Continuous recording of accommodation and pupil size using the Shin-Nippon SRW-5000 autorefractor.

A newly released commercial autorefractor, the Shin-Nippon SRW-5000 (Japan), has been found to be valid compared to subjective refraction and repeatable over a wide prescription range. Its binocular open field-of-view allows the accommodative state to be monitored while a natural environment is viewed. In conventional static mode, the device can take up to 45 readings in 1 min using digital image analysis of the reflected retinal image of a measurement ring. Continuous on-line analysis of the ring provides high (up to 60 Hz) temporal resolution of the refractive state to an accuracy of < 0.001 D. Pupil size can also be analysed to a resolution of < 0.001 mm. The measurement of accommodation and pupil size was relatively unaffected by eccentricity of viewing up to +/- 10 degrees and instrument focusing inaccuracies of +/- 5 mm. The resolution properties of the analysis are shown to be ideal for measurement of dynamic accommodation and pupil responses.