Abstract
Abstract: :
Purpose:SLT is a q–switched, melanosome specific laser used to lower intraocular pressure (IOP) in open angle glaucoma (OAG). Several studies have demonstrated significant one month response to SLT in patients with average pre–operative pressures above 22 mmHg. We are interested in investigating if SLT is equally effective in patients who have pre–operative pressures above and below 22 mmHg, and furthermore if there is a linear relationship between pre–operative and post–operative pressure. Methods:48 consecutive eyes with open angle glaucoma who received SLT treatment at The University of Chicago Hospitals (UCH) were included in the study. In addition to attaining preoperative IOP on the day of surgery, three IOP measurements were attained prior to the date of surgery to ensure that a representative baseline IOP was achieved. One month post–operative pressure was measured and recorded for each eye. Primary outcome evaluated was change in IOP from pretreatment baseline. Univariate and multivariate analyses were performed, and statistical significance was established. Results:SLT treatment was performed on 39 eyes with preoperative IOP of less than 22 mmHg(18.1 +/– 2.4mmHg) and 9 eyes with preoperative IOP of 22 mmHg or greater (24.3 +/– 2.7 mmHg.) The one month follow–up IOP for the two groups was 17.8 (.3 mmHg or 1.7% drop) and 19.4 (4.9 mmHg or 20.2% drop) with a difference in IOP drop between the groups of 4.6mmHg or 18.5% drop (P<.0005.) Based on a linear relationship, a drop of 3.6 points is expected in the first group, 3.3 points greater than achieved (p<.0005.) Conclusions:The one month diminution in IOP in patients with higher preoperative pressures (>=22 mmHg) was comparable to that reported in other studies and significantly higher (P<.0005) than the diminution achieved in patients with lower preoperative pressures (<22 mmHg.) Furthermore, the increased absolute response to SLT seen in the higher pressure group was much greater than the incremental response that would be expected from a linear relationship between preoperative pressure and pressure drop. The authors believe that preoperative pressure should be considered as a determinant of short term response to SLT treatment.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: outcomes/complications • laser