Biomedical subjects

Misako Tatebayashi

Publications and source records attributed to Misako Tatebayashi.

3 recordsLinked to original sources

PubMed2006

[Calcification on the posterior surface of an implanted silicone intraocular lens in a patient with asteroid hyalosis].

BACKGROUND: Calcification on the surface of the hydrogel intraocular lens (IOL) has been reported, but the mechanism of the surface calcification is not fully understood. We report a case of surface calcification on an implanted silicone IOL. The purpose of our study was to examine the clinical and ultrastructural findings associated with the late surface calcification of a silicone IOL. CASE: A 70-year-old Japanese man had undergone cataract surgery in his left eye, with uneventful phacoemulsification and silicone IOL (Allergan SI-55 NB) implantation with the manufacturer's cartridge and injector. He was referred again 29 months later with blurred vision, glare sensitivity, and decreased vision in his left eye. He was diagnosed as having aftercataract. Although YAG laser capsulotomy was performed, the opacity on the posterior surface gradually increased. The opacity was located mainly within the capsulotomy window on the posterior surface of the lens, although the patient maintained good visual acuity. LV : 0.2 (1.0 x S-2.0 D). The lens was removed 46 months after the initial surgery. Scanning electron microscopy (SEM) showed membranous deposits on the posterior optical surface of the silicone lens. There were high levels of phosphoric acid (P) and calcium (C) confirming calcification of the silicone IOL. Asteroid hyalosis was observed in the fellow eye of the patient. CONCLUSION: This is the first report of surface calcification of a silicone IOL in Japan. Although the mechanism of the calcification has not been determined, careful clinical follow-up of patients implanted with silicone lenses is necessary to determine if this phenomenon is rare and sporadic or if it may be more widespread. Since 5 similar cases of calcification in silicone lenses with accompanying asteroid hyalosis have been reported in other countries, we can conclude that silicone lens implantation in eyes with asteroid hyalosis should be avoided.

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PubMed2003

Lensectomy and vitrectomy decrease the rate of photoreceptor loss in rhodopsin P347L transgenic pigs.

BACKGROUND: Photoreceptor degeneration in retinitis pigmentosa (RP) runs an inevitable, gradually progressive course. A wide variety of growth factors of different origins have been shown to slow the rate of degeneration in some rodent models of RP. Recently, lens-derived neurotrophic factors have been shown to rescue degenerating ganglion cells in crush models of the optic nerve. Our objective was to evaluate the potential rescue effect of lensectomy and vitrectomy (L&V) on photoreceptor degeneration in a large-animal model, the rhodopsin P347L transgenic pig. METHODS: We operated on one eye of each of 49 3-week-old pigs--15 vitrectomies and 34 L&V, 6 of which received steroids. Retinal paraffin sections were prepared for all eyes, in addition to immunohistochemistry in four eyes, 8 weeks after L&V. RESULTS: At eight weeks after L&V, operated eyes showed significantly more nuclei in the outer nuclear layer (ONL) than the unoperated fellow eyes. The better preservation of the ONL persisted but was less prominent by 20 weeks after surgery. Steroid treatment did not markedly reduce the better preservation of the ONL seen at 8, 10, and 12 weeks after surgery. The significant difference in cell count between operated and unoperated eyes in the L&V group at 8 weeks was due to the difference in the number of rods, not the cones. CONCLUSION: Lensectomy and vitrectomy delay photoreceptor degeneration in rhodopsin P347L transgenic pigs. Lens-related rescue effect is a probable reason for the delayed degeneration.

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PubMed2002

RGD peptide-assisted vitrectomy to facilitate induction of a posterior vitreous detachment: a new principle in pharmacological vitreolysis.

PURPOSE: To evaluate a new concept in pharmacological vitreolysis by studying the efficacy of intravitreal RGD peptide-assisted vitrectomy in facilitating the separation of the posterior cortical vitreous from the retinal surface in an animal model. METHODS: Eight rabbits (16 eyes) received an intravitreal injection of 1 or 5 mg of RGD peptide in one eye and either RGE peptide (inactive control) or phosphate buffered saline in the fellow eye. After 24 hours, a pars plana vitrectomy with low aspiration (< or =30 mmHg) was performed in an attempt to create a detachment of the posterior cortical vitreous. A masked observer performed pre- and postoperative indirect ophthalmoscopy and B-scan ultrasonography. Postoperative scanning electron microscopy evaluated the vitreoretinal surface in selected eyes. Two additional rabbits received intravitreal injections of RGD peptide in one eye (1 mg and 5 mg) and 1 mg of RGE peptide in the fellow eye to examine apoptosis of the retinal cells by TUNEL assay. RESULTS: Based on postoperative ultrasound findings, six of the eight rabbits had a greater degree of posterior vitreous detachment in the RGD eye compared to the fellow eye (p = 0.03). The total number and the average number of detached quadrants in the group of RGD peptide eyes was twenty-three and 2.85 respectively compared to seven and 0.85 for the control fellow eyes (p = 0.02). Scanning electron microscopy confirmed the presence of postoperative posterior vitreous detachment. There was no evidence of retinal cell apoptosis in RGD injected eyes. CONCLUSION: RGD peptide-assisted vitrectomy facilitated posterior vitreous detachment in rabbit eyes, suggesting that RGD-containing peptides may prove to be effective adjuncts in producing posterior vitreous separation during vitreous surgery.

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