Biomedical subjects

Kyoko Ishida

Publications and source records attributed to Kyoko Ishida.

8 recordsLinked to original sources

PubMed2005

Glaucoma drainage implants in pediatric patients.

Approximately, one fifth of primary congenital glaucoma patients fail primary surgery. Also, some pediatric glaucomas respond poorly to goniotomy or trabeculectomy. In these situations, clinicians often choose trabeculectomy with mitomycin-C or a drainage implant as a surgical treatment. Glaucoma drainage device implantation is a useful option in refractory patients. When other surgical treatments have a poor prognosis for success, prior conventional surgery fails, or significant conjunctival scarring precludes filtration surgery, glaucoma drainage implant may effectively control intraocular pressure. Patients often require adjunctive glaucoma medications after surgery and may develop complications. Most of these complications, however, are reversible or resolve spontaneously, and most are not associated with vision loss.

Adolescent↗

PubMed2005

Pattern electroretinogram abnormality and glaucoma.

PURPOSE: To determine the existence of retinal ganglion cell dysfunction and associated risk factors in glaucoma suspects with increased optic disc cupping and normal visual field. DESIGN: Cross-sectional, observational study. PARTICIPANTS: Two hundred glaucoma suspect (GS) patients were identified based on optic disc abnormalities (vertical cup-to-disc ratios [C/D]>0.5; vertical C/D asymmetry >or= 0.2; disc hemorrhages; notching) in association with known glaucoma risk factors (positive family history, African American descent, increased intraocular pressure [IOP]), but normal visual fields. Forty-two patients had early manifest glaucoma (EMG). Sixteen normal black subjects were added to update previous pattern electroretinogram (PERG) normative data and to establish a normal control (NC) group with a racial breakdown comparable with that of the study groups. METHODS: Pattern electroretinograms were recorded simultaneously from both eyes using skin electrodes and automated analysis; visual fields were monitored with standard white-on-white automated perimetry (SAP) central 24-2 program; vertical C/D was evaluated by an independent reader from stereo disc photographs; and univariate and multivariate statistical analysis between PERG and other outcome measures was evaluated. MAIN OUTCOME MEASURES: Pattern electroretinogram amplitude (microV), phase (pi rad), and interocular asymmetry in amplitude and phase (%); and SAP mean deviation (MD; decibels), vertical C/D, age (years), IOP (mmHg), and race (black vs. nonblack). RESULTS: The PERG results were abnormal in at least 1 of the outcome measures in 52% of GS patients and 69% of EMG patients. The PERG amplitude was correlated weakly with both MD (P<0.01) and vertical C/D (P = 0.05). The correlation between PERG amplitude and MD and C/D was stronger (P<0.001) for interocular differences rather than absolute measures. Interocular PERG amplitude asymmetry increased with severity of disease (EMG>GS>NC; P<0.01). The PERG amplitude decline with age was steeper in patients with a more negative MD (P<0.01) and in patients with a more negative MD and a larger vertical C/D (P = 0.06). Black race (but not family history) was associated with lower PERG amplitude (P = 0.005) in GS and EMG patients, but not in normal controls (P = 0.44). CONCLUSIONS: The correlation between PERG abnormality and known risk factors for glaucoma indicates that PERG has a predictive potential for the development or progression of the disease, or both.

Adult↗

PubMed2005

[Difference of optic disc topography between a low-tension group and a high-tension group in normal-tension glaucoma patients].

PURPOSE: Glaucomatous visual field loss and optic disc damage differ by intraocular pressure (IOP) levels. In this study, we compared the optic disc topography in the high-tension group and the low-tension group in normal-tension glaucoma (NTG). METHOD: We selected NTG patients with mean deviation (MD) > or = -10.00 dB and the highest recorded IOP of < 14 mmHg or > or = 17 mmHg without glaucoma treatment. We classified NTG eyes into the following two groups: 1) a low-tension group with the highest recorded IOP of < 14 mmHg, 2) a high-tension group with the highest recorded IOP of > or = 17 mmHg. The optic disc parameters in the low-tension group eyes were compared with those in the high-tension group eyes using a Heidelberg Retina Tomograph. RESULTS: Nineteen eyes of nineteen patients were selected for each group. The cup/disc area ratio in the global sector, and the rim volume in the nasal sector of the low-tension group had deteriorated more than in the high-tension group. CONCLUSIONS: The disc topography is different between the low-tension group and the high-tension group in the nasal sector, suggesting that different pathogenetic mechanisms exist in the optic disc damage in NTG.

