Yoshinori Mitamura

Tokyo Metropolitan Institute of Medical Science, Edo, Tōkyō, Japan

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Publications (114)257.45 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To study the relationship between the retinal microstructures and the best-corrected visual acuity (BCVA) after cataract surgery in patients with retinitis pigmentosa (RP).
    The British journal of ophthalmology. 10/2014;
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    ABSTRACT: The dedicator of cytokinesis 3 (Dock3) is an atypical guanine nucleotide exchange factor that is predominantly expressed in the CNS. Dock3 exerts neuroprotective effects and stimulates optic nerve regeneration. The p38 mitogen-activated protein kinase acts downstream of apoptosis signal-regulating kinase 1 (ASK1) signaling and plays an important role in neural cell death. We assessed a therapeutic efficacy of Dock3 stimulation and p38 inhibition in retinal degeneration induced by optic nerve injury (ONI). In vivo retinal imaging using optical coherence tomography revealed that ONI-induced retinal degeneration was ameliorated in SB203580 (a p38 inhibitor)-treated WT mice and PBS-treated Dock3 overexpressing (Dock3 Tg) mice, and SB203580 further stimulated retinal protection in Dock3 Tg mice. In addition, SB203580 increased the number of regenerating axons after ONI in both WT and Dock3 Tg mice. ONI-induced phosphorylation of ASK1, p38 and the N-methyl-d-aspartate receptor 2B subunit were suppressed in the retina of Dock3 Tg mice. Inhibition of the ASK1 pathway in Dock3 Tg mice suggests that Dock3 may have an antioxidant-like property. These results indicate that overexpression of Dock3 and pharmacological interruption of p38 have synergistic effects for both neuroprotection and axon regeneration, thus combined application may be beneficial for the treatment of ONI.
    Neuroscience letters. 08/2014;
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    ABSTRACT: The aim of this study was to report the first case of polymicrobial fungal sclerokeratitis caused by infection with both Scedosporium apiospermum and Aspergillus cibarius, and notify the medical community of the possibility of infection caused by A. cibarius in humans.
    Cornea 06/2014; · 1.75 Impact Factor
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    ABSTRACT: To report the morphologic features of a choroidal osteoma using swept-source optical coherence tomography (SS-OCT) and fundus autofluorescence (FAF).
    Case reports in ophthalmology. 05/2014; 5(2):195-202.
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    ABSTRACT: We report the fundus autofluorescence (FAF), spectral-domain optical coherence tomographic (SD-OCT), microperimetric, and multifocal electroretinographic (mfERG) findings before, during, and after successful treatment of a primary intraocular lymphoma (PIOL). A 57-year-old man had biopsy-proven PIOL in his left eye, and he was treated with intravitreal methotrexate injections for 8 months. Before treatment, fundus examination disclosed many small, yellow lesions with distinct boundaries in the posterior fundus which became atrophic 9 months after the initial treatment. FAF showed a pattern of granular hypoautofluorescence and hyperautofluorescence before the treatments and patchy hypoautofluorescence corresponding to retinal pigment epithelial (RPE) atrophy after the treatments. SD-OCT showed increased nodularity at the level of and above the RPE, a separation of Bruch membrane from the RPE, partial damage of the RPE, disruption of the photoreceptor inner segment/outer segment (IS/OS) junction, multiple hyperreflective signals in the inner retina, foveal thinning, and parafoveal thickening. After treatment, the hyperreflective infiltrations in the inner retina were markedly decreased, and the RPE and IS/OS junction were restored. The foveal thinning and parafoveal thickening resolved, and the central choroidal thickness decreased. During the follow-up, the mfERGs remained decreased. In contrast, microperimetry showed a partial improvement of the retinal sensitivity. FAF and SD-OCT are useful noninvasive methods to evaluate the retinal and choroidal changes before and after treatment of PIOL. Our results suggest that visual recovery after successful treatment may be limited once macula is infiltrated.
    Journal of ophthalmic inflammation and infection. 02/2014; 4(1):7.
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    ABSTRACT: The purpose of this study is to describe the ineffectiveness of intrastromal voriconazole injection for filamentous fungal keratitis by contrasting the effectiveness for yeast keratitis.
