Masahiro Miura

University of Tsukuba, Tsukuba, Ibaraki, Japan

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Publications (74)109.59 Total impact

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    ABSTRACT: Purpose: To investigate exudative macular disease, multi-functional optical coherence tomography (MF-OCT) using a 1-μm probe band was developed. The clinical utility of MF-OCT was examined in a descriptive case series. Methods: Ten eyes of nine subjects with exudative macular disease, including one eye with age-related macular degeneration (AMD), one eye with idiopathic neovascular maculopathy, and eight eyes with polypoidal choroidal vasculopathy (PCV), were investigated. Areas of 6 × 6 mm(2) around the pathologic region were scanned with 512 × 1024 depth scans in 6.6 seconds. Structural OCT, Doppler optical coherence angiography (OCA) and cumulative phase retardation images were obtained with a single measurement. Each MF-OCT image visualized the structure, vasculature, and birefringence. Degree of polarization uniformity values were also obtained for selective visualization of the retinal pigment epithelium (RPE). The MF-OCT images were compared with conventional ophthalmic images. Results: Abnormal vasculatures were observed with Doppler OCA in all eyes and it presented high similarity to indocyanine green angiography in the midphase. The RPE and exudation in the pathologic regions were discriminated in one eye with AMD and five of eight eyes with PCV. Cumulative phase retardation visualized fibrosis scars in two of the PCV cases. Conclusions: MF-OCT revealed depth-resolved abnormal vasculatures, the integrity of the RPE and choroid, discrimination of the RPE and exudation, and existence of fibrosis scars in exudative macular diseases. Interpretation of MF-OCT examination is well matched with conventional ophthalmic examination. These results suggest MF-OCT can be used as a noninvasive ophthalmic examination tool prior to conventional examinations in clinical routines.
    Investigative ophthalmology & visual science. 07/2014;
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    ABSTRACT: The relationship between scleral birefringence and biometric parameters of human eyes in vivo is investigated. Scleral birefringence near the limbus of 21 healthy human eyes was measured using polarization-sensitive optical coherence tomography. Spherical equivalent refractive error, axial eye length, and intraocular pressure (IOP) were measured in all subjects. IOP and scleral birefringence of human eyes in vivo was found to have statistically significant correlations (r = -0.63, P = 0.002). The slope of linear regression was -2.4 × 10(-2) deg/μm/mmHg. Neither spherical equivalent refractive error nor axial eye length had significant correlations with scleral birefringence. To evaluate the direct influence of IOP to scleral birefringence, scleral birefringence of 16 ex vivo porcine eyes was measured under controlled IOP of 5-60 mmHg. In these ex vivo porcine eyes, the mean linear regression slope between controlled IOP and scleral birefringence was -9.9 × 10(-4) deg/μm/mmHg. In addition, porcine scleral collagen fibers were observed with second-harmonic-generation (SHG) microscopy. SHG images of porcine sclera, measured on the external surface at the superior side to the cornea, showed highly aligned collagen fibers parallel to the limbus. In conclusion, scleral birefringence of healthy human eyes was correlated with IOP, indicating that the ultrastructure of scleral collagen was correlated with IOP. It remains to show whether scleral collagen ultrastructure of human eyes is affected by IOP as a long-term effect.
    Biomedical Optics Express 05/2014; 5(5):1391-402. · 3.18 Impact Factor
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    ABSTRACT: Pixel clustering algorithm tailored to multi-contrast Jones matrix based optical coherence tomography (MC-JMT) is demonstrated. This algorithm clusters multiple pixels of MC-JMT in a five-dimensional (5-D) feature space which comprises dimensions of lateral space, axial space, logarithmic scattering OCT intensity, squared power of Doppler shift and degree of polarization uniformity. This 5-D clustering provides clusters of pixels, so called as superpixels. The superpixels are utilized as local regions for pixels averaging. The averaging decreases the noise in the measurement as preserving structural details of the sample. A simple decision-tree algorithm is applied to classified superpixels into some tissue types. This classification process successfully segments tissues of a human posterior eye.
    01/2014;
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    ABSTRACT: An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated.
