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Biomedical subjects

K Mukuno

Publications and source records attributed to K Mukuno.

At least 37 records · Page 2Linked to original sources
PubMed1988

Instability of eye position in the dark in cerebellar degeneration.

Fourteen cases of spinocerebellar degeneration were examined. While the patients attempted to keep their eyes in the primary position, horizontal eye movements were recorded for 1 min in total darkness by infrared reflection oculography. Instability of eye position in the dark was observed in 10 patients. The range of the eye position error was 3-6 degrees in 6 patients, 6-10 degrees in 3 patients and over 10 degrees in 1 patient. These results indicate that the cerebellum plays an important role in extraretinal (nonvisual) eye position control.

Adult↗
PubMed1987

Quantitative measurement of upper eyelid movements.

A simple and noncontact method for recording upper eyelid movement by means of a solid state image sensor has been developed. Physiological parameters of blink and lid movements during gaze change were studied in 30 normal subjects. Maximum velocity against lid displacement was analyzed. Electromyography (EMG) of the levator palpebrae as well as orbicularis oculi muscles was conducted and vertical eye movement was recorded by electrooculography (EOG). The maximum lid velocity both for upward and downward gaze change was measured; it was always faster in the downward than in the upward gaze. The duration of lid movement during upward gaze change was about 70 msec longer than that of the vertical saccadic eye movement. By EMG, a pulse-step discharge has been well known to occur in the superior rectus muscle but it was never seen in the levator palpebrae muscle in the present observation. The maximum lid velocity of downward spontaneous blink showed two-phase distributions: phase 1 with an initial flat phase in small displacement and phase 2 with a steep phase in large displacement. By EMG, only the pretarsal portion of the orbicularis muscle discharged at the initial phase; preseptal as well as pretarsal orbicular muscle discharges were noted in the second phase. The simplicity of this technique would permit its wide clinical application.

Adult↗
PubMed1986

The origin of square wave jerks: conditions of fixation and microsaccades.

The effects of various fixation stimuli on square waves of eye movements were studied in 16 normal subjects. Fixation eye movements were recorded by infrared reflection oculography under visual and nonvisual conditions. The target size was varied from 9 to 72 minutes of arc in four steps. The mean amplitude of the square wave was enlarged more than 0.5 degrees with the targets over 18 minutes of arc and in total darkness. The findings indicate that the square wave jerks are enhanced microsaccades and are closely related to the instability of the fixation eye movements.

Adolescent↗
PubMed1985

Hemispheric lateralization of spatial contrast sensitivity.

Visuospatial contrast sensitivity was determined by the Arden grating chart in 23 patients with cerebral infarctions involving the primary visual cortex or visual association cortex. Subjects were classified into three groups according to their lesions: I, 6 patients with unilateral medial occipital or occipitotemporal lesions; II, 6 patients with left lateral parieto-occipital lesions; and III, 11 patients with right lateral parieto-occipital lesions. Contrast sensitivity was markedly reduced in Group III, especially in patients having hemispatial agnosia. Group I patients with hemispatial agnosia showed almost normal contrast sensitivity. Spatial contrast sensitivity appears to be more affected when the lesion has an influence on the nondominant lateral parieto-occipital cortex.

Adult↗
PubMed1985

Electron-microscopic study of iris nerves and muscles in diabetes.

The ultrastructure of the iris muscles and innervating nerves in patients with diabetes mellitus and approximately age-matched controls was examined by electron-microscopy. The specimens were obtained during cataract surgery. There were definite histopathological alterations at the nerve terminal innervating the dilator muscle, e.g. the presence of mitochondrial abnormalities, dense bodies and lamellar structures. No change was noted at the nerve terminal to the sphincter muscle. Moderate involvement of the muscle, especially at the sphincter, was observed in the specimens of diabetics. The control specimens had no change at the nerve terminals, while moderate change was observed at the sphincter muscle. Therefore, the change in the sphincter seen in the specimens of diabetics seemed to be mainly the result of the aging process, though the existence of early sympathetic neuropathy was confirmed.

Aged↗
PubMed1983

Repair of ptosis possibly attributable to the long-term wearing of a contact lens.

