Time filter

Source Type

Ikuno Y.,Osaka University | Kawaguchi K.,Osaka University | Nouchi T.,University of Tsukuba | Nouchi T.,Computational Optics and Ophthalmology Group | And 2 more authors.
Investigative Ophthalmology and Visual Science | Year: 2010

PURPOSE. To study posterior choroidal thickness and its profile based on location in healthy Japanese subjects and the correlation with axial length, refractive error (RE), and age. METHODS. Eighty-six eyes of 43 healthy volunteers with no ophthalmic or systemic symptoms were examined with prototype high-penetration optical coherence tomography using a 1060-nm light source. Eyes with high myopia (exceeding-6 D) or with retinal/choroidal disease were excluded. The spherical equivalent RE was measured by autorefractometry, and the axial length was measured by partial coherence inferometry. RESULTS. Mean choroidal thicknesses were 354 ± 111 μm at the fovea, 364 ± 86 μm superiorly, 345 ± 108 μm inferiorly, 227 ± 532 μm nasally, and 337 ± 102 μm temporally. Subfoveal choroidal thickness was significantly greater than nasal (P < 0.01) and temporal (P < 0.05) choroidal thickness; however, there was no significant difference compared with superior (P = 0.20) and inferior (P = 0.17) choroidal thickness. The temporal choroid was significantly (P < 0.01) thicker than the nasal choroid, and the inferior choroid was significantly (P < 0.01) thinner than the superior choroid. There was a significant negative correlation between foveal choroidal thickness and axial length (P < 0.05) but a borderline correlation with the RE (P = 0.086) and age (P = 0.07). Age was the factor that was most associated with the choroidal thickness (F = 20.86; P < 0.001), followed by RE (F = 5.37; P < 0.05); axial length was not a significant factor (F = 1.47; P = 0.22) by stepwise analysis. CONCLUSIONS. The profile of choroidal thickness depends on its location. RE, axial length, and especially age are critical for evaluation of choroidal thickness. © Association for Research in Vision and Ophthalmology. Source

Nakai K.,Osaka University | Gomi F.,Osaka University | Ikuno Y.,Osaka University | Yasuno Y.,University of Tsukuba | And 5 more authors.
Graefe's Archive for Clinical and Experimental Ophthalmology | Year: 2012

Background: The aim of this work was to investigate the choroidal morphologic changes of Vogt-Koyanagi-Harada (VKH) disease in vivo using high-penetration optical coherence tomography (HP-OCT) with a long-wavelength light source (1,060 nm). Methods: Fourteen patients with VKH disease were included in this study: 12 eyes of six patients with treatment-naive acute VKH in the first 6-12 months after diagnosis and 16 eyes of eight patients in the convalescent phase with a sunset glow fundus appearance. A prototype HP-OCT instrument was used to observe the deep choroid and sclera. The choroidal thickness was measured for more than 6 months in eyes with acute disease. The choroidal thickness in patients with a sunset glow fundus appearance for 2- 9 years after the onset was also examined. Results: In 12 eyes with acute VKH disease, the baseline choroidal thickness was significantly (p<0.0001) greater than in controls. After treatment, the choroidal thickness decreased over time. However, the choroidal thickness increased markedly again in four eyes with recurrent disease. The mean thickness at 12 months was significantly less than the normal value (p<0.0001). In 16 eyes with a sunset glow fundus appearance, the choroidal thickness was significantly (p<0.0001) thinner compared to the controls. Conclusions: Significant choroidal thickness changes underlie VKH disease, which progress over time. Objective measurement of the choroidal thickness using HP-OCT may be useful for longitudinal evaluation of VKH activity. © Springer-Verlag 2012. Source

Chan A.C.,University of Tsukuba | Chan A.C.,Computational Optics and Ophthalmology Group | Kurokawa K.,University of Tsukuba | Kurokawa K.,Computational Optics and Ophthalmology Group | And 6 more authors.
Optics Letters | Year: 2016

A quantitative signal amplitude estimator for optical coherence tomography (OCT) is presented. It is based on a statistical model of OCT signal and noise, using a Bayesian maximum a posteriori (MAP) estimation framework. Multiple OCT images are used for estimation, similar to the widely utilized intensity averaging method. The estimator is less biased especially at low-intensity regions, where intensity averaging approaches the noise power and hence is biased. The estimator is applied to posterior ocular OCT images and provides high-contrast visualization of pathologies. In addition, histogram analysis objectively shows the superior performance of the estimator compared with intensity averaging. © 2016 Optical Society of America. Source

Ju M.J.,University of Tsukuba | Ju M.J.,University of British Columbia | Ju M.J.,Computational Optics and Ophthalmology Group | Hong Y.-J.,University of Tsukuba | And 13 more authors.
Optics Express | Year: 2013

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. © 2013 Optical Society of America. Source

Hong Y.-J.,University of Tsukuba | Hong Y.-J.,Computational Optics and Ophthalmology Group | Makita S.,University of Tsukuba | Makita S.,Computational Optics and Ophthalmology Group | And 11 more authors.
Optics Express | Year: 2012

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. © 2012 Optical Society of America. Source

Discover hidden collaborations