Clinical evaluation of the DBR A-scan unit.

One hundred and eight eyes of 106 patients were evaluated preoperatively with the DBR-300 A-scan ultrasonic instrument. Intraocular lens power was then calculated using the formula supplied with the instrument, and the accuracy of the instrument was evaluated. It was found that 61.1% of the eyes were within +/- 1.00 D of the calculated refractive error and 81.5% of the eyes were within +/- 1.50 D of the calculated refractive error when using a standard 3.5-mm anterior chamber depth. Various factors were then analyzed to determine which factors contributed to the inaccuracy of the instrument. No single factor could be found to account for the slight tendency toward myopia, although several were found to contribute. No single factor was found to contribute to large errors.