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Biomedical subjects

Shunji Kusaka

Publications and source records attributed to Shunji Kusaka.

At least 19 recordsLinked to original sources
PubMed2007

Residual indocyanine green fluorescence pattern after vitrectomy for idiopathic macular hole with internal limiting membrane peeling.

BACKGROUND: Internal limiting membrane (ILM) peeling with indocyanine green (ICG) staining is a commonly used procedure to treat idiopathic macular holes (MH). AIM: To report changes in the patterns of residual ICG fluorescence over time after vitrectomy using the Heidelberg Retina Angiograph 2 (HRA2, Heidelberg Engineering, Heidelberg, Germany). METHODS: 10 patients (10 eyes) who had undergone vitrectomy for MH with ILM peeling were included. 9 (90%) patients underwent ILM peeling with ICG, and 1 (10%) patient had it with triamcinolone acetonide (TA). We observed residual ICG using HRA2, postoperatively. Autofluorescence, optical coherence tomography images and best-corrected visual acuity (BCVA) measurements were also obtained. The minimal follow-up was 3 months. RESULTS: The MHs were closed postoperatively in all patients (100%). In eyes that underwent ILM peeling with ICG, the BCVA improved significantly (p<0.001) in 8 (89%) eyes and was unchanged in 1 (11%) eye. HRA2 showed the ICG fluorescence patterns but not TA postoperatively. The ICG hyperfluorescent signal was typically diffuse at the posterior retina and was hypofluorescent around the fovea. The hyperfluorescence then migrated towards the optic nerve disc presumably along the nerve fibre, and the area of ILM peeling was clearly identified. A large number of hyperfluorescent dots were observed instead of diffuse hyperfluorescence that was observed just after surgery. CONCLUSIONS: Patterns of residual ICG fluorescence were sequentially observed with HRA2 after vitrectomy for MH with ICG-assisted ILM peeling.

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PubMed2006

Evaluation of residual retinal function by pupillary constrictions and phosphenes using transcorneal electrical stimulation in patients with retinal degeneration.

BACKGROUND: To evaluate inner-retinal function by pupillary constrictions and phosphenes evoked by transcorneal electrical stimulation (TES) in patients with hereditary retinal degeneration. METHODS: Consecutive 20 eyes of 20 patients (16 with retinitis pigmentosa (RP); and four with cone-rod dystrophy (CRD)) whose visual acuity was equal to or worse than 20/2000 at Osaka University Hospital and eight eyes of eight healthy subjects were enrolled. TES was performed on with a contact lens stimulating electrode. The electrically evoked pupillary response (EEPR) was recorded by a pupillometer, and the phosphenes by the subjective responses. Three electrical current thresholds were determined: T1, threshold current for initial phosphene; T2, threshold for eliciting a phosphene extending into the central field; and P, threshold for a relative pupillary constriction > or = 3%. The EEPR and phosphene thresholds were compared with the visual acuity or the visual field. RESULTS: All T1, T2 and P were significantly higher in patients than in normals (Mann-Whitney, P<0.001). Both T1 and T2 were not correlated with visual acuity but depended on the area and location of the residual visual field. T1 and T2 in RP eyes with a EEPR was significantly lower than that in RP eyes without an EEPR. During TES, all subjects and patients had no pain, and no complications except for a slight corneal superficial punctuate keratopathy. CONCLUSIONS: The safety and the efficacy of TES to estimate the residual inner-retinal function in patients with retinal degeneration indicate that TES can be used as one of the most important test to select candidates for retinal prostheses.

Adult↗
PubMed2005

Nonvitrectomizing vitreous surgery for epiretinal membrane long-term follow-up.

