[The influence of aging and different type of targets on eye accommodation]

The influence of aging and a couple of external and internal targets on eye accommodation under monocular vision using an infrared optometer were studied. The subjects were 11 healthy adults aged 20-40. In comparison with using internal targets, the amount of accommodative response, tension velocity for accommodation and relaxation velocity for accommodation showed a tendency to increase when using an external target. In particular, these tendencies showed a predominantly in middle-aged subjects. It is suggested that external targets gives some more precise information concerning eye accommodation. In using internal targets, instrument myopia and psycho-physiological factors might bring about a disturbance of reproducibility during eye accommodation.