Objective analysis of the accommodative convergence/accommodation ratio
Lu Fa · Chinese Journal of Optometry & Ophthalmology · 2009
Objective An eye tracker and infrared autorefractor were used to measure the response and stimulus AC/A ratios.The correlation and difference between these two parameters were analyzed.Methods Thirty-four healthy college students and young faculty(25.8 years old on average) were enrolled.In the open-loop condition(left eye occluded),convergence and accommodation were measured by using a Model 310 eye tracker and a WV500 infrared autorefractor with different viewing distances.The stimulus and response AC/A ratios were then obtained and analyzed.Results There was a statistical correlation and a difference between the stimulus AC/A ratio and response AC/A ratio for these subjects.The mean ratio of response AC/A ratios versus the stimulus AC/A ratios was 1.57.Conclusion The response AC/A ratio(7.50±3.60) △/D was higher than the stimulated AC/A ratio(4.77±1.84)△/D,P=0.001.The difference occurs because most subjects show consid-erable accommodative lag.