近赤外分光法を用いた屈折負荷に対する脳機能計測: 第一報

摘要

屈折異常（近視・遠視・乱視）に対し、適切な度数のレンズを用いて眼光学系に矯正を行うことで、良好な視力（矯正視力）が得られる事はよく知られている。本研究では、近視以外の特記すべき異常を認めない健常被験者に対し、NIRSを用いて凹レンズ負荷に対する脳賦活化を計測した。視覚刺激としてランドルト環を用い、後頭葉視覚野を含む領域に対し測定を行った。異なる指標サイズ毎において、GLMにより求めたβ値を比較した。正答率を3カデゴリ（Chance，partial，visible）に分け、この段階の変化と賦活化の程度の関係について考察を行った。カテゴリの改善がみられた施行では、ほぼ全てのチャネルでβ値が正となる傾向が認められた。%NIRS (Near-infrared spectroscopy) is a spectroscopic method to assess dynamic changes in the hemoglobin concentration evoked by brain activity. In this study, we investigate the relationship between the brain activity in occipital area associated with presenting visual stimuli and the power of the lenses.rnTwo healthy volunteers with mild myopia (about -4D) participated in the experiment. Landolt's ring was used to check the visual acuity examination. In every session, task was performed with concave lenses and rest without them. We examined on convex lens of different power (-1D.-3D) and different stimulus size (0.1, 0.4, 0.7). The percentage of stimulus answered correctly (PSAC) were assigned to three categories (chance, partial, visible).rnCharacteristic changes were found in both subjects. Some of the channels in or next to visual cortex, oxygenated hemoglobin concentration changes increased significantly. We investigated the beta values, which were positive in almost all the channels when PSAC improved. In case that PSAC was chance level without lens and no longer changed better with it, beta value tends to be negative in parietal area. When PSAC is visible with lens as good as without lens, beta values are negative in almost all of the channels.rnSuitable correction of the eye brings quality of vision. On the other hand, lack of correction or overcorrection of glasses sometimes causes asthenopia, headache, waning productivity and so on. These results could contribute to qualify and quantify of the correction of the eye.