Biomedical subjects

O Hosaka

Publications and source records attributed to O Hosaka.

8 recordsLinked to original sources

PubMed1993

Photopic electroretinogram implicit time in retinitis pigmentosa.

While the implicit time of cone responses in the electroretinogram (ERG) has been suggested to have some clinical implications in retinitis pigmentosa (RP), its evaluation is not always easy in cases of typical RP because of the small amplitudes of the responses. An intense flash stimulus would be expected to improve the recordability of photopic ERG, which represents the cone responses. However, the implicit time in normal eyes has been shown to be delayed with increased stimulus intensity. Therefore, we evaluated photopic ERGs to a white flash stimulus of 3 different intensities as well as to a red flash in 14 cases of typical RP. The recordability of the response to white flash improved with the increased intensity of the stimulus. Most RP cases showed prolonged implicit time compared with that in normal eyes to each flash stimulus. Some patients who showed exceptionally normal or mildly delayed implicit time were considered to have good prognosis since they had noticed night blindness at an older age and most of their rod response in ERG was recordable.

Adolescent↗

PubMed1993

[The clinical evaluation of UF-021, a new prostaglandin related compound, in low tension glaucoma patients].

We administered UF-021 isopropyl unoprostone (Rescula) ophthalmic solution, a new prostaglandin-related compound developed as an anti-glaucoma agent, to 13 low tension glaucoma patients for 24 weeks, and clinically evaluated the effect of the intraocular pressure (IOP) reduction, visual field change, and side effects of the agent. Intraocular pressure was reduced in 11 out of 12 patients who were studied for statistical analysis. In these 12 patients, significant IOP reduction was recognized in the mean IOP for 24 weeks after the administration of UF-021. No side effects were detected in any of the 13 patients. From these results, UF-021 could be used as a new anti-glaucoma agent for low tension glaucoma, and also safer than many other anti-glaucoma agents.

Adult↗

PubMed1992

Ocular pulsation correlates with ocular tension: the choroid as piston for an aqueous pump?

In 26 random out-patients, including 13 treated glaucoma patients and ocular hypertensives, the higher the ocular tension, the greater the pulse amplitude, by Alcon pneumotonometry, at a statistically significant level. In a single untreated hypertensive, when 2-hourly pneumotonometry was done for 24 h, the correlation was similar and significant. The higher the diastolic blood pressure, the higher the ocular pulsation, also significantly. Pulsation is suggested to be a pump, the choroid being the piston, contributing (1) to an increase in the outflow of aqueous humour and (2) to a homeostatic mechanism contributing to normalization of the intra-ocular pressure, wherein pulsation increases or decreases, as the intraocular pressure increases or decreases, respectively.

Aqueous Humor↗

PubMed1992

Fundus flavimaculatus with severely reduced cone electroretinogram.

An 11-year-old girl complaining of progressive visual loss in both eyes showed atrophic macular degeneration with yellowish white flecks around the fovea in both eyegrounds. Decreased vision, central scotoma with normal peripheral visual field, and angiographic dark choroid except for transmitted hyperfluorescence in the macula and at the flecks confirmed the diagnosis of fundus flavimaculatus with atrophic macula. Electroretinograms, however, revealed severely reduced cone responses associated with almost normal rod response, which led to the diagnosis of cone dystrophy. The rare combination of angiographic evidence of fundus flavimaculatus and electroretinographically diagnosed cone dystrophy was discussed.

Child↗

PubMed1992

[The effect of stimulus intensity and background luminance on the b-wave implicit time of photopic electroretinogram in normal human eyes].

The authors studied the effect of stimulus intensity and background luminance on the b-wave implicit time of photopic electroretinogram in normal human eyes. Photopic electroretinograms were recorded at various stimulus intensities and background luminances in the range of 2.5 log scale using an integrating sphere of 30 cm diameter in the first experiment. The results from two normal eyes showed that with increasing stimulus intensity or with decreasing background luminance the b-wave implicit time of photopic electroretinogram prolonged and one or three wavelets superimposed on the ascending limb of the b-wave. The second experiment was performed using a half dome sphere of 60 cm diameter to study the b-wave implicit time at three different stimulus intensities. The results from 30 normal eyes disclosed a statistically significantly longer implicit time at the greater stimulus intensities. These results suggest that b-wave implicit time in photopic electroretinogram becomes delayed with increasing stimulus intensity and becomes shorter with brighter background luminance.

Adult↗

PubMed1992

[Static perimetry and temporal aspects of the photopic electroretinogram in sector retinitis pigmentosa].

Six cases of sector retinitis pigmentosa were studied by automated static perimetry and photopic electroretinogram. Four cases out of six revealed elevated thresholds in the lower half of the visual field, which corresponded to the normally appearing upper eyeground. They also showed delayed implicit time on the photopic electroretinogram. These results show that sector retinitis pigmentosa is not necessarily a regional retinal dystrophy.

Aged↗

PubMed1991

Electroretinogram in cone dystrophy.

Electroretinograms (ERGs) in 10 cases of cone dystrophy were studied with special respect to log(bp/bs) that represents the log of photopic ERG amplitude divided by scotopic ERG amplitude. Photopic ERGs were either greatly diminished or nonrecordable, and scotopic ERGs showed either normal or reduced amplitudes. All cases had a low value of log(bp/bs), less than the lower normal limit, indicating significantly greater impairment in cone function than in rod function. These results have proved log(bp/bs) to be helpful in confirming the diagnosis of cone dystrophy especially in cases with recordable photopic ERG and reduced scotopic ERG. Among other ERG parameters, the photopic ERG b-wave implicit time that was determined with averaging and digital amplification of the responses in 4 cases showed prolongation in 3 cases while normal in one case. Oscillatory potentials were nonrecordable or barely recordable in all cases.

Adult↗

PubMedDate not supplied

Systemic circulatory parameters. comparison between patients with normal tension glaucoma and normal subjects using ambulatory monitoring.

PURPOSE: To compare circadian changes of systemic circulation in patients with normal tension glaucoma (NTG) and normal subjects. METHODS: Forty-three patients with NTG and 226 normal subjects were enrolled in this study. Circulatory parameters, including blood pressure (BP) and pulse rate (PR), were measured in all subjects for 49 hours using an ambulatory monitoring system. In addition to a comparison between NTG patients and normal controls, the same parameters were compared between NTG patients who had progressive field defects and NTG patients who had stable field defects. RESULTS: The BP in NTG patients was significantly higher than in normal subjects. The nocturnal dip of BP in NTG patients was similar to the dip in normal subjects. However, the BP dip in NTG patients showing progressive visual field defects was significantly smaller than in patients with NTG showing stable visual field defects. Blood pressure fluctuation in sleep in the "progressive" patients was significantly greater than in the "stable" patients. Patients with NTG whose random BP was in a normal range showed a higher BP than normal subjects. The dip in PR in NTG patients was significantly lower than in normal subjects. CONCLUSIONS: An insufficient physiological nocturnal BP dip or a greater nocturnal fluctuation in BP may disturb the microcirculation of, and/or may directly damage, the optic nerve, resulting in increasing field loss in NTG.

Adult↗