Force loss induced by inhibiting cross-bridge cycling is mitigated in eccentric contraction.

We examined whether the force loss induced by 2,3-butanedione monoxime affects isometric and eccentric forces differently. Single skinned muscle fibers were activated at an average sarcomere length of 2.4 µm and then stretched to 3.0 µm. This trial was performed with and without 2,3-butanedione monoxime to calculate the magnitude of force loss attained at several time points: pre-stretch phase at 2.4 µm, eccentric phase, end of eccentric contraction, and post-stretch phase at 3.0 µm. The magnitude of force loss was significantly larger in the pre-stretch phase than at the other time points. Further, the mitigated force loss in the eccentric contraction was more prominent in the long condition than in the short condition. We suggest that the eccentric force is relatively preserved compared with the reference isometric force (pre-stretch) when cross-bridge cycling is inhibited, possibly because of the contribution of the elastic force produced by titin.

Characteristics of cases needing advanced treatment for intractable Posner-Schlossman syndrome.

BACKGROUND: In Posner-Schlossman syndrome (PSS), which is characterized by recurrent unilateral attacks of ocular hypertension. Surgical treatment is sometimes necessary because intraocular pressure (IOP) cannot be controlled with anti-glaucoma medications. To identify the clinical features of Posner-Schlossman syndrome (PSS) indicative of the need for intraocular pressure (IOP)-controlling surgery. METHODS: This study was a retrospective case-series analysis of the clinical charts of 33 patients diagnosed with PSS, who underwent surgery to control IOP or received medication only. Various clinical factors were compared between the surgical and medication groups. RESULTS: The surgical group had a higher corneal endothelial cell (CEC) density loss (p < 0.05), higher maximum IOP (p < 0.01), greater visual field loss (p < 0.01) and higher positive number for cytomegalovirus (CMV) (p < 0.001) than the non-surgical group. Eighteen of the 33 patients had a high CEC reduction ratio. Of these 18, 16 required glaucoma surgery. CONCLUSIONS: PSS patients with a higher CEC reduction ratio, higher maximum IOP, greater visual field loss and higher positive number for CMV in the aqueous humor tended to be more likely to require progressive treatment, such as glaucoma surgery.

Influence of caffeine on the maximal isometric and concentric force produced by skinned fibers.

Caffeine is one of the most famous and widely used ergogenic drugs, especially by athletes to improve sports performance. Caffeine is known to enhance muscle contraction by facilitating Ca2+ release from the sarcoplasmic reticulum. While the effect of caffeine on the cross-bridge dynamics has also investigated, the results is controversial. Therefore, the purpose of this study was to examine the influence of caffeine on cross-bridge dynamics using skinned fiber preparations from rabbit soleus (N = 19 in total). We performed isometric contractions at an average sarcomere length of 2.4 µm; thereafter, skinned fibers were shortened by 20% of the fiber length at a velocity of 0.1 mm/s (slow shortening) or 0.5 mm/s (fast shortening). The contractions were performed under both normal and caffeine-containing activating solution conditions to compare the isometric, slow concentric, and fast concentric forces between conditions. The isometric force did not differ between normal and caffeine-containing activating solution conditions. Similarly, the concentric forces obtained during the slow and fast shortening trials did not differ between conditions. We also measured the stiffness and the rate of force redevelopment (kTR) during the isometric contraction phase and found that these values were not different between normal and caffeine conditions. Based on these results, we conclude that the influence of caffeine on cross-bridge dynamics is negligible, and the ergogenic effect of caffeine, from the view of muscle contractility, is by facilitating Ca2+ release, as suggested in previous studies, and not by modulating the cross-bridge dynamics.

Association between changes in visual acuity and vision-related quality of life in Japanese patients with low vision.

