Publications (28)56.05 Total impact
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Article: Elderly case of pseudo-unilateral occult macular dystrophy with Arg45Trp mutation in RP1L1 gene.
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ABSTRACT: PURPOSE: To report a case of pseudo-unilateral occult macular dystrophy (OMD) with an Arg45Trp mutation in the RP1L1 gene and had unilateral functional changes for about 9 years. CASE REPORT: A 64-year-old woman with a decimal visual acuity of 1.0 in both eyes complained about difficulties with visual tasks because of presbyopia. At the age of 65 years, her visual acuity in the left eye decreased to 0.2, while that in the right eye was 0.7. The fundus of both eyes was normal except for drusen. After 10 years and at the age of 75 years, her visual acuity in the right eye decreased to 0.3. Focal macular electroretinograms (ERGs) at this time were severely attenuated in both eyes, while the full-field ERGs were within normal limits. Ophthalmoscopy showed that the fundus of both eyes was still normal. Genetic analysis revealed a heterozygous mutation, Arg45Trp, in the RP1L1 gene. CONCLUSIONS: These findings indicate that the phenotype in some cases of OMD with an Arg45Trp mutation in the RP1L1 gene can be unilateral for a considerable period.Documenta Ophthalmologica 04/2013; · 2.11 Impact Factor -
Article: Involvement of glial cells in the autoregulation of optic nerve head blood flow in rabbits.
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ABSTRACT: To investigate the involvement of glial cells in the autoregulation of optic nerve head (ONH) blood flow in response to elevated intraocular pressure (IOP). Rabbit eyes were treated with an intravitreal injection of l-2-aminoadipic acid (LAA), a gliotoxic compound. Twenty-four hours after the injection IOP was artificially elevated from a baseline of 20 to 50 or 70 mm Hg and maintained at each IOP level for 30 minutes. ONH blood flow was measured by laser speckle flowgraphy every 10 minutes. Ocular perfusion pressure (OPP) was calculated to investigate the relationship between ONH blood flow and OPP. To evaluate the effects of LAA on the function and morphology of retinal neurons and glial cells, electroretinogram (ERG) was monitored after injections of LAA (2.0 and 6.0 mM) or saline as a control. Histologic and immunohistochemical examinations were then performed. In the LAA-treated eyes, histologic changes selectively occurred in the retinal Müller cells and ONH astrocytes. There was not any significant reduction of amplitude or elongation of implicit time of each parameter in the ERG after LAA injection compared with control. ONH blood flow in LAA-treated eyes was significantly decreased with a reduction of OPP during IOP elevation to 50 and 70 mm Hg, whereas blood flow was maintained in control eyes during IOP elevation to 50 mm Hg. These results indicate the involvement of glial ells in the autoregulation of ONH blood flow during IOP elevation.Investigative ophthalmology & visual science 05/2012; 53(7):3726-32. · 3.43 Impact Factor -
Article: [Effect of continuous intravenous infusion of flurbiprofen axetil and tramadol hydrochloride for postoperative pain management of laparoscopic colectomy].
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ABSTRACT: In this study, we evaluated the efficacy of continuous intravenous infusion of flurbiprofen axetil (FA) combined with tramadol hydrochloride (TH) for postoperative pain control after laparoscopic colectomy. Fifty patients scheduled for laparoscopic colectomy were randomly assigned to one of the following three groups : the saline group which received saline, the FA alone group which received FA 4 mg kg-1 . 24hr-1, and the FA plus TH group which received FA 4 mg kg-1 . 24 hr-1 and TH 2 mg kg-1 . 24 hr-1 intravenously after bolus injection of FA 50 mg immediately before the end of the operation. We examined the pain scores at 4 and 24 hr, and postoperative analgesic medication use during 0-4, 4-24, and 24-48 hours. Although no significant difference was observed among pain scores for these three groups, the FA plus TH group required the lowest dose of analgesic medication. For lower abdominal incision, the FA plus TH group required the least analgesic medication in 4-48 hr. No significant difference concerning analgesic medication was observed among the three groups for upper abdominal incision. Continuous intravenous injection of FA plus TH is more effective than FA alone for postoperative pain management after laparoscopic colectomy.Masui. The Japanese journal of anesthesiology 12/2011; 60(12):1364-9. -
Article: Changes in optic nerve head blood flow, visual function, and retinal histology in hypercholesterolemic rabbits.