    Clinical ophthalmology (Auckland, N.Z.) 01/2014; 8:1075-9.
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    ABSTRACT: Topical therapy is effective for dry eye, and its prolonged effects should help in maintaining the quality of life of patients with dry eye. We previously reported that the oral administration of rebamipide (Reb), a mucosal protective agent, had a potent therapeutic effect on autoimmune lesions in a murine model of Sjögren's syndrome (SS). However, the effects of topical treatment with Reb eyedrops on the ocular lesions in the murine model of SS are unknown.
    PLoS ONE 01/2014; 9(5):e98390. · 3.53 Impact Factor
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    ABSTRACT: The purpose of this study was to compare the effectiveness of pneumatic displacement combined with intravitreal bevacizumab (IVB) with that of pneumatic displacement (PD) alone to treat massive submacular hemorrhage (SMH) secondary to polypoidal choroidal vasculopathy (PCV). Thirty-two eyes of 32 patients with massive SMH secondary to PCV were studied. Twenty-two eyes were treated with a combination of PD and 1.25 mg of intravitreal bevacizumab (PD + IVB group), and ten eyes with pneumatic displacement alone (PD group). Pretreatment, the differences in best-corrected visual acuity and size of the SMH between the two groups were not significant (P=0.59 and P=0.72, respectively). Complete displacement of the hemorrhage from under the fovea was achieved in 19 of 22 eyes (86.4%) in the PD + IVB group and in five of ten eyes (50%) in the PD group. The best-corrected visual acuity in the PD + IVB group was significantly better than that in the PD group at one, 3, and 6 months after treatment (P<0.001, P<0.001, and P<0.001, respectively). Improvement in best-corrected visual acuity by >0.3 logMAR units was obtained in 18 eyes (81.8%) in the PD + IVB group and two eyes (20%) in the PD group (P<0.001). The number of eyes that required additional treatments was significantly fewer in the PD + IVB group than in the PD group (P=0.0001). The combination of PD and IVB may be a better therapeutic procedure for eyes with massive SMH due to PCV in the short term because of the better visual outcome and less need for additional treatments.
    Clinical ophthalmology (Auckland, N.Z.) 01/2014; 8:485-92.
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    ABSTRACT: Glaucoma, one of the leading causes of irreversible blindness, is characterized by progressive degeneration of optic nerves and retinal ganglion cells (RGCs). In the mammalian retina, excitatory amino acid carrier 1 (EAAC1) is expressed in neural cells, including RGCs, and the loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP). In the present study, we found that expressions of angiotensin II type 1 receptor (AT1-R) and Toll-like receptor 4 (TLR4) are increased in RGCs and retinal Müller glia in EAAC1-deficient (KO) mice. The orally active AT1-R antagonist candesartan suppressed TLR4 and lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expressions in the EAAC1 KO mouse retina. Sequential in vivo retinal imaging and electrophysiological analysis revealed that treatment with candesartan was effective for RGC protection in EAAC1 KO mice without affecting IOP. In cultured Müller glia, candesartan suppressed LPS-induced iNOS production by inhibiting the TLR4-apoptosis signal-regulating kinase 1 pathway. These results suggest that the renin-angiotensin system is involved in the innate immune responses in both neural and glial cells, which accelerate neural cell death. Our findings raise intriguing possibilities for the management of glaucoma by utilizing widely prescribed drugs for the treatment of high blood pressure, in combination with conventional treatments to lower IOP.