    Optics Express 08/2013; 21(16):19412-36. · 3.55 Impact Factor
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    ABSTRACT: PURPOSE: A newly developed high-penetration Doppler optical coherence angiography (HP-OCA) with a 1-μm probe beam for non-invasive investigation of vascular pathology of exudative macular diseases is introduced. A descriptive case series is presented to discuss the clinical utility of HP-OCA. METHODS: Eleven eyes of 10 subjects with exudative macular disease, including 2 eyes with myopic choroidal neovascularization (mCNV), 4 eyes with age-related macular degeneration (AMD) and 5 eyes with polypoidal choroidal vasculopathy (PCV), were investigated. Two Doppler scanning modes (bi-directional and high-sensitive) of HP-OCA were used for the investigation. HP-OCA provides depth resolved and en face angiograms and a structural OCT noninvasively. The HP-OCA images were compared with fluorescein angiography (FA), indocyanine green angiography (ICGA) and color fundus images. RESULTS: The abnormal vasculature patterns observed with high-sensitive HP-OCA presented high similarity to the mid-phase of ICGA. Several abnormal Doppler signals were observed in the en face high-sensitive HP-OCA and were co-located with FA leakage. This co-location was found in 1 eye with mCNV, 4 eyes with AMD, and 1 eye with PCV. Doppler tomogram of the bi-directional mode showed abnormal Doppler signals in 3 of 5 PCV cases beneath the pigment epithelium detachment. With the high-sensitive mode, Doppler signals were found beneath the elevated retinal pigment epithelium in all untreated cases. CONCLUSIONS: HP-OCA revealed depth-resolved abnormal vasculatures in exudative macular diseases. The en face HP-OCA images showed high similarity with FA and ICGA images. These results suggest HP-OCA can be used for non-invasive and three-dimensional angiography in a clinical routine.
    Investigative ophthalmology & visual science 04/2013; · 3.43 Impact Factor
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    ABSTRACT: A principle and application of Jones matrix tomography (MT) is presented. JMT is first measures three-dimensional distribution of the Jones matrices and derives back-scattering intensity, Doppler shift, and phase retardation from the Jones matrix tomography.
    Lasers and Electro-Optics Pacific Rim (CLEO-PR), 2013 Conference on; 01/2013
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    Masahiro Miura, Takuya Iwasaki, Hiroshi Goto
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    ABSTRACT: To evaluate the effect of aflibercept treatment after developing ranibizumab tachyphylaxis for the treatment of polypoidal choroidal vasculopathy (PCV). Ten eyes from ten patients with PCV who developed ranibizumab tachyphylaxis were reviewed. Tachyphylaxis was defined as when repeated intravitreal ranibizumab (IVR) resulted in a complete lack of response after initial treatment response. All treatments were converted to intravitreal aflibercept (IVA) after development of ranibizumab tachyphylaxis. Central retinal thickness (CRT) was compared at baseline, at complete resolution after IVR, at reactivation after IVR, at initial IVA, and at 4 and 12 weeks after initial IVA. Mean number of IVR treatments before conversion to IVA was 11.3 (range 5-16). All eyes had positive therapeutic responses after conversion to IVA. Mean CRT at 4 and 12 weeks after initial IVA was significantly decreased from baseline initial IVA (P = 0.005). Switching therapy to aflibercept is effective for patients with PCV who develop tachyphylaxis to ranibizumab.
    Clinical ophthalmology (Auckland, N.Z.) 01/2013; 7:1591-5.
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    ABSTRACT: To investigate the relationship between scleral mechanical properties, its birefringence, and the anisotropy of birefringence alteration in respect of the direction of the strain by using PS-OCT. The scleral birefringence of thirty-nine porcine eyes was measured with a prototype PS-OCT. A rectangle strip of sclera with a width of 4 mm was dissected at the temporal region 5 mm apart from the optic nerve head. The strain and force were measured with a uniaxial tension tester as the sample was stretched with a speed of 1.8 mm/min after preconditioning. The birefringence of the sample was measured by PS-OCT at the center of the sample before applying, denoted as inherent birefringence, and after applying stretching of 6.5% strain. The birefringence alteration was obtained by these two measurements and correlations between birefringence and elastic parameters, tangent modulus, and structural stiffness were examined. Twenty and 19 porcine eyes were stretched in meridional or equatorial directions, respectively. A moderate positive correlation was found between the inherent birefringence and the structural stiffness. A moderate positive correlation was also found between the inherent birefringence and the tangent modulus. The birefringence increased by strains. Marginal significance was found in the birefringence alteration between meridional and equatorial strains, where the mean birefringence elevation by meridional strain was higher than that by equatorial strain. The birefringence was found to be altered by applying strain and also be related with inherent birefringence. This implies the birefringence of the sclera of the in vivo eye also could be affected by its mechanical property.
