[Low vision care].
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Activities of Daily Living↗
Biomedical subjects
K Yanashima
Publications and source records attributed to K Yanashima.
Visual function in retinitis pigmentosa related to a codon 15 rhodopsin gene mutation.
To determine the phenotype of a Japanese family in which retinitis pigmentosa cosegregates with a rhodopsin gene mutation, i.e. an asparagine-to-serine change at codon 15 (Asn-15-Ser), 5 affected and 5 unaffected members of one pedigree underwent several ophthalmic examinations as well as Ganzfeld electroretinography (ERG) and multifocal ERG. Genomic DNA samples were analyzed by PCR amplification, sequencing and restriction enzyme digestion. A codon 15 rhodopsin gene mutation (Asn-15-Ser) was found in all affected members. The region of pigmentary degeneration was localized in the lower hemiretina, and visual field defects corresponded to the retinal pigmentary changes. Scotopic ERG amplitudes, rather than photopic ERG amplitudes, were reduced. Multifocal ERG revealed a low magnitude of response density, even for the upper hemiretina, which showed no bony corpuscle pigmentation. Visual function in sectorial retinitis pigmentosa associated with rhodopsin gene codon 15 mutation is on the basis of the rod-cone dystrophy, regardless of differences in phenotypic expression.
Adult↗
Pattern electroretinogram elicited by a dartboard pattern.
The receptive field size of retinal ganglion cells is closely related to their eccentricity from the fovea. To elicit larger pattern-reversal electroretinograms (P-ERGs), it may be useful to stimulate the retina with patterns having elements that parallel this change in receptive field size. We describe a dartboard pattern consisting of reversal elements that enlarge gradually from the central to the peripheral stimulus field. The utility of the dartboard pattern for eliciting P-ERG was investigated by comparing it with the conventional uniform checkerboard pattern, but with the other stimulus parameters remaining unchanged (96% contrast, 35.9 cd/m2 mean luminance, 3.3 rev/s temporal frequency, 15 degrees circular field). The dartboard pattern produced a significantly larger P50 amplitude than did the checkerboard pattern, while no difference in peak latency was found when 54 min of arc was used as a standard check size for the checkerboard pattern. The dartboard pattern for eliciting P-ERG should prove clinically useful.
Adult↗
Visual function and gene analysis in a family with Oguchi's disease.
A family with 1 case of retinitis pigmentosa (III-1) and 2 cases of Oguchi's disease (III-2, 3) was examined in terms of electrophysiology as well as molecular biology. The proband (III-3), a 42-year-old female, and 2 older brothers (III-1, 2, aged 52 and 45 years) and 2 unaffected members in the same family participated in this study. Corrected visual acuities of the individuals with Oguchi's disease (III-2, 3) were 1.2. On funduscopy, blood vessels stood out in relief against a metallic-appearing background and a Mizuo-Nakamura phenomenon was evident. Full-field electroretinograms (ERGs) recorded from the proband were indicative of rod dystrophy, but results of other electrophysiological examinations (multifocal ERG, pattern ERG and visual-evoked cortical potential recordings) were within normal limits. Patient III-1 had corrected visual acuities of RE 20 cm/m.m. and LE 30 cm/n.d., severe chorioretinal atrophy in both fundi, and full-field ERG revealed rod-cone dystrophy. Mutation of the arrestin gene (1147de1A) was detected in all 3 patients. Visual function in each patient coincides with that of retinitis pigmentosa or Oguchi's disease, respectively.
Adult↗
[Effect of ultraviolet-filtering contact lens on rabbit eyes after exposure to ultraviolet light].
We evaluated the protective effect of a newly designed soft contact lens (SCL) on rabbit eyes. This SCL absorbs the ultraviolet B light of wavelengths between 280 nm and 320 nm. Three weeks after resecting the nictitating membrane, the rabbit corneas were covered either by the new SCL or a conventional SCL. The eyes were exposed to ultraviolet light from two 15 W lamps placed 20 cm anteriorly for 3 hours. Another three hours after the exposure, the cornea was examined first with a slitlamp biomicroscope after staining with fluorescein and then by histopathological means after enucleation. Six eyes wearing the new SCL showed moderate superficial punctate keratopathy. Six eyes wearing conventional SCL showed severe superficial keratopathy or corneal erosion. These findings were in good agreement with the histopathological findings. The new ultraviolet-filtering SCL was thus effective in protecting the rabbit cornea under our experimental conditions.
Animals↗
[Detection of parafoveal scotoma by multifocal electroretinograms].
