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Masahito Ohji

Publications and source records attributed to Masahito Ohji.

At least 19 recordsLinked to original sources
PubMed2006

Surgical outcomes of 25-gauge transconjunctival vitrectomy combined with cataract surgery for vitreoretinal diseases.

INTRODUCTION: To report surgical outcomes of 25-gauge transconjunctival vitrectomy combined with cataract surgery for the management of a variety of vitreoretinal diseases. MATERIALS AND METHODS: A retrospective, interventional case study was conducted. Chart review of a consecutive series of 150 eyes of 144 patients who underwent 25-gauge vitrectomy combined with phacoemulsification and intraocular lens implantation for epiretinal membrane (n = 62), refractory macular oedema associated with retinal vascular disorders (n = 29), idiopathic macular hole (n = 21), non-clearing vitreous haemorrhage (n = 18), rhegmatogenous retinal detachment (n = 11), tractional retinal detachment associated with proliferative diabetic retinopathy (n = 7), and subretinal haemorrhage (n = 2). Main outcome measures included preand postoperative visual acuity, operating time, intraocular pressure, intra- and postoperative complications. RESULTS: The mean follow-up period was 9.7 months (range, 6 to 26). The mean overall visual acuity improved from 20/100 preoperatively to 20/38 at final visit (P <0.001). Statistically significant improvement of visual acuity was also observed in each subgroup. Operative time was shortened in macular surgery. No intraoperative complications were noted attributable to small-gauge instruments and no cases required conversion to 20-gauge standard instrumentation. However, 12 eyes (8%) required suture placement to at least one sclerotomy site. Postoperative intraocular pressure remained stable in most cases except 18 eyes (13%) with transient hypotony during the first week after surgery. One case of retinal detachment but no case of endophthalmitis was observed throughout the follow-up period. CONCLUSIONS: 25-gauge vitrectomy combined with cataract surgery is a safe and effective system for the management of a variety of vitreoretinal diseases, especially cases requiring minimal intraocular manipulation. Further study is recommended to evaluate potential postoperative complications.

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PubMed2005

Electrophysiological and histological studies of chronically implanted intrapapillary microelectrodes in rabbit eyes.

PURPOSE: To determine the safety and efficacy of transsclerally placed intrapapillary wire microelectrodes implanted chronically into the optic nerve head of rabbit eyes. METHODS: Four platinum wire microelectrodes were passed through the sclera and implanted into the optic nerve head of five rabbit eyes for 4-6 months. Color fundus photography, fluorescein angiography, electroretinograms (ERGs), and visually evoked potentials (VEPs) were used to monitor the retina. Electrically evoked potentials (EEPs) were elicited by bipolar electrical stimulation of the optic nerve axons by different combinations of the four electrodes immediately after the implantation and at 1-month intervals thereafter. The effects of the chronic implantation of the electrodes on the morphology of the optic nerve were evaluated by histological and immunohistochemical examinations at 4 and 6 months after the implantation. RESULTS: All of the electrodes remained stable in the implanted sites throughout the post-implantation period, except for one electrode that had pulled out of the optic nerve head at 1 month after implantation. No intraocular infection, inflammation, or vitreoretinal proliferation was observed in any eye. EEPs could be elicited from each pair of electrodes at all testing times. The mean threshold currents (charge densities) to evoke EEPs increased from 19.3 +/- 9.2 microA (6.0 +/- 2.9 microC/cm2) on the implantation day to 78.8 +/- 31.9 microA (24.6 +/- 10.0 microC/cm2) at 1 month after implantation, but did not change significantly thereafter. The implicit time and amplitude of the a- and b-waves of the ERGs and of P1 of the VEPs did not change significantly throughout the post-implantation period. Histological evaluation of the optic nerve head revealed slight tissue encapsulations surrounding the electrode and increased expression of glial fibrillary acidic protein near the surface of the optic nerve. CONCLUSIONS: Implantation of transscleral intrapapillary microelectrodes appears to be safe and effective. These findings indicate that the implantation of microelectrodes in the optic nerve head should be considered for an optic nerve-based prosthesis.

Animals↗
PubMed2005

New micro vertical scissors for the surgical ablation of retinal angiomatous proliferation.