PURPOSE: To report the long-term follow-up results of nonvitrectomizing vitreous surgery for idiopathic epiretinal membrane (ERM). DESIGN: Nonrandomized comparative case series. PARTICIPANTS: Thirty patients were followed up for at least 5 years after nonvitrectomizing vitreous surgery. INTERVENTION: Epiretinal membranes were peeled without infusion of balanced salt solution and removal of the vitreous. The data from the fellow eye was the control data. MAIN OUTCOME MEASURES: We examined the visual acuities (VAs), objective refractions, and slit-lamp and Scheimpflug photographs from the preoperative and the final examinations of both eyes. Quantitative assessment of the progression of nuclear sclerosis was performed by densitometry analysis using Scheimpflug photography. The recurrence rate of ERM was determined. RESULTS: The follow-up periods ranged from 60 to 102 months (mean+/-standard deviation, 72.2+/-11.0 months). The patient ages ranged from 52 to 76 years (68.8+/-6.3 years). The final VA improved or stabilized within 2 lines in 29 of 30 eyes (96.7%). No unilateral progression of nuclear sclerosis occurred in any cases. The mean preoperative and postoperative refractions without additional surgery were -0.4+/-2.9 diopters (D) and -0.2+/-3.0 D in the operated eyes, respectively, and -0.2+/-2.5 D and 0.1+/-2.4 D, respectively, in the unoperated fellow eyes. The mean differences in the refractive error between both eyes (operated eye data minus fellow eye data) were -0.2+/-0.7 D before surgery and -0.3+/-0.8 D after surgery (P = 0.319, paired t test). The mean preoperative and postoperative nuclear densities in 16 patients were 69+/-14 nuclear density units (NDUs) and 76+/-12 NDUs in the operated eyes and 71+/-14 NDUs and 78+/-14 NDUs in the fellow eyes, respectively. The mean preoperative and postoperative differences in nuclear densities in both eyes were -2+/-2 NDUs and -2+/-5 NDUs, respectively (P = 0.836, paired t test). The ERM recurred in 10 eyes (33%), and 3 eyes underwent conventional vitrectomy combined with cataract surgery. CONCLUSIONS: Unilateral nuclear sclerosis did not progress for at least 5 years after nonvitrectomizing vitreous surgery. The recurrence rate of ERM appeared to be higher than that after conventional vitreous surgery.

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PubMed2004

Wide-angle viewing lens for vitrectomy.

PURPOSE: To report a new wide-angle viewing contact lens for vitrectomy. DESIGN: New surgical instrument. METHODS: The new wide-angle viewing lens is made of glass and polymethyl methacrylate without a plastic rim. The diameter is reduced to 16.2 mm. In addition to a smaller diameter than the currently available lens, the new lens is partially cut to reduce the lens diameter. RESULTS: A smaller diameter makes it possible to eliminate contact between surgical instruments and the wide-angle lens. Instruments can be inserted through sclerotomies without removing the wide-angle lens. The optical properties are otherwise identical to the standard wide-angle lens. CONCLUSION: The new wide-angle viewing lens may be easier to use in vitreous surgery.

Contact Lenses↗
PubMed2003

Sub-retinal hemorrhage during internal limiting membrane peeling for a macular hole.

PURPOSE: To report the occurrence of sub-retinal hemorrhage during peeling of the internal limiting membrane (ILM). CASE REPORTS: In case 1, a three-port pars plana vitrectomy was performed on a 57-year-old woman with a macular hole. Following the staining of the ILM with indocyanine green, the ILM was peeled with forceps, and a sub-retinal and vitreous hemorrhage resulted from a vein during the peeling. The bleeding was stopped by elevating the intraocular pressure. The final visual acuity was 20/30. In case 2, similar procedures were performed on a 68-year-old woman with a macular hole. A sub-retinal hemorrhage occurred while peeling the ILM. The pre-operative visual acuity was 20/300, and final visual acuity was 20/200. CONCLUSIONS: Surgeons should be aware that sub-retinal and vitreous hemorrhage can be a complication of ILM peeling.

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PubMed2003

Differential expression and distribution of Kir5.1 and Kir4.1 inwardly rectifying K+ channels in retina.

Kir5.1 is an inwardly rectifying K+ channel subunit whose functional role has not been fully elucidated. Expression and distribution of Kir5.1 in retina were examined with a specific polyclonal antibody. Kir5.1 immunoreactivity was detected in glial Müller cells and in some retinal neurons. In the Kir5.1-positive neurons the expression of glutamic acid decarboxylase (GAD65) was detected, suggesting that they may be GABAergic-amacrine cells. In Müller cells, spots of Kir5.1 immunoreactivity distributed diffusely at the cell body and in the distal portions, where Kir4.1 immunoreactivity largely overlapped. In addition, Kir4.1 immunoreactivity without Kir5.1 was strongly concentrated at the endfoot of Müller cells facing the vitreous surface or in the processes surrounding vessels. The immunoprecipitant obtained from retina with anti-Kir4.1 antibody contained Kir5.1. These results suggest that heterotetrameric Kir4.1/Kir5.1 channels may exist in the cell body and distal portion of Müller cells, whereas homomeric Kir4.1 channels are clustered in the endfeet and surrounding vessels. It is possible that homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels play different functional roles in the K+-buffering action of Müller cells.

