Biomedical subjects

E Adachi-Usami

Publications and source records attributed to E Adachi-Usami.

At least 19 recordsLinked to original sources

PubMed1992

Effect of number of test points in automated perimetry.

We studied sensitivity variation in normal subjects by changing the number of test locations under the fixed test field on automated perimetry. Using the user-defined program (Sargon), we designed five different programs that varied in the number of test points. Mean sensitivity and short-term fluctuations were obtained from the same test points of each program. The mean sensitivity within 10 degrees decreased with the increasing number of test points, whereas the short-term fluctuation increased with the increasing number of test points. Our results showed that the number of test points had an important role in measuring sensitivity and its reproducibility on automated perimetry.

Adult↗

PubMed1992

Effect of number of test points and size of test field in automated perimetry.

Sensitivity variation in normal subjects was studied, by changing the number of test locations and the size of test fields on automated perimetry. Using the Sargon program, four different programs that differed in the number of test points or in the size of test field were made. Mean sensitivity and short-term fluctuation were calculated from the same test points of each program. The program with the fewest points and the smallest size produced the greatest sensitivity and the least fluctuation. Our results showed that the number of test points and the size of test field affected the sensitivity and its reproducibility in automated perimetry.

Adult↗

PubMed1992

Assessment of central visual function after successful retinal detachment surgery by pattern visual evoked cortical potentials.

The pattern of visual recovery after successful surgery by pattern visual evoked cortical potentials (VECP), visual acuity, colour vision, and critical fusion frequency was investigated in 14 eyes with retinal detachment involving the macula. The temporal tuning characteristics in the evoked potentials were measured as based on the P100 amplitude and the frequency necessary for evoking 0 mu V amplitude, which was defined as an objective critical fusion frequency by extrapolating the curve. Significant improvement in visual acuity and colour vision was observed within 2 months postoperatively. A significantly increased P100 peak latency became shorter as the postoperative days increased. In general, a good correlation was noted between the P100 peak latency and subjectively measured visual acuity, colour vision, and critical fusion frequency. The objective critical fusion frequency measured by VECP recovered gradually during the 6 months after surgery. Functional recovery was not related to the length of time the macula was detached before surgery.

Adolescent↗

PubMed1992

Increased sensitivity with decreased numbers of test points and decreased test field size in automated perimetry of normal subjects.

Mean sensitivity (MS) was compared among programs with different numbers of test points and different test field sizes with an automated perimeter in normal subjects. The programs tested were designed by the program Sargon. Within a 10-degree visual field the MS was significantly higher with fewer test points and with a smaller test field size. The MS between 10 and 25-degree fields increased under the same conditions. Increased MS was found with decreased numbers of test points and decreased test field size within 25 degrees in automated perimetry of normal subjects.

Adult↗

PubMed1992

[Effects of MPTP on the mouse retina].

MPTP is known as a selective neurotoxin which destroys dopamine-containing neurons, and induces a model of Parkinson's disease. In the retina, MPTP acts on the amacrine cells which contain dopamine. In the present study, C57BL/6J mice were treated i.p. with MPTP (cumulative dose, 150 mg/kg), and the role of dopamine in the mouse retina was investigated electrophysiologically and immunohistochemically. ERGs were recorded before and 10, 30 and 50 days after MPTP injection. The amplitude of the oscillatory potentials was greatly reduced, and that of the b-wave to a lesser degree, while the a-wave was slightly reduced 10 days after injection. These ERG changes tended to return to the control level 50 days after injection. Immunohistochemical analysis showed that 10 days after MPTP injection the number of tyrosine hydroxylase positive amacrine cells was reduced by approximately 50%, and that these changes had lasted at least until 50 days after MPTP injection.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1992

Transient increase of b-wave in the mouse retina after sodium iodate injection.

Twenty C57 black mice received an injection of 40 mg/kg of sodium iodate through the caudal vein. The electroretinograms (ERGs) were recorded before and after injection. Flash stimuli with the maximum illuminance, 30,000 lux, were given at increasing levels of illuminance in 0.6 log U steps for 13 levels of intensity. The a- and b-wave amplitudes increased linearly with increased stimulus intensity for approximately 5.0 log U before being saturated. Twenty four hours after injection, the intensity-amplitude curve shifted toward the higher intensity region. It was calculated that the sensitivity loss of the b-wave after injection was 2.0 log U, although the maximum amplitude was larger and the peak latency was delayed. The same results were seen less obviously in the ERGs 48 hr after injection. After 96 hr, both waves were greatly attenuated and even abolished. At the time the increased ERGs were recorded, the histopathologic findings exhibited severe damage of the retina in the pigment epithelium and in the outer layer.

Animals↗

PubMed1992

Apparent accommodation in pseudophakic eyes as measured with visually evoked potentials.

We measured apparent accommodation with pattern reversal visually evoked cortical potentials in 27 pseudophakic eyes after the implantation of posterior chamber intraocular lenses. The patients ranged in age from 47-83 years. The amplitude of accommodation was not significantly different between pseudophakic eyes and normal phakic eyes. Apparent accommodation was inversely proportional to the pupillary diameter and was significantly correlated with corneal astigmatism. No significant relationship was noted between apparent accommodation and age of patients, corrected visual acuity, or refractive error.