PURPOSE: To investigate the association between vision-related quality of life (VRQOL) and changes in visual acuity (VA). METHODS: We examined the VA in 100 patients for > 1 year and evaluated the degree of its impact on VRQOL using the National Eye Institute Visual Function (VF) Questionnaire (VFQ-25; Japanese version). Before determining VFQ-25, we monitored the changes in VA in these patients for 1 year and classified them into the following two groups depending on VA changes. Patients exhibiting a decline of > 3 steps in VA, as assessed by the logarithm of the minimum angle of resolution scale, were placed in the 'decline' group (47.0%) and patients exhibiting no change in VA were placed in the 'no change' group (53.0%). We compared the VFQ-25 scores between both groups in all patients with glaucoma (GLA) and macular degeneration (MD). RESULTS: The total score of the decline was 34.9 ± 13.6 and that of the no change group was 44.6 ± 13.9: the difference in the scores between both groups was statistically significant (p = 0.006). Similar results were obtained for patients with GLA and MD (p = 0.007 and 0.003, respectively). CONCLUSION: VRQOL differed between patients with constant VA and those with reduced VA, even though VA values were equal at a certain time point.

[Appositional angle closure in narrow angle eyes].

Primary angle closure glaucoma (PACG) is a vision-threatening type of glaucoma. A high prevalence of PACG has been reported in the Asian region. In this review article, we would like to introduce novel findings on appositional angle closure, which plays an important role in the processes of PACG, based upon a new classification. Also, our studies of narrow angle eyes with the use of ultrasound biomicroscopy(UBM) revealed interesting features of appositional angle closure. Our studies showed that appositional angle closure was found frequently in dark conditions, and also that the width and location of the angles examined were significantly related to the presence of appositional angle closure. The use of UBM enabled us to observe physiologic changes in the angle structure in dark conditions, and provided us important information on the pathogenesis of PACG.

[Evaluation of quality of life characteristics and grade of legal visual impairment].

PURPOSE: To evaluate the possible correlation between quality of life (QOL) characteristics and grades of legal visual impairment. MATERIALS AND METHODS: Quality of life characteristics associated with various causes of visual loss were investigated in 237 Japanese patients in the low-vision care clinic at Tokyo University Hospital, who had been issued the official ID and handbook for the physically handicapped. The main causes of vision loss were glaucoma (87 patients), macular degeneration (35) and diabetic retinopathy (34). Using a previously developed questionnaire, we assessed the correlation between the disability index (DI) as a quality of life characteristic, and the grade of legal visual impairment. RESULTS: Total DI was 1.24 +/- 0.43, showing a very significant correlation with Handicapped Handbook grades (r = -0.44, p < .0001). The correlation coefficients were -0.63 (p < 0.0001) for diabetic retinopathy, -0.50 (p = 0.002) for macular degeneration, and -0.16 (p = 0.14) for glaucoma patients. CONCLUSION: The needs of low-vision patients correlate with the grade of legal visual impairment and it is important to understand that the needs of low vision patients differ for each disease.

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.

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.

Prevalence of appositional angle closure determined by ultrasonic biomicroscopy in eyes with shallow anterior chambers.

PURPOSE: To determine the prevalence of appositional angle closure in eyes with a shallow peripheral anterior chamber but no peripheral anterior synechia (PAS) in Japanese patients. DESIGN: Cross-sectional study. PARTICIPANTS: Eighty eyes of 80 consecutive patients with a shallow peripheral anterior chamber, determined using the method of van Herick, and no PAS. METHODS: The anterior chamber angle was classified according to Shaffer's grading with noncompression gonioscopy superiorly, inferiorly, temporally, and nasally. The absence of PAS was confirmed by compression gonioscopy if necessary. The presence of appositional angle closure and the trabecular-iris angle (T-I angle) was determined with ultrasound biomicroscopy in each quadrant under light and dark conditions. Factors related to appositional angle closure were studied using logistic analysis, and the covariates included gender, age, refraction, gonioscopic grading, and the quadrant of the angle measured. MAIN OUTCOME MEASURES: Gonioscopic grading of the angle width, the T-I angle, and the prevalence of appositional closure. RESULTS: The gonioscopic grading (P<0.001 in light and dark) and the T-I angle (P<0.001 in light and dark) varied significantly among the 4 quadrants. Narrower angle gradings were observed more frequently superiorly. The T-I angle was narrower superiorly (in light) and inferiorly (in dark) (P<0.001 and P = 0.040, respectively). The T-I angle was significantly narrower in dark than in light (P<0.001). The sites with the narrower gonioscopic gradings tended to have a smaller T-I angle (P<0.001 and P = 0.006 in light and dark, respectively). Appositional angle closure was found in at least 1 quadrant in 46 (57.5%) of 80 eyes in light and in 68 eyes (85%) in dark. Logistic analysis showed that gonioscopic grading and the quadrant were significantly related to the presence of appositional angle closure in light and dark (P<0.003 for both comparisons). CONCLUSIONS: Appositional angle closure was frequently observed in eyes with a shallow peripheral anterior chamber, especially under dark conditions in Japanese patients. The angle width, evaluated with conventional gonioscopic grading, and the quadrant of the angle were significantly related to the presence of appositional angle closure.

