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T Hikichi

Publications and source records attributed to T Hikichi.

At least 55 records · Page 3Linked to original sources
PubMed1996

Evidence of cross-link formation of vitreous collagen during experimental ocular inflammation.

PURPOSE: To determine the mechanisms of vitreous changes during ocular inflammation. METHODS: We investigated vitreous changes, with special emphasis on collagen, in an experimental model of ocular inflammation induced by intravitreal injection of endotoxin (Escherichia coli) in rabbits. RESULTS: Inflammation caused gel contraction and loss of elasticity, accompanied by release of a water-like liquid from the gel, and increases in the amount of insoluble material and high-molecular-weight components of vitreous collagen, presumably due to extensive cross-links of the collagen molecules. Those changes were partially inhibited by intravitreal injection of superoxide dismutase. CONCLUSIONS: The cross-links of vitreous collagen may promote vitreous gel contraction and release of a water-like liquid from the gel. Superoxide anion may play a role in this process.

Animals↗
PubMed1996

Imaging of epiretinal membranes in macular holes by scanning laser ophthalmoscopy.

PURPOSE: Because recognition and removal of an epiretinal membrane are important in macular hole surgery, we used the scanning laser ophthalmoscope preoperatively to study epiretinal membranes in patients with idiopathic macular holes. METHODS: We studied 67 eyes (60 consecutive patients) with idiopathic macular holes. We evaluated the thickness and the extent of the epiretinal membrane by using a scanning laser ophthalmoscope. We then compared the fundus images obtained with the scanning laser ophthalmoscope with red-free monochromatic fundus photographs. RESULTS: Confocal imaging of the fundus with either argon blue (488 nm) or argon green (514 nm) laser illumination clearly showed the epiretinal membranes. In all eyes, we observed lesions ranging from a patchy glinting light reflex to a dense epiretinal membrane. A well-demarcated dense epiretinal membrane around the macular hole was observed in seven (44%) of 16 eyes with stage 2 macular holes and in 12 (40%) of 30 eyes with stage 3 holes, but in only two (10%) of 21 eyes with stage 4 holes. The prevalence of the dense epiretinal membrane in stage 2 or 3 holes was significantly higher than in stage 4 holes (P = .025 and .024, respectively). CONCLUSIONS: Fundus imaging using the scanning laser ophthalmoscope with argon laser illumination is useful preoperatively to evaluate epiretinal membranes in eyes with idiopathic macular holes.

Aged↗
PubMed1996

[Role of the vitreous in central retinal vein occlusion].

To investigate the role of the vitreous in eyes with central retinal vein occlusion, especially in relation to neovascularization and macular edema, we conducted a retrospective chart review of the vitreous condition of 150 patients (150 eyes) with central retinal vein occlusion. Based on fluorescein angiography findings and color photographs, eyes with central retinal vein occlusion were classified as ischemic or nonischemic. In ischemic cases, retinal or optic disc neovascularization, or both, developed in eight (57%) of 14 eyes without complete posterior vitreous detachment at the final examination. The prevalence of neovascularization was significantly higher than in eyes with complete posterior vitreous detachment (0%, 0/43) at the final examination (p < 0.01). In nonischemic cases, the prevalence of no posterior vitreous detachment or partial posterior vitreous detachment with vitreomacular adhesion was significantly higher in eyes with macular edema (76%, 28/37) than in eyes without it (23%, 13/56) at the final examination (p < 0.01). Complete posterior vitreous detachment may protect against retinal or optic disc neovascularization in eyes with severe central retinal vein occlusion. Vitreomacular adhesion may cause persistent macular edema in eyes with mild central retinal vein occlusion.

Adult↗
PubMed1996

Ocular conditions associated with posterior vitreous detachment in young patients.

BACKGROUND AND OBJECTIVE: To investigate the ocular conditions associated with posterior vitreous detachment (PVD) in young patients. PATIENTS AND METHODS: The vitreous conditions of 861 patients younger than 30 years were studied retrospectively and examined biomicroscopically. RESULTS: In the first and second decades of life, retinitis pigmentosa, nondiabetic retinal vascular disorders, and a history of ocular contusion were most commonly associated with PVD. In the third decade of life, proliferative diabetic retinopathy was overwhelmingly the condition most commonly associated with PVD. CONCLUSION: This study delineated the ocular pathologic conditions associated with PVD in young patients. These findings may be useful in the management of PVD in patients younger than 30 years.

Adolescent↗
PubMed1996

Vitreous changes during ocular inflammation induced by interleukin 1 beta.

To determine the mechanisms of vitreous changes during ocular inflammation, we investigated these changes, focusing on the collagen, in an experimental model of ocular inflammation induced by intravitreal injection of interleukin 1 beta in rabbits. Inflammation caused gel contraction, with release of a watery liquid from the gel, and increases in the amount of insoluble material and high-molecular-weight components of the vitreous collagen, presumably due to extensive cross-links of the collagen molecules. The cross-links of vitreous collagen may promote vitreous gel contraction and the release of watery liquid from the gel.

