Kazuyuki Hirooka

Dr. Kazuyuki Hirooka

Department of Ophthalmology and Visual Science, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 July 2012 in BMC Ophthalmology
Verified
Journal Article
Open access
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KHKazuyuki Hirooka
Kazuyuki Hirooka
KTKaori Tenkumo
Kaori Tenkumo
AFAtsushi Fujiwara
Atsushi Fujiwara
TBTetsuya Baba
Tetsuya Baba
SSShino Sato
Shino Sato
FSFumio Shiraga
Fumio Shiraga
To compare peripapillary choroidal thickness measurements between normal and normal-tension glaucoma eyes.

1 April 2013 in Investigative Ophthalmology & Visual Science
Verified
Journal Article
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SSShino Sato
Shino Sato
KHKazuyuki Hirooka
Kazuyuki Hirooka
TBTetsuya Baba
Tetsuya Baba
KTKaori Tenkumo
Kaori Tenkumo
ENEri Nitta
Eri Nitta
FSFumio Shiraga
Fumio Shiraga
Purpose.: To evaluate relationships between the macular visual field (VF) mean sensitivity and the ganglion cell and inner plexiform layer (GCA) thicknesses. Methods.: Seventy-one glaucoma patients and 29 healthy subjects were included in this cross-sectional study. At each visit, GCA thicknesses were measured by Cirrus HD-OCT and static threshold perimetry was performed using Macular Integrity Assessment (MAIA). The relationship between the VF sensitivity and GCA thickness was examined globally, and in the superior hemiretina, inferior hemiretina, and six VF sectors with both VF and optical coherence tomography (OCT) in retinal view. Regression analysis was used to investigate the relationship between the GCA thickness and macular sensitivity. Results.: Macular VF sensitivity (dB) and GCA thickness relationships were statistically significant in each sector (R = 0.365–0.706, all P < 0.001). The highest correlation observed was between the inferotemporal average mean sensitivity and the inferotemporal average GCA thickness (R = 0.706) with both VF and OCT in retinal view. Strength of the structure–function relationship for each of the corresponding inferior sectors was higher than those for the corresponding superior sectors. The strength of the structure–function relationship of the temporal sector was higher than that of the nasal sector. Conclusions.: GCA thickness measured by Cirrus HD-OCT showed statistically significant structure–function associations with central VF. Inferotemporal central VF had the strongest association.

1 April 2006 in Investigative Ophthalmology & Visual Science
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Journal Article
Closed access
KHKazuyuki Hirooka
Kazuyuki Hirooka
OMOsamu Miyamoto
Osamu Miyamoto
PJPan Jinming
Pan Jinming
YDYinghua Du
Yinghua Du
TIToshifumi Itano
Toshifumi Itano
FSFumio Shiraga
Fumio Shiraga
To investigate the effect of D-allose, a rare sugar, against ischemia reperfusion injury in the rat retina. Retinal ischemia was induced by increasing intraocular pressure to 130 mm Hg and maintaining that level for 45 minutes. Morphometric studies were performed to study the effect of D-allose on the histologic changes induced by ischemia in the rat retina. Glutamate release from the rat retina and intravitreal P(O2) profiles were monitored during and after ischemia with a microdialysis biosensor and oxygen-sensitive microelectrodes. The release of hydrogen peroxide stained with diaminobenzidine hydrochloride was monitored by an in vitro retinal ischemia model. Seven days after the ischemia, significant reductions in both the number of ganglion cells and the thickness of the inner plexiform layer were observed. Pretreatment with D-allose significantly inhibited the ischemic injury of the inner retina. A large release of glutamate occurred during the ischemia. After the recirculation, glutamate levels were increased again and reached a maximum in approximately 20 minutes. The increases in extracellular glutamate during and after ischemia tend to be suppressed by administration of d-allose. d-Allose attenuated the increase in intravitreal P(O2) during reperfusion. After the ischemia, production of hydrogen peroxide was detected within approximately 30 minutes. D-allose suppressed the production of hydrogen peroxide. These results suggest that D-allose may protect neurons by decreasing extracellular glutamate and attenuating oxidative stress in ischemic insult.

