[Bilateral surgery: an efficient manner of creating LASIK nomograms]

Taking advantage of bilateral surgery, an efficient and predictable manner of doing Laser-assisted-in situ keratomileusis (LASIK) nomograms, is described.

We used our current technique of nomogram development with an example to described it. To evaluate a change made in the software of our LaserSight excimer laser unit: sixteen consecutive patients, operated on bilaterally, by the same surgeon, within statistically similar clinical, refractive, and surgical settings, were randomized with different nomogram for the right (OD), with a newer ablation pattern randomized in the (OS) the older sequential. Pattern. (Sequential overlapping burns) The refractive results were studied for statistical significance at 4 weeks and 6 months. The data was analyzed, using a student T test and two way Anova.

Pre-operative refractive data showed a mean sphere in OD of -10.917 +/- 1.749, and OS of -10.89 +/- 1.717, p < NS. The mean preoperative spherical equivalent OD was -9.81 +/- 1.62 and OS of -9.93 +/- 2.02, p < NS. Post-operative mean spherical equivalent at 4 weeks in OD was +1.54 +/- 1.52, and in OS was +0.43 +/- 1.9, p < 0.05. At 6 months OD randomized was of +1.20 +/- 1.24 and, OS sequential of +0.14 +/- 1.70, p < 0.05. On the cylinder component of the refraction the values were equally corrected at both time points with p < NS.

In a small group of patients, one current technique we use for nomogram development is described. Having similar statistical parameters, a significant overcorrecting with the new randomized ablation was observed, when surgery is carried out bilaterally. The change to the nomogram need then to be applied, so final refractive results are equal or better than the previous older sequential pattern. Four weeks results appeared to be time enough, since no statistical difference were observed at 6 months.