Effect of instruction modulation on objective refraction in relation to accommodative micro-fluctuation

In non-cycloplegic autorefraction, subjects are usually instructed to “relax” their vision to minimize the accommodative effects on the measurements. However, these instructions are often underestimated by operators. The aim of this study is to investigate how different methods of subject instruction can influence the measurements and whether they are susceptible to individual accommodative variation. Objective refraction was performed using autorefraction, while accommodative fluctuations were determined using an aberrometer. The aim is to determine whether subjects in whom the measurements vary according to the instructions exhibit similar accommodative micro-fluctuations, and to distinguish between myopic and hyperopic subjects. Despite the guidelines provided by device manufacturers, users vary in their adherence to instructions: our purpose is to quantify the effect of this variation.