Aged↗

PubMed2004

Identification of crucial histidines involved in carbon-nitrogen triple bond synthesis by aldoxime dehydratase.

Aldoxime dehydratase (OxdA), which is a novel heme protein, catalyzes the dehydration of an aldoxime to a nitrile even in the presence of water in the reaction mixture. The combination of site-directed mutagenesis of OxdA (mutation of all conserved histidines in the aldoxime dehydratase superfamily), estimation of the heme contents and specific activities of the mutants, and CD and resonance Raman spectroscopic analyses led to the identification of the proximal and distal histidines in this unique enzyme. The heme contents and CD spectra in the far-UV region of all mutants except for the H299A one were almost identical to those of the wild-type OxdA, whereas the H299A mutant lost the ability of binding heme, demonstrating that His(299) is the proximal histidine. On the other hand, substitution of alanine for His(320) did not affect the overall structure of OxdA but caused loss of its ability of carbon-nitrogen triple bond synthesis and a lower shift of the Fe-C stretching band in the resonance Raman spectrum for the CO-bound form. Furthermore, the pH dependence of the wild-type OxdA closely followed the His protonation curves observed for other proteins. These findings suggest that His(320) is located in the distal heme pocket of OxdA and would donate a proton to the substrate in the aldoxime dehydration mechanism.

Amino Acid Sequence↗

PubMed2004

Statistical evaluation of the diagnostic accuracy of methods used to determine the progression of visual field defects in glaucoma.

OBJECTIVE: To evaluate trend-type analyses to judge the progression of visual field damage (VFD) of glaucoma in terms of ratios of making judgments of progression and specificity, and to report a new method. DESIGN: Retrospective analysis of visual field (VF) results of actual glaucoma cases and those simulated by computer, and receiver operating characteristic curve analysis of performance of methods to judge the progression of VFD. PARTICIPANTS: One hundred five eyes of 105 open-angle glaucoma (OAG) patients with progressing VFD and 355 eyes of 355 clinically stable OAG patients for VF simulation from 4 university-based referral practices. METHODS: Methods using regression analysis of total deviation (TD), mean deviation (MD), mean TD of a sectored VF, and original scoring used in the Advanced Glaucoma Intervention Study (AGIS) were compared. A VF test was repeated twice in a short period on the 355 stable OAG eyes, and test-retest fluctuation, including variance at each test point and covariance between 2 test points, was calculated to simulate stable glaucomatous VF series by computer. The sensitivity of each method was calculated with 105 progressing VF series, and specificity was calculated with 10,000 simulated stable glaucomatous VF series. MAIN OUTCOME MEASURES: Sensitivity (ratios of making judgments of progression), specificity, and diagnostic power. RESULTS: The methods using the TD slope on one test location showed a sensitivity of 0.848 to 1.000, with a specificity of 0.105 to 0.721, and on 2 adjacent test locations showed a sensitivity of 0.848, with a specificity of 0.722. A significant negative MD slope with P<0.05 showed a sensitivity of 0.524, with a specificity of 0.945. The method using a sectored VF showed a sensitivity of 0.695, with a high specificity of 0.946. The AGIS method showed a sensitivity of 0.305 to 0.467, with a very high specificity of 0.999 to 1.000. The method using previously reported mathematically sectored VFs showed a sensitivity of 0.790, with a specificity of 0.900, and higher diagnostic power (1.69) than the others in this study population. CONCLUSIONS: Most of the methods using the TD slope were characterized by high sensitivity, the AGIS method had a very high specificity, and those using VF sectors had reasonable sensitivity and specificity.

Adolescent↗

PubMed2004

Optic disc hemorrhages detected in a large-scale eye disease screening project.

