The prognosis of myopia depends very largely upon the age of the patient. Any degree occurring in a child under the age of four should be regarded as a serious and potentially progressive condition requiring treatment. Above this age, and certainly above the age of eight or ten, low degrees — up to - 6 D — may be looked upon with less alarm; care should be exercised especially about the time of puberty, and if the age of twenty-one is passed without serious progression, the condition may be expected to remain stationary, and the prognosis may be taken as good. In the higher degrees the prognosis should always be guarded; it must be based on the appearance of the fundus and the acuity of the vision after correction. In all cases the possibility of a sudden hæmorrhage or a retinal detachment should be borne in mind.