Observation On The Effect Of IOP Lowering Medication For The Posterior Corneal Surface After LASIK By Using ObrscanⅡ Corneal Topography

Objective: To monitor the changes of the forward shift of Posterior cornealsurface which used IOP lowering medication (carteolol eye drops) after LASIKby using Orbscan II corneal topography detection system dynamically,and todiscuss the effects of IOP lowering medication to the forward shift of theposterior corneal surface after LASIK.Method: From Dec.2011to Jul.2012,we gathered up80patients (160eyes)who agreed to and accepted the laser in situ keratomileusis (LASIK) surgery inNingxia Medical University General Hospital.And there were61cases(122eyes)finished the follow-up research and involved in statistics. According the resultsof preoperative examinations to figured out the corneal cutting ratio (i.e. theratio of the cutting depth to the preoperative corneal thickness) of patients onthe basis of the particular diopters of their eyes to be corrected, divided intothree groups: group A with the corneal cutting ratio below10%, group B withthe ratio of10%-20%, and group C with the ratio over20%.Than divided theminto experimental and control groups with with simple random samplingmethods.And there were6subgroups, Experimental groups: A1， B1， C1;Control groups: A2，B2，C2.After LASIK,we give the the2%carteolol eye dropsto the patients who in experimental groups,from1week to6months after surgery. Conventional eye treatment to the control groups.Then the patientswere surveyed with their uncorrected visual acuity (UCVA), intraocularpressures (IOP) and corneal curvatures1week,1month,3months,6monthsand9months after the operation, also had the Diff-values of the forward shiftson their posterior corneal surfaces measured by the Orbscan II cornealtopography detecting system, and picked up by SPSS for statistics to be used forparameter-change analysis of the two groups.Result:1. Uncorrected visual acuity, there was no significant difference between the A1and A2（P>0.05）,the UCVA of B1&C1groups has significant difference with B2&C2(P<0.05) in1month,3months and6months after operation, while after9months such difference was narrowed down and no longer make sensestatistically（P>0.05）.2.Diff value. There was no significant difference betweenthe A1and A2（P>0.05）.The Diff value of B1has significant difference with B2in1month,3months and6months after LASIK（P<0.05），and showed a steadydownward trend, the diff value of B2increase a little in1month aftersurgery,but than get down, the rangeability is large than experimentalgroups.The diff value of C1&C2were all have significant difference in1month,3months and6months（P<0.05）.After9months from surgery there wereno significant difference between experimental and control groups.3. Cornealcurvature. There was no significant difference between the A1and A2either（P>0.05）. The corneal curvature of B1and B2had significant difference in3months and6months after LASIK. C1and C2also had Statistically significantdifference in1month,3months,and6months after.4. Intraocular pressure(IOP),B1and B2, C1and C2were significantly different between each other in1 month after LASIk (P <0.05), the rest of the groups at each time there was nostatistically significant（P>0.05）.Conclusion:1.Using intraocular pressure-lowering drugs in the early period ofpostoperation, that can reduce the forward shift of Posterior corneal surface, alsocan increase the stability ofdio pter and corneal curvature， especially do moreeffect on the cases that the corneal cutting ratio above10%;so the IOP-loweringdrugs may play the positive effect in preventing the refractio nregression．2.TheIOP-lowering drugs can be used as conventional drugs after LASIK for thepatients who has high diopter or thin corneas to maintain the stability of thecorne.3. It’s necessary to check t the forward shift of Posterior corneal surfacewhen we che check the IOP after LASIK, try to reducing corneal ectasia andavoid some complications after LASIK.