Animals↗
PubMed1996

A case of idiopathic portal hypertension complicated with narrowing of intrahepatic bile ducts.

A 37-year-old woman who had portal hypertension followed by splenomegaly, developed collateral blood flow of spleno-renal shunt and paraesophageal veins, esophageal varices and further with narrowing of intrahepatic bile ducts shown by endoscopic retrograde cholangiography was described. Liver function was almost normal except the slight elevation of serum alkaline phosphatase and gamma-glutamyl transpeptidase levels. However, endoscopic retrograde cholangiography revealed the narrowing of the intrahepatic bile ducts. The histological examination of biopsied specimen showed no prominent change in portal tracts and bile ducts without cell infiltration or fibrosis in the portal area. This case will be considered as idiopathic portal hypertension complicated by narrowing of the intrahepatic bile ducts.

Adult↗
PubMed1996

Clinical characteristics of traumatic macular holes.

The clinical characteristics of 20 eyes of 20 consecutive patients with traumatic macular hole were studied retrospectively. The macular holes were elliptical with irregular edges in 19 eyes (95%) and ranged in size from 0.2 to 0.5 DD (disc diameter). Posterior vitreous detachment (PVD) was found in only 3 eyes (15%); the vitreous was detached from the macula in only one of these 3. Other conditions found in the 20 patients included commotio retinae, vitreous hemorrhage, hyphema, and choroidal rupture. These findings strongly suggest that most traumatic macular holes develop in the absence of PVD and that the pathogenesis is independent of the occurrence of PVD. We believe that the macular rupture (hole) is caused mechanically by the force of the impact on the posterior pole and the ocular deformity which result from blunt trauma.

Accidents↗
PubMed1995

Prevalence of dry eye in Japanese eye centers.

BACKGROUND: The purpose of the investigation was to ascertain the prevalence of dry eye in new outpatients. METHODS: A total of 2127 consecutive new outpatients seen in eight Japanese centers from April 1992 to January 1993 underwent comprehensive examinations, including double vital staining and measurement of tear film break-up time, basal tear secretion, and tear clearance. Dry eye was diagnosed if patients had abnormalities of both the tear film and the ocular surface. RESULTS: Three hundred fifty-nine patients (17%) had dry eye. There was no seasonal pattern for dry eye. The condition was significantly more common in Tokyo than in suburban areas (P < 0.01). The prevalence of dry eye in visual display terminal (VDT) users and contact lens (CL) wearers was significantly higher than in non-VDT users and non-CL wearers (P < 0.05 and P < 0.02, respectively). CONCLUSION: Our findings suggest that dry eye is one of the most common ocular disorders encountered by physicians. Furthermore, if patients use VDTs or wear CLs, the likelihood of dry eye occurring is higher.

Adolescent↗
PubMed1995

Prognosis of stage 2 macular holes.

PURPOSE: We ascertained the natural course of stage 2 idiopathic macular holes to determine better treatment possibilities. METHODS: We reviewed 48 eyes with stage 2 idiopathic macular holes and followed them up for more than two years. At each examination, best-corrected Snellen visual acuity was measured by a physician masked to the hypothesis of the study. RESULTS: Stage 2 lesions progressed to stage 3 or 4 during the follow-up period in 32 (67%) and 14 (29%) of 48 eyes, respectively; two eyes (4%) remained in stage 2. In 41 (85%) of 48 eyes, the hole size enlarged during the follow-up: 32 (94%) of 34 eyes had vitreomacular attachment and nine (64%) of 14 eyes had vitreomacular separation at the final examination, for a statistically significant difference in prevalence (P = .03). Visual acuity decreased two or more Snellen lines during the follow-up period in 34 (71%) of 48 eyes, the prevalence of which was significantly higher in eyes with vitreomacular attachment at the final examination (28 of 34, 82%) than in eyes with vitreomacular separation at the final examination (six of 14, 43%) (P = .01). CONCLUSION: Even though vitreomacular separation may improve the prognosis of a macular hole, stage 2 lesions usually will develop an enlarged hole and decreased visual acuity.

Aged↗
PubMed1995

Spontaneous resolution of foveal detachments and macular breaks.

