Abstract
Abstract: :
Purpose:To establish the intraocular pressure (IOP) behavior after laser in situ keratomileusis (Lasik); to learn if a relationship between the amount of corneal ablation and IOP after Lasik does exist and to determine if the flap's thickness has any effect in the IOP after Lasik. Methods:A prospective, longitudinal, observational and descriptive study was done in the Cornea department, between march and november 2002. Preoperatory IOP, keratometry and pachymetry were measured in all patients in two occasions. All patients were treated with Lasik conventional technique. Postoperatory IOP, keratometry and pachymetry were measured in all patients. Patients were divided in three groups according to the corneal ablation applied: Group 1 less than 50 microns; Group 2 between 51 and 75 microns and Group 3 more than 76 microns. According to the flap thickness we divided two groups: Group A 180 microns and Group B 160 microns. Statistical analysis was done by Paired Student's t test. Results:We included 186 eyes from 95 patients, from which we studied 91 eyes from 46 patients. Compound Myopic Astigmatism was the most frequent diagnosis in 85% of the eyes. In all patients we found a statistically significant decreased mean IOP of 2.09 mmHg, with a mean ablation of 64.76 microns. In the groups 1,2 , 3, A and B we found a decreased IOP (P<0.05). When we compared all groups we did not found a statistically significant reduction in IOP after Lasik. A mmHg/micron relationship was done in groups 1,2 and 3 finding that a inverse proportional relation existed, in group 1 0.05mmHg/micron, group 2 0.03mmHg/micron and in group 3 0.02mmHg/micron. Conclusions: IOP underestimation after Lasik does exist, which does not depend on the amount of corneal ablation, the IOP underestimation by micron of ablation have an inverse proportional relation. The flap's thickness does not have an effect in the IOP underestimation.
Keywords: refractive surgery: LASIK • intraocular pressure • clinical (human) or epidemiologic studies: out