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J.P. Fang, L. Wang, D.D. Koch; The Clinical Significance of Cyclotorsional Rotation Registration vs. Pupil Centroid Shift Compensation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):532.
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To investigate the residual wavefront aberrations induced by the cyclotorsional rotation and pupil centroid shift.
In 64 eyes treated with the Iris Registration system of the VISX S4 laser, we found that the average cyclotorsional rotation was 2.1 ± 1.5 degrees (range 0 to 6.6 degrees) and the magnitude of pupil centroid shift was 0.27 ± 0.14 mm (range 0.04 to 0.51 mm). Based on corneal aberrations from 50 eyes of 50 subjects, we calculated the residual wavefront aberrations and Strehl ratio with cyclotorsional rotation of 2.1 degrees and horizontal decentration of 0.27 mm, respectively.
The total root–mean–square (RMS) (2nd to 6th order) and higher–order RMS (3rd to 6th order) were higher and the Strehl ratio was lower for decentration of 0.27 mm than for a cyclotorsional rotational error of 2.1 degrees (all P<0.001). However, the Strehl ratio with cyclotorsional rotation decreased significantly with increasing amounts of keratometric astigmatism (Pearson correlation coefficient –0.94, P<0.001); with astigmatism > 2 D, the Strehl ratio was comparable to that seen with decentration.
For normal eyes with astigmatism less than 2 D, the pupil centroid shift feature provides greater visual benefit than does compensation for cyclotorsional rotation registration.
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