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Biomedical subjects

O Nishi

Publications and source records attributed to O Nishi.

At least 19 recordsLinked to original sources
PubMed1992

Refilling the lens with a inflatable endocapsular balloon: surgical procedure in animal eyes.

In this report we describe the surgical details involved in refilling the lenses of 13 rabbit and 3 primate eyes using an inflatable endocapsular balloon to restore accommodation. The procedure involves endocapsular phacoemulsification through a small "buttonhole" or "dumbbell" anterior capsulotomy or minicircular capsulotomy and the simultaneous preservation of capsular integrity, including the zonules and ciliary muscles. An inflatable balloon made of thin silicone membrane is then inserted into the empty capsular bag. A liquid silicone polymer is injected into the balloon through a delivery tube, and the empty capsular bag is refilled by the inflated balloon. The procedure was found to be reproducible, and an accommodation of 6 D was confirmed in one primate eye. Capsular opacification occurred, but the proliferation and migration of residual lens epithelial cells could be hindered by abundant refilling. This lens-refilling technique may provide restoration of accommodation in future cataract surgery.

Accommodation, Ocular↗
PubMed1992

Synthesis of interleukin-1 and prostaglandin E2 by lens epithelial cells of human cataracts.

To test our hypothesis that pseudophakic inflammation, including the fibrin reaction, may be caused by cytokines, prostaglandins (PG), or both, synthesised by residual lens epithelial cells (LECs), we measured interleukin-1 alpha (IL-1 alpha) and PGE2 in the incubation medium of cultures of human LECs obtained by capsulotomy during cataract surgery. After 1 week radioimmunoassay showed that there were 1.46 (0.62) ng of PGE2/10(6) cells (mean (SD) six cultures), and after 4 weeks, there were 5.50 (2.20) ng of PGE2/10(6) cells (seven cultures). During culture the cells proliferated and underwent fibroblast-like cell changes on exposure to the plastic of the wells. In the medium of control plates to which sodium diclofenac had been added PGE2 was not detected. Some IL-1 alpha was found in four of 10 samples, each of which contained media from 12 cultures; 207 pg/10(6) cells in one of the two pools of 2-week cultures, 120 pg/10(6) cells in one pool and 139 pg/10(6) cells in another of the three pools of 3-week cultures, and 111 pg/10(6) cells in the one pool of 4-week cultures. PGE2 and IL-1 alpha may therefore be produced in vivo by residual LECs after cataract surgery, and may be involved in postoperative inflammation, including the fibrin reaction.

Cataract↗
PubMed1992

Disruption of the blood-aqueous barrier by residual lens epithelial cells after intraocular lens implantation.

We performed a clinical study to confirm whether and how residual lens epithelial cells (LECs) participate in postoperative pseudophakic inflammation, including fibrin reaction. Twenty-six eyes of 13 patients with bilateral cataracts were treated by phacoemulsification and posterior chamber intraocular lens (PC-IOL) implantation. In the eye from which LECs had not been removed, the aqueous flare was measured with a laser flare-cell meter. Flare decreased from an initial peak, increasing again to form a flare spike when LECs came into contact with the PC-IOL and began to undergo fibrous proliferation at 6 to 14 days after surgery. The spike was evidence that the blood-aqueous barrier had been disrupted again. Fibrin reaction developed in two eyes. In the other eye of each pair, from which LECs had been removed by ultrasound aspiration, neither a flare spike nor fibrous proliferation was noted. We conclude that residual LECs break down the blood-aqueous barrier as they proliferate and are involved in postoperative pseudophakic inflammation.

Adult↗
PubMed1992

[The synthesis of cytokines by human lens epithelial cells--interleukin 1 (IL-1), tumor necrosis factor (TNF) interleukin 6 (IL-6), and epidermal growth factor (EGF)].