PURPOSE: To develop new micro vertical scissors for the ablation of retinal angiomatous proliferation (RAP) to minimize possible retinal damage. DESIGN: Interventional case report. METHODS: New micro vertical scissors were developed and used for the ablation of RAP vessels. RESULTS: The length of the inner side of the tip is 180 microm, which is approximately one seventh that of regular vertical scissors. The scissors handled easily and the RAP vessels were ablated with less retinal damage compared with that associated with use of standard vertical scissors. Postoperatively, intraretinal hemorrhage was reduced and hyperfluorescence seen on indocyanine green angiography resolved. CONCLUSIONS: The new micro vertical scissors developed for the ablation of RAP vessels can be used safely and effectively during this surgical procedure.

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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

Transretinal electrical stimulation by an intrascleral multichannel electrode array in rabbit eyes.

BACKGROUND: A new method of stimulating the retina electrically, called suprachoroidal transretinal stimulation (STS), was shown to be effective in eliciting electrically evoked cortical potentials (EEPs) in Royal College of Surgeons (RCS) rats. Before extending this technique to patients, it is important to determine its safety and feasibility in eliciting EEPs from medium-size animal (rabbits). The purpose of this study was to determine the safety and efficacy of the surgical procedures used to implant an multichannel electrode array into a scleral pocket, and to determine whether the implanted electrodes can stimulate the retina effectively. METHODS: These acute experiments were conducted on six rabbits. An array of eight gold microelectrodes, embedded in polyimide, was implanted into a scleral pocket over the visual streak area. The size of the microarray was 2 x 4 x 0.180 mm. The reference electrode was implanted into the vitreous. The electrode array and reference electrodes were connected to a stimulator to deliver monophasic current pulses. Cortical responses were recorded with a stainless steel electrode implanted into each rabbit's skull over the visual cortex. After the experiment, the eyes and electrodes were examined histologically. RESULTS: The surgical procedures for electrode implantation were accomplished without serious complications. EEPs were recorded after monophasic electrical pulse stimulation from each electrode. The mean threshold for EEPs was 55.0+/-10.0 microA with a 0.5-ms duration inward current pulse. The charge delivered at threshold was about 27.5 nC, and the charge density was about 56.0 microC/cm2. Histopathological examination of the retinal tissue around the area of stimulation did not show damage at the light microscope level with the electrical parameters used. CONCLUSIONS: Our technique for STS with an intrascleral microelectrode array is safe in rabbit eyes, and EEPs were elicited by current densities that did not induce tissue damage. These results suggest that STS via intrascleral multichannel electrodes is a feasible method for stimulating the retina.

Animals↗
PubMed2004

Direct stimulation of optic nerve by electrodes implanted in optic disc of rabbit eyes.

PURPOSE: To determine whether wire microelectrodes implanted in the optic disc can be used to elicit cortical potentials. METHODS: Two or four platinum wire electrodes of two types, viz., the cut-end type and the exposed-tip type, were inserted through the vitreous and fixed in the optic disc of 16 rabbit eyes. Electrically evoked potentials (EEPs) were recorded after bipolar electrical stimulation with the two wire electrodes and by different combinations of the four-electrode system. The optic discs were examined histologically after the experiment. RESULTS: The wire electrodes were successfully implanted and fixed into different positions of the optic disc without serious complications in all 16 eyes. EEPs could be elicited after bipolar electrical stimulation of the optic nerve using either the two-electrode system or different pairs of the four-electrode system. Threshold charge densities to elicit EEPs were 0.32-0.64 mC/cm(2) in eyes using the cut-end type of electrodes and 0.93-6.21 muC/cm(2) in eyes using the exposed-tip type. The amplitude of the EEPs increased with increasing electrical stimulus intensities. Histological evaluation revealed limited damage to the neural tissue adjacent to the electrode track. CONCLUSIONS: The visual cortex can be activated by direct microelectrical stimulation of the optic nerve. The acute implantation of the wire microelectrodes into the optic disc by a transvitreal approach is feasible and results in only limited damage to the optic nerve.

Animals↗
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↗
PubMed2004

Vitrectomy and internal limiting membrane peeling for myopic foveoschisis.

