New publication: AMD and High-Penetration OCT

Our new paper is now available as publish ahead of print of IOVS. This paper demonstrates the application of new OCT with 1 micrometer probe wavelength (high-penetration OCT; HP-OCT, also referred to as long probe OCT; LP-OCT) to age-related macular degeneration. 14 eyes were involved in this study, and the clinical utility of HP-OCT was discussed. Preliminary results which suggest higher robustness of HP-OCT to cataract than standard OCT were also shown. The paper is available on the journal web site (IOVS).
>>> [Abstract and PDF at IOVS web-site]

Title: Visualization of Sub-Retinal Pigment Epithelium and Sub-Choroidal Neovascularization Morphologies of Exudative Macular Diseases by Optical Coherence Tomography with Long Wavelength Probe
Authors: Y. Yasuno, M. Miura, K. Kawana, S.Makita, M. Sato, F. Okamoto, M. Yamanari, T. Iwasaki, T. Yatagai, T. Oshika
Journal: Investigative Ophthalmology & Vision Science
Volume/Page: publish ahead of print

Joschi, Yoshiaki Yasuno

講義資料： 医療機器開発と産学連携

Lecture Material: Collaboration of University and Industry for the Development of Medical Equipment
(See below for an English version)

応用理工学概論「医療機器開発と産学連携」の講義資料を公開します。いそいで作った出来の悪いマテリアルですが… 興味のある方はどうぞ。
- PDFをダウンロード

Joschi, 安野嘉晃

Here we release a Lecture Material of ``Collaboration of University and Industry for the Development of Medical Equipment.'' This material is for the lecture of``Introduction to Applied Science and Engineering,'' which is a general introduction for the 1st year students of our University (University of Tsukuba).
The material is still very primitive and written in English... But you can download it from the following URL.
- Download PDF

Joschi, Yoshiaki Yasuno

BiOS/ARVO2008 レポート (Only in Japanese)

国際会議 SPIE BiOS/Photonics West 2008, および米眼科学会 ARVO 2008 の簡易レポートを公開します。第5回電気学会バイオメディカル・フォトニクス先端技術調査専門委員会（2008年6月16日）による報告のために作成されたレポートです。興味のある方は「安野による主観的なもの」であることをご承知の上でご参考ください。

PDFをダウンロード

Joschi, 安野嘉晃

Imaging Plarimetry in Age-Related Macular Degeneration

Our new paper was published in Investigative Ophthalmology and Visual Science (IOVS).
[Download from Journal Web Site]

The details are following

Title: Imaging Polarimetry in Age-Related Macular Degeneration

Authors: Masahiro Miura, Masahiro Yamanari, Takuya Iwasaki, Ann E. Elsner, Shuichi Makita, Toyohiko Yatagai, and Yoshiaki Yasuno

Citation: Invest. Ophthalmo. Vis. Sci. 49, 2661-2667 (2008).

PURPOSE
To evaluate the birefringence properties of eyes with age-related macular degeneration (AMD). To compare the information from two techniques—scanning laser polarimetry (GDx) and polarization-sensitive spectral-domain optical coherence tomography (OCT)—and investigate how they complement each other.

METHODS
The authors prospectively examined the eyes of two healthy subjects and 13 patients with exudative AMD. Using scanning laser polarimetry, they computed phase-retardation maps, average reflectance images, and depolarized light images. To obtain polarimetry information with improved axial resolution, they developed a fiber-based, polarization-sensitive, spectral-domain OCT system and measured the phase retardation associated with birefringence in the same eyes.

RESULTS
Both GDx and polarization-sensitive spectral-domain optical coherence tomography detected abnormal birefringence at the locus of exudative lesions. Polarization-sensitive, spectral-domain OCT showed that in the old lesions with fibrosis, phase-retardation values were significantly larger than in the new lesions (P = 0.020). Increased scattered light and altered polarization scramble were associated with portions of the lesions.

CONCLUSIONS
GDx and polarization-sensitive spectral-domain OCT are complementary in probing birefringence properties in exudative AMD. Polarimetry findings in exudative AMD emphasized different features and were related to the progression of the disease, potentially providing a noninvasive tool for microstructure in exudative AMD.

