Continuous recording of accommodation and pupil size using the Shin-Nippon SRW-5000 autorefractor J. S. Wolffsohn, B. Gilmartin, E A. H. Mallen and S. Tsujimura Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK Summary 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 ®eld-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 re¯ected 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 ^108 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. q 2001 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved. Introduction The Shin-Nippon Autorefractor has recently been shown to be accurate/valid compared to subjective refraction and reliable in both adults (Mallen et al., 2001) and children (Chat and Edwards, 2001). As well as being used to assist in clinical optometric practice, autorefractors are also used extensively in optometric research, especially if they have the ability to monitor the dynamic accommodative response, allowing data on micro¯uctuations, latencies and response times to be recorded. The advent of continuously-recording infra-red optometers for the study of accommodation has provided a wealth of information concerning the system's dynamic behaviour. The major advantages offered by infra-red optometers over subjective optometers that incorporate the Badal system, e.g. He±Ne laser optometers, is that they are objective (i.e. requir- ing no judgment or response by the subject). Although it was originally stated that viewing the laser speckled pattern does not in¯uence accommodation (Hennessy and Leibowitz, 1970), subsequent studies have demonstrated that laser optometers tend to signi®cantly affect the resting focus of the eye in up to one third of individuals (Post et al., 1984, 1985; Jaschinski-Kruza, 1991; Rosen®eld et al., 1993). Higher resting focus values were measured by a laser optometer compared to an infra-red optometer and this discrepancy was substantially enhanced when judge- ments regarding the direction of speckled motion were requested. The Canon Autoref R-1, after conversion, was an invalu- able tool for measuring dynamic accommodation objec- tively as it allowed a binocular ®eld of view through a semi-silvered mirror (McBrien and Millodot, 1985; Pugh and Winn, 1988; Collins et al., 1995). However, it needed calibration for each individual, had a limited working dynamic range (2±3 D), needed relatively large pupils (3.9 mm; Winn et al., 1989), required the use of a bite- bar, only tolerated a small degree of eye movements (38 in static mode and ,18 in dynamic mode; McBrien and Millodot, 1987; Owens, 1991) and is now no longer available. Nevertheless the Canon R-1 has been employed 108 Ophthal. Physiol. Opt. Vol. 21, No. 2, pp. 108±113, 2001 q 2001 The College of Optometrists. Published by Elsevier Science Ltd All rights reserved. Printed in Great Britain 0275-5408/01/$20.00 www.elsevier.com/locate/ophopt PII: S0275-5408(00)00050-8 Received: 5 June 2000 Revised form: 25 September 2000 Accepted: 2 October 2000 Correspondence and reprint requests to: J. Wolffsohn. Tel.: 144-121- 3593611, ext. 5160; fax: 144-121-333422-. E-mail address: j.s.w.wolffsohn@aston.ac.uk (J. Wolffsohn).