We investigated the relation between multifocal electroretinograms (M-ERGs) and artificial parafoveal scotoma. M-ERGs were recorded from normal subjects using a circular piece of black paper attached to a monitor. Lower response density around the 10 to 15 degree parafovea region was not observed up to 3 degree scotoma (visual angle), but was detected above 5 degree scotoma in field topography of M-ERGs. The shape of the scotoma in field topography was not circular but somewhat oval. The results from two cases of parafoveal retinal degeneration were in good accordance with this basic study in normal subjects. We proved that detection of parafoveal scotoma by M-ERG is limited in comparison with the results obtained by automated static perimetry.
Electroretinography↗
[Influence of the yellow-tinted intraocular lens on spectral sensitivity].
One of the complaints of patients with aphakic eyes or pseudophakic eyes implanted with UV or non-UV intraocular lenses (IOLs) is chromatopsia. To determine the extent of color distortion, we measured the spectral sensitivity curve of normal subjects with visual acuity above 1.0 with correction, if any, including subjects implanted with the yellow-tinted IOL (UVCY IOL: HOYA Co.). We found that color sensitivity in the blue range (400-440 nm) declined rapidly with subjects age. We drew a regression line plotting age against sensitivity for 66 normal subjects. Sensitivity for pseudophakic eyes implanted with UVCY and UV IOLs at 400 nm corresponds to that of subjects in their early 20's. That of pseudophakic eyes implanted with non-UV IOLs and aphakic eyes corresponded to that of infants. In summary, compared to UV IOL and non-UV IOLs, the UVCY IOL was found to best approximate the color sensitivity of healthy eyes.
Adolescent↗
Clinical features of autosomal dominant retinitis pigmentosa with rhodopsin gene codon 17 mutation and retinal neovascularization in a Japanese patient.
A 49-year-old Japanese man had autosomal dominant retinitis pigmentosa with a point mutation in codon 17 of the rhodopsin gene, resulting in a threonine-to-methionine change, and retinal neovascularization in both eyes. Pigmentary degeneration mainly in the inferior area of the fundus, and severe loss in the upper portion of the visual field were observed. Moderately preserved rod and cone functions were demonstrated by electroretinograms. These findings differed from those of Japanese and white patients with autosomal dominant retinitis pigmentosa with a codon 347 mutation and were almost the same as those of white patients with the codon 17 mutation. Our study indicates that phenotypic similarities exist among patients with the same mutation, but of different racial backgrounds. The neovascularization in the right eye diminished over a two-year period in conjunction with the progression of retinal degeneration.
Adaptation, Ocular↗
An atypical Leber's hereditary optic neuropathy with the 11778 mutation.
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Adult↗
A Japanese pedigree of autosomal dominant congenital stationary night blindness with variable expressivity.
Three cases in three successive generations of one family with autosomal dominant congenital stationary night blindness are presented. Case 1, the proband, and Case 3, his grandfather had the same electroretinographic responses: nonrecordable scotopic electroretinogram (ERG), normal but slightly diminished flicker ERG, and negative-shaped single bright-flash ERG. Their dark adaptation curves were monophasic with no rod segment. However, Case 2, the proband's father, showed different ERG findings; a moderately diminished scotopic ERG, a normal flicker ERG, and a biphasic dark adaptation curve with an elevated final rod threshold. The authors believe that these differences reflect variations in the expressivity of a single gene mutation with the lowest expressivity being seen in Case 2.
Adult↗
[Linearity and nonlinearity of pattern ERG and pattern VECP].
To investigate the linearity and nonlinearity of both pattern electroretinogram (P-ERG) and pattern visually evoked cortical potential (P-VECP), a checkerboard pattern was presented to normal subjects with the reversal rate of transient and steady-state condition. Using a personal computer (BASIC) system, we made simulated waves (linear model) at 3 to 15 rev/s stimuli summated from an original wave evoked at 1 rev/s stimulation. Both simulated P-ERGs and P-VECPs were found to be different from the original ones, and the nonlinear component, which was interpreted as the difference between the original and simulated waves, was thought to increase with the increment of pattern reversal rate. However the 2 nd harmonic component of the original wave drastically decreased at above 7.5 rev/s stimulation. Thus, it is concluded that the nonlinearity of both P-ERG and P-VECP does not correlate with those 2 nd harmonic components.
Adult↗
Luminance-unbalanced pattern onset-offset electroretinogram and visual evoked cortical potential.
The effects of a luminance-unbalanced pattern onset-offset mode of stimulation on electroretinograms and visual evoked cortical potentials were investigated. With the use of originally devised software, only offset luminance was varied from 14.7 to 62.3 cd/m2. A vertical grating pattern (1.5 c/deg, 38.8 cd/m2 mean luminance, 0.95 contrast) was presented for 260 ms and was absent for 260 ms to normal subjects. With an increase in the luminance level of the offset pattern from the lowest level, the amplitude of the onset electroretinogram increased by degrees, while that of the offset electroretinogram gradually decreased. Conversely, onset visual evoked cortical potential responses decreased gradually, and offset visual evoked cortical potentials increased correspondingly. Furthermore, the spatial tuning of the onset pattern electroretinogram was already ambiguous, even when there was only a 4-cd/m2 difference between onset and offset pattern luminances. Thus, luminance control is indispensable for pattern onset-offset stimulation.
