZ) domain, which is functionally important in the mediation of intracellular interactions. To our knowledge, this is the first report of a Japanese complete achromat with CNGA3 mutations, and of any patient with a missense mutation within the CLZ domain. The outcome suggests low frequency (7%, 1/14) of CNGA3 mutations in Japanese patients.

Autosomal dominant occult macular dystrophy with an RP1L1 mutation (R45W).

Purpose. To characterize clinical features in occult macular dystrophy (OMD) patients with the RP1L1 gene mutation (p.R45W), one of two previously described mutations in Japanese OMD patients. Methods. Mutational screening of the RP1L1 gene was performed via polymerase chain reaction and direct sequencing for seven unrelated probands (one autosomal dominant and six sporadic probands) with OMD. A comprehensive ophthalmic examination was performed, including Cirrus optical coherence tomography. Full-field electroretinography (ERG), multifocal ERG, and focal macular ERG were performed. Results. The heterozygous mutation (p.R45W) was found in only one female proband with autosomal dominant OMD, whose mother was also diagnosed with OMD and carried the mutation. Ophthalmoscopy showed bilateral normal fundi in the proband but subtle retinal pigment epithelium mottling in the mother. Both the proband and her mother had typical OMD findings: decreased visual acuity and markedly reduced central responses in the multifocal ERG and focal macular ERG. Although full-field ERG revealed normal rod and standard combined responses, photopic and 30-Hz flicker responses were slightly reduced in both the proband and her mother. Optical coherence tomography revealed that the external limiting membrane and inner segment-outer segment boundary were disorganized despite normal macular thickness in the proband, whereas the mother exhibited macular thinning with discontinuous reflectivity of the external limiting membrane and inner segment-outer segment boundary. Conclusions. The clinical phenotypes differed between the proband and her mother and were indistinguishable from other sporadic or RP1L1-unassociated OMD patients, suggesting that mutation-dependent clinical features may not be present.

Novel C8orf37 Mutations in Patients with Early-onset Retinal Dystrophy, Macular Atrophy, Cataracts, and High Myopia

ABSTRACT Purpose: More than 50 genes are reported as causative genes of autosomal recessive (ar) retinitis pigmentosa (RP) and cone-rod dystrophy (CRD). It is challenging to identify causative mutations for arRP and arCRD. The purpose of the present study was to investigate clinical and genetic features of two siblings with early-onset retinal dystrophy. Methods: Whole-exome sequencing was conducted for the two affected siblings and their unaffected brother and mother from a Japanese family. We performed complete ophthalmic examinations, including visual acuity, funduscopy, visual-field testing, electroretinography and optical coherence tomography. Results: Whole-exome sequencing analysis identified novel compound heterozygous mutations, a splice site mutation (c.374 + 2T > C in intron 4) and a deletion mutation (c.575delC [p.T192MfsX28] in exon 6) of chromosome 8 open reading frame 37 (C8orf37) gene, which encodes a ciliary protein, in both patients. The mother carried the truncating mutation, and the brother carried neither mutation. Ophthalmic examinations revealed diffuse retinal degeneration, macular atrophy, non-recordable electroretinography responses, cataracts, and high myopia in both patients, who could not be diagnosed with either RP or CRD because of the severe retinal degeneration and early onset disease. Longitudinal follow-up of the patients revealed highly progressive retinal degeneration, macular atrophy, and visual field loss. Conclusions: Recessive C8orf37 mutations have been identified in early to adolescent-onset arRP and arCRD with macular involvement. Our study identified two novel truncating mutations of the C8orf37 gene in siblings with early-onset retinal dystrophy, macular atrophy, cataracts, and high myopia.

Treatment of Dropped Nucleus with a 27-Gauge Twin Duty Cycle Vitreous Cutter

We report herein a method for the treatment of dropped nucleus during cataract surgery with a 27-gauge twin duty cycle (TDC) vitreous cutter. When a TDC vitreous cutter is used, suction flow volume is maintained even when the cutter is driven at a high speed. This enables an Emery-Little grade 3 nucleus that had been difficult to treat with a conventional 27-gauge cutter to be successfully excised using only a vitreous cutter, with no intra- or postoperative complications. A dropped lens during cataract surgery of up to moderate hardness can be removed using a TDC cutter alone with a 27-gauge cutter system.

Dominant optic atrophy caused by a novel OPA1 splice site mutation (IVS20+1G-->A) associated with intron retention.

