Patent ID: 7470026

Claim:
A method for measuring operating visual acuity, comprising: a displaying step of displaying an optotype mark on a display device; a response-accepting step of accepting, via an input device, a subject's response input in response to the displayed optotype mark; a determining step of causing a computing device to determine whether the accepted response is correct or incorrect, wherein if a result of the determination indicates that the current response of the subject is correct and if a previous response or one of a previous and a last-but-one responses is incorrect, the computing device determines that an optotype mark corresponding to the same visual acuity as a current visual acuity is to be presented next; if the result indicates that the current response of the subject is correct and if the previous response is correct or both the previous and last-but-one responses are correct, the computing device determines that an optotype mark corresponding to visual acuity which is one level higher than a current level is to be presented next; and if the result indicates that the current response is incorrect, the computing device determines that an optotype mark corresponding to visual acuity which is one level lower than the current level is to be presented next; a storing step of storing in a memory at least a visual acuity level corresponding to the displayed optotype mark and the result of determination performed in the determining step; a timer-determining step of determining whether a predetermined time or a predetermined number of display operations is reached, wherein if the predetermined time or the predetermined number of display operations is not reached, the computing device causes an optotype mark corresponding to the result of the determination to be displayed next in a subsequent displaying step; and an output step of causing an output device to output a measurement result when the predetermined time or a predetermined number of responses is reached.