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Motohiro Kamei

Publications and source records attributed to Motohiro Kamei.

26 records · Page 2Linked to original sources
PubMed2003

Optical coherence tomographic findings of macular holes and retinal detachment after vitrectomy in highly myopic eyes.

PURPOSE: Macular holes cause retinal detachments in highly myopic eyes. Because degenerative macular changes often coexist, biomicroscopic evaluation of macular hole status after retinal reattachment is sometimes difficult. We studied macular holes with retinal detachment after vitrectomy using optical coherence tomography and evaluated the anatomic status of the hole and factors associated with anatomic success. DESIGN: Retrospective, nonrandomized, comparative study. PATIENTS: Sixteen eyes that underwent vitrectomy for retinal detachment associated with a macular hole were included. Internal limiting membrane peeling with indocyanine green was performed in 14 eyes; the epiretinal membrane was peeled with a diamond-dusted membrane scraper alone in two eyes. All retinas reattached postoperatively. The follow-up period at the optical coherence tomography examination was at least 6 months. METHODS: Optical coherence tomography was performed vertically and horizontally, and the presence of a persistent macular hole was determined. Other information was obtained from patient records. RESULTS: The macular holes closed in seven of 16 eyes (44%). Age, sex, axial length, preoperative best-corrected visual acuity, duration of symptoms, preoperative refractive error, and the preoperative area of the retinal detachment were not significantly correlated with hole closure. Improved postoperative best-corrected visual acuity (P <.05) was significantly associated with macular hole closure, and more frequent visual improvement (P =.06) was of borderline significance. CONCLUSIONS: The success rate was lower than those obtained in eyes without myopia or in myopic macular holes without retinal detachments. Macular hole closure may predict improved visual outcome for patients with retinal detachment and macular holes. Optical coherence tomography detects persistent macular holes in highly myopic eyes with retinal detachment.

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PubMed2002

Drusen proteome analysis: an approach to the etiology of age-related macular degeneration.

Drusen are extracellular deposits that accumulate below the retinal pigment epithelium on Bruch's membrane and are risk factors for developing age-related macular degeneration (AMD). The progression of AMD might be slowed or halted if the formation of drusen could be modulated. To work toward a molecular understanding of drusen formation, we have developed a method for isolating microgram quantities of drusen and Bruch's membrane for proteome analysis. Liquid chromatography tandem MS analyses of drusen preparations from 18 normal donors and five AMD donors identified 129 proteins. Immunocytochemical studies have thus far localized approximately 16% of these proteins in drusen. Tissue metalloproteinase inhibitor 3, clusterin, vitronectin, and serum albumin were the most common proteins observed in normal donor drusen whereas crystallin was detected more frequently in AMD donor drusen. Up to 65% of the proteins identified were found in drusen from both AMD and normal donors. However, oxidative protein modifications were also observed, including apparent crosslinked species of tissue metalloproteinase inhibitor 3 and vitronectin, and carboxyethyl pyrrole protein adducts. Carboxyethyl pyrrole adducts are uniquely generated from the oxidation of docosahexaenoate-containing lipids. By Western analysis they were found to be more abundant in AMD than in normal Bruch's membrane and were found associated with drusen proteins. Carboxymethyl lysine, another oxidative modification, was also detected in drusen. These data strongly support the hypothesis that oxidative injury contributes to the pathogenesis of AMD and suggest that oxidative protein modifications may have a critical role in drusen formation.

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PubMed2002

Changes in fluorescein angiogram early after surgical removal of choroidal neovascularization in age-related macular degeneration.

BACKGROUND: Retinal pigment epithelial (RPE) defects inevitably occur in surgical removal of choroidal neovascularization (CNV) in age-related macular degeneration (AMD). RPE can proliferate and cover the denuded area, but the healing process has not been investigated in humans. To understand the RPE wound-healing process, we estimated the changes in fluorescein angiograms early after CNV removal. METHODS: Ten consecutive patients with exudative AMD underwent CNV removal without gas tamponade. Fluorescein angiography was performed within 4 days of surgery and again 1 or 2 weeks postoperatively. Areas of leakage were measured using a computer-assisted image analyser. The decreasing rate of leakage was calculated as the change in disc areas of leakage per day (DA/day). RESULTS: The rates of decreasing leakage ranged from 0 to 0.42 DA/day (mean, 0.24 +/- 0.15 DA/day; median, 0.26 DA/day). The rate of decreasing leakage correlated with changes in visual acuity (r = 0.642, P = 0.0456). CONCLUSION: The retinal pigment epithelial wound after surgical removal of choroidal neovascularization may heal at the rate of 0.24 disc areas/day based on the blood retinal barrier function in patients with age-related macular degeneration. A faster rate of decreasing leakage may be associated with better visual prognosis.

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PubMed2002

Reading ability after macular translocation surgery with 360-degree retinotomy.