Accommodation, Ocular↗

PubMed1991

Senile changes of crystalline lens: effects on the delayed latency of pattern visually evoked potentials in phakic and pseudophakic eyes.

We recorded visually evoked cortical potentials to pattern stimuli (PVECPs) in 22 patients who received a posterior chamber intraocular lens implant. The mean latency of the P100 obtained from patients was not significantly different from that of age-matched normal phakic subjects. Furthermore, we found that both groups showed a similar increased delay of the P100 latency with age. The results of this study indicated that the senile opacity of the crystalline lens does not contribute to changes of PVECPs with age. These alterations may be due to senile changes of the neural pathway.

Aged↗

PubMed1991

Effect of test field size on the results of automated perimetry in normal subjects and patients with optic neuritis.

The mean sensitivities of the same 8 central test points were compared in two different programs of an automated Octopus perimeter in normal subjects and in patients recovered from optic neuritis (visual acuity 0.8 or better). The programs differed in terms of the size of the stimulated visual field. One program tested the central 30 degrees and the other, central 8.4-degree visual field. It was found that the mean sensitivity tended to become higher when stimulating small field size in both normal persons and patients with optic nauritis.

Adolescent↗

PubMed1991

Pattern visually evoked cortical potential and magnetic resonance imaging in optic neuritis.

We studied the extent of optic nerve lesion with magnetic resonance imaging (MRI) in 24 patients with optic neuritis and compared it with visually evoked cortical potentials (VECP). Patients were divided into acute and chronic stage groups according to the duration of the disease from its onset. The short TI inversion recovery (STIR) mode of the MRI was selected for study. In the acute stage group, abnormally high signals of optic nerve on MRI were demonstrated in 11 of 12 eyes, and the amplitude and peak latency of pattern VECP were unrelated to the extent of the optic nerve lesion visualized by MRI. Conversely, in the chronic stage group, the abnormal MRI findings were exhibited in 19 of 23 eyes, and the relationship between the measurements was statistically significant. This difference in the optic nerve lesion observed by MRI between the acute stage and the chronic stage of optic neuritis may indicate pathophysiologic differences in their origins.

Acute Disease↗

PubMed1990

Electroretinograms and pattern visually evoked cortical potentials in central areolar choroidal dystrophy.

We describe three patients with central areolar choroidal dystrophy whose electroretinograms (ERGs) and pattern visually evoked cortical potentials (VECPs) confirmed their macular dysfunction. Visual fields measured by Goldmann perimetry showed central relative scotomata corresponding to a dystrophic lesion. Dark adaptation curves were slightly abnormal either in the first curve or in the second curve, depending on the visual acuity. Color vision was disturbed irregularly. Fluorescein angiography revealed a loss of the choriocapillaries, and a hyperfluorescent border outlined the dystrophic lesion. Single-flash dark-adapted ERGs and scotopic ERGs were almost normal, while photopic and flicker ERGs showed slightly attenuated amplitudes. Conversely, VECPs to pattern reversal stimulation were greatly affected for both transient and steady-state stimuli. We conclude that, in central areolar choroidal dystrophy, pattern VECPs can provide more information on macular dysfunction than does the ERG.

Adult↗

PubMed1990

Haloperidol delays visually evoked cortical potentials but not electroretinograms in mice.

Visually evoked cortical potentials (VECPs) and electroretinograms (ERG) to flash stimulation were studied in one ICR strain mouse and 23 ICR mice, respectively. The effect of a dopamine receptor blocker, haloperidol, on both responses was investigated. Significant peak latency prolongation was found in VECPs following injection of haloperidol, while the amplitude reduction of the b-wave was found in ERG. No effect of anesthetics only on ERG was found. It has been assumed that haloperidol affects VECPs related function mainly the higher visual pathway. However, the slight decrease of the b-wave amplitude of ERG could not exclude the possibility of the toxic effect on the retina.

Animals↗

PubMed1990

[The influence of miosis on the central visual field].

We studied the effects of miosis on mean sensitivity in cases of glaucoma and normal subjects. The visual field in 30 degrees was measured by an automated perimeter Octopus. The subjects consisted of 13 cases (24 eyes) with open angle glaucoma and 10 normal subjects (10 eyes). Glaucomas had a 1.8dB reduction of mean sensitivity with a decrease in pupil size from greater than 3mm to less than 2mm with 3% or 4% pilocarpine, regardless of age and mean sensitivity. Normal subjects showed a depression of 1.6-1.8dB with a decrease in pupil size from more than 3mm to less than 2mm with 3% pilocarpine. There were no significant changes of mean sensitivity in pupil size over 3mm in normal. There was no difference in the reduction of mean sensitivity with miosis between cases of glaucoma and normal subjects. The mean sensitivity measured under conditions of pupil size over 3mm before glaucoma surgery could be quantitatively compared with that of the pupil after operation.

