Biomedical subjects

Chihiro Mayama

Publications and source records attributed to Chihiro Mayama.

7 recordsLinked to original sources

PubMed2006

No apparent association between ocular perfusion pressure and visual field damage in normal-tension glaucoma patients.

PURPOSE: To investigate the correlation of ocular perfusion pressure (OPP) with general and localized visual field damage in normal-tension glaucoma (NTG) patients. METHODS: Correlations between OPP, blood pressure, age, intraocular pressure, refractive error, and extent of visual field damage in the eye with the worst mean deviation (MD) were investigated retrospectively in 94 eyes of 94 NTG patients. Visual fields were analyzed statistically with respect to 15 sectors between two age-matched groups of subjects with high or low OPP. RESULTS: Significant positive correlations were found between OPP and age (P < 0.001), blood pressure and age (P < 0.05), and MD and refractive error (P < 0.01). OPP had no significant correlation with MD or mean sensitivity in the visual field in any of the visual field sectors. CONCLUSION: OPP and systemic blood pressure have no evident effect on the extent or pattern of visual field damage in NTG.

Adolescent↗

PubMed2006

Correlation between hemifield visual field damage and corresponding parapapillary atrophy in normal-tension glaucoma.

PURPOSE: To evaluate the correlation between the superior or inferior half area of parapapillary atrophy (PPA) and the corresponding hemifield visual field damage (VFD) in normal-tension glaucoma. DESIGN: Cross-sectional study. METHODS: patients: One hundred nine eyes of 109 consecutive patients with normal-tension glaucoma. observation procedures: Topography parameters of the optic nerve head and PPA (zone beta) area were obtained with the Heidelberg Retina Tomograph (HRT), and VFD was evaluated with the 30 to 2 program of Humphrey Field Analyzer. The HRT parameters and PPA area were determined separately in superior and inferior half regions. main outcome measures: Partial correlation coefficients of the superior and inferior areas of PPA with refractive error, axial length, HRT parameters, and corresponding hemifield VFD. RESULTS: In simple correlation analyses, significant correlation was found between the inferior PPA area and the superior hemifield VFD (Spearman rank correlation coefficient; Rs = -0.32; P < .001) but not between the superior PPA area and the inferior hemifield VFD (Rs = 0.05; P = .6). Age, refractive error, axial length, and height variation contour were associated significantly with the total, superior, and inferior areas of PPA, respectively (P < .01). Multiple regression analyses showed that the superior PPA area was associated significantly with only axial length (P < .001), and the inferior PPA area was associated significantly with the axial length and the superior hemifield VFD (P < .001). CONCLUSIONS: In patients with normal-tension glaucoma, only the inferior half area of PPA correlated significantly with glaucomatous VFD. Axial length and myopia were associated with both the superior and inferior half areas of PPA.

Cross-Sectional Studies↗

PubMed2006

Plasma endothelin-1 level in Japanese normal tension glaucoma patients.

PURPOSE: To compare the plasma concentration of endothelin-1 (ET-1) among patients < 60 years of age with normal-tension glaucoma (NTG), primary open-angle glaucoma (POAG), and in age-matched normal participants. METHODS: Plasma concentration of ET-1 was determined in 30 NTG 18 POAG patients, and 19 age-matched normal participants using an enzyme immunoassay. RESULTS: The ET-1 level was 1.49 +/- 0.51 pg/ml in the NTG patients (49.4 +/- 8.8 years), 1.58 +/- 0.64 pg/ml in the POAG patients (44.7 +/- 10.7 years), and 1.33 +/- 0.50 pg/ml in the normal participants (49.9 +/- 5.6 years). The ET-1 levels were not significantly different among the three groups, and no significant correlation with the extent of visual field damage, intraocular pressure (IOP), refraction, or age was seen in the glaucoma patients. CONCLUSIONS: The plasma ET-1 level showed no difference among NTG patients, POAG patients, and normal participants < 60 years of age in the Japanese population.

Adult↗

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

Influence of peripheral iridectomy on intravitreous penetration of topical nipradilol.

PURPOSE: Penetration of drug from the anterior chamber to the vitreous is substantial in aphakic eyes, but negligible in normal phakic eyes. The purpose of this study is to investigate the effect of the presence of peripheral iridectomy (PI) which bypasses iris-lens diaphragm on the drug penetration from the anterior chamber to the vitreous. METHODS: Twelve Japanese White rabbits underwent PI in a randomly chosen eye and the same procedures except removal of the peripheral iris in the contralateral eye. Nine weeks after the procedure, topical instillation of 20 microl of 1% nipradilol into the both eyes was repeated three times at five-minute intervals, and two hours later the animals were sacrificed and the both eyes were enucleated. Concentrations of nipradilol in the aqueous and vitreous were determined using a high-performance liquid chromatography. RESULTS: The concentrations of nipradilol were significantly greater in the eyes with PI than those in the contralateral control eyes in the aqueous (5636 +/- 1688 vs 2835 +/- 663 ng/g, mean +/- standard error, n = 12, p = 0.0028) and in the anterior vitreous (11.9 +/- 2.5 vs 5.6 +/- 1.0 ng/g, p = 0.0047), while not in the posterior vitreous or in the posterior retina-choroid. The ratios of the nipradilol concentrations in the anterior or posterior vitreous to that in the aqueous were not significantly different between the both eyes. CONCLUSIONS: The presence of PI had little effect on the penetration of topically instilled nipradilol from the anterior chamber to vitreous.

Administration, Topical↗

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↗

PubMedDate not supplied

Bilateral iris metastases from prostate cancer.

BACKGROUND: Iris metastases of malignant tumors are not common, and most of the cases are unilateral. To our knowledge, there has been no report of bilateral iris tumors metastasized from prostate cancer. CASE: A 71-year-old man with a history of prostate cancer presented with bilateral iris tumors and secondary glaucoma. He had had multiple bone metastases, and had undergone chemotherapy. OBSERVATIONS: Gray-white fleshy tumors spread in the iris of both eyes. Iridocyclitis and secondary glaucoma were present. After external beam radiotherapy, the iris tumors regressed remarkably in volume. CONCLUSIONS: We observed a rare case of bilateral iris tumors, which had probably metastasized from prostate cancer. The tumors were well controlled with conservative therapies including radiation. We believe this article is the first report of bilateral iris tumors metastasized from prostate cancer.

Aged↗