    Cell Death & Disease 01/2014; 5:e1333. · 6.04 Impact Factor
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    Mariko Egawa, Yoshinori Mitamura, Yuki Hayashi, Takeshi Naito
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    ABSTRACT: The purpose of this study was to evaluate the findings on spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) in three eyes with primary intraocular lymphoma (PIOL). The medical records of three eyes from three patients with biopsy-proven PIOL and retinal infiltrations were reviewed. The SD-OCT and fluorescein angiographic findings were evaluated in the three eyes and FAF images in two eyes. The PIOL in the three patients was monocular. Vitreous opacities and retinal infiltrations were observed in the three eyes, and iritis was present in two eyes. The cytologic diagnosis was class V in two eyes and class III in one eye. The interleukin-10/interleukin-6 ratio was >1.0 in the vitreous and aqueous humor of the three eyes. The FAF images for two eyes showed abnormal granular hyperautofluorescence and hypoautofluorescence which were the reverse of the pattern in the fluorescein angiographic images. In all three eyes, SD-OCT showed hyper-reflective infiltrations at the level of the retinal pigment epithelium (RPE), a separation of the Bruch membrane from the RPE, damage to the RPE, disruption of the photoreceptor inner segment/outer segment junction, and multiple hyper-reflective signals in the inner retina. Because of the characteristic FAF and SD-OCT findings in these eyes with PIOL, we suggest that these noninvasive methods may be used for a rapid diagnosis of PIOL and also for understanding the pathology of PIOL.
    Clinical ophthalmology (Auckland, N.Z.) 01/2014; 8:335-41.
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    ABSTRACT: Glaucoma is one of the leading causes of irreversible blindness that is characterized by progressive degeneration of optic nerves and retinal ganglion cells (RGCs). In the mammalian retina, excitatory amino-acid carrier 1 (EAAC1) is expressed in neural cells, including RGCs, and the loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP). Brimonidine (BMD) is an α2-adrenergic receptor agonist and it is commonly used in a form of eye drops to lower IOP in glaucoma patients. Recent studies have suggested that BMD has direct protective effects on RGCs involving IOP-independent mechanisms, but it is still controversial. In the present study, we examined the effects of BMD in EAAC1-deficient (KO) mice, an animal model of normal tension glaucoma. BMD caused a small decrease in IOP, but sequential in vivo retinal imaging and electrophysiological analysis revealed that treatment with BMD was highly effective for RGC protection in EAAC1 KO mice. BMD suppressed the phosphorylation of the N-methyl-D-aspartate receptor 2B (NR2B) subunit in RGCs in EAAC1 KO mice. Furthermore, in cultured Müller glia, BMD stimulated the production of several neurotrophic factors that enhance RGC survival. These results suggest that, in addition to lowering IOP, BMD prevents glaucomatous retinal degeneration by stimulating multiple pathways including glia-neuron interactions.
    Cell Death & Disease 01/2014; 5:e1341. · 6.04 Impact Factor
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    ABSTRACT: We present a case of prepapillary vascular loops complicated by a suspected macroaneurysm rupture which was treated with intravitreal bevacizumab (IVB). A 62-year-old woman presented with decreased vision and myodesopsia in her left eye. Her best-corrected visual acuity (BCVA) was 0.6 in the left eye. Fundus examination disclosed an elevated, round, and reddish lesion, retinal hemorrhage at the superior aspect of the optic disc, retinal opacification along the superior branch retinal artery, and a small vitreous hemorrhage. Optical coherence tomography showed a serous retinal detachment, and indocyanine green angiography demonstrated prepapillary vascular loops and a hypofluorescent area with hyperfluorescent margins. These findings suggested the presence of a macroaneurysm. No filling of the dye in the aneurysm-like dilatation suggested a blockage of the lumen with a thrombus which might be associated with a branch retinal artery occlusion (BRAO). A diagnosis of prepapillary vascular loops complicated by a suspected macroaneurysm rupture and BRAO was made. Because of a persistent serous retinal detachment, IVB was performed. One month later, the BCVA improved to 1.0. Fundus examination disclosed an organized yellowish-white macroaneurysm and resolution of the serous retinal detachment. We recommend careful monitoring of patients with prepapillary vascular loops because of complications such as macroaneurysm rupture and BRAO.
    Case reports in ophthalmological medicine. 01/2014; 2014:157242.
