Corneal Astigmatism Measurements Comparison among Ray-Tracing Aberrometry, Partial Coherence Interferometry, and Scheimpflug Imaging System

Table 5

Difference between 3 mm axial corneal astigmatism measurements centered on the pupil and corneal vertex obtained using Pentacam.

	Astigmatism centered on the pupil	Astigmatism centered on the vertex	Difference ( − V) ± SE
Astigmatism magnitude (D)	1.72 ± 0.83	1.88 ± 0.90	−0.16 ± 0.03	<0.001
Astigmatism cardinal	0.58 ± 1.62	0.60 ± 1.79	−0.02 ± 0.03	0.612
Astigmatism oblique	−0.04 ± 0.85	−0.05 ± 0.89	0.01 ± 0.01	0.480

V = astigmatism centered on the corneal vertex; D = diopters;  = astigmatism centered on the pupil; SE = standard error. Paired two-tailed t-test. Statistcally significant at the 5% level.