Natsuko Hatsusaka

Kanazawa Institute of Technology, Kanazawa-shi, Ishikawa-ken, Japan

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Publications (7)4.17 Total impact

  • Journal of Cataract and Refractive Surgery 11/2014; · 2.75 Impact Factor
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    ABSTRACT: To compare and evaluate changes in the retinal image with age in Japanese adults with transparent crystalline lenses. Shibuya-ku, Tokyo, Japan. Cross-sectional study. The study comprised right eyes with corrected distance visual acuity better than 0.0 logMAR. A point-spread function analyzer (PSF-1000) was used to measure retinal image contrast with 3.0 mm pupils under maximum mydriasis. A wavefront analyzer (KR9000PW) was used to measure higher-order aberrations (HOAs) with 4.0 mm pupils. The lens transparency property was estimated by the backward light-scattering intensity of each layer of the lens and the optical distance (mm) photographed by an anterior segment analysis system (EAS-1000). The Pearson product-moment correlation (R(2)) was used for statistical analysis; the significance level was 5%. The study comprised 269 patients (mean age 39.7 years ± 7.7 [SD]). The retinal image contrast degenerated significantly with age; the largest difference was seen with the 0.423 logMAR optotype, for which the decrease was 5.4% every decade. Backward light-scattering intensity (R(2) = 0.030, P<.01) and HOAs (R(2) = 0.032, P<.01) correlated negatively with retinal image contrast. Retinal image contrast in eyes with transparent lenses degenerated with age. The decrease was most prominent at the middle frequency domain and was due to the increase in HOAs and light-scattering intensity. No author has a financial or proprietary interest in any material or method mentioned.
    Journal of Cataract and Refractive Surgery 08/2012; 38(10):1783-7. · 2.75 Impact Factor
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    ABSTRACT: To assess the validity of the solar ultraviolet index (UVI) as a determiner of eye risk under different conditions of facial profiles and orientation, and reflected light. Ocular UV radiation (UVR) exposure was measured as a function of the time of the day (solar altitude) using a two-dummy-type mannequin dosimetry system with embedded UVR (260-310 nm) sensors, in September and November in Kanazawa, Japan, on a motorized sun-tracking mount with one dummy face directed toward the sun and the other away from the sun. A bimodal distribution of UV-B exposure was found in September for the face directed toward the sun, which differed dramatically from the pattern of ambient UVR exposure and measurements taken on the top of the head and those for the eye taken later in the year. Although the overall level was lower, a higher solar altitude is associated with higher UVR exposure in the condition facing away from the sun. The UVI is based on ambient solar radiation on an unobstructed horizontal plane similar to our measures taken on the top of the head, which differed so much from our measures of ocular exposure that UVI as a determiner of eye risk is deemed invalid. The use of the UVI as an indicator for the need for eye protection can be seriously misleading. Doctors should caution patients with regard to this problem, and eye protection may be warranted throughout the year.
    Eye & contact lens 07/2011; 37(4):191-5.
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    ABSTRACT: Magnetoencephalography (MEG) is one of the most promising applications of biomagnetics. In order to expand and establish MEG applications, an evaluation standard for MEG systems is necessary. We have proposed and fabricated a practical dry phantom that is composed of two isosceles-triangle coils based on Ilmoniemi’s model. The uncertainty level of the phantom itself has not always been stated in the literature. In this study, we evaluated the phantom by two methods: a 3-D measurement of the coils with X-ray computed tomography, and a magnetic field measurement with an MEG system. In the former, the maximum displacement of the estimated position of the equivalent current dipole was . In the latter, the displacement was 0.68 0.19 mm. The uncertainty level was found and less than 0.1 mm, or less than 0.2 mm; therefore, we can assess the MEG system itself with an uncertainty level of 0.2 mm. The displacement in the magnetic measurement larger than the uncertainty level of 0.2 mm is estimated due to the systematic error of the MEG system. Hence, dimensional and magnetic measurements are effective for evaluation of the phantom and the MEG. Index Terms—Magnetoencephalography, measurement uncertainty, phantoms, superconducting quantum interference devices (SQUIDs).
    IEEE Transactions on Magnetics 01/2011; 47(10):3853-3856. · 1.42 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the interaction of the auditory pathway at the level of the primary auditory cortex by magnetoencephalography (MEG). Auditory evoked magnetic fields have been investigated from the beginning of MEG studies. We examined auditory responses in healthy 13 subjects, 6 males and 7 females. The responses were averaged by 100 stimulus presentations of each measurement. We could find clear response peaks, such as N100m and P200m in 12 subjects. Especially in N100m, it revealed that there were some patterns and it was not simple to determine contralateral dominancy or hyperactivity of the right auditory cortex over the left, and there were some differences with previous studies. In this measurement, we could classify them into three major groups using the isofield contour map and peak amplitude of N100m. The explanation of individual variation requires further investigations of binaural integration and interaural differentiation.
    International Congress Series 01/2004; 1270:161-164.
  • Natsuko Hatsusaka, Masanori Higuchi
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    ABSTRACT: Although many studies have reported auditory evoked magnetic fields in a wakeful state, it is not clear how the auditory evoked magnetic field is affected by a half-sleep state. We investigated change in the auditory evoked magnetic field in a half-sleep state. Eight normal hearing subjects (five men, three women) participated in this study. In order to make a half-sleep state, the measurement was started about 1 h after having lunch. Auditory stimulation was 1000 Hz tone bursts and was delivered to the right ear through an air tube attached to an earplug. The responses were averaged by 100 stimuli. A significant response was observed after the N1m response in a half-sleep state. This response was estimated to come from the deep area. We speculate that it has some relation to the theta rhythm activities and is synchronized with auditory stimulation.
    International Congress Series 01/2004; 1270:165-168.
  • Masanori Higuchi, Natsuko Hatsusaka
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    ABSTRACT: We are studying how to find the early stages of dementia, such as Alzheimer's disease (AD), by using a MEG system. In relation to brain functions and dementia, memory defects are characterized as the most obvious signs of dementia. In a preliminary study, we tried to measure the visual evoked magnetic field related to memory function by using a simple memory task. In the memory task measurement, the subject memorized one figure for a few seconds, and then counted the number of memorized figures that appeared in the sequence of figures presented randomly. Evoked responses by visual stimuli were averaged for each condition. We compared the results of the control and memory task and identified the components, which seem to be related to memory functions.
    International Congress Series 1270:188–191.