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ABSTRACT: We investigated the effects of hypercholesterolemia on optic nerve head (ONH) blood flow, visual function, and retinal histology in a rabbit model. Hypercholesterolemia was induced in rabbits by feeding them a high cholesterol (1%) diet for 12 weeks. Changes in blood pressure, intraocular pressure (IOP), and ONH blood flow were monitored at 6 and 12 weeks after treatment. The autoregulation of ONH blood flow as detected by laser speckle flowgraphy was verified by an artificial elevation of IOP at 12 weeks. Visually evoked potentials (VEPs) were also recorded and analyzed at 6 and 12 weeks. Finally, a histological examination as well as immunohistochemistry to endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) was performed. In the hypercholesterolemic rabbits, blood pressure, IOP, and ONH blood flow did not alter significantly throughout this study. The autoregulation of ONH blood flow against IOP elevation was found to be impaired at 12 weeks. The amplitudes of the first negative peak of VEPs were diminished. Both the density of the retinal ganglion cells and the thickness of the inner nuclear layer and photoreceptor cell layer were reduced. Immunoreactivity to eNOS was reduced and that to iNOS was enhanced in the hypercholesterolemic rabbits compared to those in the normal control rabbits. The results of this study show that hypercholesterolemia induces impairment in the autoregulation of ONH blood flow and deterioration in visual function and histology. Downregulation of eNOS activity might be one of the causes for impairment of the autoregulation. Enhanced activity of iNOS might be involved in the impaired visual function and histology.Experimental Eye Research 12/2011; 93(6):818-24. · 3.26 Impact Factor -
Article: Effects of fasudil, a Rho-associated protein kinase inhibitor, on optic nerve head blood flow in rabbits.
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ABSTRACT: To investigate the effects of fasudil, a Rho-associated coiled coil-forming protein kinase (ROCK) inhibitor, on normal or impaired optic nerve head (ONH) blood flow in a rabbit model. ONH blood flow was measured by laser speckle flowgraphy. Changes in ONH blood flow were examined during a continuous intravenous infusion of fasudil with and without the application of N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor. Effects of topical fasudil on ONH blood flow were investigated in normal eyes or models of ocular circulation impairment induced by the application of endothelin (ET)-1. Visual-evoked potentials (VEPs) and morphologic and histologic changes were also analyzed in the ET-1-injected eyes. A continuous intravenous infusion of fasudil had no significant effect on normal ONH blood flow, yet it prevented or improved the ONH blood flow impairment induced by the intravenous injection of L-NAME. Repeated intravitreal injections of ET-1 twice a week for 4 weeks decreased the ONH blood flow, prolonged the VEPs' implicit time, enlarged the optic cup, and decreased retinal ganglion cells. Multiple doses of topical fasudil ameliorated the ONH impairments caused by ET-1. These results show that systemic or topical fasudil suppresses impairment of ONH blood flow, function, and morphology induced by L-NAME or ET-1. A ROCK inhibitor can be useful for the treatment of impaired ONH blood flow.Investigative ophthalmology & visual science 01/2011; 52(1):64-9. · 3.43 Impact Factor -
Article: Disruption of gap junctions may be involved in impairment of autoregulation in optic nerve head blood flow of diabetic rabbits.