Dominant optic atrophy (DOA) is the most common form of inherited primary optic neuropathy. The purpose of the current study was to report a novel OPA1 splice site mutation and investigate the impact of the mutation on pre-mRNA splicing in a female proband and her father diagnosed with DOA. We evaluated visual acuity, retinal fundi and kinetic visual fields. Color vision phenotypes were determined using the Farnsworth Panel D-15 and the Farnsworth-Munsell 100-hue tests. All 28 coding exons of the OPA1 gene were analyzed with polymerase chain reaction (PCR) amplification and direct sequencing. Total RNA extraction from white blood cells followed by reverse transcription-PCR (RT-PCR) was performed. We identified a novel heterozygous G to A mutation at position +1 of intron 20 (g.IVS20+1G→A) in both patients. RT-PCR analysis revealed that the first 25 bp from intron 20 plus exon 20 were spliced onto exon 21. No difference in expression of mutant and wild-type transcripts was found within the linear range of amplification. Clinically, both patients exhibited reduced visual acuities, pallor of optic discs, decreased sensitivities of central visual fields and blue-yellow color vision defects. Previously, only one mechanism (skipping of exon) of pre-mRNA splicing defects has been reported among OPA1 splice site mutations. Our study demonstrates that the mechanism of intron retention is a novel type of pre-mRNA splicing defects. The mutant transcript with a premature termination codon is likely to encode a truncated protein, due to a translational frameshift (V672fsX675), that lacks 289 amino acids of the C-terminal end. Therefore, it is suggested that haploinsufficiency underlies DOA in the patients. However, we could not exclude the possibility that the truncated protein has a dominant negative activity because the mutant transcript is insusceptible to nonsense-mediated mRNA decay.

Pedicle Internal Limiting Membrane Transposition Flap Technique for Refractory Macular Hole.

BACKGROUND AND OBJECTIVE To determine the efficacy of the pedicle internal limiting membrane (ILM) transposition flap technique for refractory macular holes (MHs) in which the inverted ILM flap technique cannot be performed. PATIENTS AND METHODS The pedicle ILM flap transposition technique was conducted by transconjunctival microincision vitrectomy. The authors attempted to peel the remaining ILM inferior from the MH to create an ILM flap. This ILM was still attached to the retina at the upper part of the MH and covered the MH. Finally, fluid-gas exchange was performed. After surgery, patients remained face-down for 1 week. This procedure was performed in two eyes. RESULTS There were no adverse events, and MHs were closed successfully in both study eyes. CONCLUSION The pedicle ILM flap transposition technique has the potential to improve functional and anatomical outcomes in patients with refractory MHs.

Mutation analysis of BEST1 in Japanese patients with Best's vitelliform macular dystrophy

Purpose To describe the clinical and genetic features of Japanese patients with Bests vitelliform macular dystrophy (BVMD). Patients and methods This study examined 22 patients, including 16 probands from 16 families with BVMD. Comprehensive ophthalmic examinations were performed, including dilated funduscopy, full-field electroretinography (ERG) and electro-oculography (EOG). BEST1 mutation analysis was performed by Sanger sequencing. Results All 16 probands exhibited characteristic BVMD fundus appearances, abnormal EOG, and normal ERG responses with the exception of one diabetic retinopathy proband. Genetic analysis identified 12 BEST1 variants in 13 probands (81%). Of these, 10 variants (p.T2A, p.R25W, p.F80L, p.V81M, p.A195V, p.R218H, p.G222E, p.V242M, p.D304del and p.E306D) have been previously reported in BVMD, while two variants (p.S7N and p.P346H) were novel, putative disease-causing variants. Single BEST1 variants were found in 12 probands. The one proband with compound heterozygous variants (p.S7N and p.R218H) exhibited typical BVMD phenotypes (pseudohypopyon stage and vitelliruptive stage in the right and left eyes, respectively). Conclusions Twelve different variants, two of which (p.S7N and p.P346H) were novel, were identified in the 13 Japanese families with BVMD. Compound heterozygous variants were found in one proband exhibiting a typical BVMD phenotype. Our results suggest that BEST1 variants do play a large role in Japanese patients with BVMD.

Efficacy of Intravitreal Triamcinolone Acetonide for Diabetic Macular Edema After Vitrectomy

PURPOSE To compare the efficacy of intravitreal injection of triamcinolone acetonide (IVTA) for diabetic macular edema (DME) in vitrectomized eyes with DME without vitrectomy eyes. METHODS This retrospective comparative study evaluated the efficacy of IVTA treatment of DME in 26 consecutive eyes (23 patients). Changes in mean best-corrected visual acuity (VA) and mean central retinal thickness (CRT) were retrospectively evaluated before IVTA and during the 6-month period after IVTA. RESULTS Subjects were divided into 2 groups: 13 consecutive eyes (11 patients) with proliferative diabetic retinopathy or DME that underwent vitrectomy (vitrectomized group), and 13 consecutive eyes (12 patients) with DME who received IVTA, but did not undergo vitrectomy (nonvitrectomized group). In the vitrectomized group, there was a significantly decreased CRT for up to 4 months as compared to the thicknesses before IVTA. In the nonvitrectomized group, there was a significantly decreased CRT for up to 5 months after IVTA. In both groups, there was significant improvement in the VA for up to 4 months after IVTA. CONCLUSION IVTA may represent a valid treatment option for DME, even in vitrectomized eyes.