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Biomedical subjects

F Kayazawa

Publications and source records attributed to F Kayazawa.

At least 19 recordsLinked to original sources
PubMed1992

Blood-aqueous barrier in eyes with retinal vein occlusion.

PURPOSE: The purpose of this study is to examine the changes of blood-aqueous barrier function in cases of central or branch retinal vein occlusion. METHODS: In addition to fluorophotometry of the aqueous humor and posterior vitreous, the authors used a method that quantifies protein in the aqueous (aqueous flare) by measuring the intensity of scattered laser light. RESULTS: Aqueous and posterior vitreous fluorescein concentrations and aqueous flare were significantly higher than in unaffected fellow eyes or eyes of visually normal age-matched controls both in central and branch retinal vein occlusions. They also were significantly higher in eyes with central vein occlusion than in those with branch vein occlusion. Among those eyes with central vein occlusion, aqueous and posterior vitreous fluorescein concentrations and aqueous flare were significantly higher in the hemorrhagic than in the venous stasis type of disease. Among eyes with branch vein occlusion, cases at the acute stage showed significantly higher amounts of aqueous and posterior vitreous fluorescein concentrations and aqueous flare than did those with chronic occlusion. CONCLUSION: The authors believe that increased amounts mainly reflect blood-ocular barrier disruption. Not only the blood-retinal barrier but also the blood-aqueous barrier disruption is a common sequela in the disorder.

Aged↗
PubMed1989

[Increase in aqueous flare by a therapeutic dose of mannitol in humans].

To evaluate the effects of mannitol on aqueous flare (aqueous protein concentration), we administered an intravenous clinical therapeutic dose to normal young adults (average age, 20.1 years), to normal older adults (average age, 61.3 years), and also to patients with diabetes mellitus, systemic hypertension, or pseudoexfoliation syndrome who were about to undergo intraocular surgery (average age, 66.4 years). Protein and cell levels in the aqueous fluid were determined with a device that measures laser light scattering in the aqueous fluid. Mannitol increased aqueous flare intensity. In all subjects, aqueous flare intensity was greatest around one hour following drug administration; the magnitude and the duration of the aqueous flare increase were significantly greater in normal older subject than in normal young adults; the magnitude was essentially the same in older adults with and without diseased barrier. The effect was reversed within 6 hours of drug administration in normal subjects. We considered the findings to represent changes in actual aqueous protein concentration and discussed the possible causes of this phenomenon.

Adult↗
PubMed1989

Biphasic fluorescence decay in kinetic vitreous fluorophotometry.

Eyes of 15 normal subjects and 24 diabetic patients underwent kinetic vitreous fluorophotometry at five, six, eight, ten, 24, and 48 hours after intravenous administration of sodium fluorescein 10 mg/kg. Exponential decay constants (Kv) were calculated for the period between five and 24 hours (Kv1) and for that between 24 and 48 hours (Kv2). In normal subjects and diabetic patients with background retinopathy, Kv1 was larger than Kv2, indicating biphasic fluorescence decay. However, in patients with proliferative retinopathy, Kv1 was significantly smaller than in other subjects, so Kv1 - Kv2 was smaller than that of the controls.

Diabetic Retinopathy↗
PubMed1987

Indomethacin and the epinephrine-induced breakdown of the blood-ocular barrier in rabbits.

Using aqueous and vitreous fluorophotometry, the authors examined the blood-aqueous and blood-retinal barrier functions in three groups of pigmented rabbits. Epinephrine (1.25%) was applied topically five times daily and indomethacin (0.5% sesame oil suspension) was applied topically three times daily to one eye of each of the animals in Group 1; under the same regimen, epinephrine and indomethacin placebo were administered to one eye of each of the animals in Group 2 and epinephrine placebo and indomethacin placebo were administered to one eye of each of the animals in Group 3. Fluorophotometry was done 1, 2, and 3 months after drug administration. The results showed that epinephrine induced disruption of the blood-aqueous barrier 2 and 3 months after drug administration, and that the magnitude of this disruption increased with time. Epinephrine also induced disruption of the blood-retinal barrier 3 months after drug administration. Indomethacin significantly prevented disruption of the blood-aqueous barrier at 2 and 3 months and significantly prevented disruption of the blood-retinal barrier at 3 months. The magnitudes of the barrier disruptions in eyes treated with both epinephrine and indomethacin were slightly higher than, or the same as, those of the control eyes. The results strongly indicated that the epinephrine-induced disruption of the blood-ocular barrier was partially caused by prostaglandins and other cyclo-oxygenase products whose biosynthesis was initiated by epinephrine.

Animals↗
PubMed1984

Keratoconus with pellucid marginal corneal degeneration.

Examination of 1,625 Japanese patients with keratoconus and 20 patients with pellucid marginal corneal degeneration showed that 17 patients with pellucid degeneration also had keratoconus in the central portion of the cornea. Three patients with pellucid degeneration without keratoconus showed bilateral involvement. Among the 17 cases of pellucid degeneration with keratoconus, eight patients showed bilateral involvement and the others showed unilateral involvement. Pellucid marginal corneal degeneration with or without keratoconus may be a variant of keratoconus or a different manifestation of the same etiologic factor.

Adult↗
PubMed1984

Ocular fluorophotometry in patients with essential hypertension.

Ocular fluorophotometry (OFP) was performed on 38 normal subjects and 71 patients with essential hypertension who showed hypertensive retinal vascular change without hemorrhages and exudates. The average fluorescein concentration one hour after dye injection in the posterior vitreous and the anterior chamber of hypertensive patients was higher than that of normal controls. In patients who showed only minimal arteriosclerotic change or minimal arteriosclerotic plus minimal hypertensive change, at 60 minutes fluorescein values in the posterior vitreous and anterior chamber were at normotensive levels. Conversely, in patients who showed marked hypertensive change, the values were higher than in normal controls. Our results indicate that permeability may change in hypertensive patients even when no retinal hemorrhage and fluorescein leakage are observed by fluorescein fundus angiography, and OFP may contribute in quantification and grading of retinal vascular damage by hypertension.

