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BACKGROUND: To experimentally compare the optical performance of two different Extended-Depth-of-Focus (EDOF) intraocular lenses (IOLs) using a standardized optical bench set-up. METHODS: In this experimental study, following IOLs were assessed: the TECNIS® Symfony ZXR00 (Johnson&Johnson, Santa Ana, USA) and the AT LARA 829MP (Carl Zeiss Meditec, Jena, Germany) IOLs. The through-focus modulation transfer function (MTF) values were measured at a spatial frequency of 50 lp/mm and at aperture sizes of 2, 3, and 4.5 mm. Each IOL was measured while centered using ISO 11979-2 Model 1 (aberration-free) and Model 2 (+ 0.28 µm spherical aberration) corneas. United States Air Force (USAF) target images were also recorded for a qualitative evaluation. RESULTS: At 2 mm pupil with ISO1 cornea, the primary and secondary foci of both IOLs appeared to merge, providing an elongated depth of focus. At 3 and 4.5 mm pupil sizes, the through-focus MTF curves of both IOLs showed a bifocal-like V-pattern. While the Symfony IOL showed an overall superior MTF values when measured with the ISO2 cornea, the opposite propensity could be observed with the AT LARA IOL. This optical behavior could be qualitatively confirmed by the USAF target images. CONCLUSIONS: Although the two EDOF IOLs share similarities in their optical properties, the main difference lies in their optical design and performance with respect to spherical aberration. Such characteristics should be taken into account during IOL and patient selection.

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PURPOSE: Development of a means for quantitative estimation of lenticular and zonular dynamics by using real-time imaging of human autopsy eyes during implantation of different intraocular lens (IOL) models. METHODS: Isolated lenticular structures from human autopsy eyes were prepared in vitro. The following IOLs were implanted: a one-piece C-loop haptic IOL, a three-piece C-loop haptic IOL, and a one-piece plate-type IOL. The amount of deformation of lenticular structures during implantation was calculated and the movements visualized with two cameras. The results were transformed to two-dimensional graphs using a newly developed image-processing algorithm. RESULTS: For both one-piece plate-type and one-piece C-loop haptic IOLs, the amount of capsular bag deformation from its initial shape was greater in the direction of posterior center of the capsule, as detected by side camera, than in the direction of the equator (or periphery), as detected by front camera. The mean peak deformation values were 51% and 36% (as measured by side and front cameras, respectively) for one-piece plate-type IOL and 25% and 20% for one-piece C-loop haptic IOL. For three-piece C-loop haptic IOL, the capsular bag distention was almost equal in both posterior and peripheral directions, with mean peak deformation values reaching 39% and 38%. CONCLUSIONS: The new experimental means of lenticular imaging and quantified dynamics from two different angles allowed three-dimensional understanding of specific behavior of each IOL. Our model not only exposes the capsular bag for recording during implantation, but also objectively compares the individual movement values and reveals different zonular and capsular stress patterns, depending on IOL model. TRANSLATIONAL RELEVANCE: The novel "Choi-Apple View" allows a three-dimensional quantitative analysis of capsular dynamics and IOL implantation behavior.

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PURPOSE: To determine the diagnostic value of the ganglion cell-inner plexiform layer (GCIPL) thickness in glaucomatous eyes with superior or inferior visual hemifield defects. PATIENTS AND METHODS: Eighty-five patients with glaucoma (42 isolated superior hemifield defects and 43 isolated inferior hemifield defects) and 46 normal subjects were enrolled. All patients underwent Cirrus high-definition optical coherence tomography and standard automated perimetry. The area under the receiver operating characteristic curve (AUC) was calculated to determine the diagnostic ability of the GCIPL and peripapillary retinal nerve fiber layer (pRNFL). RESULTS: In the superior hemifield defect glaucoma group, the best parameters for discriminating normal eyes from glaucomatous eyes were the inferotemporal GCIPL thickness (0.942), inferior quadrant RNFL thickness (0.974), and 7 o'clock sector RNFL thickness (0.999). For diagnosing inferior hemifield defect glaucoma, the AUCs of all GCIPL parameters (0.331 to 0.702) were significantly lower than that of the superior quadrant RNFL thickness (0.866, P<0.05). CONCLUSIONS: The diagnostic ability of GCIPL parameters was similar to that of the pRNFL parameters in superior hemifield defect glaucoma. However, the diagnostic performance of the GCIPL parameters was significantly inferior to those of the pRNFL parameters in eyes with inferior hemifield defect glaucoma.

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Optofluidics is one of the most remarkable areas in the field of microfluidic research. Particle manipulation with optofluidic platforms has become central to optical chromatography, biotechnology, and µ-total analysis systems. Optical manipulation of particles depends on their sizes and refractive indices (n), which occasionally leads to undesirable separation consequences when their optical mobilities are identical. Here, we demonstrate rapid and dynamic particle manipulation according to n, regardless of size. Integrated liquid-core/solid-cladding (LS) and liquid-core/liquid-cladding (L(2)) waveguides were fabricated and their characteristics were experimentally and theoretically determined. The high and low n particles showed the opposite behaviors by controlling the contrast of their n values to those of the working fluids. The LS waveguide was found to successfully manipulate particles according to n, and the L(2) waveguide was found to provide additional system stability and flexibility, compared to the LS system.

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We demonstrate a simple and efficient device for the continuous label-free separation of microparticles using travelling surface acoustic waves (TSAW). A focusing interdigitated unidirectional transducer released high frequency (133.3 MHz) TSAW normal to the fluid flow direction to segregate 3 µm particles from 10 µm particles with a separation efficiency of 100%. The TSAW based separator does not necessitate a tight alignment of the PDMS microchannel with the transducer.

