Evaluation The Change Of Posterior Cornea Surface Using Pentacam After Excimer Laser Keratomileusis

ObjectiveUsing Pentacam observe the change and influential factors of posterior cornea surface after three operation Sub-Bowman keratomileusis(SBK), laser in situ keratomileusis (LASIK) and laser subepithelial keratomileusis(LASEK) for myopia patient.MethodProspective clinical observation study.100 patients to enter,81 patients completion follow up of the total , 36 patients of SBK,24 patients of LASIK and 21 patients of LASEK, the right eye is to observe. The changes in parameters in posterior cornea surface height point, posterior cornea elevation for 1.5㎜ distance to cornea culminated point of the anodic, below, temple, nasal side, temple side, upper temple, below temple, upper nose and below nose analyzed using pentacam preoperatively, 1 month and 3 months postoperatively. The changes in parameters of CACD, AV, cornea ABFSD and PBFSD were analysede. Matched-pairs t analysis every group parameters of preoperatively, 1 month and 3 months postoperatively ,pearson correlation analysis compare the relationship of influential factor to posterior cornea surface height point, multiple factor variance analysis the compare relationship of three group.ResultThe object we investigative postop no one to happen suspect of keratoconus or keratoconus. Preoperative,postop 1 month and postop 3 month posterior cornea surface height point discern is: SBK group is(0.79±2.58)μm,(-0.50±4.00)μm ,(-1.29±2.46)μm,LASIK group is(0.79±2.58)μm,(-0.50±4.00)μm ,(-1.29±2.46)μm,LASEK group is(1.38±3.04)μm,(0.00±2.38)μm,(1.08±3.09)μm. Three group comparison postop 3 month posterior cornea surface height point variation SBK group and LASEK group(P﹤0.05)have statistical significance, LASIK group and LASEK group(P﹤0.05)have statistical significance.SBK group postop variation of posterior cornea surface height point with all factors dependability no statistical significance(P﹥0.05).LASIK group postop 3 month posterior cornea surface height point variation with cornea flap thickness have midrange dependability (R=0.55,P﹤0.05), there is statistical significance; But with other factors no statistical significance(P﹥0.05).LASEK group postop 1 month posterior cornea surface height point variation with preoperative cornea PBFS DS have midrange correlation dependability(R=0.58,P﹤0.05), there is statistical significance(P﹥0.05). The change of posterior cornea surface height point and posterior cornea elevation for 1.5㎜distance to cornea culminated point all correspondence low in three group after excimer laser keratomileusis, but the change is very small.Postop 1 month,3 month CACD and AV all diminish compare with preoperative, SBK group 1 and 3 month CACD discern diminish (0.03±0.07)mm and (0.04±0.07) mm, there is(P﹤0.05)have statistical significance compare with preoperative; LASIK group 1 and 3 month CACD discern diminish (0.1±0.26)mm and (0.04±0.09) mm, LASEK group 1 and 3 month CACD discern diminish (0.03±0.08)mm and (0.04±0.09)mm, but LASIK group and LASEK group the change of CACD no statistical significance(P﹥0.05)postop compare with preoperative.ConclusionAetio-group case postop expecting RBT≥294μm, corneal thickness≥417μm, overview 3month no development to expand of the posterior surface of cornea.The point height of the posterior cornea surface was relatively lower in all of the three groups using Pentacam after excimer laser keratomileusis. We presume change anterior surface of cornea curvature and corneal thickness chance influence Pentacam and generate measure declination on posterior cornea surface height pointThe three group CACD and AV all correspondence low in postop compare with preoperative, but the change is very small. The influence factors are measuring declination of Pentacam after excimer laser keratomileusis or the lens location shift forward because of the change of eye regulative.