PURPOSE: To investigate the prevalence and characteristics of optic disc hemorrhages. MATERIALS AND METHODS: We took IMAGEnet fundus photographs of 14,779 participants, aged 40 years or older in a large-scale eye disease screening project conducted in Tajimi, Japan. A single researcher reviewed all of the photographs for the presence of ocular abnormality in the optic nerve head and retina, paying special attention to the presence or absence of optic disc hemorrhages. Glaucomatous optic neuropathy was diagnosed based on the presence of nerve fiber layer defects and/or the appearance of the optic disc. RESULTS: Fundus photographs of 13,965 cases (27,930 eyes) were successfully reviewed bilaterally. We found disc hemorrhages at 92 locations of 92 (0.3%) eyes of 88 (0.6%) cases. Twenty-four hemorrhages of 23 (26%) cases were found in bilateral non-glaucoma cases and the remaining 68 hemorrhages of 65 (74%) cases were found in glaucoma cases. The prevalence of disc hemorrhages was 8.2% in 793 glaucoma cases and 0.2% in non-glaucoma cases. Hemorrhages developed significantly more frequently in females and in the elderly. The hemorrhages were predominantly found in the inferotemporal and superotemporal regions. The intraocular pressure was less than 20 mm Hg in all cases. The mean intraocular pressure was 15.0 mm Hg for glaucoma cases with hemorrhages and 13.9 mm Hg for non-glaucoma cases with hemorrhages. CONCLUSION: Disc hemorrhages occur more frequently in females, in elderly persons, and in glaucoma cases in Japanese aged 40 or older. The intraocular pressure of the eyes with disc hemorrhages is close to that of the normal population.

Adult↗

PubMed2003

Characteristics of visual field progression in patients with normal-tension glaucoma with optic disk hemorrhages.

PURPOSE: To study the characteristics of visual field progression in patients with normal-tension glaucoma (NTG) with optic disk hemorrhages. DESIGN: Observational study. METHODS: Fifty-eight eyes of 58 untreated patients with NTG who had at least five reliable visual fields of the Humphrey Field Analyzer (central 30-2) within the follow-up period of more than 24 months were enrolled. Of these, 27 eyes had optic disk hemorrhages in their clinical courses. Pointwise linear regression analysis was done using total deviation values of the fields at each of 74 test locations in each patient. Progression was defined as the points of negative slopes with P <.01. A whole visual field was concentrically divided into three clusters: the areas within 10 degrees, 10 to 20 degrees, and 20 to 30 degrees. Percentages of the progressed points of the three clusters and a whole field were compared between the groups with and without optic disk hemorrhages. RESULTS: No significant differences were found in patients' backgrounds, including initial mean deviation values, follow-up periods, and the number of visual field examinations between the 27 patients with optic disk hemorrhages and the 31 without. The group with optic disk hemorrhages showed significantly higher percentages of progressed points within the 10-degree area compared with the group without optic disk hemorrhages (mean +/- SD: 13.1 +/- 13.7%; 5.1 +/- 8.5%, respectively; P =.0086, Student t test), whereas no significant differences were found in the other two clusters or in a whole field. CONCLUSIONS: Patients with NTG with optic disk hemorrhages tend to show visual field progression in areas within 10 degrees.

Adult↗

PubMed2002

Myopia and advanced-stage open-angle glaucoma.

OBJECTIVE: To investigate the effect of myopic refraction on the central visual field in patients with advanced open-angle glaucoma (OAG). DESIGN: Multicenter cross-sectional study. PARTICIPANTS: Three hundred thirteen OAG eyes (176 eyes of 176 primary open-angle glaucoma [POAG] patients and 137 eyes of 137 normal-tension glaucoma [NTG] patients) with clear ocular media and a mean deviation (MD) <-15 dB. Patients with a recorded maximum intraocular pressure (IOP) of 22 mmHg or greater were classified as POAG, and those with an IOP of 21 mmHg or less were classified as NTG. METHODS: Multiple regression analysis was used to study the influence of refraction on 12 central test points of the C30-2 Humphrey program, and the differences in visual field defects between POAG and NTG eyes were examined using logistic discriminant analysis. In the multiple regression analysis, total deviation (TD) of the 12 test points was graded and used as the dependent variable, and MD and the spherical equivalent refraction were the explanatory variables. In the logistic discrimination analysis, TD, MD, and refraction were covariants that determined the OAG subtypes. MAIN OUTCOME MEASURES: TD values of the 12 central test points (C30-2 program). RESULTS: Higher myopic refraction was significantly associated with more damage at a point just temporal and inferior to the fixation point in POAG eyes, whereas it was significantly associated with less damage at test points just temporal and superior to the fixation point in NTG eyes. After correcting for the influence of refraction, POAG eyes had significantly more damage at a test point just temporal and inferior to the fixation point, whereas NTG eyes had significantly more damage at those test points nasal and inferior to the fixation point. CONCLUSIONS: High myopia constitutes a threat to the remaining lower cecocentral visual field and is one of the factors that interfere with the quality of vision in advanced OAG with high IOP but not low IOP.

Cross-Sectional Studies↗