    PLoS ONE 01/2013; 8(3):e58716. · 3.53 Impact Factor
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    ABSTRACT: To evaluate the absolute blood flow rate in a single choroidal vessel using Doppler optical coherence tomography (OCT). Three choroidal vessels were selected in the right eye of three normal subjects, and were measured with Doppler OCT at a 1020-nm probe wavelength. The pulsatile change of the blood flow was obtained from synchronized measurement of Doppler OCT and plethysmography. Absolute blood flow rates in choroidal vessels were calculated from Doppler OCT volume data. The cyclic change of the blood flow was quantitatively obtained. Absolute blood flow velocities and blood flow rates at peak systole [mean (SD)] were 46.9 (12.5) mm/s and 5.9 (3.6) μL/min, respectively. The coefficient of variation of three sets of measurements [mean (SD)] was 9.3 (4.9%). Doppler OCT and plethysmography provided an accurate quantitative assessment of the blood flow in choroidal vessels. This measurement technique could prove valuable to the study of choroidal blood flow in normal and pathologic conditions.
    Investigative ophthalmology & visual science 09/2012; 53(11):7137-41. · 3.43 Impact Factor
  • Ophthalmology 07/2012; 119(7):1497-8. · 5.56 Impact Factor
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    ABSTRACT: An office based Doppler and polarization sensitive swept-source optical coherence tomography (Doppler-PS-SS-OCT) was developed for diagnosis and evaluation of abnormalities of anterior eye segment in clinic. A healthy eye was measured in vivo by the Doppler PS-OCT. The results showed that the Doppler PS-OCT may have potential to identify blood vessels and discriminate fibrous tissues in abnormalities, such as scarring in bleb, and scleral inflammation.
    Proc SPIE 02/2012;
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    ABSTRACT: A high-penetration swept-source optical coherence tomography (HP-SS-OCT) system based on a 1-μm short cavity laser is developed. Doppler OCT processing is applied, along with a custom-made numerical phase stabilization algorithm; this process does not require additional calibration hardware. Thus, our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. The bidirectional blood flow and vasculature in the deep choroid was successfully imaged via two Doppler modes that use different time intervals for Doppler processing. En face projection image of squared power of Doppler shift is compared to ICGA, and the utility of our method is verified.
    Optics Express 01/2012; 20(3):2740-60. · 3.55 Impact Factor
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    ABSTRACT: To investigate a relationship between birefringence and elasticity of porcine sclera ex vivo using polarization-sensitive optical coherence tomography (PS-OCT). Elastic parameters and birefringence of 19 porcine eyes were measured. Four pieces of scleral strips which were parallel to the limbus, with a width of 4 mm, were dissected from the optic nerve head to the temporal side of each porcine eye. Birefringence of the sclera was measured with a prototype PS-OCT. The strain and force were measured with a uniaxial material tester as the sample was stretched with a speed of 1.8 mm/min after preconditioning. A derivative of the exponentially-fitted stress-strain curve at 0% strain was extracted as the tangent modulus. Power of exponential stress-strain function was also extracted from the fitting. To consider a net stiffness of sclera, structural stiffness was calculated as a product of tangent modulus and thickness. Correlations between birefringence and these elastic parameters were examined. Statistically significant correlations between birefringence and all of the elastic parameters were found at 2 central positions. Structural stiffness and power of exponential stress-strain function were correlated with birefringence at the position near the optic nerve head. No correlation was found at the position near the equator. The evidence of correlations between birefringence and elasticity of sclera tested uniaxially was shown for the first time. This work may become a basis for in vivo measurement of scleral biomechanics using PS-OCT.
    PLoS ONE 01/2012; 7(9):e44026. · 3.53 Impact Factor
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    ABSTRACT: A combination of high-penetration spectral-domain optical coherence tomography (central wavelength: 1,020 nm) and an enhanced depth imaging protocol (HP-EDI-OCT) was used to evaluate 5 eyes of 5 patients with polypoidal choroidal vasculopathy (PCV). In all eyes, HP-EDI-OCT provided high-contrast images of PCV lesions in the subretinal pigment epithelium (sub-RPE). In the space between the RPE line and Bruch's membrane, various PCV lesions, including vascular networks, polypoidal lesions, and sub-RPE hemorrhage, were clearly identified. The chorioscleral interface was clearly observed, and the entire structure of the choroid was readily identified. Thus, HP-EDI-OCT was useful for evaluating sub-RPE lesions of PCV.