PURPOSE: Myopic foveoschisis is common in high myopia. We report results of a pilot study of vitrectomy for patients with myopic foveoschisis. DESIGN: Interventional case series. METHODS: In an institutional setting five patients with high myopia (six eyes), and who had progressive visual impairment presumably due to myopic foveoschisis were studied. No eyes had a macular hole preoperatively based on optical coherence tomography (OCT). We performed vitrectomy including vitreous cortex removal, internal limiting membrane (ILM) peeling, and gas tamponade. Patients were followed for at least 6 months. Best-corrected visual acuity (BCVA), OCT. Scanning laser ophthalmoscope (SLO) microperimetry was examined in three eyes. RESULTS: The foveal detachment resolved completely in five eyes and partially in one eye. No serious complications developed including macular hole formation or retinal detachment; BCVA improved more than two lines in all eyes (100%) 6 months postoperatively (P <.01); SLO microperimetry showed smaller scotoma compared with preoperatively and stabilized fixation. CONCLUSIONS: Vitrectomy with vitreous cortex removal, ILM peeling, and gas tamponade could be useful to treat myopic foveoschisis in highly myopic eyes. Because the natural course of the disease is not well-understood, further study should establish indications for this surgery.

Basement Membrane↗
PubMed2004

Vitreoretinal surgery with slit-lamp illumination combined with a wide-angle-viewing contact lens.

PURPOSE: To evaluate the feasibility of illuminating the fundus by combining a wide-angle-viewing contact lens and slit lamp attached to a surgical microscope during retinal reattachment surgery and vitrectomy. DESIGN: An interventional study. METHODS: We combined slit-lamp illumination and a wide-angle-viewing contact lens to visualize the fundus during retinal reattachment surgery and vitrectomy. RESULTS: We clearly observed the fundus using this combination approach during conventional retinal reattachment surgery, which we completed without using an indirect ophthalmoscope. With slit-lamp illumination, the wide-angle-viewing contact lens provided a wider area of illumination than a planoconcave contact lens during vitrectomy in addition to an area of illumination as wide as that obtained using a light pipe. CONCLUSIONS: Combining slit-lamp illumination and a wide-angle-viewing contact lens seems to provide a useful alternative method for viewing the fundus during vitreoretinal surgery.

Contact Lenses↗
PubMed2004

Retinal changes after macular translocation with 360-degree retinotomy in monkey eyes.

PURPOSE: To determine the morphologic and functional changes of the fovea and retina of monkey eyes after macular translocation with 360-degree retinotomy. DESIGN: Experimental study. METHODS: The retinas of eight monkey eyes were surgically translocated with a 360-degree retinotomy with procedures similar to those used on human eyes. At 1, 2, and 3 months after the surgery, the six eyes that had successful surgery were studied by light and transmission electron microscopy, terminal deoxynucleotidyl transferase (TdT)-dNTP terminal nick-end labeling (TUNEL) assay, and immunohistochemistry with peanut agglutinin (PNA) lectin and glial fibrillary acidic protein (GFAP). Retinal physiology was assessed by scotopic and photopic electroretinograms (ERGs). RESULTS: The fovea was successfully translocated approximately 30 to 40 degrees superiorly in six eyes. The translocated macula and fovea had a normal layered architecture with no TUNEL-positive cells, minimal misalignment of the outer segments, and strong immunoreactivity to GFAP. The mean amplitudes of the scotopic and photopic b-waves were significantly reduced at 1 month after the surgery, and there was only a slight recovery at 3 months. No significant changes were observed in the mean implicit times after the surgery. CONCLUSION: These findings indicate that macular translocation surgery with 360-degree retinotomy results in minimal morphologic alterations but significant depression of electrophysiologic function.

Animals↗
PubMed2004

Macular translocation with chorioscleral outfolding: 2-year results.

