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E Adachi-Usami

Publications and source records attributed to E Adachi-Usami.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1989

Clinical and electrophysiological findings in three patients with toluene dependency.

We recorded the electrophysiological findings of three patients with toluene dependency who developed visual disturbance. In five of six eyes the peak latency of the pattern visual evoked cortical potential was prolonged as compared with that of normal subjects. The amplitude and the latency of the a-wave of the electroretinogram were decreased in five of the six eyes and prolonged in four. Those of the b-wave in patients were less affected than the a-wave: in one of six eyes the amplitude of the b-wave was decreased and in two the b-wave latency was prolonged. The amplitudes of the oscillatory potentials were decreased in three of six eyes. The electroretinogram was investigated in one patient and showed little increase in amplitude during light stimulation, so that a lowered light peak to dark trough ratio was obtained. Our findings suggest that any part of the visual pathway, including the distal part of the retina and retinal pigment epithelium, might be impaired by the chronic inhalation of toluene vapors.

Adolescent↗
PubMed1989

Accommodation power determined with transient pattern visual evoked cortical potentials in diabetes.

Changes of accommodation power by aging were measured with pattern reversal visual evoked cortical potentials (VECPs) in 45 normal subjects and 32 patients suffering from diabetes mellitus. Transient VECPs were recorded by increasing minus power lenses in front of the eye at one-diopter steps, up to the point where no VECP was recordable. It was found that the amplitude of the P100 component became attenuated linearly with increased accommodation stimulus. The regression line was calculated from the VECP amplitude vs. accommodation stimulus plots (in diopters) and the objective accommodation was determined by extrapolating the line to 0 microV amplitude. The measured accommodation power with pattern VECPs was attenuated significantly in the normal group over 40 years old and in diabetics, and also was found to be larger by approximately 2.5 diopters than that obtained subjectively by the near-point rule.

Accommodation, Ocular↗
PubMed1989

Bilateral macular colobomas in Leber's congenital amaurosis.

Two siblings with Leber's congenital amaurosis had bilateral macular colobomas, nystagmus, extinguished ERGs, and degenerative salt and pepper like changes in the fundus. They had non-recordable or non-meaningful visually evoked cortical potentials in response to both flash and pattern stimuli. The ophthalmic conditions were thought to be inherited as an autosomal recessive trait.

Adolescent↗
PubMed1989

Pattern visual evoked cortical potential measurement of luminance threshold in retinitis pigmentosa.

We measured the luminance threshold in eight patient (12 eyes) with retinitis pigmentosa using pattern reversal visual evoked cortical potentials (PVECPs). With decreasing pattern luminance (0 to 3.0 log unit neutral density filters), the amplitude of the p 100 component decreased linearly. Luminance threshold was determined by extrapolating the regression line of amplitude as a function of luminance to 0 microV. Our results showed that luminance threshold measured by PVECP was approximately 1.2 log units higher in patients with retinitis pigmentosa than in age-matched normal controls. Thus the PVECP may provide a way of quantitatively evaluating central retinal visual function in patients with retinitis pigmentosa.

Adolescent↗
PubMed1989

[Evaluation of color pattern VECP in deutan].

Using an Equi-Energy-Color Pattern Generator, color vision experiments were performed on nine normal subjects, six cases of deuteranomalies, and six cases of deuteranopias with the use of Visually-evoked cortical potentials (VECPs). Checkerboard patterns, consisting of the pairing of any chosen one of three colors with its complementary color in terms of equal energy, were used. The pairing of a neutral color with its complementary color of protan, deutan and tritan were displayed on a color TV monitor. We measured the amplitude and latency of P100 component of VECPs. Cases of deuteranopia showed significantly smaller amplitude and longer latency of P100 component in protan and deutan responses than did normal subjects. Cases of deuteramomaly showed significantly smaller amplitude and longer latency of P100 component in only protan response compared to those of normal subjects. It was possible to objectively detect the deutan in color pattern VECPs.

Adolescent↗
PubMed1989

Quantitative evaluation of electroretinogram before cataract surgery.