27 March 2012 in Clinical & Experimental Ophthalmology
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Journal Article
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KHKazuyuki Hirooka
Kazuyuki Hirooka
AFAtsushi Fujiwara
Atsushi Fujiwara
CSChieko Shiragami
Chieko Shiragami
TBTetsuya Baba
Tetsuya Baba
FSFumio Shiraga
Fumio Shiraga

Verified
Journal Article
Open access
PDF file
Naoki OkadaNaoki Okada
Naoki Okada
KHKazuyuki Hirooka
Kazuyuki Hirooka
HOHiromitsu Onoe
Hiromitsu Onoe
YMYumiko Murakami
Yumiko Murakami
HOHideaki Okumichi
Hideaki Okumichi
YKYoshiaki Kiuchi
Yoshiaki Kiuchi
We compared surgical outcomes in patients with either primary open-angle glaucoma or exfoliation glaucoma after undergoing combined phacoemulsification with either a 120° or 180° incision during a Schlemm’s canal microhook ab interno trabeculotomy (μLOT-Phaco). This retrospective comparative case series examined 52 μLOT-Phaco eyes that underwent surgery between September 2017 and December 2020. Surgical qualified success was defined as an intraocular pressure (IOP) of ≤20 mmHg, ≥20% IOP reduction with IOP-lowering medications, and no additional glaucoma surgery. Success rates were evaluated by Kaplan-Meier survival analysis. The number of postoperative IOP-lowering medications and occurrence of complications were also assessed. Mean preoperative IOP in the 120° group was 16.9 ± 7.6 mmHg, which significantly decreased to 10.9 ± 2.7 mmHg (p < 0.01) and 11.1 ± 3.1 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.8 ± 1.4 to 1.4 ± 1.4 (p < 0.01) at 24 months. Mean preoperative IOP in the 180° group was 17.1 ± 7.0 mmHg, which significantly decreased to 12.1 ± 3.2 mmHg (p = 0.02) and 12.9 ± 1.4 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.9 ± 1.2 to 1.4 ± 1.5 (p < 0.01) at 24 months. The probability of qualified success at 24 months in the 120° and 180° groups was 50.4% and 54.6%, respectively (p = 0.58). There was no difference observed for hyphema formation or IOP spikes. Surgical outcomes were not significantly different between the 120° and 180° incisions in Schlemm’s canal.

14 March 2016 in PLOS ONE
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Journal Article
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KHKazuyuki Hirooka
Kazuyuki Hirooka
KMKana Misaki
Kana Misaki
ENEri Nitta
Eri Nitta
KUKaori Ukegawa
Kaori Ukegawa
SSShino Sato
Shino Sato
ATAkitaka Tujikawa
Akitaka Tujikawa
This study was conducted in order to compare relationships between the macular visual field (VF) mean sensitivity measured by MAIATM (Macular Integrity Assessment), MP-3, or Humphry field analyzer (HFA) and the ganglion cell and inner plexiform layer (GCA) thicknesses. This cross-sectional study examined 73 glaucoma patients and 19 normal subjects. All subjects underwent measurements for GCA thickness by Cirrus HD-OCT and static threshold perimetry using MAIATM, MP-3, or HFA. VF and OCT in the retinal view were used to examine both the global relationship between the VF sensitivity and GCA thickness, and the superior hemiretina and inferior hemiretina. The relationship between the GCA thickness and macular sensitivity was examined by Spearman correlation analysis. For each instrument, statistically significant macular VF sensitivity (dB) and GCA thickness relationships were observed using the decibel scale (R = 0.547–0.687, all P < 0.001). The highest correlation for the global (R = 0.682) and the superior hemiretina (R = 0.594) GCA thickness-VF mean sensitivity was observed by the HFA. The highest correlation for the inferior hemiretina (R = 0.687) GCA thickness-VF mean sensitivity was observed by the MP-3. Among the three VF measurement instruments, however, no significant differences were found for the structure-function relationships. All three VF measurement instruments found similar structure-function relationships in the central VF.