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ABSTRACT: To determine whether an impairment of the autoregulatory mechanism of blood flow in the optic nerve head (ONH) is present in diabetic rabbits and whether the impairment results from the uncoupling of gap junctions. Experiments were performed on six alloxan-induced diabetic rabbits and six healthy control animals. In a test of the integrity of the autoregulatory mechanism, the intraocular pressure (IOP) was elevated from the 20-mm Hg baseline to 50 and then to 70 mm Hg. The capillary blood flow in the ONH was measured every 10 minutes by the laser speckle method, with simultaneous measurements of blood pressure. Ocular perfusion pressure (OPP) was calculated at each step, and the relationship between blood flow and OPP was analyzed. In addition, octanol, gap27 (gap junction uncouplers), or balanced saline solution was injected into the vitreous of healthy rabbits, with the balanced saline solution-injected eyes serving as the control. Changes in the ONH blood flow in response to the IOP elevation were determined in the same way. Diabetic rabbits had a significant decrease in ONH blood flow when the OPP was reduced by an elevation of the IOP to 50 or to 70 mm Hg, whereas the ONH blood flow was well maintained in healthy rabbits. After injection of octanol (10.0 mM) or gap27 (10 μM), a reduction of OPP resulted in a significant decrease in ONH blood flow in the healthy rabbits. These results indicate that autoregulation is disrupted in diabetic animals, and uncoupling the gap junctions in healthy rabbits also disrupts the autoregulation.Investigative ophthalmology & visual science 01/2011; 52(5):2153-9. · 3.43 Impact Factor -
Article: [Case of unilateral impairment of short-wavelength sensitive cone with sudden onset].
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ABSTRACT: Compare to either the middle or the long cones, short cones (S-cone) are easily damaged. A 62 year-old men complained of acute tritan OS. The corrected visual acuity was 1.2 OU. Routine ocular examinations showed no remarkable abnormalities, but we detected impaired responses using S-cone ERG and blue-on-yellow perimetry OS. We diagnosed this case as acute damage of the blue cone. S-cone damage can be determined by electro-physiological and psychophysical examinations in cases of unilateral color abnormality.Nippon Ganka Gakkai zasshi 06/2010; 114(6):527-33. -
Article: [Anesthetic management of laser surgery using PCPS for tracheal tumor].
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ABSTRACT: Primary tracheal cancer is extremely rare, but critical tracheal stenosis is seen in many cases. Although laser resection or stent placement is performed under general anesthesia, anesthetic management for tracheal tumor is extremely difficult in terms of airway management. We report a 65-year-old woman scheduled to undergo bronchoscopic laser surgery and insertion of Dumon stent for tracheal tumor which severely obstructed the upper airway. Anesthesia was maintained with propofol, fentanyl and dexmedetomidine. Percutaneous cardiopulmonary support (PCPS) was established via the femoral artery and vein prior to induction of anaesthesia. Tumor resection was performed, but the stent placement was cancelled because a rigid bronchoscope could not be inserted due to difficult laryngeal exposure. Tracheostomy was then performed after weaning from PCPS. Although desaturation due to unsuccessful venous drainage and difficult ventilation by laryngeal edema during the operation and tracheal obstruction by a clot after the operation was observed, the patient's clinical condition improved. In cases of severe tracheal stenosis, airway obstruction by hemorrhage, secretion and laryngeal edema, etc. occur easily. Therefore, some kind of measures should be taken for the operation and a number of precautions must be taken during the perioperative period.Masui. The Japanese journal of anesthesiology 06/2010; 59(6):744-8. -
Article: Acute Infarction at the Opto-Chiasmal Junction Detected by Diffusion Weighted Magnetic Resonance Imaging
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ABSTRACT: ABSTRACT A localized infarction at the junction of the optic nerve and chiasm (opto-chiasmal junction) is rare and difficult to detect by conventional neuro-imaging techniques. The purpose of this report is to show the diagnostic potential of diffusion-weighted magnetic resonance imaging for lesions at this location. A 62-year-old woman complained of sudden visual loss in her left eye. Visual field testing strongly suggested that the left opto-chiasmal junction was damaged. Diffusion weighted imaging demonstrated an area of restricted diffusion at the left opto-chiasmal junction, whereas the T2 weighted and fluid-attenuated inversion recovery sequences revealed no abnormality.11/2009; 33(5):257-260. -
Article: Peripheral cone dystrophy in an elderly man.
Clinical and Experimental Ophthalmology 01/2009; 36(9):897-9. · 1.98 Impact Factor -
Article: Shift of temporal responsivity curve of pattern reversal visually evoked potentials to lower frequencies in patients after recovery from optic neuritis.
