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Biomedical subjects

Hitoshi Nishihara

Publications and source records attributed to Hitoshi Nishihara.

7 recordsLinked to original sources
PubMed2007

Effect of ophthalmic solution components on acrylic intraocular lenses.

PURPOSE: To investigate the effect of ophthalmic solution components on the surface of acrylic intraocular lenses (IOLs). SETTING: Department of Opthalmology, Showa University School of Medicine. METHODS: Measurement of the contact angles of ophthalmic solutions on 3 acrylic IOLs was performed. The solutions were diclofenac sodium (Diclod), bromfenac sodium (Bronuck), betamethasone phosphate (Rinderon), dibekacin sulfate (Panimycin), polysorbate 80 (Tween 20), benzalkonium chloride, chlorobutanol, methylparahydroxybenzoate, and propylparahydroxybenzoate. The IOLs were incubated at 35 degrees C for 2 weeks in undiluted ophthalmic solutions and in 1:10 dilutions of ophthalmic solution components. The IOLs were sectioned and observed by scanning electron microscopy. RESULTS: The contact angle of Diclod and Bronuck solutions was the smallest. The contact angle of Rinderon and Panimycin was similar to that of distilled water. Scanning electron microscopy examination of IOLs incubated in ophthalmic solution components showed intralenticular changes. The IOLs immersed in ophthalmic solutions did not show any change, even after extended incubation. CONCLUSION: The chemical components of ophthalmic solutions, such as surfactants and solvents, permeate acrylic IOLs, suggesting the potential for long-term adverse effects of eyedrops in pseudophakic eyes.

Acrylic Resins↗
PubMed2006

Capsular stabilization device to preserve lens capsule integrity during phacoemulsification with a weak zonule.

We describe a new capsular stabilization device for suspending a lens with weak zonular support. It is flexible, 10.0 mm in length, and fashioned from 5-0 nylon. The contact portion is bent at 1.25 mm with an end bifurcating to form a T-shape to minimize stress on the capsular equator. After a continuous curvilinear capsulorhexis is created, the capsular stabilization devices to hook the capsulotomy margin are inserted. The T-shaped end is passed around the anterior capsular flap to fit the curvature of the equator. Phacoemulsification and aspiration using this device was performed in 12 eyes of 9 patients, and the usefulness and complications were analyzed. The capsular stabilization devices suspended the capsule and facilitated safe phacoemulsification in all eyes. Posterior capsule rupture occurred in 2 eyes. None of the cases had notable postoperative complications. This device ensures a stable capsule-iris complex and reduces surgical risks.

Adult↗
PubMed2005

[Automatic pulse system for conducting ultrasonic cataract operation].

PURPOSE: For use in phacoemulsification and aspiration (PEA) with a high frequency pulse sytem, we invented an Automated Pulse System(APS) in which the ultrasonic energy level and the percentage of ultrasonic pulses per second are regulated by a foot-pedal and suotion mechanism. METHOD: We compared the APS and the conventional continuous ultrasonic system experimentally by inserting a cataract model in an extracted aphakic pig eye. RESULT: Ultrasonic use time was not significantly different between the two methods. Gross ultrasonic energy and operation time were significantly decreased in the APS method (p < 0.05). CONCLUSION: Automatically, APS increases ultrasonic frequency and the percentage of ultrasonic pulses in nuclear emulsification. APS is an effective way to reduce the utilization of ultrasonic energy in the pulse mode without complicated foot-pedal control.

Animals↗
PubMed2004

[Comparison of surface light scattering of acrylic intraocular lenses made by lathe-cutting and cast-molding methods--long-term observation and experimental study].

PURPOSE: To compare the long-term clinical and experimental results of soft acrylic intraocular lenses(IOLs) manufactured by the lathe-cut(LC) method and by the cast-molding(CM) method. METHODS: This was a retrospective study of 20 patients(22 eyes) who were examined in a 5- and 7-year follow-up study. Sixteen eyes were implanted with polyacrylic IOLs manufactured by the LC method and 6 eyes were implanted with polyacrylic IOLs manufactured by the CM method. Postoperative measurements included best corrected visual acuity, contrast sensitivity, biomicroscopic examination, and Scheimpflug slit-lamp images to evaluate surface light scattering. Scanning electron microscopy and three-dimensional surface analysis were conducted. RESULTS: At 7 years, the mean visual acuity was 1.08 +/- 0.24 (mean +/- standard deviation) in the LC group and 1.22 +/- 0.27 in the CM group. Surface light-seatter was 12.0 +/- 4.0 computer compatible tapes(CCT) in the LC group and 37.4 +/- 5.4 CCT in the CM group. Mean surface roughness was 0.70 +/- 0.07 nm in the LC group and 6.16 +/- 0.97 nm in the CM group. CONCLUSION: Acrylic IOLs manufactured by the LC method are more stable in long-termuse.

Acrylic Resins↗
PubMed2003

Surface scattering in implanted hydrophobic intraocular lenses.

PURPOSE: To describe surface scattering, a new phenomenon in polyacrylic intraocular lenses (IOLs), and discuss the possible cause of this finding. SETTING: Showa University, Fujigaoka Hospital, Yokohama, Kanagawa, Japan. METHODS: This observational case series involved 40 patients who received the AcrySof(R) IOL (Alcon Laboratories, Inc.) as part of a clinical trial in 1991. Four patients (5 eyes) were evaluated. Thirty-three patients had the same surgery in 1999, and the findings in these patients were compared with those in the earlier patients. Lens surface scattering was evaluated by area densitometry using Scheimpflug photography. No statistical analysis was done because of the small sample size. RESULTS: The 5 IOLs implanted in 1991 showed various degrees of surface scattering. The degree of scattering was greater than that in the 1999 group. There was no degradation in visual performance and no manifestation of intraocular inflammation or other adverse effect from the IOLs in either group. Attempts to remove foreign material on the IOL using the neodymium:YAG (Nd:YAG) laser were unsuccessful. CONCLUSIONS: The surface scattering did not appear to be due to deposition of foreign material on the IOL surface. Densitometry and the results of Nd:YAG laser treatment suggest that the changes occurred in the near-surface layer. Phase separation of water near the IOL surface in the inherently hydrophobic material may explain the phenomenon. Newer AcrySof IOLs appear to have less surface scattering.

Acrylates↗
PubMed2002

[Light scattering observed on the surface of acrylic intraocular lenses ten years after implantation].

PURPOSE: To report the long-term status of acrylic intra-ocular lenses. CASES: We describe two cases of increased light scattering on the surface of acrylic intraocular lenses ten years after implantation. The scattering was non-symptomatic and visual acuity was normal. Biomicroscopy and a Scheimpflug photography system showed that the scattering apparently derived from the anterior surface of the lens, but no deposit or membranous structure was observed on the lens surface. CONCLUSION: Surface scattering from acrylic intra-ocular lenses is a new finding in long-term observations. A possible etiology may be structural changes of the internal polymer.

Acrylic Resins↗