The ERGs (electroretinogram) of dense mature cataractous eyes were compared with those of the fellow eyes with good visual acuity in 22 senile patients who showed normal preoperative ERG. The mean amplitudes of the a- and b-waves were slightly reduced in the cataractous eyes as compared to those of the fellow eyes, but the difference was not significant. The light-absorbing effect of the cataract based on the a- and b-wave amplitudes was 0.5 log units. Another group of 13 eyes with senile mature cataract showed abnormal preoperative ERG. Chorioretinal atrophy was the most common cause of the subnormal ERG. Postoperative visual acuity was lower in cataractous eyes with subnormal ERGs than in eyes with normal ERGs. Despite the fact that it does not always reflect the macular function and the visual pathway, the ERG still remains a reliable guide in evaluating the visual prognosis before cataract surgery.

Aged↗
PubMed1989

[Objective assessment of senile changes in visual function by visually evoked cortical potentials].

The P100 peak latency of pattern visually evoked cortical potentials (P-VECP) was found to increase and amplitude decrease in the elderly depending on stimulus conditions. Using either of these as a criterion, changes of visual function with aging were quantitatively assessed both in humans and animals. Contrast threshold was found to increase at higher spatial frequency ranges and the luminance threshold increased more than 0.8 log unit. Also, the contrast threshold increased due to a smaller pupillary area and there was progressive decrease of the temporal frequency curves with age for lower frequency ranges of less than 10 rev/sec. In addition, a sensitivity decrease for the upper visual field was detected plus blue-yellow defects and a decrease in the amplitude of accommodation. In order to exclude the effect of senile changes of the crystalline lens, the luminance threshold, the accommodation power and color sense were investigated in pseudo-phakic eyes with a posterior chamber lens. No significant differences were found between phakic and pseudo-phakic eyes. Accordingly, it was suggested that reduced transparency and yellowish changes of the crystalline lens do not essentially contribute to the loss of function in the elderly found in the present study, but the neuronal pathway was responsible. As a clinical model of senescence, cases of juvenile parkinsonism were investigated, during L-dopa treatment and after ceasing it. The deficiency of the neural-transmitter of the higher visual pathway was indicated in the elderly, also. Animal experiments on neuronal dysfunction in rats and mice suggested no aging effects in ERGs, whereas VECP peak latency for higher temporal frequencies increased with age. The assumption that the elderly changes occur at the neuronal level was supported by a loss of optic nerve fibers in mice with age. The numbers of optic nerve fibers measured were 48,115, 50,875 in the 3-month-old and 6-month-old groups, respectively, and decreased to 43,175 in the 30-month-old group. Though our results indicated the senescence of visual function at the neuronal level, it was not as much as shown by other sensory organs. It was therefore presumed that there might be a certain feed-back system from the brain to the retina.

Adolescent↗
PubMed1989

[Human flash visually evoked cortical potentials under different levels of halothane anesthesia].

Flash visually evoked cortical potentials (FVECPs) were recorded in 13 surgical patients under different levels of halothane anesthesia, altering the rate of stimulus frequency from 0.5 Hz to 10 Hz. VECPs were obtained in the awake state under premedication with atropine sulphate, and at end-tidal halothane concentrations of 0.38%, 0.75%, 1.13% and 1.5%. The peak latency of P1 (the major positive component with a latency of about 100 msec) progressively increased from 116.7 +/- 3.3 msec (mean +/- SE) in the awake state to 124.3 +/- 6.3 msec, 136.5 +/- 5.2 msec, 151.5 +/- 5.2 msec and 166.3 +/- 8.7 msec with increasing halothane concentration. Significant reductions in P1 amplitude were observed to 2 Hz, 5 Hz and 10 Hz stimuli, whereas there were no significant changes in amplitude to 0.5 Hz and 1 Hz stimuli. P1 amplitude plotted against stimulus frequency had a maximum at 10 Hz in the awake state. This curve gradually and preferentially attenuated at higher frequencies as halothane concentration increased.

Adult↗
PubMed1989

[Magnetic resonance imaging (MRI) in the diagnosis of optic neuritis and neuropathy].

