Far-field infrared system for the high-accuracy in-situ measurement of ocular pupil diameter

It is known that human visual performance is influenced by the ocular pupil diameter. So that we can analyze its effect on visual acuity, we developed a high-accuracy measuring system by which the pupil size can be monitored simultaneously with visual acuity examinations. We used infrared illumination and a far-field imaging setup in order not to disturb the subject. In this paper we present our measuring system comprising a camera, an infrared reflector and a unique evaluation/controlling software. According to our experimental results continuous pupil monitoring is feasible with ±0.2 mm spatial accuracy. The new system allows us to reveal delicate tendencies in pupil accommodation during visual acuity tests.