Calibration of the Canon R-1 autorefractor for continuous measurement of accommodation

The Canon Autoref R-1 is an infrared optometer, which allows free-space viewing. Pugh and Winn have described hardware modifications necessary to con vert the Autoref R-1 from an instrument capable of taking single static measurements of the eye's accommodative (refractive) status to an instrument capable of continuous measurement of the accommodative status of the eye. We describe two methods of calibrating the Autoref R-1 for continuous measurement of accommodation for any individual eye. In the first method we establish the relationship between accommodation stimulus/response and the voltage output of the Autoref R-1. In the second method we calibrate the voltage output of the Autoref R-1 with the position of the internal focusing lens system ( wave form) in reference to the stimulus/response relationship. The assumptions and sources of error underlying these calibration techniques are discussed. We present data on the accuracy of the calibration of the Autoref R-1 for continuous measurements, by comparing repeated static and continuous readings taken under identical stimulus conditions. The differences between static and continuous readings are small (