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Dive into the research topics where Kei Akaiwa is active.

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Featured researches published by Kei Akaiwa.


British Journal of Ophthalmology | 2016

Diurnal variations in luminal and stromal areas of choroid in normal eyes

Takamasa Kinoshita; Yoshinori Mitamura; Kayo Shinomiya; Mariko Egawa; Akiko Iwata; Akiko Fujihara; Yoko Ogushi; Kentaro Semba; Kei Akaiwa; Eisuke Uchino; Shozo Sonoda; Taiji Sakamoto

Aims To determine the diurnal variations of the luminal and stromal areas of the choroid in normal eyes. Methods This was a prospective observational study of 38 eyes of 38 normal subjects. The blood pressure, heart rate, intraocular pressure and enhanced depth imaging optical coherence tomographic (EDI-OCT) images were recorded every 3 hours between 6:00 and 21:00 hours. The horizontal EDI-OCT images of the subfoveal choroid were converted to binary images. The central choroidal thickness (CCT), total cross-sectional choroidal area, the luminal areas, stromal areas and the ratio of luminal area to total choroidal area (L/C ratio) were determined. Results There were significant diurnal variations in the CCT, total choroidal area, luminal area and L/C ratio with the maximum values at 6:00 hours and the minimum values at 15:00 hours (p<0.001 for the CCT, p=0.011 for the total choroidal area, p<0.001 for the luminal area and p=0.014 for the L/C ratio). There was no significant variation in the stromal area (p=0.216). The range of fluctuation in the CCT was significantly correlated with that in the luminal area and the total choroidal area (p<0.001). However, there was no significant correlation between the fluctuation range in the CCT and that in the stromal area (p=0.095). There was no statistical relationship between the systemic parameters and the choroidal parameters. Conclusions The changes in the luminal area are most likely responsible for the diurnal change in the CCT and subfoveal choroidal area. Trial registration number UMIN000019060, Pre-results.


British Journal of Ophthalmology | 2016

Changes of choroidal structure after corticosteroid treatment in eyes with Vogt–Koyanagi–Harada disease

Mariko Egawa; Yoshinori Mitamura; Kei Akaiwa; Kentaro Semba; Takamasa Kinoshita; Eisuke Uchino; Shozo Sonoda; Taiji Sakamoto

Aims To report the changes of the choroidal structure in the enhanced depth imaging optical coherence tomographic (EDI-OCT) images after high-dose corticosteroid treatment for acute Vogt–Koyanagi–Harada (VKH) disease. Methods Retrospective, observational case series. Thirty-four eyes of 17 patients with acute VKH disease were examined by EDI-OCT before, and 1, 4 and 52 weeks after the treatment. The EDI-OCT images were binarised by ImageJ, a publicly accessible software. The luminal, stromal and total choroidal areas and ratio of luminal/stromal area (L/S ratio) were measured in the subfoveal choroid of 1500 µm width. The area of the peripapillary atrophy (PPA) was measured in the fundus photographs at 1 and 52 weeks. For statistical analyses, a generalised estimating equation method was used to eliminate the effect of within-subject intereye correlations. Results Before treatment, the EDI-OCT images could not be binarised because of poor image quality in most of the cases. After treatment, the luminal, stromal and total choroidal areas were significantly decreased during the follow-up period (all p<0.05). The L/S ratio significantly fluctuated over time (p=0.0201), and was significantly lower at 4 weeks than at 1 week (p=0.0158). The L/S ratio at 1 week was significantly correlated with increase in the PPA area, subsequent chronic recurrences and total dose of corticosteroid (p<0.0001, p=0.0006, p=0.0037, respectively). Conclusions The L/S ratio measured by binarisation of EDI-OCT images was predictive factor for the progression of PPA, subsequent chronic recurrences and total dose of corticosteroid, and may serve as a marker for degree of choroidal inflammation in the VKH disease.


PLOS ONE | 2016

Changes in Choroidal Structures in Eyes with Chronic Central Serous Chorioretinopathy after Half-Dose Photodynamic Therapy

Takamasa Kinoshita; Yoshinori Mitamura; Terumi Mori; Kei Akaiwa; Kentaro Semba; Mariko Egawa; Junya Mori; Shozo Sonoda; Taiji Sakamoto