We proposed the hypothesis that pseudophakic inflammation, including the fibrin reaction, may be caused by cytokines and/or prostaglandins, synthesized by residual lens epithelial cells (LEC). To test our hypothesis, we measured IL-1 alpha, TNF-alpha, IL-6 and EGF in the culture media of human LEC, obtained by capsulotomy during cataract surgery, by ELISA. IL-1 alpha was detected in one of the two pools of 2-week cultures (20.7 pg/10(5) cells), in two of the three pools of 3-week cultures (12.0 pg/10(5) cells and 13.9 pg/10(5) cells), and in one pool of 4-week cultures (11.1 pg/10(5) cells). IL-6 was detected in 1-week culture (195 pg/10(5) cells) and in 7-week culture (81.6 pg/10(5) cells). TNF-alpha and EGF were not detected. During culture, the cells proliferated and underwent fibroblast-like changes on exposure to the plastic wells. IL-1 and IL-6 may be also produced in vivo by residual LEC contacting with posterior chamber lens after cataract surgery, and these mediators may play a role in postoperative inflammation including fibrin reaction.

Cells, Cultured↗
PubMed1991

Intercapsular cataract surgery with lens epithelial cell removal. Part III: Long-term follow-up of posterior capsular opacification.

In 144 eyes in 144 patients with senile cataract the rate of posterior capsular opacification requiring YAG capsulotomy up to 36 months following intercapsular cataract surgery with lens epithelial cell removal using ultrasound and aspiration was evaluated and compared to the rate for 471 senile cataractous eyes in patients who had had posterior chamber lens implantation following phacoemulsification and extracapsular cataract extraction without lens epithelial cell removal. Posterior capsular opacification occurred in 3.7% of patients who had lens epithelial cell removal, significantly less (P less than .01) than the 10.8% found in the control group. Lens epithelial cell removal is considered an effective method of preventing capsular opacification.

Adult↗
PubMed1991

Intercapsular cataract surgery with lens epithelial cell removal. Part IV: Capsular fibrosis induced by poly(methyl methacrylate).

Characteristic lens epithelial cell behavior in the pseudophakic eye was examined by comparing 30 eyes that had extracapsular cataract surgery by the intercapsular technique and posterior chamber intraocular lens (IOL) implantation with lens epithelial cell removal but without anterior capsule capsulectomy and nine aphakic eyes that had the same procedure but without posterior chamber lens implantation over a mean follow-up period of 30 and 23 months, respectively. Fibrous anterior capsule opacification was observed in 83% of the pseudophakic eyes in the area of contact with the IOL, while the region beyond the margin of the IOL remained transparent. Fibrous anterior capsular opacification was not noted in the aphakic eyes. This suggests that the IOL material, poly(methyl methacrylate), stimulates lens epithelial cells to undergo fibrous metaplasia and to produce collagen fibers. Various cytokines such as IL-1 and TGF-beta synthesized by lens epithelial cells may play a crucial role as mediators in the process. We recommend that this effect be considered as a parameter of biocompatibility in developing and evaluating new biomaterials.

Adult↗
PubMed1991

Bilateral oculomotor nerve palsies due to posterior cerebral arterial compression relieved by microvascular decompression--case report.

A 59-year-old male developed peripheral oculomotor nerve paresis due to compression by the left posterior cerebral artery (PCA), which was successfully treated by microvascular decompression. Two months later, a similar oculomotor nerve paralysis due to the same mechanism occurred contralaterally and was also treated by microvascular decompression. The previous condition was probably caused by arteriosclerotic changes in the PCA, and the following condition by postsurgical adhesion of the arachnoid membrane. The possibility of vascular compression should be considered when oculomotor nerve palsy rapidly develops, although not proven by angiography.

Cerebral Angiography↗
PubMed1991

[Tissue culture of human lens epithelial cells. Part II: Suppressive effect of diclofenac sodium on their proliferation and metaplasia].

We studied the suppressive effect of a non-steroidal anti-inflammatory drug (NSAID) on the proliferation and fibrous metaplasia of human lens epithelial cells (LEC) in cell culture. We cultured human LEC attached to a round piece of the central anterior capsule obtained by anterior capsulotomy during cataract surgery and added diclofenac sodium, the concentration of which varied from 0.5 microgram/ml to 30 micrograms/ml gradually. Proliferation as well as fibrous metaplasia of LEC were suppressed. Histopathological examination revealed cell degeneration and death. Besides the apparent inhibition of diclofenac sodium on the biosynthesis of prostaglandins, this suppressive effect on LEC proliferation also may play a role in anti-inflammation after intraocular lens implantation. Further, secondary cataract may be prevented by this effect.