Frequency doubling technology and scanning laser tomography in eyes with generalized enlargement of optic disc cupping.

PURPOSE: To characterize functional and structural changes in eyes with generalized enlargement of optic disc cupping (vertical cup/disc ratio > or = 0.8), normal intraocular pressure, normal standard achromatic automated perimetry (SAP) results, and no other ophthalmoscopic findings suggesting glaucoma (large C/D eyes) using frequency doubling technology (FDT) and the Heidelberg Retina Tomograph (HRT). METHODS: This comparative observational case series included 30 large C/D eyes (30 subjects), 17 eyes (17 patients) with early-stage normal tension glaucoma with generalized enlargement of optic disc cupping (NTG eyes), and 25 eyes from 25 normal subjects (normal eyes). Results with Humphrey 30-2, FDT N-30 threshold programs, and HRT were compared among these groups. Large C/D eyes were subdivided into FDT-normal and -abnormal eyes according to the predetermined criteria and HRT parameters were compared among them. RESULTS: No significant difference was seen in HRT parameters between the large C/D and NTG eyes. In the large C/D eyes, FDT mean deviation was lower than in the normal eyes and higher than in the NTG eyes, whereas FDT pattern standard deviation was smaller than in the NTG eyes (P = 0.02-0.03). Among HRT parameters, only cup shape measure (CSM) showed significant negative correlation with FDT mean deviation in the large C/D eyes. Between FDT-normal and -abnormal subgroups, only CSM showed significant difference (P < 0.01). CONCLUSION: Frequency doubling technology showed abnormalities in large C/D eyes. Only CSM showed significant correlation with FDT result and difference between those with normal and abnormal FDT results. In management of large C/D eyes, FDT and CSM will be useful to detect functional and structural change.

Specificity and sensitivity of glaucoma detection in the Japanese population using scanning laser polarimetry.

AIMS: To investigate the usefulness of the scanning laser polarimeter (GDx; GDx Nerve Fiber Analyzer) for glaucoma detection in the Japanese population, and to investigate the difference in the thickness of retinal nerve fibre layer (RNFL) between normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). METHODS: 69 eyes of 69 normal subjects and 115 eyes of 115 chronic open angle glaucoma patients (60 NTG and 55 POAG patients) were studied. The thickness of RNFL was measured with GDx. An eye was diagnosed as glaucomatous, if at least one original GDx variable showed p <5%. The difference in thickness of RNFL between the NTG and POAG groups was then investigated. RESULTS: 46 normal eyes (66.7%) were diagnosed as not glaucomatous (no variables showing p <5%), and 93 glaucomatous eyes (46 NTG and 47 POAG eyes) (80.9%) were diagnosed as glaucomatous. Actual values of average thickness, ellipse average, superior average, and superior integral were significantly lower in the POAG group than those in the NTG group. CONCLUSIONS: New variables which elucidate focal RNFL defects or early changes are needed to improve the moderate detection ability found in this present study. The pattern of the change in RNFL may differ in NTG and POAG groups.

Spontaneous posterior dislocation of intraocular lenses fixated in the capsular bag.

We report 4 cases of complete posterior dislocation of an intraocular lens (IOL) in the capsular bag occurring a mean of 5.5 years after uneventful cataract surgery. In all 4 cases, posterior chamber IOLs were fixated within the capsulorhexis. The patients experienced sudden loss of vision without an episode of trauma or ocular disease. Using a 3-port pars plana vitrectomy, the IOLs were explanted through a limbal incision and a new IOL was sutured to the ciliary sulcus. Histological examination indicated that zonular fibers were severed at the site of insertion in the capsule.