PURPOSE: To evaluate the results of macular translocation with radial chorioscleral outfolding in patients with subfoveal choroidal neovascularization (CNV) and to identify factors associated with decreased postoperative visual acuity. DESIGN: Retrospective interventional case series. METHODS: Twenty-seven consecutive patients with surgically treated subfoveal CNV were operated on and followed for more than 2 years. Macular translocation with radial chorioscleral outfolding was performed using titanium clips. Surgical outcomes including visual acuity, foveal displacement, surgically induced astigmatism, and complications were recorded. Factors associated with decreased visual acuity postoperatively were identified by multiple logistic regression analysis. RESULTS: Foveal displacement ranged from 349 to 3391 (median, 1576) microm. Surgically induced astigmatism ranged from 0 to 3.0 (median, 0.5) diopters. Visual acuity after surgery improved in 19 of the 27 patients (70.4%; median, 5 lines), but in 14, final vision ultimately decreased from the best postoperative level. Final visual acuity improved from the preoperative level in 11 patients (40.7%), remained unchanged in seven (25.9%), and decreased in nine (33.3%). In our series, the mean preoperative vision was 20/174, the best postoperative visual acuity was 20/74, and the mean final vision was 20/167. Factors associated with a decrease in postoperative visual acuity included the postoperative enlargement of CNV. CONCLUSION: Macular translocation with radial chorioscleral outfolding improved or stabilized the vision in 66.7% of patients with subfoveal CNV over the course of more than 2 years. Closing the CNV or preventing its further growth is required to maintain a better postoperative visual acuity.

Adult↗
PubMed2004

Multiple components of epiretinal tissues detected by triamcinolone and indocyanine green in macular hole and retinal detachment as a result of high myopia.

PURPOSE: To examine three layers of membranes detected by triamcinolone acetonide (TA) and indocyanine green (ICG) during surgery for macular hole and retinal detachment (MHRD) as a result of high myopia. DESIGN: Histologic study. METHODS: We excised three layers of membranes visualized with TA and ICG that were tightly adhering to the retinal surface during vitrectomy and examined them by transmission electron microscopy. RESULTS: The first membrane was made of acellular collagen fibers, suggestive of vitreous, and the second was comprised of parts of fibroblast-like cells and collagen fibrils, suggesting a proliferative epiretinal membrane. The third membrane was an internal limiting membrane. CONCLUSIONS: Multiple components of epiretinal tissue could be delaminated with the assistance of TA and ICG during surgery for myopic MHRD.

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PubMed2004

Macular translocation surgery and retinal circulation times.

PURPOSE: To quantify and compare the retinal circulation times before and after macular translocation surgery. METHODS: In nine patients undergoing macular translocation with 360-degree retinotomy, arm-retina and arteriovenous passage times were quantified from preoperative and postoperative scanning laser fluorescein angiograms. A control group of eight patients who had not undergone any intraocular surgery was also evaluated. The time that between injection into the antecubital vein and the appearance of fluorescein at two selected points on superotemporal and inferotemporal arteries near the disk provided the arm-retina time. For the arteriovenous passage time, 50% of the maximal fluorescence time difference was assessed from the intensity curves of arteries and corresponding veins at the same points for the arm-retina time. Postoperative measurements were obtained an average of 10.6 months after surgery. RESULTS: No significant difference was noted between preoperative and postoperative values of the arm-retina time (mean +/- SD: 14.41 +/- 2.73 seconds versus 14.67 +/- 3.85 seconds, respectively; P = 0.84) or that of the arteriovenous passage time (2.66 +/- 0.74 seconds versus 2.47 +/- 0.68 seconds, respectively; P = 0.37) in the study group. The arm-retina time (14.96 +/- 2.01 seconds) and arteriovenous passage time (2.44 +/- 0.68 seconds) in the control group did not differ from preoperative and postoperative arm-retina times (P = 0.65 and P = 0.85) and arteriovenous passage times (P = 0.54 and P = 0.93) in the study group. The arteriovenous passage time correlated with the degree of retinal rotation around the optic disk in the study group (r = -0.70; P = 0.04). CONCLUSION: Macular translocation surgery does not alter retinal macrocirculation in the long term.

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PubMed2004

Evaluation of choroidal perfusion of the new central macular area by dilution analysis of indocyanine green angiography after macular translocation.