Adult↗
A mutation of mitochondrial DNA in Japanese families with Leber's hereditary optic neuropathy.
Leber's hereditary optic neuropathy (LHON) is a maternally inherited disease characterized by optic nerve degeneration associated with severe bilateral visual loss in young men and occasionally in women. A mitochondrial DNA (mtDNA) replacement mutation in LHON patient, G to A transition at nucleotide position (nt) 11778 converting the 340th arginine to histidine in the NADH dehydrogenase subunit 4, was detected as SfaNI site polymorphism (Wallace et al., Science, 242: 1427-1430, 1988). To evaluate if the SfaNI site loss can be used to diagnose LHON patients, mtDNAs from peripheral blood of six affected males including five probands from five unrelated Japanese families with LHON, a pair of parents and a normal sister of one of the probands and 4 control persons were analyzed using PCR amplification method. The mutation of leukocyte mtDNA at nt 11778 was identified in all of the affected patients, the normal mother and the sister examined, while the father who is normal and 4 control persons did not show the change. These findings support that the mutation at nt 11778 is also associated with LHON in the Japanese and the test of the SfaNI site loss described here is useful for confirming the clinical diagnosis of LHON patients with the mutation at nt 11778.
Asian People↗
[A trial of molecular diagnosis in Leber's optic neuropathy].
The high frequency of mitochondrial DNA mutation at the nucleotide position (nt) 11,778 was reported in cases of Leber's hereditary optic neuropathy (LHON) after the first report by Wallace et al.. We already reported that it provided a simple diagnostic test by means of PCR (polymerase chain determined the diagnosis of LHON in a case. No nt 11,778 mutation was found in patients with the other optic nerve diseases and in normal controls. This shows the usefulness of molecular diagnosis in LHON. Problems of genetic counselling for patients and female carriers and the possibilities to clarify the cause of LHON were discussed.
DNA↗
[Ocular symptoms in mitochondrial myopathy].
The corneal endothelial cells in 6 cases of mitochondrial myopathies were examined by specular microscope, and electron microscopic studies of the cornea were made in one autopsy case. The cornea was clear and the thickness was within the normal range. The endothelial cell mean size was larger in 3 out of 10 eyes than among controls and the variance of endothelial cell size was larger in all of 10 eyes than among controls. The difference was found to be statistically significant. Electron microscopical findings of the cornea revealed mitochondrial abnormalities. Inclusions were observed in the stromal keratocyte.
Adult↗
Association of ectodermal dysplasia, ectrodactyly and macular dystrophy: EEM syndrome (case report).
The authors reported a 41-year-old female patient with EEM (ectodermal dysplasia, ectrodactyly and macular dystrophy) syndrome with hypotrichosis, teeth anomaly, split hand complex and retinal changes with prominent pigmentations located in the posterior pole of the retina. Retinal degeneration had shown minimal progression during 11 years. A longer follow-up period was necessary to make a definite diagnosis of these fundus changes. This is an isolated case born from a consanguineous marriage.
Adult↗
[Pattern reversal electroretinogram--effect of check size, luminance, field size and defocusing].
Using a high water-content soft-contact-lens electrode we recorded pattern electroretinograms (P-ERGs) of subjects responding to reversal checkerboard stimuli and the stimulus parameters were varied in order to investigate normal P-ERG properties. The P-ERG varied with changing luminance, field size and defocusing parameters in the same way as P-VECP, but differed from P-VECP with changes in the check size parameter. These results suggest that the spatial tuning observed in P-VECP could not be discerned in this P-ERG study. It cannot be denied that P-ERG is distorted by P-VECP, which has a larger amplitude at about 100 ms after stimulation. In the future it will be necessary to investigate the origin of P-ERG under experimental conditions separating contrast-related response from luminance-related response.
Adult↗
Topographical study of stereo-related potentials.
In order to estimate objectively binocular vision and especially stereopsis, random dot stereograms generated by a personal computer were used. Brain activity during stereopsis was topographically studied by visually evoked potentials (VEPs). The potentials evoked by binocular viewing of patterns without disparity, e.g. correlogram, were very similar to the potentials evoked from patterns with disparity, i.e. stereogram, as many authors have already indicated. To derive the stereo-related potentials from the VEP elicited by stereograms, the potentials evoked by correlograms were subtracted from the potentials evoked by stereograms, and the differences of topographical distribution between normal and stereoblind subjects were investigated.
Adult↗