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ABSTRACT: To investigate the responsivity of the visual system to pattern reversal stimuli of different reversal rates in optic neuritis patients after a full recovery of visual acuity. Thirty eyes with optic neuritis and 30 eyes of age-matched normal controls were studied. Steady-state pattern reversal visually evoked potentials (P-VEPs) were recorded using reversal rates of 2, 10, 20 and 30 Hz. The relationship between the amplitudes of the P-VEPs and reversal rate was analysed. The temporal responsivity curves of the two groups were compared. The means ± standard deviations (SDs) of the P-VEP amplitudes in the normal controls were 7.08 ± 2.97, 8.60 ± 2.37, 4.69 ± 1.99 and 2.11 ± 1.24 μV at reversal rates of 2, 10, 20 and 30 Hz, respectively. The comparable amplitudes from the recovered optic neuritis patients were 8.01 ± 2.45, 6.57 ± 2.54, 2.73 ± 1.76 and 0.94 ± 1.27 μV. The mean amplitude of the P-VEPs elicited at a reversal rate of 2 Hz was not significantly different from that of normal controls. However, the amplitudes of the P-VEPs at reversal rates of 10, 20 and 30 Hz were significantly smaller in the recovered optic neuritis patients than in the controls. In addition, the average maximum amplitude of the P-VEPs was obtained at 10 Hz in normal subjects and at 2 Hz in the recovered optic neuritis patients. These results indicate that the peak of the temporal tuning curve of the P-VEP shifts to lower frequencies in recovered optic neuritis eyes, and that the reduced amplitudes at higher frequencies seem to be characteristic of the visual system of patients with recovered optic neuritis.Acta ophthalmologica 11/2008; 87(7):780-3. · 2.44 Impact Factor -
Article: Reduced retinal function in amyloid precursor protein-over-expressing transgenic mice via attenuating glutamate-N-methyl-d-aspartate receptor signaling.
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ABSTRACT: Here, we examined whether amyloid-beta (Abeta) protein participates in cell death and retinal function using three types of transgenic (Tg) mice in vivo [human mutant amyloid precursor protein (APP) Tg (Tg 2576) mice, mutant presenilin-1 (PS-1) knock-in mice, and APP/PS-1 double Tg mice]. ELISA revealed that the insoluble form of Abeta(1-40) was markedly accumulated in the retinas of APP and APP/PS-1, but not PS-1 Tg, mice (vs. wild-type mice). In APP Tg and APP/PS-1 Tg mice, immunostaining revealed accumulations of intracellular Abeta(1-42) in retinal ganglion cells and in the inner and outer nuclear layers. APP Tg and APP/PS-1 Tg, but not PS-1 Tg, mice had less NMDA-induced retinal damage than wild-type mice, and the reduced damage in APP/PS-1 Tg mice was diminished by the pre-treatment of N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester, a gamma-secretase inhibitor. Furthermore, the number of TUNEL-positive cells was significantly less in ganglion cell layer of APP/PS-1 Tg mice than PS-1 Tg mice 24 h after NMDA injection. The phosphorylated form of calcium/calmodulin-dependent protein kinase IIalpha (CaMKIIalpha), but not total CaMKIIalpha or total NMDA receptor 1 (NR1) subunit, in total retinal extracts was decreased in non-treated retinas of APP/PS-1 Tg mice (vs. wild-type mice). CaMKIIalpha and NR2B proteins, but not NR1, in retinal membrane fraction were significantly decreased in APP/PS-1 Tg mice as compared with wild-type mice. The NMDA-induced increase in p-CaMKIIalpha in the retina was also lower in APP/PS-1 Tg mice than in wild-type mice. In electroretinogram and visual-evoked potential recordings, the implicit time to each peak from a light stimulus was prolonged in APP/PS-1 mice versus wild-type mice. Hence, Abeta may impair retinal function by reducing activation of NMDA-receptor signaling pathways.Journal of Neurochemistry 09/2008; 107(1):279-90. · 4.06 Impact Factor -
Article: [The ocular features in a father and a son with central areolar choroidal dystrophy].