PURPOSE: To evaluate the possible long-term alterations of choroidal perfusion parameters in the new central macular area after macular translocation surgery. METHODS: Eleven subjects with subfoveal neovascular membrane secondary to age-related macular degeneration or degenerative myopia underwent indocyanine green angiography by using a scanning laser ophthalmoscope before and after macular translocation (mean, 10 months after surgery). Fluorescence intensity of the new central macular area over time was evaluated. Parameters derived from the intensity curves included 10% filling time, ascending slope, and maximal intensity of brightness. The 10% filling time reflects the rapidity of the early choroidal filling phase, whereas the slope of the filling of the curve shows the speed of blood entrance into the choroid. Maximal intensity of brightness indicates vascular density of the area. RESULTS: No statistical difference was encountered before or after macular translocation in 10% filling time (14.25 +/- 2.09 seconds versus 16.20 +/- 2.95 seconds), slope of the ascending portion of the curve (0.12 +/- 0.04 versus 0.11 +/- 0.04), and maximal intensity of brightness (0.89 +/- 0.09 versus 0.88 +/- 0.07) in the new central macular area. The rotational degree of the retina against the retinal pigment epithelium did not show any significant correlation with 10% filling time, slope, or maximal intensity of brightness. CONCLUSION: Choroidal perfusion parameters in the new foveal region do not change after macular translocation surgery.

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PubMed2004

Nonaxoplasmic transfer of indocyanine green into the optic nerve after intravitreal application.

PURPOSE: To investigate whether indocyanine green (ICG) migrates into the optic nerve after intravitreal application in the rabbit eye. METHODS: Gas vitrectomy was performed in one eye of adult Dutch belted rabbits by pars plana injection of 0.4 ml of 100% C3F8 (n = 10). One week later, vitrectomy was performed and 0.2 ml of 0.25% ICG was instilled into the vitreous cavity of these vitrectomized eyes. After 30 seconds of ICG application, the vitreous cavity was rinsed with balanced salt solution plus. Unoperated rabbits served as controls (n = 2). Globes, optic nerves, and the entire brain were removed, and ICG fluorescence of the specimens was examined with a digital fundus camera starting from the first day to the fourth postoperative week. Other rabbit eyes (n = 2) were injected with ICG directly into the vitreous without vitrectomy, and assessed for ICG signal after 1 day of ICG application. In the second part of the experiment, four rabbit eyes were gas vitrectomized and ICG was instilled onto retina after blockage of axonal flow by vinblastine. They were evaluated on the first (n = 2) and seventh postoperative days (n = 2). RESULTS: No fluorescein was detected in the visual pathways and the brains of the control group of rabbits. The optic nerves of the ICG-instilled eyes were stained diffusely with ICG starting from the first day after surgery. ICG injected nonvitrectomized eyes showed similar ICG staining patterns when compared with vitrectomized eyes. ICG staining pattern of the optic nerve did not differ in vinblastine-pretreated eyes. Fluorescence extended along the intraorbital portion of the optic nerve but did not transport more posteriorly in all animals. At the fourth week after vitrectomy, ICG signal was still detectable, but staining was less intense. CONCLUSION: Intravitreal ICG injection results in nonaxoplasmic extension into the optic nerve in the rabbit.

Animals↗
PubMed2004

Foveal sensitivity and fixation stability before and after macular translocation with 360-degree retinotomy.

PURPOSE: To evaluate the functional changes of the fovea by scanning laser ophthalmoscopy (SLO) fundus perimetry after macular translocation with 360-degree retinotomy, and to determine whether the preoperative macular function estimated by the sensitivity of the fovea and the stability of fixation can predict visual acuity after the surgery. METHODS: Macular translocation with 360-degree retinotomy and simultaneous torsional muscle surgery were performed on 25 eyes of 25 patients with choroidal neovascularization. The index of foveal sensitivity (Isens) and the index of fixation stability (Ifix) before and after surgery were calculated from the microperimetric data. The preoperative Isens and Ifix were compared with postoperative Isens and Ifix, respectively. The correlations of preoperative Isens and Ifix with the visual acuity after the translocation surgery (VApost) were calculated. RESULTS: Isens increased in 14 (56%) of 25 eyes. Ifix improved in 10 (40%) of 25 eyes. The preoperative Isens and VApost were moderately correlated (r = 0.434, P = 0.0295), while the preoperative Ifix and VApost were highly correlated (r = - 0.530, P = 0.0057). CONCLUSION: An increase in foveal sensitivity and an improvement in the fixation stability were demonstrated quantitatively by microperimetry. The preoperative foveal sensitivity and fixation stability were correlated with the postoperative visual acuity. Microperimetry using SLO can be used to investigate foveal function before and after the translocation and to predict the postoperative visual acuity.

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