Keiichiro Minami

Mr. Keiichiro Minami

orcid

Research Focus & Metrics

Academic Career Length

34Years (1993-Present)

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

Representative Publications

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1 October 2012 in Journal of Cataract & Refractive Surgery
Verified
Journal Article
Closed access
KMKeiichiro Minami
Keiichiro Minami
YKYasushi Kataoka
Yasushi Kataoka
JMJiro Matsunaga
Jiro Matsunaga
SOShinichiro Ohtani
Shinichiro Ohtani
MHMasato Honbou
Masato Honbou
KMKazunori Miyata
Kazunori Miyata
To assess the efficiency of ray-tracing intraocular lens (IOL) power calculation with anterior segment optical coherence tomography (AS-OCT) in normal eyes with cataract. Miyata Eye Hospital, Miyakonojo, Miyazaki, Japan. Case series. The study comprised consecutive patients who had cataract surgery and obtained a corrected visual acuity of 0.15 logMAR or better postoperatively. Preoperatively, Placido topography and AS-OCT measurements were taken during a routine examination. The predicted postoperative refractions were obtained using 3 methods: the SRK/T formula with autokeratometry, ray-tracing calculation with Placido topography data, and ray-tracing calculations with AS-OCT measurement of both corneal surfaces. The refractive errors from the manifest refraction spherical equivalent were compared 1 month postoperatively, and the effects of corneal eccentricity and posterior corneal curvature were evaluated. Seventy patients (102 eyes) were enrolled. There was no significant difference in refractive errors (P=.89). The refractive error with the SRK/T formula was correlated significantly with corneal eccentricity (P=.0017); the ray-tracing calculations were unaffected. There was a weak correlation with the posterior corneal curvature in the ray-tracing calculations performed with Placido topography (P<.0002). The accuracy of the ray-tracing IOL power calculations using AS-OCT data was comparable to that of the conventional formula and minimized the effect of corneal eccentricity and posterior corneal curvature.

9 July 2018 in BMC Ophthalmology
Verified
Journal Article
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KMKeiichiro Minami
Keiichiro Minami
TTTadatoshi Tokunaga
Tadatoshi Tokunaga
KOKeiichiro Okamoto
Keiichiro Okamoto
KMKazunori Miyata
Kazunori Miyata
TOTetsuro Oshika
Tetsuro Oshika
The prospective observation study aimed to evaluate changes in corneal higher-order aberrations induced by advancement of pterygium using an anterior-segment optical coherence tomography (AS-OCT) and Zernike aberration analysis. The corneal topography of 284 eyes with primary pterygia originating from the nasal region was measured using an AS-OCT (SS-1000, Tomey). With anterior corneal elevation data, Zernike polynomial coefficients were calculated in diameters of 1.0, 3.0, and 5.0 mm, and the coma, spherical, coma-like, spherical-like, and total higher-order aberrations were obtained. Pterygium size was also measured as a ratio of positions of the pterygium end with respect to the corneal diameter and categorized in eight classes: less than 15%, 15–20%, 20–25%, 25–30%, 30–35%, 35–40%, 40–45, and 45% or larger. Increases in the aberrations were analyzed with reference to those in eyes with pterygium size < 15%. The mean age of the participants was 69.3 years, and the pterygium size ranged from 2 to 57% (mean: 28.8%). The coma aberration significantly increased when the pterygium size was 45% or larger in 1.0 and 3.0 mm diameters and over 25–30% in 5.0 mm diameter. Similar increases were found in the pterygium sizes exceeding 45, 40, and 25%, respectively, in the coma-like, spherical-like, and total higher-order aberrations. On contrast, there was no increase in the spherical aberration. Increases in higher-order aberrations reflected the pterygium size, and significant aberrations were induced in 5.0 mm diameter when the end exceeded 25% of corneal diameter. The use of AS-OCT and Zernike analysis could enable objective grading of pterygium advancement based on changes in corneal optics.

1 April 2010 in Journal of Cataract & Refractive Surgery
Verified
Journal Article
Closed access
HBHiroko Bissen-Miyajima
Hiroko Bissen-Miyajima
KMKeiichiro Minami
Keiichiro Minami
MYMami Yoshino
Mami Yoshino
MNMariko Nishimura
Mariko Nishimura
SOShinchi Oki
Shinchi Oki
To evaluate whether autorefractometry values after implantation of diffractive multifocal intraocular lenses (IOLs) correlate with manifest refraction values. Tokyo Dental College Suidobashi Hospital, Tokyo, Japan. This retrospective study evaluated eyes that had cataract surgery with implantation of a diffractive multifocal IOL. One month or more postoperatively, the autorefraction values were compared with the manifest refraction values to determine the correlation between the 2 methods in sphere, cylinder, and spherical equivalent (SE). The study evaluated 156 eyes of 84 patients. The mean spherical refraction was 0.13 diopters (D) +/- 0.66 by autorefraction and 0.26 +/- 0.50 D by manifest refraction. The mean cylinder value was 0.94 +/- 0.58 D and 0.61 +/- 0.48 D, respectively. The mean SE was -0.34 +/- 0.66 D and -0.06 +/- 0.48 D, respectively. All 3 measurements by autorefraction and manifest refraction were well correlated (r(2) = 0.67, 0.66, 0.64, respectively). Findings show that postoperative autorefraction can be used to estimate the manifest refraction in eyes with diffractive multifocal IOLs. No author has a financial or proprietary interest in any material or method mentioned.