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The optical force on a non-spherical particle subjected to a loosely focused laser beam was calculated using the dynamic ray tracing method. Ellipsoidal particles with different aspect ratios, inclination angles, and positions were modeled, and the effects of these parameters on the optical force were examined. The vertical component of the optical force parallel to the laser beam axis decreased as the aspect ratio decreased, whereas the ellipsoid with a small aspect ratio and a large inclination angle experienced a large vertical optical force. The ellipsoids were pulled toward or repelled away from the laser beam axis, depending on the inclination angle, and they experienced a torque near the focal point. The behavior of the ellipsoids in a viscous fluid was examined by analyzing a dynamic simulation based on the penalty immersed boundary method. As the ellipsoids levitated along the direction of the laser beam propagation, they moved horizontally with rotation. Except for the ellipsoid with a small aspect ratio and a zero inclination angle near the focal point, the ellipsoids rotated until the major axis aligned with the laser beam axis.

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This paper describes a method for particle manipulation in a liquid-core/liquid-cladding optical waveguide system. Step-index and graded-index waveguides were modeled with consideration for, respectively, miscible and immiscible core and cladding fluids. The characteristic motions of four different particles with refractive indices of 1.59, 1.48, 1.37, and 1.22 were examined. The guided beam was assumed to be Gaussian in shape. Our results showed that high-refractive-index particles converged at the center of the core fluid due to a positive gradient force, whereas low-refractive-index particles converged at the flow periphery. The nonlinearity of the particle motion increased as the flow velocity and the guided beam waist decreased and the laser power and the particle size increased. The initial beam waist of the guided beam in the graded-index waveguide did not significantly affect the characteristics of the particle motion due to the effects of diffusion.

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The behavior of double emulsions in a cross-type optical particle separation system was studied for different combinations of refractive indices and different inner and outer layer radii. The radii and refractive indices of the double emulsions were easily adjusted by taking advantage of the coflowing geometry of a cross-type optical particle separation device. An analytical expression of the optical forces on a pair of concentric spheres was derived using the photon stream method in the ray optics regime. The predicted trajectories of the double emulsions by the optical force agreed well with the experimental data. This work has potential uses in cell separation by morphometry, drug delivery vehicle, and emulsion-based biomedical applications.

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A method for improving the size-based particle separation technique known as pinched flow fractionation (PFF) has been demonstrated experimentally and analyzed by performing numerical calculations. Since the particles in the pinched region are pushed by an optical scattering force, the original particle position with respect to the wall is modulated. This position modulation in the pinched region is amplified in the broadened region along the streamline. This enhancement of separation is achieved by imposing an optical force on the original PFF design. Three different polystyrene latexes (PSLs) with diameters of 2, 5, and 10 µm were separated with PFF and optically enhanced PFF (OEPFF) devices. The separations achieved with the two devices were compared and enhancements in the separation distance by factors of up to approximately 15 were achieved. Theoretical calculations were also performed to interpret these results.

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Validation and interpretation of reconstructed images using a multi-frequency electrical impedance tomography (mfEIT) requires a conductivity phantom including imaging objects with known complex conductivity (sigma + iomegaepsilon) spectra. We describe imaging experiments using the recently developed mfEIT system called the KHU Mark1 with the frequency range of 10 Hz to 500 kHz. Using a bio-impedance spectroscopy (BIS) system, we first measured complex conductivity spectra of different imaging objects including saline, agar, polyacrylamide, TX151, animal hide gelatin, banana and cucumber. Based on an analysis of how conductivity and permittivity affect measured complex boundary voltages, we suggested a new complex version of a multi-frequency time-difference image reconstruction algorithm. Imaging experiments were conducted to produce time-difference images of the objects at multiple frequencies using the proposed algorithm. Images of a conductor (stainless steel) and an insulator (acrylic plastic) were used to set a common scale bar to display all images. Comparing reconstructed time-difference images at multiple frequencies with measured complex conductivity spectra, we found that they showed an overall similarity in terms of changes in complex conductivity values with respect to frequency. However, primarily due to the limitation of the difference imaging algorithm, we suggest that multi-frequency time-difference images must be interpreted in terms of relative contrast changes with respect to frequency. We propose further imaging studies using biological tissues of known complex conductivity spectra and using human subjects to find clinical applications of the mfEIT system.

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Multi-channel multi-frequency electrical impedance tomography (EIT) systems require a careful calibration to minimize systematic errors. We describe novel calibration methods for the recently developed KHU Mark1 EIT system. Current source calibration includes maximization of output resistance and minimization of output capacitance using multiple generalized impedance converters. Phase and gain calibrations are used for voltmeters. Phase calibration nulls out the total system phase shift in measured voltage data. Gain calibrations are performed in two steps of intra- and inter-channel calibrations. Intra-channel calibration for each voltmeter compensates frequency dependence of its voltage gain and also discrepancy between design and actual gains. Inter-channel calibration compensates channel-dependent voltage gains of all voltmeters. Using the calibration methods described in this paper, we obtained 1 MOmega minimal output impedance of the current source in the frequency range 10 Hz-500 kHz. The reciprocity error was as small as 0.05% after intra- and inter-channel voltmeter calibrations. To demonstrate effects of calibration in reconstructed images, we used a homogenous phantom from which uniform images should be produced. Reconstructed time- and frequency-difference images using uncalibrated data showed spurious anomalies. By using calibrated data, standard deviations of time- and frequency-difference images of the homogenous phantom were reduced by about 40% and 90%, respectively.

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