Purpose To determine the structural changes in the choroid after half-dose photodynamic therapy (hPDT) in eyes with chronic central serous chorioretinopathy (CSC). Methods This was a retrospective interventional study of 29 eyes of 29 patients who underwent hPDT for chronic CSC with serous retinal detachment (SRD) and were followed for ≥3 months. Enhanced depth imaging optical coherence tomographic (EDI-OCT) images of the subfoveal choroid were converted to binary images. The central choroidal thickness (CCT), the cross sectional subfoveal choroidal area, the hyporeflective and hyperreflective areas of the inner, outer, and whole choroid were determined at the baseline, and at 1, 3, and 12 months after the hPDT. Results The SRDs were resolved in 26 (89.7%) eyes at 3 months after the hPDT. The mean CCT (P = 0.001), the total choroidal area (P = 0.001), and the hypo-reflective area (P = 0.003) of the whole choroid were significantly decreased from the baseline at 3 months. The hyperreflective area of whole choroid was not significantly changed during the study period (P = 0.083). The hyperreflective but not the hyporeflective area of the inner choroid was significantly decreased at 3 months (P = 0.001, P = 1.000, respectively). The hyporeflective but not the hyperreflective area of the outer choroid was significantly decreased at 3 months (P = 0.001, P = 1.000, respectively). Conclusions The hyperreflective area of the inner choroid and hyporeflective area of the outer choroid were significantly decreased after hPDT for chronic CSC. Because the hyperreflective and hyporeflective area correspond to the choroidal stroma and vessels, respectively, the decreased CCT and subfoveal choroidal area after hPDT may be attributed to a decrease in the exudative changes in the inner choroidal stroma and the reduction of the dilation of the outer choroidal vessels.


British Journal of Ophthalmology | 2017

Changes of choroidal structure after intravitreal aflibercept therapy for polypoidal choroidal vasculopathy

Erina Daizumoto; Yoshinori Mitamura; Hiroki Sano; Kei Akaiwa; Masanori Niki; Chihiro Yamanaka; Takamasa Kinoshita; Mariko Egawa; Shozo Sonoda; Taiji Sakamoto

Aims To quantify the changes of the choroidal structure in the enhanced depth imaging optical coherence tomographic (EDI-OCT) images after intravitreal aflibercept (IVA) injections for polypoidal choroidal vasculopathy (PCV). Methods Retrospective, observational case series. Forty eyes of 40 treatment-naive patients who underwent IVA for PCV were examined by EDI-OCT before, and 3 months and 12 months after IVA. The EDI-OCT images were binarised by ImageJ software. The cross-sectional luminal and stromal areas of the inner and outer subfoveal choroid of 1500 µm width were quantified. Results The stromal but not the luminal area of the inner choroid was significantly decreased at 3 months and 12 months after the IVA (stromal area, both p<0.001; luminal area, both p>0.050). On the other hand, the luminal but not the stromal area of the outer choroid was significantly decreased at 3 months and 12 months (luminal area, both p<0.001; stromal area, both p>0.050). The Pachychoroid Index, ratio of luminal/stromal area (L/S ratio) of the outer choroid divided by the L/S ratio of the inner choroid, was significantly decreased at 3 months and 12 months (both p<0.050). The Pachychoroid Index was increased and returned almost to the baseline level after recurrences and decreased again after successful re-treatment. The baseline Pachychoroid Index was significantly correlated with the presence of a dry macula, thinner fovea and better visual acuity at 12 months (all p<0.050). Conclusion The binarisation of the EDI-OCT images can be used to quantify the activity of PCV and to predict the prognosis after IVA.


Clinical Ophthalmology | 2016

Optical coherence tomography parameters predictive of visual outcome after anti-VEGF therapy for retinal vein occlusion

Akiko Fujihara-Mino; Yoshinori Mitamura; Naoki Inomoto; Hiroki Sano; Kei Akaiwa; Kentaro Semba

Purpose To determine the optical coherence tomography (OCT) parameters that are predictive of visual outcome after anti-VEGF therapy for a retinal vein occlusion (RVO). Methods Fifty-seven eyes with macular edema (ME) secondary to a central or branch RVO treated with bevacizumab or ranibizumab were studied. Spectral-domain OCT and microperimetry were performed before, 1, 3, and 6 months after the treatment and at the final visit. Central retinal thickness (CRT), macular volume (MV), integrity of the external limiting membrane (ELM), ellipsoid zone (EZ), and foveal bulge (FB), and photoreceptor outer segment (PROS) length were determined. Results The mean follow-up period was 17.8±11.5 months. In 46 of the 57 eyes, a resolution of the ME was achieved. The pretreatment CRT and MV, presence of intact ELM, EZ, and FB, and PROS length at the time of ME resolution were significantly correlated with the best-corrected visual acuity and retinal sensitivity at the final visit (P<0.050). Multiple regression analyses showed that the pretreatment MV had the highest correlation with the posttreatment best-corrected visual acuity and retinal sensitivity (P<0.050). Conclusion The CRT, MV, ELM, EZ, FB, and PROS length are predictive factors for the visual outcome after anti-VEGF therapy for RVO.


