Research On Intraocular Pressure After Corneal Refractive Surgery

Part one Measurements of intraocular pressure after conductive keratoplasty【Objective】To investigate the possible impact of conductive keratoplasty(CK)on intraocular pressure(IOP).【Methods】36 eyes of 30 patients with presbyopia enrolled in this study. IOP was measured with NCT and GAT before and after surgery. Data was analyzed with paired t-test.【Results】After CK, a significant decrease was observed in NCT and GAT measurements. The change in IOP readings was not correlated with age, sex, keratometric readings, or attempted correction.【Conclusion】The applanation tonometer appears to underestimate the true IOP after CK. The GAT and NCT measurements after CK can not be judged by the normal value in tradition, which will delay early diagnosis of steroid glaucoma after CK. Part two Comparison of dynamic contour tonometer and applanation tonometer【Objective】To evaluate the performance of dynamic contour tonometer(DCT)(Swiss Microtechnology, AG)before and after corneal refractive surgery by comparing it to Goldmann applanation tonometer(GAT)and non-contact tonometer(NCT).【Methods】IOP was measured in 60 eyes of 30 patients with myopia before and after laser in situ keratomileusis(LASIK)and in 36 eyes of 30 patients with presbyopia before and after conductive keratoplasty. The relationship between corneal curvature, central corneal thickness(CCT)and NCT, GAT, DCT readings was determined using multiple correlation analysis.【Results】NCT and GAT readings dropped significantly after LASIK and CK. The preoperatively and postoperatively DCT measurements did not differ significantly. Corneal curvature and CCT correlated with NCT and GAT measurements but not with DCT measurements.【Conclusion】Neither CCT nor corneal curvature can influence DCT readings. Therefore, DCT may be better suited for monitoring IOP in unoperated eyes and in eye that have had corneal refractive surgery.