Search PubMed⌕ Search

Biomedical subjects

A Kakehashi

Publications and source records attributed to A Kakehashi.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Vitreous videography with a scanning laser ophthalmoscope].

We used a scanning laser ophthalmoscope (SLO) to attempt better visualization of the posterior vitreous than conventional biomicroscopy. We observed the posterior vitreous using the SLO in patients with age- or disease-related vitreous changes. We compared the results using lasers of several wavelengths. The detailed structure of the posterior hyaloid membrane, its collagen mesh structure with premacular defect, and the prepapillary glial ring were clearly visualized by direct laser illumination. Persistent attachment of the vitreous gel to the macula through the oval defect in the posterior hyaloid membrane was seen even with repeated eye rotations. Short wavelength laser was preferable to a long wavelength one for observing the posterior hyaloid membrane. Vitreous opacities were clearly visualized with all lasers as dark spots with fundus monitoring by retro illumination. Thus in vivo visualization of the posterior hyaloid membrane and vitreous gel was achieved using this new technique, which is more advantageous than the conventional biomicroscopy because of its monochromatic laser delivery system with confocal light detection.

Adolescent↗
PubMed1995

[Differential diagnosis of macular breaks by microperimetry with a scanning laser ophthalmoscope].

To improve differential diagnosis of macular breaks, microperimetry with a scanning laser ophthalmoscope (SLO) was performed. Fifty consecutive macular breaks were detected by biomicroscopy and indirect ophthalmoscopy, and SLO microperimetry was performed on each. Of the 50 eyes, 22 eyes were diagnosed with idiopathic macular breaks by biopmicroscopy and indirect ophthalmoscopy because of a cuff. SLO microperimetry also showed dense scotoma within the macular break and relative scotoma on the cuff in the 22 eyes. However, diagnosis was not done only by biomicroscopy and indirect ophthalmoscopy in the other 28 eyes because of the absence of a cuff. SLO microperimetry differentiated the full thickness macular breaks from pseudo-or lamellar breaks in these eyes. SLO microperimetry is useful for differentiating their prognosis, and determining the need for surgical treatment.

Aged↗
PubMed1995

[Biomicroscopic findings of premacular posterior vitreous].

The presence of vitreous gel in front of the macular area is still controversial. In order to understand the anatomy of the premacular vitreous, the posterior vitreous was observed biomicroscopically and slit-lamp photographs were taken in 100 eyes without posterior vitreous detachment. We defined the premacular vitreous as the lacuna seen when optically empty space, a demarcated oval shaped dark area without Tyndall phenomenon, was observed in front of the macula. Although the premacular vitreous showed liquefaction, the Tyndall-phenomenon, indicating the presence of formed vitreous gel, was observed in most cases. Premacular lacuna was observed in 3 cases with high myopia, and in one case with vitreoretinal degeneration syndrome. The bursa premacularis or premacular precortical vitreous pocket observed in autopsy eyes could barely be observed in living eyes.

Adolescent↗
PubMed1995

[Observing idiopathic macular break by scanning laser ophthalmoscope vitreous videography].

We used vitreous videography in conjunction with the scanning laser ophthalmoscope (SLO) to evaluate the pathogenesis of idiopathic macular breaks. The fundamental aspect of this method is videographic documentation of the mobile posterior vitreous and an operculum. The high reflectivity from the vitreous gel using the SLO clearly showed the mobility of the operculum and the posterior vitreous in the idiopathic macular breaks. In some cases without posterior vitreous detachment, the operculum initially was suspended superior to the macular break and anterior to the retinal surface. Upon ocular movement, the operculum moved down smoothly in front of the macular break. The findings of these vitreous videographs using the SLO suggest that anteriorly oriented vitreous traction is one cause of idiopathic macular breaks.

Aged↗
PubMed1995

Vitreous videography using the scanning laser ophthalmoscope.

To establish the method of vitreous videography using the scanning laser ophthalmoscope, we observed the vitreous in patients with age- or disease-related vitreous changes. We compared the results using four laser wavelengths. The detailed structures of the posterior vitreous cortex, a premacular defect, and a prepapillary glial ring were clearly shown under direct laser illumination. A short wavelength laser was found to be superior to a long wavelength laser for observing the posterior vitreous cortex. Vitreous opacities were clearly shown as dark spots under retroillumination using any of the four laser wavelengths. In vivo visualization of the vitreous was achieved using this new technique, which is superior to conventional biomicroscopy because of its monochromatic laser delivery system and confocal light detection capacity.

Adolescent↗
PubMed1994

Vitreomacular observations. I. Vitreomacular adhesion and hole in the premacular hyaloid.