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    ABSTRACT: Purpose: To evaluate the choroidal thickness and volume in healthy pediatric individuals by swept-source optical coherence tomography (SS-OCT) and to compare the findings to those of adults. Methods: One hundred eyes of 100 healthy pediatric volunteers (3-15 years) and 83 eyes of 83 healthy adult volunteers (24-87 years) were examined by SS-OCT with a tunable long wavelength laser source. The three-dimensional raster scan protocol was used to construct a chroidal thickness map. When the built-in software delineated an erroneous chorioscleral border in the B-scan images, manual segmentation was used. Results: The central choroidal thickness and volume within a 1.0-mm circle were significantly larger in the children (260.4±57.2μm, 0.205±0.045mm(3)) than in the adults (206.1±72.5μm, 0.160±0.056 mm(3); both P<0.0001). In the children, the mean choroidal thickness of the nasal area was significantly thinner than that of all other areas (P<0.005). Pediatric choroidal thinning with increasing age in the central area was faster than that in the outer areas. Stepwise regression analysis showed that the axial length and body mass index had the highest correlation with the choroidal thickness ( R(2)=0.313, P<0.0001). Conclusions: The macular choroidal thickness and volume in the pediatric individuals were significantly larger than those in the adults. The pediatric choroidal thinning with increasing age is more rapid in the central area. Pediatric choroidal thickness is associated with several systemic or ocular parameters, especially the axial length and body mass index. These differences should be remembered when the choroidal thickness is evaluated in pediatric patients with retinochoroidal diseases.
    Investigative ophthalmology & visual science 10/2013; · 3.43 Impact Factor
  • T Katome, Y Mitamura, F Hotta, A Mino, T Naito
    Eye (London, England) 08/2013; · 1.97 Impact Factor
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    ABSTRACT: The elucidation of the routes of transmission of a pathogen is crucial for the prevention of infectious diseases caused by bacteria that are not a resident in human tissue. The purpose of this report is to describe a case of suture-related conjunctivitis caused by Pseudomonas aeruginosa for which we identified the transmission route using pulsed-field gel electrophoresis (PFGE). A 38-year-old man, who had undergone surgery for glaucoma 2 years ago previously, presented with redness, discomfort, and mucopurulent discharge in the right eye. A 9--0 silk suture had been left on the conjunctiva. A strain of P. aeruginosa was isolated from a culture obtained from the suture, and the patient was therefore diagnosed with suture-related conjunctivitis caused by P. aeruginosa. The conjunctivitis was cured by the application of an antimicrobial ophthalmic solution and removal of the suture. We used PFGE to survey of the indoor and outdoor environments around the patient's house and office in order to elucidate the route of transmission of the infection. Three strains of P. aeruginosa were isolated from the patient's indoor environment, and the isolate obtained from the patient's bathroom was identical to that from the suture. The case highlights the fact that an indoor environmental strain of P. aeruginosa can cause ocular infections.
    BMC Research Notes 07/2013; 6(1):245.
  • Retina (Philadelphia, Pa.) 05/2013; · 2.93 Impact Factor
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    ABSTRACT: With recent development of spectral-domain optical coherence tomography (SD-OCT), the pathological changes of retina can be observed in much greater detail. SD-OCT clearly delineates three highly reflective lines in the outer retina, which are external limiting membrane (ELM), photoreceptor inner and outer segment (IS/OS) junction, and cone outer segment tips (COST) in order from inside. These lines can serve as hallmarks for the evaluation of photoreceptor condition. In retinitis pigmentosa (RP) leading to photoreceptor degeneration, the ELM, IS/OS, and COST lines are shortened with the progression of the disease. In addition, shortening of the ELM, IS/OS and COST lines is significantly associated with each other. The line length is longest in the ELM, followed by the IS/OS, and COST, suggesting that retinal layer becomes disorganized first at the COST, followed by the IS/OS and finally the ELM. This finding is consistent with the previous report that the earliest histopathological change in RP is a shortening of the photoreceptor outer segments. On the other hand, retinal layer becomes restored first at the ELM, followed by the IS/OS and finally the COST after macular hole surgery. There may be a directionality of photoreceptor impairment or restoration on optical coherence tomographic image.
