To compare preoperative visual acuities in patients who underwent cataract surgery between 1982 and 2000.
Information on visual acuity (VA), ocular disease and general disease was obtained from records relating to samples of consecutive cataract operations in 1982, 1985, 1990, 1995 and 2000 in two hospitals in the Vaasa region of Finland.
Between 1982 and 2000, the average preoperative VA in the operated eye increased by 0.85 logMAR units (from logMAR 1.56 to logMAR 0.71) or 8.5 log lines. Corresponding decimal values are 0.03 and 0.2, respectively. In the better eye, VA increased from logMAR 0.64 to logMAR 0.37. Corresponding decimal values are 0.23 and 0.43, respectively. The incidence of cataract surgery increased from 1.0 to 7.2 operations per 1000 of the population per year over the period. For an annual increase of one operation per 1000 inhabitants, the increase in average VA before surgery is 1.3 log lines in the operated eye and 0.4 log lines in the better eye. The number of patients with visual impairment (WHO definition: VA