Magnetic resonance imaging (MRI) was performed in thirty patients who had been suffering from optic neuritis (ON). Twenty-one cases were caused by multiple sclerosis (MS) and in 9 cases the causes been defined. In MRI, abnormalities were found in 17 out of 21 MS cases in several places such as near the ventricles, mid-brain, spinal cord etc. Increased signals from the optic chiasm to optic radiation were found in 5 cases. However, abnormal MRI findings did not always correspond to Goldmann visual field defects. In 3 out of 9 cases of ON with unknown causes, high signals in the white matter of the brain were found, and it was suggested that those may develop to MS. MRI was, thus, proved to be very useful for the diagnosis of MS.

Adolescent↗
PubMed1989

[Subjective measurement of apparent accommodation in pseudophakic eyes with pattern VECPs].

Apparent accommodation was measured subjectively with pattern reversal visually evoked cortical potentials (PVECPs) in 22 pseudophakic eyes (20 patients, 47-83 years of age) after implantation of posterior chamber intraocular lenses. No significant difference was found in the obtained amplitude of accommodation measured with PVECPs between pseudophakic eyes and normal phakic eyes. Moreover this amplitude was independent from the age of patients, corrected visual acuity, or refractive errors. In one case, however, the amplitude of apparent accommodation was reduced with artificial dilating of the pupil diameter and contribution of the depth of focus to the apparent accommodation was indicated.

Accommodation, Ocular↗
PubMed1989

[Relationship between central visual field and pattern VECP in optic neuritis].

We compared the visual field within 10 degrees with the latency and amplitude of the P100 component of pattern visually evoked cortical potentials (PVECPs) in optic neuritis. Twenty five eyes of 17 cases with optic neuritis suffered from multiple sclerosis (MS) and in 21 eyes of 17 cases optic neuritis was caused by unknown etiology. The visual field was tested by program 31 of the automated perimeter Octopus. PVECPs were recorded with a television system. The visual field was considered to be abnormal for when at least one abnormal point was found within a 10-degree field. P100 peak latency of PVECPs with above normal mean latency plus 2SD was defined as abnormally prolonged. The abnormalities found by 10-degree visual field and PVECPs latency correlated significantly both in cases of MS and unknown cause. The eyes with mean loss of over 4dB within a 10-degree visual field invariably had a delayed latency. Those with an abnormal central point or abnormal points in the lower part within 10-degree visual field had a delayed latency. The latency was estimated in relation to causes, age, visual acuity and visual field. The cases with worse vision or worse field showed a tendency to have a prolonged latency. In unilateral cases the ratio of PVECPs amplitude between affected eyes and healthy fellow eyes was studied. The eyes which had abnormal visual field within 10 degrees and a delayed latency showed reduced amplitude of at most 61% compared with that of the healthy fellow eyes(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Effects of aging on the temporal frequency characteristics determined by pattern visually evoked cortical potentials.

Pattern reversal visually evoked cortical potentials were recorded from 70 normal volunteers, aged from 4 to 70 years. Eleven reversal frequencies between 1 and 20 rev/sec were presented. The progressive reduction in the amplitude of the P100 component with age for lower frequency ranges was shown up to the age decade of 30-39 years and the temporal tuning curve became a constant pattern after 40 years. However, there was a trend that the maxima of the tuning curve shifted toward lower frequencies with age after 30 years.

Adolescent↗
PubMed1988

Comparison of automated perimetry and pattern visually evoked cortical potentials in optic neuritis.

Twenty-one eyes of thirteen patients suffering from optic neuritis were examined with the Octopus automated perimeter and pattern visually evoked cortical potentials. All eyes had visual acuity of 0.2 or better. Visual field examination was measured by program 31 or 33, which tests the central 30-degree fields in a 6-degree grid. Pattern evoked potentials were obtained by reverse checkerboard stimulation of 3 rev/sec. A prolonged P100 latency was related to at least one abnormal point in the central nine points of program 31. All seven eyes with one abnormal point in the center had a delayed peak latency. The patients with either the normal central nine points of program 31 or normal peak latency had visual acuity of 0.6 or better. The graphs of visual acuity by Octopus compared with pattern evoked potential were very similar. With program Delta, the sensitivity loss ratio, i.e., the ratio of the mean loss at eccentricity of less than 10 degrees over less than 30 degrees, was related to the peak latency in optic neuritis caused by multiple sclerosis.

Adolescent↗