Abstract
Purpose: :
To evaluate the influence of LASEK and central corneal thickness(CCT) on intraocular pressure(IOP) measurements by Goldmann applanation tonometer, rebound tonometer(iCareTM) and noncontact tonometer.
Methods: :
Patients who underwent LASEK during Sep, 2009 and May, 2010 were recruited. Intraocular pressure was measured using the Goldmann applanation tonometer(GAT), iCare rebound tonometer(RBT) and noncontact tonometer(NCT) before surgery, 1 month, 2 months, 4 months and 6 months after uneventful refractive surgery for myopia. To compare the preoperative and postoperative results, we selected the cases with the time of IOP measurements within 1 hour.
Results: :
The IOP was measured in 235 eyes (118 patients). The IOP before LASEK measured by GAT (mean 15.59 ± 2.69mmHg[SD]) was statistically significantly lower than by RBT (mean 15.97 ± 3.43mmHg) and by NCT (14.83 ± 3.11mmHg) (P=.029 and <.01, Paired T test). The mean difference of GAT and RBT was 0.38 and the 95% limits of agreement ranged from -4.78 to 5.51. The correlation of preoperative IOP and CCT was significant in all tonometers(GAT, RBT, NCT r=0.298, 0.459, 0.530, p<.01, Pearson correlation test). The IOP after LASEK measured by GAT (mean 13.11 ± 2.55mmHg) was statistically significantly higher than by RBT (mean 12.89 ± 2.80mmHg) and by NCT (10.23 ± 2.45mmHg) (P=.005 and <0.001, Paired T test). The correlation of postoperative IOP and CCT was significant in all tonometers (GAT, RBT, NCT r=0.289, 0.317, 0.493, p<0.001, Pearson correlation test). The mean difference of GAT and RBT was 0.22 and the 95% limits of agreement ranged from -2.57 to 2.13. The effect of CCT change on IOP measurements were significantly correlated only by NCT(GAT, RBT, NCT r=0.088, 0.027, 0.465, p=0.372, 0.785, <0.001). Keratometry change was not correlated with IOP(GAT, RBT, NCT r=0.028, 0.088, 0.216, p=0.780, 0.380, 0.030)
Conclusions: :
There was a greater decrease in IOP measurement after LASEK by NCT than RBT and RBT than GAT, but the error range was decreased in all IOP measurements. The correlation between CCT reduction and IOP reduction was not statistically significant in GAT and RBT, but the residual CCT was correlated to all IOP measurements. In case of LASEK, IOP measurements by RBT is more useful than NCT that GAT is subconsciously injurious.
Keywords: intraocular pressure • refractive surgery