    Ophthalmic Surgery Lasers and Imaging 01/2012; 43 Online:e5-9. · 1.46 Impact Factor
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    ABSTRACT: We evaluated the 2-year efficacy of combined intravitreal ranibizumab (IVR) treatment and photodynamic therapy (PDT) for treatment-naïve polypoidal choroidal vasculopathy (PCV). Twenty-two eyes of 22 Japanese patients with treatment-naïve PCV were prospectively recruited. All eyes had angiographic features of PCV according to indocyanine green angiography. The initial combination treatment regimen included a session of PDT with IVR. A total of three consecutive IVR treatments were given at 4-week intervals. Eyes were retreated with IVR or PDT at specific times. We evaluated the mean visual acuity and mean central retinal thickness (CRT) at 3, 6, 9, 12, 18, and 24 months after initial treatment. At month 9, visual acuity had improved by 5.7 letters (P = 0.10). Subsequently, mean visual acuity gradually decreased, and the difference from baseline was diminished to 2.9 letters at 24 months (P = 0.43). Mean CRT was significantly decreased from baseline over the 24-month follow-up (P < 0.05). With PDT combined with IVR for PCV, visual acuity improved during year 1, but the benefit decreased in year 2.
    Clinical Ophthalmology 01/2012; 6:1633-8.
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    ABSTRACT: We present a case series of cornea and anterior segment disorders investigated by an office-based polarization-sensitive optical coherence tomography (PS-OCT). Blebs of glaucoma patients treated by trabeculectomy, and corneas of keratoconus and keratoplasty patients were measured by PS-OCT. Birefringence formations in trabeculectomy bleb were measured in 1 control eye and 3 eyes of trabeculectomy model rabbits. Polarization insensitive scattering OCT and the depth-resolved birefringence were measured simultaneously by PS-OCT. Abnormal birefringence was observed in keratoconus cases with advanced thinning and with a rupture of Descemet's membrane. The graft-host interface of the keratoplasty case showed abnormal birefringence. The appearance of abnormal birefringence in the cornea was likely to be an indication of cross-linking of collagen fibrils. The measurement of rabbit showed abnormal birefringence in the scarring eyes. Wide regions of strong birefringence were observed in the eyes of trabeculectomy patients who had high intraocular pressure. Visualization of scarring in bleb by PS-OCT may be useful for the planning of secondary surgery. PS-OCT showed promising for the study and diagnosis diseases related to abnormal fibrous tissues of the cornea and anterior eye segment.
    Biomedical Optics Express 08/2011; 2(8):2392-402. · 3.18 Impact Factor
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    ABSTRACT: We performed retinal and choroidal thickness mapping by three-dimensional high-penetration optical coherence tomography (OCT) and evaluated the choroidal thickness distribution throughout the macula in healthy eyes. Forty-three eyes of 43 healthy Japanese volunteers were evaluated by 1060-nm swept-source OCT. The eyes were scanned with a three-dimensional raster scanning protocol, and the mean retinal and choroidal thicknesses of the posterior sectors were obtained. The sectors were defined by the Early Treatment Diabetic Study (ETDRS) layout. These data were compared by age (23-56 years), spherical equivalent refractive error (between +0.9 D and -10.3 D), and axial length (22.9-27.6 mm). The mean retinal and choroidal thicknesses of the ETDRS area were 284 ± 14 μm and 348 ± 63 μm respectively. The mean regional choroidal thicknesses in the nasal inner macula and nasal outer macula were significantly smaller than those in all other sectors. The mean regional choroidal thickness in most sectors showed a significant negative correlation with axial length and a significant positive correlation with refractive error. In eyes with a long axial length (>25.0 mm), the mean regional choroidal thickness of five sectors showed a significant negative correlation with age. The coefficient of variation of choroidal thickness between sectors showed a significant negative correlation with axial length, and a positive correlation with refractive error. The mean retinal thickness in each sector was not significantly correlated with the mean choroidal thickness, age, axial length, or refractive error. The choroidal thickness map showed a distribution entirely different from the retinal thickness map. Choroidal thickness varies significantly with location, axial length, refractive error, and age. These variations should be considered when evaluating choroidal thickness.