    Journal of Ophthalmology 01/2013; 2013:518170. · 1.37 Impact Factor
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    ABSTRACT: We report a case of methicillin-resistant Staphylococcus aureus (MRSA) keratitis after Descemet's stripping automated endothelial keratoplasty (DSAEK). An 87-year-old woman who had undergone a DSAEK 4 months previously was referred to Tokushima University Hospital with a diagnosis of infectious keratitis after DSAEK. A white abscess and infiltration in the inferior cornea of the right eye were observed. We started an empiric therapy using topical levofloxacin and chloramphenicol on the basis of the microscopic findings of the corneal scraping concurrently with cultivation of the cornea. A strain of MRSA was isolated from the corneal sample. Although the strain was susceptible to chloramphenicol, it was resistant to quinolone. The keratitis improved rapidly due to empiric therapy, and topical steroids could be resumed 6 days after initiation of the empiric therapy. To our knowledge, this is the first case of MRSA keratitis, and the second case of bacterial keratitis, after DSAEK. MRSA keratitis can occur following uneventful DSAEK. The empiric therapy on the basis of results from a light microscopic examination of a Gram-stained corneal scraping and restarting topical steroids in the early stages of medication contributed to the good clinical course of this case.
    Case reports in ophthalmology. 01/2013; 4(3):269-273.
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    ABSTRACT: BACKGROUND: To compare the therapeutic effects of panretinal photocoagulation (PRP) combined with intravitreal bevacizumab (IVB) and cryoretinopexy (CR-IVB) to that of PRP combined with IVB alone in eyes with neovascular glaucoma (NVG). DESIGN: Retrospective, consecutive, case-control study. METHODS: The medical records of 102 eyes of 96 patients with NVG due to proliferative diabetic retinopathy, central retinal vein occlusion, and ocular ischemic syndrome were reviewed. The mean age of the patients was 59.6 ± 11.5 years, with a range of 34 to 84 years. Patients received either 1.25 mg/0.05 ml of IVB combined with 360° of cryotherapy of the peripheral retina (CR-IVB subgroup) or IVB alone (IVB alone subgroup) as adjunctive treatments to PRP. The patients were followed for at least 12 months. Fifty-four eyes of 49 patients had open-angle NVG; 30 of these eyes were treated by CR-IVB, and 24 eyes by IVB alone. Forty-eight eyes of 48 patients had angle-closure NVG; 22 of these eyes were treated by CR-IVB, and 26 eyes were by IVB alone. Failure was defined as a postoperative intraocular pressure (IOP) >21 mmHg for two consecutive follow-up visits, or the need of additional surgery such as trabeculectomy or diode laser cycloablation. The differences in the success rates between the CR-IVB and IVB alone subgroups for the eyes with open-angle and closed-angle NVG were compared. RESULTS: The success rate at 12 months in eyes with open-angle NVG was 80.0 % in the CR-IVB subgroup and 41.7 % in the IVB alone subgroup (P = 0.0096). In eyes with angle-closure NVG, the success rate at 12 months was 22.7 % in the CR-IVB subgroup and 0 % in the IVB-alone subgroup (P = 0.030). CONCLUSION: The significantly better IOP control after PRP combined with cryotherapy and IVB than after PRP with IVB alone indicates that cryotherapy enhances the effectiveness of PRP for neovascular glaucoma for at least 1 year.
    Albrecht von Graæes Archiv für Ophthalmologie 12/2012; · 1.93 Impact Factor
  • The British journal of ophthalmology 11/2012; · 2.92 Impact Factor

Publication Stats

964 Citations
257.45 Total Impact Points

Institutions

  • 2012
    • Tokyo Metropolitan Institute of Medical Science
      Edo, Tōkyō, Japan
    • Sapporo City General Hospital
      Sapporo, Hokkaidō, Japan
    • Sohag University
      Sawhāj, Sūhāj, Egypt
    • National Center for Global Health and Medicine in Japan
      Japan
  • 2011
    • Chiba Rosai Hospital
      Tiba, Chiba, Japan
  • 2005–2010
    • Tokyo Metropolitan Institute
      Edo, Tōkyō, Japan
  • 2007–2009
    • Chiba University
      • Department of Ophthalmology and Visual Science
      Chiba-shi, Chiba-ken, Japan
  • 2001–2006
    • Sapporo Medical University
      • Division of Ophthalmology
      Sapporo, Hokkaidō, Japan