Amacrine Cells↗
PubMed2003

Protective effect of nilvadipine against glutamate neurotoxicity in purified retinal ganglion cells.

We determined the effect of nilvadipine, a dihydropyridine-type calcium channel blocker, in preventing glutamate neurotoxicity in purified retinal ganglion cells (RGCs). RGCs were purified from dissociated rat retinal cells (postnatal days 6-8), using a modified two-step panning method, and cultured in serum-free medium containing neurotrophic factors and forskolin. RGC survival after exposure to glutamate (25 microM) with nilvadipine or other calcium channel blockers was measured by calcein-acetoxymethyl ester staining after 3 days in culture. Changes in the level of intracellular Ca(2+) ([Ca(2+)](i)) were measured with fura-2 fluorescence. Induction of apoptosis was evaluated using the TDT-dUTP terminal nick-end labeling technique. The neurotoxic effects of low doses of glutamate were blocked by a specific alpha-amino-3-dihydro-5-methylisoxazole-4-propionate-kainate receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione (20 microM). Simultaneous application of nilvadipine (1-100 nM) with glutamate protected against glutamate neurotoxicity in a dose-dependent manner. Calcium-imaging experiments showed that the glutamate-evoked [Ca(2+)](i) increase was significantly blocked by nilvadipine (P<0.001), but not nifedipine and diltiazem, in about 50% of RGCs. In addition, the application of nilvadipine significantly reduced glutamate-induced apoptosis (P<0.001). These findings suggest that nilvadipine may partly inhibit glutamate-induced apoptotic cell death by blocking calcium influx via voltage-dependent calcium channels in purified RGCs.

Animals↗
PubMed2003

Experimental study of viscoelastic in the prevention of corneal endothelial desiccation injury from vitreal fluid-air exchange.

PURPOSE: To evaluate the usefulness of viscoelastic in protecting the corneal endothelium from desiccation injury associated with fluid-air exchange in a rabbit model. DESIGN: Experimental study. METHODS: Rabbit eyes undergoing pars plana lensectomy and vitrectomy were insufflated with either dry or humidified air for 20 minutes following introduction of either Opegan (sodium hyaluronate 1.0%; Santen, Osaka, Japan) or Viscoat (sodium hyaluronate 3%-chondroitin sulfate 4%; Alcon, Tokyo, Japan) into the anterior chamber. In two other groups of rabbit eyes, the same procedure was performed without using any viscoelastic agent. Corneas obtained from rabbits undergoing surgery were compared with corneas obtained from rabbits not undergoing surgery. Potential alterations in the corneal endothelium were investigated by scanning electron microscopy, by Phalloidin-FITC staining of actin and by in vitro measurements of corneal permeability for carboxyfluorescein using a diffusion chamber. RESULTS: Scanning electron microscopy displayed less distortion of corneal endothelium with Opegan and Viscoat compared with the dry air-only exposed corneas. Using humidified air in Opegan and Viscoat coated corneas maintained the normal actin cytoskeleton during fluid-air exchange. Paracellular leakage was much less with Opegan and Viscoat use following infusion of dry air comparing to that of dry air-only group (P =.026 and P =.041). The difference was much more striking following humidified air infusion in Opegan or Viscoat coated corneas comparing to dry air-only infused corneas (P <.002 and P <.002). CONCLUSIONS: Coating of rabbit corneal endothelium with Opegan or Viscoat before fluid-air exchange largely prevents dry air damage to the endothelium. Infusion of humidified air further protects corneal endothelium during fluid-air exchange in aphakic rabbit eyes.

Actins↗
PubMed2003

Optical coherence tomographic evaluation of a surgically treated traumatic macular hole secondary to Nd:YAG laser injury.

PURPOSE: To report the importance of optical coherence tomographic (OCT) evaluation of a macular hole caused by neodymium:yttrium-aluminum-garnet (Nd:YAG) laser injury. DESIGN: Observational case report. METHODS: A 33-year-old man presented with an accidental Nd:YAG laser-induced macular hole in his right eye. After observing the course of the macular hole by OCT, the macular hole was treated by standard pars plana vitrectomy. The appearance of the macular hole was also followed up postoperatively. RESULTS: Seven days after the injury, OCT showed a full-thickness macular hole without a fluid-cuff or swelling of the surrounding retina. Twenty-one days after the injury, however, OCT disclosed that the retina around the macular hole was swollen. After vitrectomy, OCT showed that the macular hole was closed, and the visual acuity improved from 20/30 to 20/20. CONCLUSIONS: Surgical treatment can improve the visual function of eyes with a Nd:YAG laser-induced macular hole. Optical coherence tomography is valuable in providing precise information about the condition of the macula.

