Abstract
Purpose :
To compare total corneal astigmatism and keratometric astigmatism measurements in pseudophakic eyes, using manifest refractive as reference standard.
Methods :
Pseudophakic eyes with nontoric monofocal IOL and no other ocular pathology were enrolled in the study. Anterior, posterior and total astigmatism were measured by OCT (Avanti-XR) and Scheimpflug tomography (Pentacam). Keratometric astigmatism was measured by automated keratometry (IOLMaster 500). Each measurement was repeated three times. The difference between MR astigmatism and corneal astigmatism was calculated by the magnitude of vector differences.
Results :
Twenty eight pseudophakic eyes from 22 subjects were included in the study. The average MR astigmatism magnitude was 0.55 ± 0.53 D. The repeatability of anterior astigmatism was similar for all 3 instruments (Table 1). OCT had significantly better repeatability in posterior astigmatism than Scheimpflug tomography (Table 1). Total corneal astigmatism, as measured by either OCT or Scheimpflug tomography, had similar magnitude of difference with MR astigmatism (Table 1). Both differences (p = 0.01) were significantly smaller than that between keratometric and MR astigmatism (Table 1).
Conclusions :
Total corneal astigmatism is closer to MR astigmatism than keratometric astigmatism. OCT has better repeatability for posterior corneal astigmatism measurement than Scheimpflug tomography.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.