Determination of intraocular lens power: a comparison with and without ultrasound

Two consecutive and sequential series of 100 pseudophakic patients were compared. In the first series intraocular lens power was determined by clinical means. In the second series axial length, using an easily operated commercially available A-scan unit, keratometry, and estimation of anterior chamber depth data were entered into an electronic calculator programmed to determine intraocular lens power. In the first series 47% of patients had a residual refractive error of 1 diopter or less, whereas 72% were within this range in the second series. With clinical lens power determination, there were three cases of residual deviation from emmetropia of more than 4 diopters; there was none greater than 3 diopters in the group using the A-scan. Lens power determination is more accurate using ultrasonography and the presently available instrumentation can be incorporated easily into a busy private practice.