Biometric analysis of intraocular lens power required to produce emmetropia: results of 450 implants.

We analyzed 450 consecutive cases of intraocular lens implantation (omitting only two inadvertent implantations in patients with high myopia) to determine the dioptric lens power in each case required to produce emmetropia. The mean was 18.3 D with a standard deviation of 2.6 D. The data did not conform to a normal or Gaussian distribution because of an abnormally high number of cases that required greater than 25 D to achieve emmetropia and clustering between 17 to 19 D. The deviation from a normal distribution may be explained by our considering patients with high hyperopia and high myopia (which are for the most part excluded from intraocular lens data) to be separate populations. The data are valuable to the intraocular lens surgeons, in that they demonstrate the range and frequency of intraocular lens powers needed to achieve emmetropia in a large population sample.