L'influence de la sensibilité des patients sur la précision du résultat de la réfraction

Abstract

For years, it has been a tradition to determine eyeglass and contact lens prescriptions in step of 0.25 diopters. This limit imposed by the technology of subjective refraction instruments: in fact, trial glasses, manual or automated refractors all operate with trial lenses in step of 0.25 δ and only allow separate actions, and therefore successive, on the sphere, the cylinder and the axis of the correction sought. This work shows how patient's sensitivity can influence the accuracy of smaller diopter changes. We also discuss the different measurement methods and the perspectives offered by the new techniques of precise subjective refraction. To answer the problem, a theoretical and practical study is made on a group of patients to determine the dioptric sensitivity by the step of 0.12 δ and different tests are used during a subjective examination. The results show that most patients are sensitive to small changes and prefer this step for their correction.