PURPOSE: Variations in vitreomacular adhesions and the significance of a hole in the premacular hyaloid membrane were studied clinically to better understand vitreomacular pathology. METHODS: With an El-Bayadi-Kajiura aspheric preset lens, the authors used a vitreous examination technique on 96 eyes, which were divided into three groups. Findings were recorded photographically. RESULTS: Group 1 (25 eyes, 26%) included eyes with a partial posterior vitreous detachment and a residual vitreomacular attachment, but no hole in the premacular hyaloid. All eyes in this group, except one, showed another complication. Diabetic retinopathy and retinal vein occlusion were the most frequent problems noted. Premacular fibrosis, often present in these eyes, may have been precipitated by a vascular complication in the retina. In groups 2 and 3 (71 eyes, 74%), a hole was seen in the premacular hyaloid. Group 2 (46 eyes, 48%) comprised eyes showing a partial posterior vitreous detachment with a strand of vitreous that extruded through the hole in the posterior hyaloid and adhered to the macula. In group 3 (25 eyes, 26%), the hole in the premacular hyaloid was accompanied by a total posterior vitrous detachment. The most common complication noted in eyes in groups 2 and 3 was premacular fibrosis (34 of 71 eyes, 47.9%). The persistence of a residual vitreous attachment to the macula was accompanied by a significantly greater frequency of visual acuity equal to or worse than 20/200. CONCLUSIONS: Variations in vitreomacular pathology seem to result from differences in the strength of the vitreomacular adhesion and in the process of vitreous liquefaction and shrinkage. In patients with a hole in the premacular hyaloid membrane, the vitreomacular attachment is stronger than the vitreous attachment to other parts of the retina. The latter feature may cause visual acuity deterioration. When there is a hole in the premacular hyaloid membrane, the presence or absence of a vitreomacular adhesion may affect the prognosis for macular function.

Adult↗
PubMed1994

Molecular mechanisms of photochemically induced posterior vitreous detachment.

Vitreous gel contraction and syneresis, commonly associated with age- and disease-related posterior vitreous detachment (PVD), were induced by a hematoporphyrin (HP)-photosensitized reaction. Calf vitreous gel was irradiated by white light in the presence of HP. Gel weights of the vitreous samples after 24 h of irradiation decreased by 14%, the irradiated control without HP by 8% and the control with HP stored in the dark by 8%. No significant difference in vitreous gel compressibility was found between the irradiated controls and the irradiated samples. In separate experiments, collagen gel in a glass capillary and hyaluronic acid (HA) were irradiated with white light in the presence of HP. The control collagen gel (irradiated without HP and stored in the dark with HP) decreased in length by 0.6% after 96 h, the experimental gel with HP decreased in length by 1.3 and 1.9% after 24- and 96-hour irradiation by visible light, respectively. The irradiated HA monitored by high-performance liquid chromatography showed a molecular weight decrease in the HP-treated polymer. Because the HP-sensitized reaction predominantly produces singlet oxygen, collagen gel contraction and HA degradation, in this case, are likely caused by this active oxygen species.

Animals↗
PubMed1993

Evidence for singlet oxygen-induced cross-links and aggregation of collagen.

Singlet oxygen, generated by a hematoporphyrin-photosensitized reaction, was shown to cause insolubilization and an increase in molecular weight of acid soluble type I collagen and vitreous collagen as manifested in sodium dodecyl sulfate polyacrylamide gel electrophoresis. No such changes in the molecular properties of collagen could be observed when the irradiation was carried out in the presence of sodium azide, a singlet oxygen quencher. The increase in molecular weight and insolubilization of the collagen solution was attributed to extensive cross-links in the protein molecules.

Animals↗
PubMed1993

Vitreous findings in cases of optic nerve pits and serous macular detachment.

We examined biomicroscopically the relationship between the optic nerve and the vitreous in 17 eyes of 16 consecutive patients with pits of the optic nerve that demonstrated an associated serous detachment of the macula. The posterior vitreous was attached in 15 eyes (88%); the posterior vitreous was partially detached with a vitreous strand terminating at the optic pit in two eyes (12%). Of the 15 eyes without posterior vitreous detachment, 11 (73%) had an anomalous Cloquet's canal that was markedly condensed and terminated at the margin of the pit. During ocular movement, we observed a back-and-forth movement of the anomalous Cloquet's canal and a pulsating translucent membrane that covered the pit. Our findings suggest that the intravitreal traction on the optic pit by the anomalous Cloquet's canal may have a role in the development of macular detachment.

