Biomedical subjects

J Akiba

Publications and source records attributed to J Akiba.

At least 55 records · Page 3Linked to original sources

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

Biomicroscopic vitreous videography.

PURPOSE: The authors report on the technique of biomicroscopic vitreous videography using the recently developed charge coupled device (CCD) video camera. METHODS: The authors performed biomicroscopic vitreous videography using the CCD video camera connected to a slit-lamp biomicroscope to examine 50 eyes with age- or disease-related vitreous changes in 50 patients. The cases were categorized as follows: 20 normal senile eyes; 10 eyes with retinal breaks; 10 eyes with diabetic retinopathy; 5 eyes with uveitis; and 5 eyes with high myopia. Noncontact positive preset lenses were used for observing the posterior vitreous; a wide-angle funduscopic contact lens and a three-mirror contact lens were used to observe the peripheral vitreoretinal changes. RESULTS: Using the CCD video camera, dynamic vitreous changes were documented clearly using real-time television monitoring. The video system also allowed rapid review of the vitreous changes. CONCLUSION: This new biomicroscopic vitreous videography system will contribute to the study of vitreoretinal diseases and be valuable as an educational tool.

Adult↗

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

[Traumatic macular hole and posterior vitreous].

We studied retrospectively the clinical features of 18 eyes of 18 patients with traumatic macular hole. The macular hole was elliptical with irregular edges in 17 eyes (94%) and its size ranged from 1/5 to 1/2 of the disc diameter. Posterior vitreous detachment was found in 3 eyes (17%); the vitreous was detached from the macula in only one of these 3 eyes. Commotio retinae, vitreous hemorrhage, hyphema, or choroidal rupture was also found in several eyes. These findings suggest that traumatic macular hole develops usually in the absence of posterior vitreous detachment and its pathogenesis is independent of the occurrence of posterior vitreous detachment. We speculate that blunt trauma-induced deformity of the eyeball or impact on the posterior pole provides a mechanical cause for the macular rupture.

Adolescent↗

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

[Natural outcome of idiopathic macular hole].

To ascertain the natural outcome of idiopathic macular holes, we studied 186 eyes with the disorder: stages 1 (48 eyes), 2 (30 eyes), 3 (71 eyes), and 4 (37 eyes), which were followed for over twelve months. In 11 (23%) eyes with stage 1 lesions full-thickness macular hole developed during the follow-up period, and in 12 (25%) eyes visual acuity decreased two or more Snellen lines. Twenty-five (83%) and 21 (70%) eyes with stage 2 lesions, 39 (55%) and 22 (31%) eyes with stage 3 lesions, and 7 (19%) and 5 (14%) eyes with stage 4 lesions had enlarged macular holes and decreased visual acuity during the follow-up, respectively. The present results suggest that different stages of macular holes have different natural outcomes and the treatment should be based on their stages.

Aged↗

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

Mechanisms of photo-induced vitreous liquefaction.

To understand the mechanisms of photo-induced vitreous liquefaction, this study investigated the effects of free radicals on collagen and hyaluronic acid (HA). Bovine vitreous collagen or HA was irradiated by visible light in the presence of riboflavin (RF) as a photosensitizer. The changes in the molecular weight of collagen and HA were monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography, respectively. Free radicals were shown to cause an increase in the high-molecular-weight components and insolubilization of the vitreous collagen and a decrease in the molecular weight of HA. The change in molecular properties of the vitreous collagen could be attributed to extensive crosslinks of the molecules. Since RF is present in the vitreous, which is irradiated by visible light over a lifetime, both cross-links of vitreous collagen and degradation of HA may contribute to age-related vitreous liquefaction.

Animals↗

PubMed1994

[Spectral transmittance of normal human crystalline lens].

The spectral transmittance and non-tryptophan fluorescence of human crystalline lenses were evaluated. Eleven eye bank lenses and three lenses of prematurity of retinopathy patients were investigated. All lenses absorbed the short wavelength light below 430 nm strongly. The transmission of the short wavelength visible light decreased gradually with age. There was a positive correlation between the fluorescence intensity ratio of non-tryptophan to tryptophan fluorescence and the logarithm of age. It was thought that the generation of non-tryptophan fluorescence might be a first-order chemical reaction.

Adult↗

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

Effect of the vitreous on the prognosis of full-thickness idiopathic macular hole.

We studied 112 eyes with full-thickness idiopathic macular holes (mean follow-up period, 5.7 years) to ascertain the effect of the vitreous on prognosis. Eyes were divided as follows: group 1, 58 eyes with no posterior vitreous detachment; group 2, 25 eyes with no posterior vitreous detachment initially and development of complete posterior vitreous detachment during follow-up; and group 3, 29 eyes with complete posterior vitreous detachment. In group 1, the macular hole enlarged in 37 eyes (64%), and the surrounding retinal detachment enlarged in 29 (50%); visual acuity decreased in 20 eyes (34%) by two or more Snellen lines. These percentages were significantly higher than in group 3 (14%, 10%, and 10%; P = .01, P = .01, and P = .03, respectively). Eyes with a full-thickness macular hole with no posterior vitreous detachment may have a greater risk of enlargement of the macular hole and surrounding retinal detachment, and thus a worse prognosis than eyes with posterior vitreous detachment.

Aged↗

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

Molecular mechanisms of posterior vitreous detachment.

To determine a molecular mechanism for posterior vitreous detachment and contraction of vitreous gel, the effects of serum components on bovine vitreous were systematically studied. Incubation of vitreous gel with calf serum caused a contraction of the gel accompanied by the release of a waterlike liquid. The low molecular weight fraction (M(r) < 10,000) of serum was ineffective in this process, whereas incubation of the vitreous with the high molecular weight fraction resulted in changes in the gel structure similar to those caused by serum alone. Individually, transglutaminase (factor XIIIa) was found to be most effective in inducing gel contraction. The effect was more pronounced when transglutaminase was used with fibronectin. Since transglutaminase is known to promote collagen-collagen or collagen-fibronectin-collagen cross-links, the contraction of the vitreous in this case can be attributed to the formation of similar cross-links.

Animals↗

PubMed1993

Prevalence of posterior vitreous detachment in high myopia.

BACKGROUND: Posterior vitreous detachment is known to develop early in high myopia. However, the prevalence of posterior vitreous detachment in relation to patient age and degree of myopia has not been studied by modern vitreous examination methods. METHODS: The vitreous conditions of 224 eyes with high myopia (> -6 diopters [D]) were examined biomicroscopically with a +90-D present lens and a Goldmann three-mirror contact lens. The vitreous conditions of 220 eyes with emmetropia (between -1 and +1 D) also were studied and served as controls. RESULTS: In high myopia, no patients 29 years of age or younger had posterior vitreous detachment. Thereafter, the prevalence of posterior vitreous detachment increased with age (i.e., 23%, 29%, 44%, and 72% in the fourth through seventh decades, respectively, and 100% of patients 70 years or older). Moreover, posterior vitreous detachment developed earlier in severe high myopia (> -10 D) than in moderate high myopia (> -6 to -10 D). In emmetropia, no patients 39 years of age or younger had posterior vitreous detachment, and its prevalence also increased with age (i.e., 8%, 23%, 44%, 74%, and 86% in the fifth through ninth decades, respectively). CONCLUSION: In high myopia, posterior vitreous detachment develops increasingly with age and degree of myopia. Although the sample size in each age group was small, the results suggested that posterior vitreous detachment may develop nearly 10 years earlier in highly myopic than in emmetropic eyes.

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↗