PURPOSE: To report reading ability using a standardized reading chart after macular translocation with 360-degree retinotomy in eyes with age-related macular degeneration (AMD) or with myopic choroidal neovascularization (mCNV). DESIGN: Interventional case series. METHODS: In 34 eyes of 34 patients with subfoveal choroidal neovascular membrane (AMD, 23; mCNV, 11), macular translocation surgery with 360-degree retinotomy and simultaneous extraocular muscle surgery were performed. The average age was 67.4 +/- 7.9 years, and the average follow-up period was 7.6 +/- 3.3 months. The best-corrected far visual acuity (FVA) was measured with a standardized visual acuity chart using Landolt Cs, and the critical print size (CPS) was determined with the Japanese version of the Minnesota reading chart (MNREAD-J Chart) preoperatively and postoperatively. Preoperative and postoperative change in the CPS was compared with the subjective visual improvement as assessed by a questionnaire. RESULTS: The postoperative improvement of FVA was statistically significant in eyes with mCNV (P =.010) but not significant in eyes with AMD (P =.495). The postoperative improvement of CPS was statistically significant both in eyes with AMD (P =.027) and in eyes with mCNV (P =.004). The subjective visual improvement was significantly correlated with the change of CPS in patients after a second better eye surgery. CONCLUSIONS: After macular translocation with 360-degree retinotomy, the improvement of reading ability was significant in eyes with both AMD and mCNV. We conclude that this surgical method is well suited to improve reading ability of patients with AMD or mCNV.

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PubMedDate not supplied

Transretinal electrical stimulation with a suprachoroidal multichannel electrode in rabbit eyes.

PURPOSE: Several approaches for placing an electrode device for visual prosthesis have been previously proposed. In this study, we investigated if transretinal stimulation from the suprachoroidal space can elicit an electrical evoked potential (EEP) in albino rabbits. METHODS: A flat electrode array (polyimide plate, platinum electrode) was developed and used for this study. After performing a scleral incision at 2-2.5 mm from the limbus and placing an anchoring suture, the array was inserted into the suprachoroidal space in the posterior portion of the eye by direct observation under a microscope. A platinum wire was implanted into the vitreous space as a reference electrode. For electrical stimulation, a biphasic pulse was used. When the electrode was stimulated, the EEP was recorded. RESULTS: When the electrical stimulation from the suprachoroidal space was applied, the EEP could be recorded with an epidural electrode, and the threshold was 66.0 +/- 32.1 micro A (420 micro C/cm(2)) [corrected]. placement of the array and the electrical stimulation. CONCLUSIONS: Transretinal electrical stimulation from the suprachoroidal space could elicit EEP, suggesting that this approach may be useful for a retinal prosthesis system.

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PubMedDate not supplied

Electrical stimulation with a needle-type electrode inserted into the optic nerve in rabbit eyes.

PURPOSE: To investigate whether electrical stimulation of the optic nerve can elicit an electrical evoked potential (EEP) in rabbits and to determine whether such stimulation is a useful approach for the placement of a visual prosthesis. METHODS: Two needle-type electrodes were inserted into the optic nerve using a transvitreal approach. For electrical stimulation, monophasic and biphasic pulses were used. By stimulating the optic nerve, the EEP was elicited. After evaluation of the EEP, a histological study was carried out. RESULTS: When electrical stimulation was applied, the EEP could be recorded. The threshold with monophasic and biphasic stimulation was 10 +/- 0 microA and 20 +/- 8.2 microA, respectively. Histological examination revealed no major complications, such as bleeding or degeneration, which might have resulted from the insertion of electrodes or the electrical stimulation. CONCLUSIONS: Electrical stimulation of the optic nerve can elicit an EEP, suggesting that this approach may be useful for a visual prosthesis system.

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PubMedDate not supplied

Radial optic neurotomy for the management of hemicentral retinal vein occlusion: long-term follow-up study.

PURPOSE: To assess the efficacy of radial optic neurotomy (RON) for hemicentral retinal vein occlusion (hemi-CRVO) in patients with follow-up of >12 months. METHODS: Five consecutive patients with hemi-CRVO were enrolled in the study and underwent vitrectomy with RON. The effects of this treatment were assessed by visual acuity, optical coherence tomography, indocyanine green angiography, and kinetic visual field testing. RESULTS: The median and mean visual acuities improved from 20/250 to 20/50 and from 20/286 to 20/51, respectively. Four patients (80%) had visual acuity improvement of > or =3 lines; visual acuity in 1 patient (20%) remained the same. Visual acuity in all four eyes with preoperative visual acuity of <20/200 improved to >20/200 12 months after surgery. Foveal thickness was gradually reduced during the follow-up period. Chorioretinal anastomosis was detected by indocyanine green angiography in 3 eyes (60%). A temporal visual field defect was found in two eyes. No neovascularization on the iris, angle, optic disk, or retina was detected postoperatively. CONCLUSION: Visual acuity may improve more with RON compared with the natural history of the disease, and no neovascular formation may occur after RON, suggesting that this procedure may be an effective treatment for hemi-CRVO.

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