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.

Noninvasive angiography is demonstrated for the in vivo human eye. Three-dimensional flow imaging has been performed with high-speed spectral-domain optical coherence tomography. Sample motion is compensated by two algorithms. Axial motion between adjacent A-lines within one OCT image is compensated by the Doppler shift due to bulk sample motion. Axial displacements between neighboring images are compensated by a correlation-based algorithm. Three-dimensional vasculature of ocular vessels has been visualized. By integrating volume sets of flow images, two-dimensional images of blood vessels are obtained. Retinal and choroidal blood vessel images are simultaneously obtained by separating the volume set into retinal part and choroidal parts. These are corresponding to fluorescein angiogram and indocyanine angiogram.

Optical coherence tomography (OCT) is now a well-established modality for high-resolution cross-sectional and three-dimensional imaging of transparent and translucent samples and tissues. Conventional, intensity based OCT, however, does not provide a tissue-specific contrast, causing an ambiguity with image interpretation in several cases. Polarization sensitive (PS) OCT draws advantage from the fact that several materials and tissues can change the light’s polarization state, adding an additional contrast channel and providing quantitative information. In this paper, we review basic and advanced methods of PS-OCT and demonstrate its use in selected biomedical applications.

A two- and three-dimensional swept source optical coherence tomography (SS-OCT) system, which uses a ready-to-ship scanning light source, is demonstrated. The light source has a center wavelength of 1.31 μm, -3 dB wavelength range of 110 nm, scanning rate of 20 KHz, and high linearity in frequency scanning. This paper presents a simple calibration method using a fringe analysis technique for spectral rescaling. This SS-OCT system is capable of realtime display of two-dimensional OCT and can obtain three-dimensional OCT with a measurement time of 2 s. In vivo human anterior eye segments are investigated two- and three-dimensionally. The system sensitivity is experimentally determined to be 112 dB. The three-dimensional OCT volumes reveal the structures of the anterior eye segments, which are difficult to observe in two-dimensional OCT images. A two dimensional tomographic movie shows a dynamic motion of a human iris.

Retinal, choroidal and scleral imaging by using swept-source optical coherence tomography (SS-OCT) with a 1-μm band probe light, and high-contrast and three-dimensional (3D) imaging of the choroidal vasculature are presented. This SS-OCT has a measurement speed of 28,000 A-lines/s, a depth resolution of 10.4 μm in tissue, and a sensitivity of 99.3 dB. Owing to the high penetration of the 1-μm probe light and the high sensitivity of the system, the in vivo sclera of a healthy volunteer can be observed. A software-based algorithm of scattering optical coherence angiography (S-OCA) is developed for the high-contrast and 3D imaging of the choroidal vessels. The S-OCA is used to visualize the 3D choroidal vasculature of the in vivo human macula and the optic nerve head. Comparisons of S-OCA with several other angiography techniques including Doppler OCA, Doppler OCT, fluorescein angiography, and indocyanine green angiography are also presented.

Purpose.: 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. Methods.: 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. Results.: 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). Conclusions.: 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.