    Albrecht von Graæes Archiv für Ophthalmologie 05/2011; 249(10):1485-92. · 1.93 Impact Factor
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    ABSTRACT: Two optical coherence tomography (OCT) modalities can visualize the choroid: high-penetration OCT (HP-OCT) using a long wavelength, and enhanced depth imaging technique using Heidelberg OCT (EDI-OCT). The purpose of this study was to compare and investigate the agreement among the retinal/choroidal thickness parameters. Twenty-four eyes of 12 healthy volunteers were examined simultaneously using the prototype swept-source HP-OCT and EDI-OCT. Six independent examiners measured the central retinal/choroidal thicknesses on horizontal B-scan images. The reliability was evaluated by intraclass correlation coefficient (ICC). Intervisit reproducibility was assessed by examining 10 of the volunteers 4 months later. Using HP-OCT, the average of all measurements was 209.1 ± 12.9 μm in the retina and 292.7 ± 77.3 μm in the choroid, and using EDI-OCT, 212.5 ± 13.3 μm in the retina and 283.7 ± 84.1 μm in the choroid. An intersystem comparison showed that the ICCs were 0.661 (95% confidence interval [CI], 0.535-0.754) for the retina and 0.921 (95% CI, 0.875-0.948) for the choroid. Using HP-OCT, the interexaminer ICC reproducibility values were 0.630 (95% CI, 0.447-0.791) for the retinal thickness and 0.912 (95% CI, 0.835-0.958) for the choroidal thickness; using EDI-OCT, the values for the retinal and choroidal thicknesses were 0.788 (95% CI, 0.607-0.898) and 0.970 (95% CI, 0.948-0.985), respectively. The intervisit ICC values for the retinal and choroidal thicknesses were 0.504 (95% CI, 0.376-0.609) and 0.893 (95% CI, 0.864-0.916). The retinal and choroidal thicknesses were well-correlated between the instruments. Higher reliability and reproducibility are expected for the choroidal thickness measurements despite with higher morphologic interindividual variations.
    Investigative ophthalmology & visual science 04/2011; 52(8):5536-40. · 3.43 Impact Factor
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    ABSTRACT: Fast method for identifying the internal limiting membrane (ILM) and retinal pigment epithelium (RPE) from optical coherence tomography images is demonstrated. To avoid unnecessary increment of calculation time, a strong downsampling of the original data set is performed to reduce a number of processed pixels. In ILM segmentation, the obtained data cube is filtered with two different kinds of parameters and two estimates for the position of ILM is determined. A simple smoothness value is determined for both estimates and better estimate is used for future processing. A smaller portion of pixels around estimated ILM are extracted from the down sampled data and filtered again and new estimation for ILM position is determined. That procedure is repeated with smaller portion of pixels around ILM and with different filtering parameters. The principle of RPE segmentation is very much similar with ILM identification. Only the used filtering and processing parameters are changed. Algorithm was tested with eight data sets with good reliability. Over 97% of each scans had smaller segmentation error than 5 pixels. Total required data processing time (ILM and RPE segmentation) for data volume with (600x1500x128) pixels was less than 9 seconds.
    Proc SPIE 02/2011;
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    ABSTRACT: Purpose. To demonstrate the clinical application of a noninvasive, three-dimensional, vascular imaging technique called Doppler optical coherence angiography (OCA). To evaluate the vascular architecture of polypoidal choroidal vasculopathy (PCV) using Doppler OCA. Methods. The authors prospectively examined the eyes of four healthy subjects and 15 PCV patients. Three-dimensional vascular flow imaging was performed using high-speed, high-resolution, and high-penetration spectral-domain Doppler optical coherence tomography. Two-dimensional images of the retina, choroid, and vascular lesions were obtained simultaneously. Results. Distribution of blood flow detected by Doppler OCA imaging corresponded well with that by indocyanine angiographic imaging. PCV lesions were localized in the space between the retinal pigment epithelium and the Bruch's membrane. Conclusions. The authors found using Doppler OCA that PCV lesions are similar in architecture to choroidal neovascularization in age-related macular degeneration. Doppler OCA facilitates rapid and noninvasive examination of exudative macular diseases.
    Investigative ophthalmology & visual science 01/2011; 52(5):2689-95. · 3.43 Impact Factor

Publication Stats

621 Citations
109.59 Total Impact Points

Institutions

  • 2007–2014
    • University of Tsukuba
      • Department of Ophthalmology
      Tsukuba, Ibaraki, Japan
    • Indiana University Bloomington
      • School of Optometry
      Bloomington, IN, United States
  • 2003–2014
    • Tokyo Medical University
      • Department of Ophthalmology
      Edo, Tōkyō, Japan
  • 2009
    • University of Oulu
      • Optoelectronics and Measurement Techniques Laboratory
      Oulu, Oulu, Finland
  • 2008
    • Korea Advanced Institute of Science and Technology
      Sŏul, Seoul, South Korea
  • 2002–2004
    • Massachusetts Eye and Ear Infirmary
      • Schepens Eye Research Institute
      Boston, MA, United States