We investigated the dominant eye of 123 Korean over twenty years old, then examined the refractive correlation of dominant eye, the unaided visual acuity and over-correlation. The results of these investigations are following. 91 persons of the whole number, 74%, have the dominant eye of right. The refractive correlation to the glasses are the high dominant eye. There are many men who are the same in unaided visual acuity. In men, they prefer to have the non-dominant eye but in women, they like better to have the dominant eye. The unaided visual acuity of ametropia, however, prefer to have the non-dominant eye in both men and women. In case of over-correction of an eye, there was affected the response of the other eye over 50% at the same time and the case of over-correction of dominant eye has more number than that of non-dominant eye.