Limbal relaxing incision during cataract extraction versus photoastigmatic keratectomy after cataract extraction in controlling pre-existing corneal astigmatism.

摘要

BACKGROUND: The techniques of limbal relaxing incision (LRI) and photoastigmatic keratectomy (PAK) are both effective methods for correcting pre-existing astigmatism with cataract extraction, but no previous study has directly compared them. PURPOSE: To compare the effects of limbal relaxing incision (LRI) and photoastigmatic keratectomy (PAK) on preoperative astigmatism and higher-order aberrations (HOAs) in eyes undergoing cataract surgery. SETTING: Kitasato University Hospital, Japan. PATIENTS AND METHODS: A retrospective study of eyes which had undergone phacoemulsification and intraocular lens implantation through an astigmatically neutral incision either accompanied by LRI (LRI group, 20 eyes) or followed after 3 months by PAK (PAK group, 27 eyes), to control pre-existing corneal astigmatism. RESULTS: Among eyes that underwent LRI, manifest astigmatism (corrected to the corneal plane) averaged -1.72 +/- 0.95 D preoperatively and -0.98 +/- 0.58 D postoperatively. Corneal astigmatism averaged 2.03 +/- 0.49 D preoperatively and 1.34 +/- 0.60 D postoperatively. Among eyes that underwent PAK, manifest astigmatism averaged -2.02 +/- 0.64 D preoperatively and -0.70 +/- 0.58 D postoperatively. Corneal astigmatism averaged 2.30 +/- 0.81 D preoperatively and 1.05 +/- 0.36 D postoperatively. With regard to HOAs, in the LRI group, corneal HOAs averaged 0.172 +/- 0.051 microm (total aberrations for 4 mm pupil diameter) and 0.681 +/- 0.433 microm (total, 6 mm) preoperatively, but 0.172 +/- 0.053 microm (total, 4 mm) and 0.651 +/- 0.187 microm (total, 6 mm) postoperatively. In the PAK group, the corneal HOAs averaged 0.179 +/- 0.073 microm (total, 4 mm) and 0.679 +/- 0.314 microm (total, 6 mm) preoperatively, but 0.206 +/- 0.095 microm (total, 4 mm) and 0.816 +/- 0.380 microm (6 mm, total) postoperatively. The only statistically significant differences in the postoperative HOAs between LRI and PAK groups were in the S4 and S6 (spherical and spherical-like aberrations being bigger in the PAK group ).There were no vision-threatening complications in either group. CONCLUSIONS: PAK is more effective than LRI in the control of pre-existing manifest astigmatism. LRI causes less accentuation of the spherical HOAs than PAK.