Experimental evaluation finds laser speckle velocity less accurate than traditional refraction methods, suggesting limitations for observer ametropia.
The validity of expressions for the position of the plane of stationarity, apparent speed of speckle movement, and estimated observer ametropia is examined for laser refraction, using a cylindrical drum. The agreement between theory and experiment is satisfactory. It appears unlikely, however, that methods of subjective refraction depending on estimation of speckle velocity can match the accuracy and precision of those based on rendering the plane of stationarity conjugate with the observer's retina. Even with experienced observers, refractive values based on estimates of speckle speed showed the unsatisfactorily large standard deviation of ∼0.5 D.S.
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Charman et al. (1979) studied this question.
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