Adult↗

PubMed1990

Flash electroretinograms and pattern visually evoked cortical potentials in Behçet's disease.

Behçet's disease with posterior uveitis was studied in 12 cases by flash electroretinography (FERG) and pattern visually evoked cortical potential (PVECP). Disappearance of oscillatory potentials was the initial change noted in FERG. Subnormal FERG and a delay in peak latency of the P100 component of PVECP were observed in patients with poor visual acuity and long-standing Behçet's disease. Amplitudes of PVECP were significantly decreased in these patients. It was suggested that FERG together with PVECP were good indicators for monitoring posterior segment changes and visual prognosis in Behçet's disease.

Adult↗

PubMed1990

[Aging effects on upper and lower half visual fields by VECPs and automated static perimetry].

We studied the aging effects on upper and lower half visual fields using pattern VECPs with half fields stimuli and automated static perimetry. The subjects, consisting of 56 normal volunteers ranging in age from 10 to 69 years old, were divided into three groups (10-29, 30-49, 50-69 years old). Their visual acuities were better than 1.0 and refractive errors were within +/- 2.0 diopters. Perimetry was performed with an automated perimeter (Octopus, program 61). An artificial pupil of 3 mm was used after cycloplegia with 1% tropicamide to eliminate senile miosis effects in recording of VECPs. Subjective light sensitivity decreased with age and there was a noticeable hiatus between the third and fourth decades. However the age-related decrease in sensitivity showed no difference between the upper and lower half fields. However VECPs results showed that with aging the P100 peak latency did not increase for lower half field stimuli, but increased for the upper half field stimuli, especially for smaller check sizes. These results suggested that there were different aging processes a in the upper and lower half fields and higher neural factors participated in the effects.

Adolescent↗

PubMed1990

[MRI lesions of the optic nerves in optic neuritis].

Magnetic resonance imaging (MRI) was performed in 14 patients with optic neuritis. Three patients suffered from multiple sclerosis but the etiologies of the remaining 11 cases could not be identified. They were bilateral in 6, and unilateral in 8. The MR images were compared with the symptomatic lesions of optic neuritis and pattern reversal VECP. The STIR mode (short time inversion recovery), was employed for the MRI in the orbit and T2-weighted mode in the brain. In 11 eyes with hyperemia of the optic disc, 7 eyes showed a high signal in the optic nerve with the MRI, and 9 eyes showed an abnormal pattern VECP. Seven eyes with normal disc and two eyes with a pale disc showed a high signal in the optic nerve with MRI, those 9 eyes had abnormal pattern VECP. The high signal in the optic nerve was not related to visual acuity or visual field abnormalities of patients. However, the degree of the high signal of the optic nerve lesion in MRI was associated with the clinical course and prognosis of the optic neuritis. The degree of the high signal of the optic nerve lesion decreased with the recovery of visual acuity in optic neuritis.

Adolescent↗

PubMed1990

[Spatial frequency characteristics of upper and lower hemiretina with pattern reversal VECPs].

We studied the spatial frequency characteristics in the upper and lower hemiretina using pattern reversal VECPs. The subjects were 56 normal volunteers ranging in age from 14 to 69 years old. The latency of the first major positive component (P100) of VECPs was measured using checker board pattern stimuli under varying conditions of spatial frequency (112', 56', 28', 14', 7'). For the upper hemiretinal stimuli, the P100 peak latency vs spatial frequencies curve reached minimum at 56' approximately 28' and increased at both lower and higher frequencies. For the lower hemiretinal stimuli, this curve shifted towards lower frequencies. The results suggested that the spatial frequency characteristics between the upper and lower hemiretina were different.

Adolescent↗

PubMed1990

Senescence of visual function as studied by visually evoked cortical potentials.

Visual functions in senescence were assessed quantitatively by the pattern reversal visually evoked cortical potentials (VECP) in human subjects and animals. The results obtained in the elderly showed an elevation of contrast threshold, ie, lowered sensitivity, for higher spatial frequency, and a rise in the luminance thresholds. There was also an overall suppression in the temporal frequency curves, a sensitivity decrease for the upper half of the visual field, a blue-yellow defect and a decrease in the amplitude of accommodation. Studies of the pseudophakic eye with an intraocular lens verified that the lower transparency and yellowish changes of the crystalline lens and senile miosis do not entirely account for the depressed visual function in the elderly. The delay of P100 peak latency of the VECP in patients with juvenile Parkinson's disease after cessation of L-dopa indicated the deficiency of dopamine in these patients, which in turn was considered as a clinical model of senescence. Optic nerve fiber counts in mice showed a significant decrease in the aged group. It was considered that there is neuronal senescence other than in the eye itself. The results can be illustrated by the following daily life experience. In the evening, an elderly person would have difficulty in identifying a cat as a calico cat if the cat were atop a wall and running quickly through the visual field. It was surprising, however, that the senescence found in the visual function was not as great as that found in the other sensory organs. As further studies, investigation of the feedback mechanism from the brain to the retina and the compensatory mechanism should be made.

Accommodation, Ocular↗