PLOS ONE | 2016

Effects of Exercise on the Structure and Circulation of Choroid in Normal Eyes

Takamasa Kinoshita; Junya Mori; Natsuki Okuda; Hiroko Imaizumi; Masanori Iwasaki; Miho Shimizu; Hirotomo Miyamoto; Kei Akaiwa; Kentaro Semba; Shozo Sonoda; Taiji Sakamoto; Yoshinori Mitamura; Gianni Virgili

Aims To determine the effects of dynamic exercise on the circulation and the luminal and stromal areas of the choroid in normal eyes. Methods This was a prospective interventional study of 38 eyes of 38 normal subjects enrolled by invitation. The systolic and diastolic blood pressures, heart rate, intraocularpressure, mean ocular perfusion pressure (MOPP), choroidal blood velocity, and enhanced depth imaging optical coherence tomographic (EDI-OCT) images were recorded before, and immediately after mild dynamic exercise. The same measurements were recorded after 10 min of rest. The choroidal blood velocity was measured bylaser speckle flowgraphy, and the mean blur rate was used for the evaluations. The horizontal EDI-OCT images of the subfoveal choroid were converted to binary images. The central choroidal thickness (CCT), total cross sectional choroidal area, luminal areas, stromal areas, and the ratio of luminal area to total choroidal area (L/C ratio) were determined from these images. Results The systolic and diastolic blood pressures, heart rate, MOPP, and the mean blur rate were significantly increased immediately after the exercise and significantly decreased 10 minutes after the exercise. There wereno significant changes in the mean CCT, the mean total choroidal area, the mean luminal and stromal areas, and the mean L/C ratio after the exercise. Conclusions Our results suggest that a rest period is needed before measurements of blood flow velocity but not necessary for the EDI-OCT imaging to determine the choroidal thickness and area.


Cell Death and Disease | 2017

Edaravone suppresses retinal ganglion cell death in a mouse model of normal tension glaucoma

Kei Akaiwa; Kazuhiko Namekata; Yuriko Azuchi; Xiaoli Guo; Atsuko Kimura; Chikako Harada; Yoshinori Mitamura; Takayuki Harada

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. Loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP) and exhibits glaucomatous pathology including glutamate neurotoxicity and oxidative stress. In the present study, we found that edaravone, a free radical scavenger that is used for treatment of acute brain infarction and amyotrophic lateral sclerosis (ALS), reduces oxidative stress and prevents RGC death and thinning of the inner retinal layer in EAAC1-deficient (KO) mice. In addition, in vivo electrophysiological analyses demonstrated that visual impairment in EAAC1 KO mice was ameliorated with edaravone treatment, clearly establishing that edaravone beneficially affects both histological and functional aspects of the glaucomatous retina. Our findings raise intriguing possibilities for the management of glaucoma by utilizing a widely prescribed drug for the treatment of acute brain infarction and ALS, edaravone, in combination with conventional treatments to lower IOP.


Investigative Ophthalmology & Visual Science | 2018

Topical Ripasudil Suppresses Retinal Ganglion Cell Death in a Mouse Model of Normal Tension Glaucoma

Kei Akaiwa; Kazuhiko Namekata; Yuriko Azuchi; Hiroki Sano; Xiaoli Guo; Atsuko Kimura; Chikako Harada; Yoshinori Mitamura; Takayuki Harada

Purpose To assess if ripasudil has a neuroprotective effect using mice with excitatory amino acid carrier 1 (EAAC1) deletion (EAAC1 knockout [KO] mice), a mouse model of normal tension glaucoma. Methods Topical administration (5 μL/day) of two different concentrations of ripasudil (0.4% and 2%) were applied to EAAC1 KO mice from 5 to 12 weeks old. Optical coherence tomography, multifocal electroretinograms, the measurement of intraocular pressure (IOP), and histopathology analyses were performed at 5, 8, and 12 weeks old. Retrograde labeling of retinal ganglion cells (RGCs), immunoblot, and immunohistochemical analyses of phosphorylated p38 mitogen-activated protein kinase (MAPK) in the retina were performed at 8 weeks old. Results Topical ripasudil ameliorated retinal degeneration and improved visual function in EAAC1 KO mice at both 8 and 12 weeks old. Ripasudil reduced IOP and strongly suppressed the phosphorylation of p38 MAPK that stimulates RGC death in EAAC1 KO mice. Conclusions These results suggest that, in addition to IOP reduction, ripasudil prevents glaucomatous retinal degeneration by neuroprotection, which is achieved by suppressing cell-death signaling pathways.


Case reports in ophthalmological medicine | 2014

Prepapillary Vascular Loops Complicated by Suspected Macroaneurysm Rupture

Kei Akaiwa; Yoshinori Mitamura; Takashi Katome; Kentaro Semba; Mariko Egawa; Takeshi Naito

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.


BMC Ophthalmology | 2015

Changes of choroidal structure after treatment for primary intraocular lymphoma: retrospective, observational case series.

Mariko Egawa; Yoshinori Mitamura; Hiroki Sano; Kei Akaiwa; Masanori Niki; Kentaro Semba; Shozo Sonoda; Taiji Sakamoto

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Mariko Egawa

University of Tokushima

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Hiroki Sano

University of Tokushima

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Chikako Harada

Tokyo Medical and Dental University

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