The invention relates to a method for measuring visual acuity of a subject, said method comprising the steps ofproviding a set of optotypes,providing a pre-calculated value of similarity for pairs of optotypes selected from the set of optotypes,displaying to the subject sub-sets of optotypes of the set of optotypes in different optotype size,receiving for each displayed optotype of one of said sub-set of optotypes of a given optotype size a response of the subject indicative of an optotype (identified optotype) selected from the set of optotypes,registering for each response a value of similarity corresponding to the pre-calculated value of similarity of the pair of optotypes consisting of the displayed optotype and the identified optotype indicated in the response,calculating a value of rate of recognition for each optotype size, the value of rate of recognition for a given optotype size being an average of the registered values of similarity for the responses to the optotypes displayed in the given optotype size,determining the visual acuity from the values of rate of recognition.The invention further relates to a system and a computer program for carrying out the method.