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ABSTRACT: To report the ocular features of a father and son with central areolar choroidal dystrophy (CACD) who had similar fundus appearance. Case 1. A 37-year-old man noticed impairment of his vision since several months prior to his visit to our hospital. His corrected visual acuity was 0.6 OD and 1.0 OS. Well demarcated chorioretinal atrophy with a width of 2-3 disc diameters in the macular area was observed in both ocular fundi. Optical coherence tomography (OCT) at the chorioretinal atrophy areas showed thinning of retinal thickness with a disappearance of a line corresponding to the outer segment of the photoreceptor cells, but thickening of a line of the retinal pigment epithelium. Electroretinogram(ERG) and electrooculogram(EOG) showed deteriorated responses. Case 2 was a 67-year-old man, the father of patient 1. His corrected visual acuity was 0.1 OD and 0.2 p OS. Fundus appearance was similar to that of case 1. His ERG and EOG also showed similar impaired responses. His OCT also showed findings similar to those of case 1, but the retina was thinner than in case 1 in the chorioretinal atrophy area. The rest of the retina outside the chorioretinal atrophy area in these CACD patients also seemed to be damaged because both the ERG and EOG showed damage. These two cases revealed that a CACD patient could maintain relatively good visual acuity, even though the chorioretinal atrophy had involved the foveal area, and also indications were that retinal functions had been damaged.Nippon Ganka Gakkai zasshi 09/2008; 112(8):688-94. -
Article: Endothelin-1 (ET-1) is increased in rat retina after crushing optic nerve.
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ABSTRACT: To determine the alterations in the expression of endothelin-1 (ET-1) and its specific receptors in the sensory retina after optic nerve injury. The optic nerve of the right eye of Wistar rats was crushed. The sensory retinas were removed 1, 2, 4, 7, and 14 days after the surgery, and the amount of ET-1 in the retinas was measured by radioimmunoassay, and the mRNA levels of ET(A) and ET(B) receptors were determined by real-time PCR. The ET-1 levels in the sensory retinas following the optic nerve crush were 8.83 +/- 2.23 and 9.99 +/- 4.83 pg/mg protein on days 7 and 14 after the injury, while those in the sham controls were 4.55 +/- 1.36 and 4.85 +/- 1.57 pg/mg protein, respectively. The increase was significant on day 7 (p = 0.003, ANOVA followed by t- test), but not on day 14 (p = 0.054). The mRNA levels of the ET(A) and ET(B) receptors in the retina after the optic nerve crush was significantly increased on day 7. A two-fold increase was recognized in ET(B) receptors. Immunohistochemical analyses revealed that the ET-1 expression was increased mainly in the inner retinal layers, including the nerve fiber layer and ganglion cell layer (GCL). The increased immunoreactivity of the ET(B) receptor was seen in the GCL cells and also in the outer nuclear layer. An increase in the intraretinal ET-1 may be involved in the retinal remodeling after the optic nerve is crushed.Current eye research 08/2008; 33(7):611-20. · 1.51 Impact Factor -
Article: Electroretinographic study of spontaneously diabetic Torii rats.
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ABSTRACT: Spontaneously diabetic Torii (SDT) rats are an inbred strain of rats with a non-obese type 2 diabetes mellitus that were isolated from an outbred colony of Sprague-Dawley (SD) rats. Electroretinograms (ERGs) were recorded from SDT and SD (controls) rats at 10- and 44-weeks-of-age to determine their retinal function. The amplitudes and implicit times of the ERGs of the right and left eyes were not significantly different indicating that the intra-individual variation was small. Both amplitudes and implicit times of the ERGs in the SDT rats were not significantly different from those of SD rats at 10-weeks-of-age. At 44-weeks-of-age, however, the a- and b-waves and the oscillatory potentials were significantly reduced with prolonged implicit times in the SDT rats compared to SD rats. These depressed ERGs may reflect vascular and neuronal damage throughout the retina as are seen in the advanced stages of human diabetic retinopathy. Thus, the SDT rat can be used to study the retinal physiology of diabetic retinopathy.Documenta Ophthalmologica 04/2008; 117(3):191-6. · 2.11 Impact Factor -
Article: Endothelin-1 (ET-1) causes death of retinal neurons through activation of nitric oxide synthase (NOS) and production of superoxide anion.