Adolescent↗
PubMed1993

Vitreous photography with a wide-angle funduscopic lens.

A wide-angle funduscopic lens was used to take slit-lamp photographs of the posterior vitreous. The lens was then evaluated for its optics, magnification, field of view, and photographic usefulness and compared with the photographs taken using double aspheric preset lenses. The advantages of the wide-angle funduscopic lens were its wider field of view and ability to photograph the vitreous in the presence of a small pupil and cataract. The drawbacks were the darker image, low magnification, and artifactitious light reflection from the lens. The slit-lamp photographs using the wide-angle funduscopic lens were very useful in some complicated cases.

Eye Diseases↗
PubMed1993

Biomicroscopic findings of posterior vitreoschisis.

The clinical entity of posterior vitreoschisis, splitting of the posterior cortical vitreous, is not well known. We confirmed its presence biomicroscopically in cases with posterior vitreous detachment and found it mostly associated with retinal vascular diseases, usually manifesting as two dense vitreous membranes with defects. When posterior vitreoschisis develops in an otherwise normal eye, it may not manifest as two membranes, but can form a crescent-shaped, optically empty space in the posterior vitreous cavity. Because its management is different, posterior vitreoschisis should be differentiated from other, apparently similar, conditions, especially posterior vitreous detachment.

Adult↗
PubMed1993

A comprehensive approach to biomicroscopic vitreous examination.

We recommend a biomicroscopic vitreous examination that combines an anterior vitreous examination done without using a neutralizing lens and a posterior vitreous examination using the high-power (low-magnification) double aspheric positive preset lens. When detailed observation of the posterior and peripheral vitreous are required, we also recommend the additional use of a low-power (high-magnification) double aspheric preset lens and the Goldmann three-mirror lens. Details of the anterior vitreous can be examined best without using a neutralizing lens and those of the posteror vitreous, by using the low-power double aspheric preset lens. The high-power double aspheric preset lens provides a wider field of view and more accessibility when the patient has small pupils and cataracts than the low-power double aspheric preset lens. The peripheral vitreous is best observed using a Goldmann three-mirror lens. We believe the method we describe can serve as a guide for a comprehensive clinical biomicroscopic vitreous examination.

Adolescent↗
PubMed1992

Fellow eyes in idiopathic macular hole cases.

The fellow eyes in 84 cases of unilateral idiopathic macular hole were studied retrospectively to determine prognoses and risk factors for this disorder. On initial examination, 15 of 84 eyes (18%) had a macular cystic lesion (group 1), 23 (27%) had a yellow spot in the fovea (group 2), and 46 (55%) had a normal macula (group 3). Of the 84 eyes, 58 (69%) had posterior vitreous attachment. During a mean follow up of 39 months, macular hole developed in 8 of 15 eyes (53%) in group 1, and in 6 of 23 eyes (26%) in group 2. However, a macular hole did not develop in eyes with posterior vitreous separation or a normal macula. Although the risk of developing a macular hole may have been overestimated in our study, posterior vitreous attachment and macular abnormalities may be important in predicting macular hole formation in the fellow eyes in idiopathic macular hole cases.

Aged↗
PubMed1991

Vitreous photography with a +90-diopter double aspheric preset lens vs the El Bayadi-Kajiura preset lens.

Two fundus lenses, a 90-diopter preset lens and a 58.6-diopter El Bayadi-Kajiura lens, were compared. The lenses were evaluated with regard to their optics, magnification, field of view, and photographic usefulness in photographing the posterior vitreous. The 90-diopter lens provided a wider field of view but lower magnification. Both lenses permitted high-quality vitreous photographs through the slit lamp, but the 90-diopter lens allowed photographs to be taken through small pupils and some lens opacities.

Aged↗
PubMed1991

Role of the vitreous in posterior segment neovascularization in central retinal vein occlusion.

We retrospectively studied the relationship between the vitreous condition and the development of retinal or optic disc neovascularization in 60 eyes with central retinal vein occlusion associated with extensive retinal ischemia. At initial examination, 24 of 60 eyes (40%) with central retinal vein occlusion had complete posterior vitreous detachment, a prevalence significantly higher than in the fellow eyes. During a mean follow-up period of 43 months, 13 of 34 eyes (38%) without posterior vitreous detachment developed retinal or disc neovascularization, or both, but none of the 24 eyes with complete posterior vitreous detachment developed neovascularization (P less than .001). Our results suggest that central retinal vein occlusion may induce the development of posterior vitreous detachment, and that posterior vitreous detachment may play a role in protecting eyes with central retinal vein occlusion from posterior segment neovascularization.

Adult↗