2000 年 71 巻 3 号 p. 292-299
Eyelid and eyeball movements are important aspects in determining the awareness level of a resting domestic animal. We have developed an apparatus for measuring the movement of eyelids and eyeballs of domestic animals. The apparatus consists of a charge-coupled device (CCD) camera that is placed in the eyelid region of a head mask. The device emits an infrared light from a diode as a light source. Two types of apparatus have been developed. One uses a wire system, and the other uses a measurable telemetry system in an unrestricted state. The weight of the device with the wire system is about 50g, and the device with the telemetry system weighs about 880g. The operating time of the telemetry system is 24h or more when nickel-hydrogen is used as the power supply. In an experiment using the wire system with a calf, the movements of the eyelid and eyeball could be divided into four categories: fully open eyelid movement, half-closed eyelid movement, fully closed eyelid movement, and eyeball movement. Results of the measurement experiment showed that the time during which the calf's eyelids were half-closed or fully closed while lying down was longest from midnight to 7: 00 a. m. Furthermore, the eyelids were half-closed or fully closed even during rumination. During the daytime, there were long periods when the animal's eyelids were fully open and eyeball movement was very active. In an experiment with a horse, we used the telemetry system device to measure eyelid and eyeball movements for 24h continuously without any discomfort for the animal.
