Measuring the accommodative response with a double-pass system: comparison with the Hartmann-Shack technique.

The current study aims at analysing the suitability of the double-pass technique in measuring the accommodative response. A custom-built setup which allowed simultaneous double-pass and Hartmann-Shack measurements was used. Several metrics to assess the accommodative response were tested and compared. In order to validate double-pass based measurements, the accommodative response was measured in 10 young adults under monocular viewing conditions with an open field fixation test. Accommodation was stimulated with the push up method in the 0-5diopters (D) range with a 1-D step. We found no significant differences among accommodative response measurements obtained with the several metrics compared in the double-pass and the Hartmann-Shack technique. In addition, differences between the double-pass and Hartmann-Shack techniques were not statistically significant. However, we obtained slightly higher values in the measured accommodative response with the double-pass system than those usually reported by other authors. The double-pass technique takes into account all factors influencing retinal image quality. Consequently, we consider this technique as a potential powerful candidate for the analysis of accommodation.