In Finland during the 20-year period 1958-78 35 patients with amblyopia lost the vision of the healthy eye. In more than 50% the cause was traumatic. The incidence of the loss of the healthy eye was 1.75 +/- 0.30 per thousand. During the same period in Finland the overall blindness rate of children was 0.11 per thousand and of adults aged 15-64 years 0.66 per thousand. For the amblyopic patient the risk of becoming blind is markedly higher than for the general population.