Biomedical subjects

Kazuno Negishi

Publications and source records attributed to Kazuno Negishi.

5 recordsLinked to original sources

PubMed2004

Time course of lens capsule staining using trypan blue and indocyanine green: in vitro study in porcine eyes.

PURPOSE: To determine whether staining of the lens capsule with trypan blue 0.1% and indocyanine green (ICG) 0.5% diminishes with time and whether it differs between the anterior and posterior capsules. SETTING: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. METHODS: Crystalline lenses removed from porcine eyes were stained for 10 seconds with 0.1 mL of trypan blue 0.1% or indocyanine green 0.5%. They were then placed in distilled water and observed for the persistence of staining over time. In a second experiment, the anterior chamber and internal aspects of the anterior capsule and internal and vitreous aspects of the posterior capsule were gently irrigated with 0.1 mL of trypan blue 0.1% or ICG 0.5%. After 10 seconds, the capsules were irrigated with distilled water and the staining intensities were compared. RESULTS: Staining was not diminished 30 seconds, 5 minutes, or 1 hour after application of either dye. No difference was evident in staining intensity or diminution with time between the anterior and posterior capsules, but the external aspects were stained more than the internal aspects with both dyes. Trypan blue produced more intense staining than ICG. CONCLUSIONS: Since the intensity of capsule staining in the intact lens did not change during a 1-hour immersion in water, capsule dyes may not dissipate fully during cataract surgery. As possible long-term adverse effects have not been ruled out, capsule dyes should be used in a low concentration for a short exposure time.

Animals↗

PubMed2002

Elschnig pearl formation along the neodymium:YAG laser posterior capsulotomy margin. Long-term follow-up.

PURPOSE: To examine the long-term occurrence and course of Elschnig pearl (string of pearls) formation along neodymium:YAG (Nd:YAG) laser posterior capsulotomy margins. SETTING: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. METHODS: The clinical records of eyes having an Nd:YAG posterior capsulotomy to treat posterior capsule opacification after cataract surgery were retrospectively reviewed. Kaplan-Meier and Cox proportional hazards analysis were performed. RESULTS: Among 201 eyes, string of pearls developed in 139 (69.2%). The mean follow-up after the Nd:YAG posterior capsulotomy was 32.1 months +/- 25.3 (SD). At 2 years, the cumulative probability of developing string of pearls was 77.0% (95% confidence interval [CI], 70.6%-83.4%), after which it reached a plateau. Among the 139 eyes, 100 had sufficient data to be reviewed to assess the long-term outcome (mean follow-up from Nd:YAG posterior capsulotomy, 43.7 +/- 26.0 months). A second Nd:YAG posterior capsulotomy was performed in 18 eyes (18.0%) to treat progression of string of pearls, typically within 2 years after the initial Nd:YAG capsulotomy. The string of pearls disappeared spontaneously in 31 eyes (31.0%). The probability of disappearance was 80.4% (95% CI, 63.4%-97.4%) 8 years after the Nd:YAG posterior capsulotomy. Cox proportional hazards analysis identified no factor significantly favoring the disappearance of the string of pearls. CONCLUSIONS: String of pearls was a common complication after Nd:YAG laser posterior capsulotomy. About 20% of cases were progressive and required a second capsulotomy; however, most regressed over several years.

Cataract↗

PubMedDate not supplied

Visual simulation of retinal images through a decentered monofocal and a refractive multifocal intraocular lens.

PURPOSE: To evaluate the effect of decentration of a monofocal intraocular lens (IOL) and a refractive multifocal IOL on retinal image quality using a new visual simulation system. METHODS: Using a new visual simulation system, we performed visual simulation of a monofocal and a multifocal IOL at 5, 4, 3, 2, 1, and 0.4 m with several decentered IOL positions from 0 to 1.0 mm through a 3- or 4-mm aperture using Landolt visual acuity (VA) charts. The VA was estimated under each condition from the simulated retinal image. RESULTS: With a monofocal IOL, the image was affected minimally by decentration at 4 and 5 m; at 2 and 3 m, the image contrast decreased slightly with increased decentration. With the multifocal IOL, some loss of image contrast developed at all distances compared with the monofocal IOL; however, the images of the Landolt's rings were still recognizable under all conditions. CONCLUSIONS: Our results suggest that up to 1.0 mm of decentration of a monofocal and multifocal IOL would not greatly affect the retinal image quality.

Foreign-Body Migration↗

PubMedDate not supplied

Evaluation of optical function using a new point spread function analysis system in cataractous and pseudophakic eyes: preliminary results.

PURPOSE: To evaluate optical function in cataractous and pseudophakic eyes using the new point spread function (PSF) analysis system in a clinical setting. METHODS: We applied this new analysis system in the study of two cataractous eyes and one pseudophakic eye of two patients. Using a PSF analyzer, double-pass PSF was measured directly for each subject, and the single-pass modulation transfer function (MTF) and single-pass PSF were calculated. The simulated retinal images of various sizes of Landolt's rings and their contrast characteristics were also calculated by the PSF analyzer. RESULTS: The MTF and the contrast of the simulated retinal images degraded in cataractous eyes were compared with data for normal eyes; the degradation pattern depended on the opacification pattern. The MTF and the contrast of the simulated retinal images in the pseudophakic eye improved significantly compared with the cataractous eyes, although both values were lower in the pseudophakic eye than in young normal eyes. CONCLUSIONS: Our data showed degradation of optical function in cataractous and pseudophakic eyes in comparison with optical function in young normal eyes. If further accumulations of PSF data are made, it may be possible to establish an objective standard by which to measure the progression of cataract, as well as an objective indication for treatment in the future.

Aged↗

PubMedDate not supplied

Calculation of ocular single-pass modulation transfer function and retinal image simulation from measurements of the polarized double-pass ocular point spread function.

The single-pass modulation transfer function (MTF(sgl)) is an important numerical parameter that can help elucidate the performance and some processes of the human visual system. In previous studies, the MTF(sgl) was calculated from double-pass point spread function (PSF) measurements. These measurements include a depolarized reflection component from the retina that introduces a measurement artifact, and they require long acquisition times to allow averaging to reduce speckle. To solve these problems, we developed a new ocular PSF analysis system (PSFAS) that uses polarization optics to eliminate the depolarized retinal reflection component, and a rotating prism to increase measurement speed. Validation experiments on one patient showed that the MTF(sgl) measured by PSFAS agrees closely with the MTF calculated from contrast sensitivity measurements. A simulated retinal image was calculated by convolution of Landolt rings with the calculated single-pass PSF provided by the PSFAS. The contrast characteristic then was calculated from the simulated retinal images. These results indicate that the MTF(sgl) obtained using the PSFAS may be a reliable measure of visual performance of the optics of the eye, including the optical effects of the retina. The simulated retinal images and contrast characteristics are useful for evaluating visual performance.

Adult↗