1 October 2016 in Journal of Cataract & Refractive Surgery
Verified
Journal Article
Closed access
YNYoshihiko Ninomiya
Yoshihiko Ninomiya
KMKeiichiro Minami
Keiichiro Minami
KMKazunori Miyata
Kazunori Miyata
SEShuichiro Eguchi
Shuichiro Eguchi
RSRie Sato
Rie Sato
TOTetsuro Oshika
Tetsuro Oshika
To assess 1-year clinical results of toric intraocular lenses (IOLs) in eyes having with-the-rule (WTR), against-the-rule (ATR), or oblique corneal astigmatism. Four ophthalmic surgical sites, Japan. Prospective case series. One of 3 toric IOLs or 1 nontoric IOL was implanted in eyes having phacoemulsification and IOL implantation. The study comprised 218 eyes (155 patients). Based on the suggestion of an online toric calculator with anterior corneal curvature data, 63 eyes received the SN6AT3 IOL with a cylinder power of 1.50 diopters [D] at IOL plane (1.50 D cylinder IOL) 55 eyes the SN6AT4 IOL with a cylinder power of 2.25 D at IOL plane (2.25 D cylinder IOL), and 58 eyes the SN6AT5 IOL with a cylinder power of 3.00 D at IOL plane (3.00 D cylinder IOL) (all Acrysof IQ toric), and 42 eyes received the SN60WF IOL (nontoric IOL). One hundred ninety-four eyes (89.0%) completed 1-year of follow-up. The centroid error in predicted residual astigmatism calculated using vector analysis was close to the origin in eyes with WTR astigmatism (0.17 diopter [D] @ 174.9 ± 0.54 D), while those with ATR and oblique astigmatism were significantly shifted toward the ATR direction (P < .001). The distance from the origin was significantly smaller in the WTR group than in ATR and oblique groups (P < .05). The centroid errors were shifted toward ATR in all toric IOL groups (P < .001); however, the distance from the origin was not different between groups (P = .52). Postoperatively, the mean absolute misalignment of the IOLs was 5.92 degrees ± 5.59 (SD) at 1 day and 6.24 ± 5.87 degrees at 1 year. The results of other clinical parameters were excellent, with no significant differences between astigmatism categories or IOL models. Based on anterior corneal curvature alone, toric IOLs undercorrected ATR and oblique astigmatism; however, 1-year clinical results of toric IOLs were highly stable and satisfactory. None of the authors has a financial or proprietary interest in any material or method mentioned.

12 March 2018 in Japanese Journal of Ophthalmology
Verified
Journal Article
Closed access
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KMKeiichiro Minami
Keiichiro Minami
KMKazunori Miyata
Kazunori Miyata
AOAtsushi Otani
Atsushi Otani
TTTadatoshi Tokunaga
Tadatoshi Tokunaga
STShouta Tokuda
Shouta Tokuda
SAShiro Amano
Shiro Amano

31 March 2017 in Cornea
Verified
Journal Article
Closed access
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KMKazunori Miyata
Kazunori Miyata
KMKeiichiro Minami
Keiichiro Minami
AOAtsushi Otani
Atsushi Otani
TTTadatoshi Tokunaga
Tadatoshi Tokunaga
STShouta Tokuda
Shouta Tokuda
SAShiro Amano
Shiro Amano
Purpose: To propose a grading system of pterygium severity based on corneal higher-order irregularity (HOI) and to evaluate postoperative changes in corneal irregularity of the graded pterygia. Methods: In 268 eyes of 226 patients undergoing excision surgery of primary nasal pterygium, Placido corneal topography images were taken before and until 6 months after surgery. The best-corrected visual acuity (BCVA) and pterygium size with respect to the corneal diameter were also measured. HOI components within 1.0-, 3.0-, and 5.0-mm diameters were obtained using Fourier harmonic analysis of corneal topography data. With threshold levels when the HOIs for 3 diameters steeply increased, 4 levels of grading from 0 (mild) to 3 (severe) were determined. Associations of the grades with the preoperative surface regularity index (SRI), irregular components (IRRs) obtained from the 3.0-mm diameter Fourier analysis, and BCVA were examined. Time-course changes in the indexes after surgery were evaluated for each grade. Results: There were 62, 65, 41, and 100 eyes in grades 0 to 3, respectively. Preoperatively, the SRI in grade 3 was significantly higher than in the other grades (P < 0.001), and the IRR and BCVA varied with the grade (P < 0.001). Between 1 and 6 months postoperatively, grade 3 pterygia showed significant changes in the SRI and IRR (P = 0.013 and 0.017, respectively), whereas there was no change after 3 months postoperatively in the SRI, IRR, and BCVA for all other grades. Conclusions: The proposed grading effectively classified the severity of pterygia and evaluated postoperative restoration of corneal irregularity. Using corneal topographic data allowed for objective evaluation of pterygium severity.