In recent years contact lenses have become more popular from the ophthalmological viewpoint and because they are easy to wear and aesthetically more acceptable than eyeglasses. One of the complications produced by wearing contact lenses, however, is ptosis. We have had a patient with ptosis possibly due to the long-term wearing of a contact lens in one eye. We performed a skin resection together with repair of the aponeurosis of the levator muscle of the upper eyelid. According to our investigations, there has been only one report on the repair of aponeurosis of the levator muscle of the upper eyelid for this type of problem, and the approach and findings were similar to ours.

Blepharoptosis↗
PubMed1983

Internuclear ophthalmoplegia associated with ipsilateral downbeat nystagmus and contralateral incyclorotatory nystagmus.

A case of left internuclear ophthalmoplegia combined with downbeat nystagmus and right incyclorotatory nystagmus on left downward gaze, left exotropia and skew deviation is presented. All signs subsided completely within about 3 months after the onset of the disease. The etiology was possibly of vascular origin. The potential site of the lesion causing these oculomotor signs is discussed.

Cerebrovascular Disorders↗
PubMed1983

Three types of blink reflex evoked by supraorbital nerve, light flash and corneal stimulations.

Three types of blink reflex were evoked by 1) supraorbital nerve stimulation, 2) light flash stimulation and 3) corneal touch. The blink reflex response was recorded simultaneously for both eyes by electromyography of the orbicularis oculi muscles of the lower eyelid. After supraorbital nerve stimulation, ipsilateral early response (R1) and bilateral late responses (R2) were demonstrated. The light flash stimulation evoked the photic early and late responses. The latency times of the R1, R2 and the photic early responses were determined in 22 normal subjects. The corneal touch was exactly timed using a new device and the latency time of the corneal blink reflex was determined. The latency of the ipsilateral corneal blink reflex was significantly shorter than that of the contralateral reflex. The blink reflexes by supraorbital nerve stimulation and light flash were studied concurrently in 7 patients with neurological disorders of vascular origin. The photic reflex was disturbed by bilateral occipital lobe lesions and also by affection of the rostral midbrain. The reflexes were not affected by lesions in the medial longitudinal fasciculus but were disturbed by widespread brainstem lesions of Foville syndrome. Clinical significance of a combined use of the supraorbital nerve and light flash stimulation was emphasized.

Adult↗
PubMed1982

Pupillary analyses in Graves' disease.

Using electronic videopupillography, the direct pupillary response to light and edge light pupillary oscillation by slit light stimulus was examined in patients with hyperthyroidism and in controls. Amplitude of constriction, velocities of constriction and dilatation significantly reduced in the patients in pupillary response to light. The pupillary oscillation was also reduced in the amplitude of oscillation as well as in the velocities of dilatation and constriction. These alterations in pupillary response to light correlated only with the triiodothyronine-RSU test. The oscillation correlated with the duration of the disease. The results indicated that the pupil dynamics were abnormal in patients with hyperthyroidism and this can be demonstrated by sensitive pupillography.

Adolescent↗
PubMed1981

Grating test of contrast sensitivity in patients with Minamata disease.

Thirty cases of Minamata disease caused by methyl mercury poisoning with the lesion mainly at the occipital cortex were selected and their spatial contrast sensitivity of vision was examined by the Arden grating chart. At the same time their visual acuity, visual field, and visual evoked cortical potential (VECP) were also investigated. In all cases the results of the Arden test indicated abnormality. Poor results were obtained at higher frequencies of the gratings. VECP elicited by grating pattern reversal stimulus was undertaken in 12 cases out of the 30. The results revealed abnormality almost equal to that shown by the Arden test. Seven out of the 12 cases showed no VECP response. The other 5, giving a response, showed abnormality: when the size of the grating became smaller at higher frequencies, the VECP paused or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement with the results of the Arden test. Visual acuity and visual field tests were less sensitive in detecting abnormality. The Arden chart is a sensitive clinical tool for patients with lesions at the cerebral cortex. Furthermore, the test can be used for screening patients who may have come in contrast with organic mercury.

Adult↗