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New astigmatism metric correlates with manifest refractive cylinder
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SAN FRANCISCO — A novel method of determining corneal astigmatism correlates with manifest refractive cylinder more closely than other measures, according to a study presented here.
George Stamatelatos, BScOptom, described the method known as CorT at the American Society of Cataract and Refractive Surgery meeting.
George Stamatelatos
"We looked at a new approach to incorporate a lot more data into corneal astigmatism management," he said. "CorT is a better representation of corneal astigmatism when compared to manifest refractive cylinder and when incorporating all of the data using summated vector means."
CorT showed lower ocular residual astigmatism (ORA) and less variability than simulated keratometry (Sim K), manual keratometry (manual K), corneal wavefront aberrometry and paraxial curvature matching, Stamatelatos said.
The retrospective study included 498 patients. The Humphrey Atlas 9000 (Carl Zeiss Meditec) was used to measure corneal topography in all eyes. A summated vector mean of Placido rings was used to calculate Sim K, manual K, corneal wavefront measurements, paraxial curvature matching and CorT. All measurements were compared with manifest refractive cylinder.
Only anterior corneal measurements were analyzed; posterior measurements were not taken.
Study results showed that ORA magnitude with CorT was significantly lower than magnitude measurements taken with manual K, Sim K, corneal wavefront aberrometry and paraxial curvature matching (P < .001), Stamatelatos said.
Disclosures: Stamatelatos has no relevant financial disclosures. Noel A. Alpins, MD, the lead author, receives research support from ASSORT.