J Korean Ophthalmol Soc.  1993 Nov;34(11):1101-1108.

Classification of Corneal Topography and Analysis of Astigmatism based on Computer-Assisted Videokeratography

• Koo KL
• Choi SK
• Lee HY

Abstract

We evaluated the corneal topography of 109 eyes which have 1 diopter or more astimatism, with computer-assisted videokeratography(Eye Sys CAS). There was 11% with round pattern, 17.4% with oval pattern, 49.5% with symmetric bow-tie pattern, 19.3% with assymmetric bow-tie pattern, 2.8% with irregular pattern. 70% of subjects had right and left eyes classified into the same group. There was statistically significant difference among the patterns for keratometric astigmatism and difference among the groups which were classified by the location of the area of highest refractive power for keratometric and total astigmatism. The mean angular separation between flat and steep meridian was 89.2 degrees and ranged from 78.61 degrees to 100.67 degrees. The mean residual astigmatism was 0.547 diopter. In the with-the rule astigmatism type, when the total astigmatism less than 1.89 diopter, residual astigmatism neutralize the corneal astigmatism, but when the total astigmatism increase more than 1.89 diopter, residual astigmatism tend to increase the total astigmatism.

Keyword

Computer-Assisted Videokeratography; Astigmatism; Round; Oval; Bow-Tie

MeSH Terms

Astigmatism*
Classification*
Corneal Topography*