[Measuring accommodation time with a laptop computer].

PURPOSE: Presently, there are no completely reliable examinations such as focus from a distant place to a near place during daily work. We developed a simple testing system for accommodation time using a 5 m chart and a laptop computer. MATERIAL AND METHODS: We studied 177 healthy peoples. They turned their eyes from the 5 m chart to the display of the personal computer at about 70 cm in front of the eyes. We measured the minimum time(MTC) for recognizing three Kanji(Chinese characters) randomly chosen from a total of 15 characters on the display. RESULT: The MTCs with + 1.25 D added were shorter than those with complete correction. The MTCs in both conditions extended with age. In subjects less than 40 years old, the MTCs measured with both eyes were significantly shorter than those with a single eye completely corrected. In subjects over 40 years old, there was no difference. The MTCs were shorter significantly with complete correction than with + 1.25 D added. The MTCs decreased as the accommodative amplitude increased. CONCLUSION: There is significant correlation between the accommodative amplitude and the MTCs. We can use the MTCs as one method of measuring time of accommodation.