Cell Division↗
PubMed1991

Removal of lens epithelial cells by dispersion with enzymatic treatment followed by aspiration.

We conducted a preliminary trial of a method of lens epithelial cell removal in cataract surgery that combined mechanical and pharmaceutical treatments. The cells were first loosened from their junctional complexes with Dispase, a preparation of a neutral protease used for separating cells in tissue culture. To avoid intraocular tissue damage, the enzyme preparation was dissolved in sodium hyaluronate and injected into the capsular bag, which was carefully preserved during endocapsular cataract surgery. The cells were then removed by irrigation and aspiration. The results of experiments in vitro and in rabbits and, judging from the histopathologic examination, with negligible damage to the zonules or corneal endothelium.

Animals↗
PubMed1990

Micropunch for 'buttonhole' anterior capsulotomy in endointercapsular cataract surgery.

We describe a micropunch for removing a round piece of anterior capsule (with a diameter of 500 microns) and a technique to prevent enlargement of the linear anterior capsulotomy by tearing in endointeracpsular cataract surgery. The anterior capsule at both capsulotomy ends is excised by the micropunch, and the resulting continuous, round, smooth-edged margin prevents tearing due to reduced concentration of stress.

Cataract Extraction↗
PubMed1990

Anterior capsule-supported intraocular lens. A new lens for small-incision surgery and for sealing the capsular opening.

A new intraocular lens made of PMMA and fixed in the anterior capsular opening is introduced. The lens diameter is 4 mm and the lens has no haptics in the conventional sense but is finely grooved around the circumference edge. The lens is inserted into the anterior capsule via a very small-diameter opening created by mini-circular capsulorhexis. The anterior capsular opening, with a round, smooth-edged margin, avoids stress concentration and, therefore, the capsule does not easily tear. This opening catches the lens and chokes it along the grooved edge. In animal experiments, firm fixation was obtained. This lens may be adequate for small-incision surgery, and in the future it may be used to prevent leakage of filling material during refilling of the lens, since it acts as a part of the anterior capsule and seals the capsular opening completely.

Animals↗
PubMed1990

Nucleus removal following circular capsulorhexis: surface cortex aspiration.

A technique for nucleus removal following circular capsulorhexis is described. After a continuous circular capsulotomy, soft surface cortex surrounding the nucleus is aspirated by an irrigation/aspiration device to separate the nucleus from cortical material and reduce its diameter. With phacoemulsification, the separated nucleus is rotated within the capsular bag and emulsified. With planned extracapsular cataract extraction, the upper nucleus equator is brought out of the capsular bag using an irrigating capsule retractor. The nucleus is then delivered by simple expression or by a Nishi delivery cannula.

Cataract Extraction↗
PubMed1990

Extracapsular cataract extraction with keyhole capsulorhexis and lens epithelial cell removal.

Circular capsulorhexis with its round continuous anterior capsule opening allows secure fixation of a posterior chamber intraocular lens. The smooth capsular margin edge reduces stress concentration and the risk of radial tears but it makes nucleus delivery in planned extracapsular cataract extraction very difficult. This report describes a technique of small circular capsulorhexis with one relaxing incision that gives a keyhole-shaped capsular opening. A new irrigating capsule retractor for nucleus hydrodissection is also described. This technique is safe and highly reproducible and it allows secure posterior chamber lens fixation.

Cataract Extraction↗
PubMed1990

New posterior chamber lens with open circular haptic for a small capsular opening: preliminary report.

This report describes a single-piece poly-(methyl methacrylate) posterior chamber lens for implantation through a small capsular opening. It has open circular loops with an eyelet at each loop end. The optic is 6 mm in diameter and the overall diameter of the intraocular lens (IOL) is 11 mm. The lens diameter can be reduced to 7 mm by grasping the eyelets at both open loop ends with a specially designed holding forceps. The IOL is inserted in the capsular bag after circular capsulorhexis or through a linear capsulotomy in the intercapsular technique. This IOL is adaptable to a small capsular opening and maintains the usual shape of the capsular bag, similar to a disc lens.

Aged↗