Adult↗
PubMed1984

Ocular fluorophotometry in diabetic patients without apparent retinopathy.

A fluorophotometer was remolded to gain high S-N ratio by photomultiplier cooling system, and ocular fluorophotometry of 65 diabetic patients without apparent retinopathy and 38 normal controls was performed. The mean fluorescein concentration one and two hours after intravenous dye injection, only lenticular autofluorescence in diabetics was significantly higher statistically, however, the variances were greater in the retina, the vitreous, and the anterior chamber. The rate of VF in the posterior vitreous more than M + 2 SD (the mean value and standard deviation of the normals) appeared significantly higher in diabetics. The case with abnormal posterior vitreous fluorophotometric value do not necessarily show the abnormal VF value in the anterior chamber. There were no significant difference statistically between the diabetic subgroups classified by the duration of the disease, metabolic control condition, associated hypertension of hyperlipemia, and the method of metabolic control.

Adult↗
PubMed1984

Ocular fluorophotometry using high S-N ratio fluorophotometer.

fluorophotometer was remolded to improve S-N (Sensitivity-Noise) ratio by means of photomultiplier cooling system, and ocular fluorophotometry was performed in 13 subjects aged from 20 to 40 (mean 32.5) years old and 13 subjects aged from 55 to 62 (mean 59.2) years old to assess aging effect on the blood-ocular barrier. The results revealed that the fluorescence value at the midvitreous, lenticular autofluorescence, and the anterior chamber of older group is higher than that of the younger group (p less than 0.05). The higher value of midvitreous may be derived from increase of diffusion rate due to vitreous liqueation rather than the blood-retinal barrier abnormalities.

Adult↗
PubMed1984

Clinical application of temporal modulation transfer function.

The temporal modulation transfer function (temporal MTF) was measured in normal controls and in patients with retinal diseases, optic neuritis and amblyopia. The temporal MTF of controls showed "band-pass" filter properties, having a peak sensitivity at about 15 Hz at 1,000 trolands of mean retinal illuminance. As the retinal illuminance was reduced, the sensitivity decreased, first at high temporal frequencies, then the peak sensitivity decreased. Finally at low temporal frequencies the sensitivity decreased and the peak shifted toward the lower frequency. In retinal diseases, abnormal temporal MTF was detected, and the curves were very similar to those of normal controls when retinal illuminance was reduced. These patterns were not specific to any retinal diseases, and the severity of the condition seemed to determine the pattern. In optic neuritis, an attenuated sensitivity was detected in all frequency ranges; however, the degree of attenuation was more severe than that found in retinal diseases even when the visual acuity was similar. At the convalescent stage, the low frequency sensitivity was restored first, and high frequency loss was observed even when the visual acuity was recovered to 1.0. Two amblyopic patients showed an attenuated sensitivity in the high and intermediate frequency ranges, and in one case sensitivity was attenuated in all frequencies. Three other patients showed normal sensitivity. By occlusion of the nonamblyopic eye, recovery of the sensitivity was observed in one patient whose visual acuity improved.

Adolescent↗
PubMed1983

Spatio-temporal modulation transfer function in retinal diseases.

Spatio-temporal modulation transfer function was measured in patients with retinal disease (central serous choroidopathy, retinal branch vein occlusion, retinitis pigmentosa) using microcomputer controlled monitor-TV display system. Sensitivity loss in high spatial frequency ranges at 1.0 Hz temporal frequency was the characteristic finding in those diseases, and the results suggest that the sustained channel of the visual perception system is more impaired than the transient channel in retinal diseases involving the macula.

Adult↗
PubMed1983

Segmental retinal periarteritis with branch arterial occlusion.

An 18-year-old woman complained of acute visual field loss in the right eye due to branch arterial occlusion. Similar disease occurred in the left eye two years later. Extensive laboratory examination revealed no factor of etiologic significance, and no sign of uveitis was observed. The retinal arterioles around the optic disc were segmentally inflamed angiographically, which led to their obstruction. Corticosteroid therapy (betamethazone, 3.0 mg/day) improved the arteriolitis within two weeks.

Adolescent↗
PubMed1983

Temporal contrast sensitivity in optic neuritis and amblyopia.

Temporal contrast sensitivity was measured in patients with optic neuritis and anisometropic amblyopia. In optic neuritis, attenuated sensitivity was detected at all frequency ranges; however, its degree was more severe than that of retinal diseases even when visual acuity was the same. At the convalescent stage, the low-frequency sensitivity was restored first, and high-frequency loss was observed even when the visual acuity was restored to 1.0. Two amblyopic patients showed attenuated sensitivity at high- and intermediate-frequency ranges, and in one case all frequency sensitivity attenuated. Three other patients showed normal sensitivity. By occlusion of the nonamblyopic eye, recovery of sensitivity was observed in one patient, whose visual acuity improved.

Adolescent↗
PubMed1983

Retinal arteriolar tortuosity with macular hemorrhage.

A 58-year-old Japanese woman showed bilateral retinal arteriolar tortuosity with macular hemorrhage. Ophthalmoscopically, the retinal vein was normal, and other arteriosclerotic and hypertensive arteriolar changes were slight. The medical examination and laboratory tests did not reveal any significant etiologic factors. The hemorrhage absorbed rapidly, and visual outcome was excellent. To our knowledge, this case is the first reported in an Oriental.

Arterioles↗