Near-infrared Spectroscopy of the Visual Cortex in Unilateral Optic Neuritis

Near-infrared spectroscopy (NIRS) is an optical method to assess dynamic changes in the hemoglobin concentration evoked by brain activity 1-4. We applied this technique to five patients with unilateral optic neuritis and investigated whether or not NIRS could detect visual dysfunction objectively in clinically affected eyes. Six healthy volunteers (one man and five women, age 25-39 years) with normal vision and five patients with acute unilateral optic neuritis (two men and three women, age 13-56 years) were examined. Informed consent was obtained from each subject or patient. This study was carried out with approval from the Institutional Review Board of the National Saigata Hospital. In Patient 1, NIRS was measured twice--when the visual acuity in the right eye was 20/200 and 20/40. In Patient 2, NIRS was measured three times--when the visual acuity in the right eye was 20/200, 20/40, and 20/20. The other three patients were tested only once. We used an OM-100A (Shimadzu Corporation, Kyoto, Japan) near-infrared spectroscopy system, with wavelengths at 780, 805, and 830 nm, to monitor changes in the oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), and total hemoglobi