Comparing Treting The Manifest Versus The Topographic Astigmatism In Topography Guided Lasik

To investigate whether topography-guided laser in situ keratomileusis (LASIK) based on the topographic astigmatism obtained from the topolayzer(Contoura) (Alcon Laboratories, Inc., Fort Worth, TX) leads to better refractive outcomes compared to treatment according to the clinically measured manifest refractive astigmatism in primary myopic astigmatism.

Kasr Alainy Hospital and Dar Aloyon Hospital

A prospective randomized study conducted on 60 eyes with myopic astigmatism of 1.5 diopters or more that had LASIK using the Alcon WaveLight EX500 excimer laser and T-CAT/Contourasoftware. They were divided into three groups according to the treatment strategy, treating the manifest astigmatism in one group, the topographic astigmatism with change in the spherical power in the second group and treating the topographic astigmatism without change in the spherical power in the third group. The postoperativeefficacy, safety, accuracy, the residual refractive astigmatism and the residual anterior corneal astigmatism and cylindrical vector analysis were compared in the three groups.

The postoperative Uncorrected Distant Visual Acuity(UDVA) in each group separately was better than the preoperative Corrected Distant Visual Acuity(CDVA) (58% had UDVA better than 20/20 and gained 1 line or more)however eyes treated with the topographic astigmatism without change in the spherical power showed statically best results (75% had UDVA better than 20/20). The residual anterior corneal astigmatism was lower in this group (the mean 0.47vs 0.95 and 0.59). No significant difference was noted in the residual refractive astigmatism, but it was also the least in that group (mean-0.16 vs -0.25 and -0.23) 

Topography guided LASIK is a safe and effective ablation profile for treatment of myopic astigmatism. Treating according to the topographic astigmatism shows the best outcome as regards the vision and residual astigmatism.