Adult↗
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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PubMed2003

Trypan blue staining in vitreoretinal surgery.

PURPOSE: To evaluate the efficacy of trypan blue for staining the internal limiting membrane (ILM) and epiretinal membranes (ERM) in vitreoretinal surgery. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Fifty eyes of 50 patients with macular pucker (n = 22), macular hole (n = 18), or a combination (n = 2), proliferative vitreoretinopathy (n = 5), or diabetic retinopathy (n = 3). METHODS: Trypan blue 0.2% was used to stain the ILM or ERM during vitreoretinal surgery. MAIN OUTCOME MEASURES: The intraoperative visibility of the membranes was scored as poor, moderate, good, or excellent. RESULTS: The application of trypan blue onto the ILM or the ERM resulted in a useful bluish staining, facilitating the identification, delineation, and removal of the membranes in all surgeries. No residual staining or adverse effects related to the dye were observed. CONCLUSIONS: Trypan blue stains both ILM and ERM and might be an useful tool in vitreoretinal surgery.

Adult↗
PubMed2002

Sutureless contact lens ring system during vitrectomy.

PURPOSE: To report a new sutureless ring system to fix corneal contact lens in place during vitrectomy. DESIGN: New surgical instrument. METHODS: The sutureless ring system consists of a stainless steel ring that has two upright tabs 180 degrees apart with a hook on the top and two elastic silicone bands 8 mm in diameter to fix the ring to the eyelid speculum. RESULTS: The contact lens fixed in place with the sutureless ring was stable and allowed intraoperative visualization of the fundus. CONCLUSION: This suture-free contact lens system facilitates visualization of the fundus during vitrectomy allowing shorter surgical time. It also enables us to avoid additional trauma associated with the lens ring fixation procedure.

Contact Lenses↗
PubMed2002

Effects of humidified and dry air on corneal endothelial cells during vitreal fluid-air exchange.

PURPOSE: To report the immediate anatomic and functional alterations in corneal endothelial cells following use of humidified air and dry air during vitreal fluid-air exchange in rabbits. DESIGN: Experimental study. METHODS: Rabbits undergoing pars plana vitrectomy and lensectomy were perfused with either dry or humidified air during fluid-air exchange for designated durations. Three different experiments were performed. First, control and experimental corneas were examined by scanning electron microscopy (SEM). Second, corneas were stained with Phalloidin-FITC and examined by fluorescein microscopy. Finally, third, transendothelial permeability for carboxyfluorescein was determined using a diffusion chamber. RESULTS: While different from the corneal endothelial cells, those cells exposed to humidified air were less stressed than cells exposed to dry air by SEM. Actin cytoskeleton was found highly disorganized with dry air exposure. Humidified air maintained the normal actin cytoskeleton throughout the 20 minutes of fluid-air exchange. Paracellular carboxyfluorescein leakage was significantly higher in dry air insufflated eyes compared with that of the humidified air after 5, 10, and 20 minutes of fluid-air exchange (P =.002, P =.004, and P =.002, respectively). CONCLUSIONS: Dry air stress during fluid-air exchange causes significant immediate alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelium in aphakic rabbit eyes. Use of humidified air largely prevents the alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelial cells.

Actins↗
PubMed2002

Two novel point mutations of the XLRS1 gene in patients with X-linked juvenile retinoschisis.

PURPOSE: To report two novel point mutations of the XLRS1 gene in two Japanese patients with X-linked juvenile retinoschisis. DESIGN: Observational case reports. METHODS: The exons, including the flanking introns of XLRS1, were amplified by polymerase chain reaction and analyzed by direct sequencing. RESULTS: One novel splice donor site mutation (IVS2 + 1g to a) and one missense mutation of exon 6 (Ala211Thr) were found. CONCLUSIONS: Genetic findings identifying mutations in the XLRS1 gene will lead to earlier and more accurate diagnosis of X-linked juvenile retinoschisis.

Base Sequence↗
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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