PURPOSE: To evaluate the mechanism of spontaneous resolution of foveal detachments and idiopathic macular breaks. METHODS: We reviewed the records of 139 consecutive eyes (94 patients) with either a foveal detachment or a macular break in patients who were examined between 1989 and 1992. There were 26 men and 68 women (mean age, 66.9 +/- 6.9 years). They were either unoperated on or observed during the period that preceded surgery. Each patient underwent complete ophthalmic examination in addition to slit-lamp photography of the vitreomacular interface and microperimetry with the scanning laser ophthalmoscope. RESULTS: Eight eyes demonstrated spontaneous resolution. A foveal detachment was noted in five eyes (five patients) and a stage 2 macular break in three eyes (three patients). The mean duration of observation was 33 months (range, one to 144 months). Resolution of the foveal detachments occurred without the development of posterior vitreous detachment. In each eye, the presence of a pseudo-operculum, indicating vitreofoveal separation, was accompanied by flattening of the foveal detachment without detectable posterior vitreous detachment. The three eyes with stage 2 macular break resolved after premature development of a posterior vitreous detachment. CONCLUSIONS: Foveal detachment and macular break resolution seem to result from the release or weakening of vitreous traction on the fovea. Reattachment of the foveal retina preserves fair to good visual acuity. Surgical intervention is contraindicated (1) in eyes in which foveal detachment flattens and develops a pseudo-operculum and (2) when a posterior vitreous detachment develops in an eye with a stage 2 macular break. Careful biomicroscopic vitreous examination and microperimetry with the scanning laser ophthalmoscope are extremely useful methods for adequate examination of these patients.

Aged↗
PubMed1995

Course of vitreomacular traction syndrome.

PURPOSE: Although the course of vitreomacular traction syndrome is necessary to treat patients or to establish the value of the surgical technique, little information is available about its course. In this study, we ascertained the natural history of vitreomacular traction syndrome. METHODS: We retrospectively studied 53 consecutive symptomatic eyes with vitreomacular traction syndrome. RESULTS: In 43 (81%) of 53 eyes with cystoid macular changes at the diagnostic examination, 29 (67%) of 43 had cystoid changes that persisted during the median follow-up period of 60 months. The visual acuities at the time of the final examination decreased two Snellen lines or more from the initial measurement in 34 (64%) of 53 eyes. During the follow-up period, six (11%) of 53 eyes developed complete posterior vitreous detachment. The number of eyes with resolved cystoid changes or stable visual acuity was significantly higher when complete vitreomacular separation occurred (six of six) than when it did not (three [8%] of 37, P = .01; 13 [28%] of 47, P = .01). CONCLUSIONS: Most symptomatic eyes with vitreomacular traction syndrome underwent a further decrease in visual acuity. Complete vitreomacular separation, which occurs infrequently in eyes with the disorder, allows resolution of cystoid changes and improvement of visual acuity.

Aged↗
PubMed1995

Risk of bilateral idiopathic preretinal macular fibrosis.

To ascertain the risk of the development of bilateral idiopathic preretinal macular fibrosis, we retrospectively studied 380 consecutive patients with idiopathic preretinal macular fibrosis. Eighty (21%) patients had bilateral involvement. Sixteen (39%) of 41 patients with diabetes, 40 (28%) of 144 with hypertension, and 12 of 21 (57%) with bilateral high myopia had bilateral involvement. The prevalence of bilateral involvement was significantly higher in patients with these three pathologies than in patients without these conditions (p < 0.01, p < 0.02 and p < 0.01, respectively). In patients with diabetes or hypertension, no significant difference was found in the prevalence of posterior vitreous detachment (PVD) between involved or uninvolved eyes. Diabetes, hypertension even without retinopathy, and high myopia may be risk factors for bilateral involvement of idiopathic preretinal macular fibrosis. Factors other than PVD may be involved in the development of idiopathic preretinal macular fibrosis in patients with diabetes or hypertension.

Adolescent↗
PubMed1995

Role of the vitreous in central retinal vein occlusion.

PURPOSE: The role of the vitreous in eyes with CRVO and its relationship to neovascularization and macular edema, in particular, were investigated. METHODS: A retrospective chart review of the vitreous condition of 136 patients (136 eyes) with CRVO was performed. Based on fluorescein angiography findings and color photographs, eyes with CRVO were classified as either ischemic or nonischemic. RESULTS: In ischemic cases, retinal or optic disc neovascularization or both developed in 8 (57%) of 14 eyes with no or partial posterior vitreous detachment (PVD) at the final examination. The prevalence of neovascularization was significantly higher than in eyes with complete PVD (0%, 0 of 38) at the final examination (P < 0.01). No significant relationship was found between iris neovascularization development and the vitreous condition or between the prevalence of PVD and macular edema. In nonischemic eyes, the prevalence of no PVD or partial PVD with vitreomacular attachment was significantly higher in those with macular edema (76%, 25 of 33) than in eyes without (25%, 13 of 51) at the final examination (P < 0.01). CONCLUSION: Complete PVD may protect against retinal or optic disc neovascularization in eyes with severe CRVO. Vitreomacular attachment may cause persistent macular edema in eyes with mild CRVO.

