Changes in Corneal Astigmatism and High Order Aberrations After Clear Corneal Tunnel Phacoemulsification Guided by Corneal Topography

ABSTRACT PURPOSE: To study changes in corneal astigmatism and high order aberrations after clear corneal tunnel phacoemulsification guided by corneal topography. METHODS: All patients were randomly assigned to the test group or the control group. Corneal topography-guided clear corneal tunnel phacoemulsification followed by intraocular lens (IOL) implantation was performed on 22 eyes of 16 patients in the test group and conventional temporal corneal tunnel phacoemulsification and IOL implantation were performed on 22 eyes of 21 patients in the control group. The corneal astigmatism and high order aberrations were measured using the NIDEK OPD-Scan aberrometer and topographer preoperatively and up to 3 months after surgery. The corneal astigmatism and sixth order root-mean-square (RMS) for corneal coma, trefoil, spherical, secondary coma, and secondary spherical aberrations at 4-mm pupil diameters were compared. RESULTS: Fifteen (69%) eyes in the test group and 8 (36%) eyes in the control group achieved ≥ 20/25 uncorrected visual acuity 3 months after surgery, which was statistically significant (P<.05). The best spectacle-corrected visual acuity was ≥20/20 in 14 (63%) eyes in the test group and 10 (45%) eyes in the control group. The mean surgically induced astigmatism in the test group was 0.58±0.39 diopters (D) compared with 0.73±0.41 D in the control group. The change in corneal astigmatism from preoperative to 3 months after surgery was -0.17±0.32 D for the test group and 0.10±0.41 D for the control group, which was statistically significant (P<.05). The RMS value of trefoil aberrations increased, and all other aberrations decreased at 3 months after surgery in the test group. The RMS values of all corneal high order aberrations increased in the control group, with the increase in trefoil being statistically significant. The comparison of surgically induced high order aberrations between the two groups showed that corneal coma, trefoil, and secondary coma were significantly different. CONCLUSIONS: Clear corneal tunnel phacoemulsification and IOL implantation guided by corneal topography can yield better visual acuity by reducing the pre-existing astigmatism and inducing less corneal aberrations than conventional temporal corneal tunnel phacoemulsification. [J Refract Surg. 2006;22:S1083-S1088.]