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Normal Toric Cornea

LASIK in Modesto / Stockton – Dr. Ash
Visante OMNI Evaluation

30 -year-old male was seeking LASIK eye surgery in Modesto. His refractions were:
    right eye +3.75 - 5.50 x 015 --> 20/15
    left eye +3.75 - 5.00 x 180 --> 20/15

His corneal pachymetries were right eye 502 microns and left eye 504 microns by ultrasound pachymeter. His keratometric measurements were relatively high. Right eye 43.12, 48.12 @ 096 and left eye 43.37, 48.12 @ 090.

Anterior Axial Curvature is in top left and is the standard print out from the ATLAS Corneal Topographer. The high regular corneal astigmatism is clearly noted in a standard bow-tie distribution. The Anterior Mean Curvature is in the bottom left showing a very normal distribution pattern. The Anterior Mean Curvature is also available data from the ATLAS. The Anterior Elevation map is also available from the ATLAS. In the top right, it is assuming a spherical cornea and clearly it can be noted where the cornea rises above that sphere and area that are below. The flaw with this map is that in highly astigmatic corneas, the better fit would be an ellipsoid that would account for the differences in the corneal curvatures.

The Visante Global Pachymap is in the top center, showing a normal regular thickness distribution. When comparing the corneal thickness with known regular distribution, one can see that relative other corneas it is thinner, but the map has a normal, regular pattern as presented in the Relative Pachymetry map in the middle bottom.

Visante omni is used to present the Posterior Elevation data in the bottom right. Here we have assumed a spherical cornea and again just as the anterior surface, the flaw of this design is that it does not account for the corneal curvature differences in the different meridians. In order to correct these flaws an assumption of best fit ellipsoid cornea is made below.

 
 Normal Toric Cornea evaluated using the Visante omni with best fit sphere module
 

With the change in the assumption and a best fit ellipsoid cornea, the Posterior Elevation map now looks perfectly regular as well as a much more regular Anterior Elevation map on the top right. Pay attention to the fact that the scale in this case has ben auto set to 0.25 microns, therefore creating huge noise as seen.  In this Holladay report, the anterior tangential map also replaced the anterior mean curvature in the bottom left size.

This case presents an individual considering LASIK eye surgery that may have by some been considered a non-candidate due to the relative high keratometric readings in the 48's and very thin corneas. This patient on the Visante Omni was able to demonstrate regular cornea and has undergone iLASIK procedure with excellent success. Patient is 20/20 each eye with best spectacle correction visual acuity of 20/15.

 Normal Toric Cornea evaluated using the Visante omni with best fit toric ellipsoid module

 

 

 

 

 

07/04/11


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