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ABSTRACT: Endothelin-1 (ET-1) is the most potent and long-acting vasoconstricting peptide presently known. In addition to its vascular effects, endothelin signaling pathway exists in the central nervous system (CNS), which is deeply related to neuronal degeneration. In the present study, we evaluated the effect of ET-1 on death of retinal neurons consisting mainly of amacrine cells, and its interaction with nitric oxide synthase (NOS) and superoxide production. Cultured retinal neurons from fetal rats were exposed to various doses of ET-1 (0.1, 1.0, 10 and 100nM). Neuronal toxicity of ET-1 was assessed by trypan blue exclusion, Hoechst 33,258 staining and TUNEL assay at different times. Intracellular levels of nitric oxide (NO), superoxide and peroxynitrite were determined semiquantitatively by DAF2-DA, hydroethidine and dihydrorhodamine-123, respectively. The effects of adding SOD (100U/ml) and L-NAME with ET-1 on these changes were evaluated. In addition, the receptor mechanisms involved in these reactions were determined by BQ-123 and BQ-788, receptor antagonists for ET A and ET B receptors, respectively. Exposure of cultured retinal neurons to ET-1 reduced the percentage of living cells in a dose- and time-dependent way, and the percentage of living cells was significantly increased by addition of SOD and L-NAME. Fluorometric analyses revealed that ET-1 increased the intracellular NO level in a dose- and time-dependent manner. The intracellular superoxide and peroxynitrite levels were also significantly increased 24h after incubation with 100nM of ET-1, and this elevation was suppressed by SOD and L-NAME. These ET-1-induced alterations were significantly suppressed when both BQ-123 and BQ-788 were added simultaneously with ET-1 to the medium. These results indicate that the neuronal death caused by ET-1 is most likely mediated by the activation of NOS in association with the formation of superoxides and peroxynitrite.Experimental Eye Research 02/2008; 86(1):118-30. · 3.26 Impact Factor -
Article: Abnormalities of visual-evoked potentials and pupillary light reflexes in a family with autosomal dominant occult macular dystrophy.
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ABSTRACT: Occult macular dystrophy (OMD) is an unusual inherited or sporadic macular dystrophy characterized by an essentially normal appearing ocular fundus and normal ocular circulation determined by fluorescein angiography but with a progressive decrease of visual acuity. We present a family with OMD who have a delay in the implicit times of both the visual-evoked potentials and the pupillary light reflexes. Because these delays are usually indicative of optic nerve disorders, deciding on a diagnosis between OMD and optic nerve disorder should be done carefully. We are not aware of any studies that have reported these findings in patients with OMD.Clinical and Experimental Ophthalmology 12/2007; 35(8):781-3. · 1.98 Impact Factor -
Article: Angiotensin II receptor blocker inhibits abnormal accumulation of advanced glycation end products and retinal damage in a rat model of type 2 diabetes.
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ABSTRACT: The effects of an angiotensin II receptor blocker (ARB) on the accumulation of one of advanced glycation end products (AGEs), pentosidine, expression of vascular endothelial growth factor (VEGF) and retinal function were investigated in Spontaneously Diabetic Torii (SDT) rats. Candesartan, an ARB, was administered to SDT rats from 10 to 44 weeks of age and the results compared with untreated SDT rats and SD rats. Electroretinograms (ERGs) were recorded to evaluate retinal function. At 44 weeks of age, pentosidine was quantified in the vitreous, lens and plasma using high-performance liquid chromatography (HPLC). Real-time reverse transcription-PCR (RT-PCR) analysis was also performed in order to measure VEGF mRNA expression in the retina. Histological changes were examined and immunohistochemistry for pentosidine performed on the retina and retinal microvasculature. In untreated SDT rats, the amplitudes of a- and b-waves, oscillatory potentials were reduced significantly at 44 weeks of age compared with the 10-week levels, whereas they remained unchanged in SDT rats treated with candesartan. The concentration of pentosidine in the vitreous and lens did not change in treated SDT rats but increased in untreated SDT rats. Retinal VEGF mRNA expression was inhibited in treated SDT rats. Histologically, proliferative tissue was detected around the optic disc, with pentosidine being detected only in untreated SDT rats. Our findings indicate the ARB may inhibit the development of diabetic retinopathy by reducing the accumulation of pentosidine, one of AGEs and expression of VEGF in the retina.Experimental Eye Research 10/2007; 85(3):406-12. · 3.26 Impact Factor -
Article: High infusion pressure in conjunction with vitreous surgery alters the morphology and function of the retina of rabbits.