Adult↗
PubMed1995

Relationship between premacular cortical vitreous defects and idiopathic premacular fibrosis.

PURPOSE: To investigate the relationship between the defect in the premacular cortical vitreous detached from the retina and the development of idiopathic premacular fibrosis. METHODS: One hundred six consecutive patients (106 eyes) with posterior vitreous detachment but no other ocular disorders were prospectively studied. All follow-up periods were longer than 6 months. The vitreous condition was studied using an aspherical, +58.6-diopter preset lens with a slit-lamp. RESULTS: The detached premacular cortical vitreous was a continuous, unbroken sheet in 93 (88%) of the 106 eyes; in 13 (12%) eyes, the detached premacular cortical vitreous had an oval or round defect ranging from 4 to 7 disc diameters over the macula. At the study's conclusion, 36 (34%) of the 106 eyes had idiopathic premacular fibrosis; 70 (66%) eyes did not. The defect in the detached premacular vitreous was observed in 9 (25%) of the 36 eyes that eventually developed idiopathic premacular fibrosis and in 4 (6%) of the 70 eyes that did not undergo such development. The incidence of the defect in the detached premacular cortical vitreous was significantly higher in eyes with idiopathic premacular fibrosis than in eyes without (P = 0.011). Nine (69%) of thirteen eyes with the defect in the detached premacular cortical vitreous developed premacular fibrosis, whereas only 25% of eyes without the defect developed it. Twenty-seven (75%) of thirty-six eyes with premacular fibrosis did not have a defect in the detached premacular cortical vitreous. CONCLUSIONS: The defect in the detached premacular cortical vitreous probably occurs because the premacular cortical vitreous remains attached to the internal limiting lamina when a posterior vitreous detachment develops. The vitreous that remains attached to the macula may be related to the development of idiopathic premacular fibrosis.

Adult↗
PubMed1995

Vitreous observation using a CCD camera and a computerized unit for image processing and storage.

PURPOSE: This study was conducted to evaluate a new technique of vitreous observation. METHODS: The authors used commercially available devices, including a slit-lamp, monochromatic charge coupled device (CCD) camera, and a computerized unit for image processing and storage, to observe the vitreous and the vitreoretinal relationship. RESULTS: The authors obtained good images of the vitreous and the vitreoretinal relationship using the new technique. Furthermore, the image stored in the computer could be accessed and used for patient explanations instantly. CONCLUSION: This technique is useful for documenting the vitreous and can help determine the role of the vitreous in many vitreoretinal disorders.

Aged↗
PubMed1995

Natural outcomes of stage 1, 2, 3, and 4 idiopathic macular holes.

AIMS: A study was carried out to ascertain the natural outcome of each stage of idiopathic macular hole. METHODS: One hundred and fifty four eyes with different stages of idiopathic macular holes were retrospectively studied: stage 1 (40 eyes), 2 (25 eyes), 3 (58 eyes), and 4 (31 eyes). RESULTS: Of 27 of 40 eyes with a stage 1 lesion with posterior vitreous attachment to the macula initially, nine (33%) eyes developed a full thickness macular hole. No stage 1 lesions with posterior vitreous separation from the macula initially progressed to full thickness holes. Twenty one (84%) of 25 eyes with a stage 2 lesion, 32 (55%) of 58 eyes with a stage 3 lesion, and five (16%) of 31 eyes with a stage 4 lesion underwent macular hole enlargement during the median follow up period of 3 years. Visual acuity decreased two or more lines of Snellen equivalent during the follow up period in 12 (30%) eyes with a stage 1 lesion, 17 (68%) eyes with a stage 2 lesion, 17 (29%) eyes with a stage 3 lesion, and four (13%) eyes with a stage 4 lesion. The percentage was significantly higher in eyes with stage 2 lesions than the other stages (p < 0.01). CONCLUSION: The results suggest that the different stages of idiopathic macular holes have different natural outcomes, and the management depends on the stage at presentation.

Age Distribution↗
PubMed1995

T1 measurements with clinical MR units.

To improve accuracy and feasibility of the proton spin-lattice relaxation time (T1) measurements in routine Magnetic Resonance Imaging (MRI), a phantom with polyvinyl alcohol gels and gadrinium diethylene triamine pentaacetic acid solutions was imaged with 1.5T clinical MR units and T1s were calculated by fitting several models to the observed signal intensities. When an inversion-recovery sequence was applied, we were able to measure T1 with a high degree of precision by taking into account the imperfection of the inversion pulse. With a Turbo-fast low angle shot sequence, we were able to obtain T1 in a short time, but low signal-to-noise ratio limited the precision. Signal intensity with SE sequence was susceptible to variation with the effective flip angle of 90 degrees RF pulse and not suited for T1 measurement.

Image Processing, Computer-Assisted↗