Image of the week in Optics InfoBase

The volume rendering image of the optic nerve head in our new publication entitled "Full-range, high-speed, high-resolution 1μm spectral-domain optical coherence tomography using BM-scan for volumetric imaging of the human posterior eye" was selected to "Image of the week" in Optics InfoBase.

New publication: Full-range, high-speed 1um SD-OCT

Full-range, high-speed, high-resolution 1μm spectral-domain optical coherence tomography using BM-scan for volumetric imaging of the human posterior eye

This our paper is now available on Optics Express.

>>[Abstract and PDF]

Citation
S. Makita, T. Fabritius, and Y. Yasuno, "Full-range, high-speed, high-resolution 1μm spectral-domain optical coherence tomography using BM-scan for volumetric imaging of the human posterior eye," Opt. Express 16, 8406-8420 (2008).


Abstract
An alternative optical coherence tomography (OCT) to clinical ophthalmic 830 nm spectral-domain OCTs (SD-OCT) is demonstrated. An axial resolution of 7.4 μm, ranging depth of 4.2 mm in tissue, sensitivity of 98.5 dB, and detection speed of 38,300 axial scans/s have been achieved. These are comparable or superior to those of recently commercially available ophthalmic 830 nm SD-OCTs in clinics. In addition, fast volumetric imaging for the in vivo human posterior eye with high-contrast of the choroid is achieved. A broadband 1.04 μm light source enables the high-contrast and high resolution imaging of the retina and choroid. The ranging depth is extended by applying a full-range imaging method with an electro-optic modulator (BM-scan method). A prototype high-speed InGaAs line scan camera with 1024 pixels is used. A newly reported sensitivity improvement property of the BM-scan method demonstrates a sensitivity enhancement of 5.1 dB. We also introduce a newly developed resampling calibration method of spectrum that is independent of the intrinsic dispersion mismatch of the interferometer. The three-dimensional structure of the in vivo human optic nerve head with a very deep cupping is successfully visualized.

New publication: PS-SS-OCT

Now the paper about PS-SS-OCT with continuous source polarization modulation is available on Optics Express.


M. Yamanari, S. Makita, and Y. Yasuno, "Polarization-sensitive swept-source optical coherence tomography with continuous source polarization modulation," Opt. Express 16, 5892-5906 (2008)
http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-8-5892

Abstract
We present fiber-based polarization-sensitive swept-source optical coherence tomography (SS-OCT) based on continuous source polarization modulation. The light source is a frequency swept laser centered at 1.31 μm with a scanning rate of 20 kHz. The incident polarization is modulated by a resonant electro-optic modulator at 33.3 MHz, which is one-third of the data acquisition frequency. The zeroth- and first-order harmonic components of the OCT signals with respect to the polarization modulation frequency have the polarimetric information of the sample. By algebraic and matrix calculations of the signals, this system can measure the depth-resolved Jones matrices of the sample with a single wavelength scan. The phase fluctuations of the starting trigger of wavelength scan and the polarization modulation are cancelled by monitoring the OCT phase of a calibration mirror inserted into the sample arm. We demonstrate the potential of the system by the measurement of chicken breast muscle and the volumetric measurement of an in vivo human anterior eye segment. The phase retardation image shows an additional contrast in the fibrous tissue such as the collagen fiber in the trabecular meshwork and sclera.

New publicationo: Quantitative Doppler OCT

Quantitative retinal-blood flow measurement with three-dimensional vessel geometry determination using ultrahigh-resolution Doppler optical coherence angiography

Our new paper was just published on Optics Letters.
This paper is open access and freely available on the follwoing link.

>> [Abstract and PDF]


Citation
S. Makita, T. Fabritius, and Y. Yasuno, "Quantitative retinal-blood flow measurement with three-dimensional vessel geometry determination using ultrahigh-resolution Doppler optical coherence angiography," Opt. Lett. 33, 836-838 (2008)

Abstract
Retinal blood flow quantification by retinal vessel segmentation with Doppler optical coherence angiography is presented. Vessel diameter, orientation, and position are determined in an en face vessel image and two representative cross-sectional flow images of the vessel. Absolute blood flow velocity is calculated with the help of the measured Doppler frequency shift and determined vessel angle. The volumetric flow rate is obtained with the position and the region of the vessel lumen. The volumetric blood flow rate of retinal arteries before and after a bifurcation is verified in a healthy human eye.