[Frequency-doubling perimetry in examination of open-angle glaucoma with hemifield defect].

OBJECTIVE: To determine whether frequency-doubling perimetry (FDP) can find visual field defect of early glaucoma which can not be found by conventional perimetry. METHODS: Forty-nine eyes of 49 patients with open-angle glaucoma and hemifield defect detected by Humphery Field Analyzer (HFA) were tested by both FDP (threshold test C-20) and Heidelberg Retina Tomograph (HRT). For each hemifield, its FDP result was evaluated. According to the FDP results in intact HFA hemifields, the patients were divided into FDP normal group and FDP abnormal group. The HRT parameters of half disk corresponding to the intact HFA hemifields were compared between these two groups. RESULTS: There was a strong correlation between the mean sensitivity of FDP and mean deviation of HFA results (r = 0.58, P < 0.01). In intact HFA hemifields, 41% (20/49) of eyes showed visual loss in FDP tests, while in defective HFA hemifields, only 2% (1/49) of eyes was normal in FDP test. For the HRT parameters of half disk corresponding to the intact HFA hemifields, cup area and cup/disk area ratio were statistically bigger and rim area and rim volume were statistically smaller in FDP abnormal group than in FDP normal group. CONCLUSION: FDP is able to detect early glaucomatous visual field damage which can not be detected by HFA, but can be explained by the optic nerve glaucomatous changes in HRT parameters.

Relationship between vision-related quality of life in Japanese patients and methods for evaluating visual field.

PURPOSE: To investigate the relationship between methods used to evaluate the visual field (VF) and vision-related quality of life (VRQOL) in Japanese patients. METHODS: We evaluated the VRQOL of 50 patients using the National Eye Institute Visual Function Questionnaire 25 (VFQ-25). Patients meeting the following criteria were assessed: (1) a Goldmann perimetry (GP) test conducted within 3 months of the initial visit; (2) best-corrected decimal visual acuity (VA) of the better eye when VRQOL was measured was less than 0.3 but more than 0.05. The VF was estimated based on a composite measure of the V-4e isopters of both eyes, as measured by GP. We calculated the VF using the American Medical Association (AMA) score, the Esterman disability score (EDS), the functional field score (FFS), the composite VF area calculated with area measurement software, and SR, an evaluation method based on solid angles. We then studied the relationships between the VFQ-25 score and the VF scores. RESULTS: Only EDS correlated significantly with the VFQ-25 score (r = 0.34, P = 0.02); AMA scoring did not correlate with the VFQ-25 score. CONCLUSION: It is necessary to reexamine standard VF evaluation methods.

Ultrasound biomicroscopy in narrow peripheral anterior chamber eyes with or without peripheral anterior synechiae.

AIM: To compare the configurations of the anterior ocular segment including the anterior chamber (AC) angle and ciliary body between eyes with a narrow AC angle (ACA) with and without peripheral anterior synechiae (PAS). PATIENTS AND METHODS: One hundred and one eyes of 101 consecutive patients with a temporal peripheral AC depth one-quarter of the corneal thickness or less were included. Gonioscopy and ultrasound biomicroscopy were performed under light and dark conditions. The existence of PAS was further confirmed with compression gonioscopy with indentation. Eyes with findings suggestive of plateau iris configuration or those with glaucomatous optic neuropathy were carefully excluded. The biometric parameters including the ACA, the angle opening distance at 500 mum, the trabecular-ciliary process distance, the iris-zonule distance, and the scleral-ciliary process angle were determined. RESULTS: PAS were found in 43 (43%) of the 101 eyes. There were no differences in age, refractive error, or intraocular pressure between PAS-positive and PAS-negative eyes (P>0.1). ACA, iris-zonule distance, scleral-ciliary process angle under light and/or dark conditions were significantly smaller in the PAS-positive eyes than in the PAS-negative eyes (P<0.05). CONCLUSIONS: Shallow peripheral AC depth and relatively anteriorly located ciliary body was significantly associated with the presence of PAS in eyes with a narrow ACA.