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ABSTRACT: To investigate the effects of high infusion pressure in conjunction with pars plana vitrectomy (PPV) on retinal morphology and function in rabbits. Pars plana vitrectomy was performed under urethane (0.8 mg/kg) anaesthesia in the right eye of albino rabbits following phacoemulsification and aspiration (PEA). The left eyes were not touched. After PEA, the animals were divided into two groups. In six eyes, intraocular pressure (IOP) was increased to 80 mmHg for 30 mins (high-pressure group) and in five eyes IOP was maintained at 40 mmHg for 30 mins (low-pressure group). The IOPs were regulated by the height of the bottle of balanced salt solution (BSS) and monitored with a pressure transducer. After the pressure elevation, vitreous fluid was collected to measure the glutamate concentration. Then, PPV was performed for 15 mins in both groups under an infusion pressure of 40 mmHg. In five additional rabbits, PEA alone was performed in the right eye, and vitreous fluid was collected (PEA group). Functional alterations were assessed by recording visual evoked potentials (VEPs) and electroretinograms (ERGs). Ten days after the IOP changes, the animals were killed with intravenous pentobarbital sodium and the eyes were prepared for histological analysis. Damage to retinal ganglion cells (RGCs) was quantified by counting the number of cells in the ganglion cell layer (GCL). The contralateral eyes in the high-pressure group served as controls (n = 6). The mean implicit time (IT) of the VEPs in the high-pressure group was significantly longer than that before the IOP elevation, by 114-124% (p < 0.05, paired t-test), and also than that of control eyes (p < 0.05, anova followed by t-test). No significant changes in the VEPs were detected in either the low-pressure group or the PEA group. There were significantly fewer cells in the GCL in the high-pressure group (24.7/mm) than in the control animals (41.4/mm; p < 0.05, Dunnett's test). The number of cells in the GCL in the low-pressure and PEA groups did not significantly differ to that in the controls. The amplitudes of the ERG a- and b-waves were not significantly changed (p > 0.05, paired t-test). These results suggest that high infusion pressure in conjunction with PPV leads to morphological and functional changes in the retina. The absence of ERG changes and presence of VEP changes suggest that these changes were due to damage to RGCs, which supports the morphological observations.Acta Ophthalmologica Scandinavica 09/2007; 85(6):633-9. · 1.85 Impact Factor -
Article: Glutamate level in optic nerve head is increased by artificial elevation of intraocular pressure in rabbits.
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ABSTRACT: Neurons can be damaged by the activation of glutamate receptors, but whether glutamate is related to the development of glaucomatous optic neuropathy is still controversial. The purpose of this study was to measure the acute changes in the glutamate levels in the optic nerve head (ONH) of rabbits induced by an artificial elevation of the intraocular pressure (IOP). A concentric microdialysis probe was inserted into the ONH of rabbits via the pars plana. The probe was perfused with Ringer's solution, and the levels of glutamate in 10-min dialysate samples were measured repeatedly using high-performance liquid chromatography. After the glutamate level was stabilized for at least 60 min, the IOP was adjusted to three levels; 120 mm Hg (n=11), 60 mm Hg (n=12), and 15 mm Hg (control group; n=11). The IOP was altered by changing the height of a bottle of Ringer's solution, which was connected to the anterior chamber by a 23-gauge needle. The IOP levels were maintained for 60 min, and the glutamate levels were determined every 10 min during the 60 min. The mean basal levels of glutamate in the 10-min dialysate were not significantly different among the three groups. The glutamate levels remained unchanged and stable in the controls, but elevation of the IOP significantly increased the level of the glutamate in the dialysate (IOP60, P=0.012; and IOP120, P=0.005: repeated measures ANOVA). Elevation of the IOP causes an increase in the glutamate levels in the ONH of rabbits. This suggests a possible interaction between glutamate metabolism and the IOP in the ONH.Experimental Eye Research 04/2006; 82(3):465-70. · 3.26 Impact Factor
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2002–2012
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Osaka Medical College
- Department of Ophthalmology
Takatsuki, Osaka-fu, Japan
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