Fourier analysis of irregular astigmatism after implantation of 3 types of intraocular lenses.

PURPOSE

To evaluate irregular astigmatism after silicone, acrylic, and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation using Fourier analysis of videokeratography data.

METHODS

Two hundred forty eyes having phacoemulsification and IOL implantation were randomly assigned to 1 of 3 groups: 3.5 mm incision and silicone IOL, 4.1 mm incision and acrylic IOL, or 6.5 mm incision and PMMA IOL. All eyes had videokeratographic examinations preoperatively and 2, 4, and 10 days and 1 and 3 months postoperatively. The dioptric data of the central cornea were decomposed into spherical equivalent, regular astigmatism, and irregular astigmatism (decentration and higher-order irregularity) components using Fourier analysis.

RESULTS

Regular astigmatism in the PMMA group was greater than in the silicone and acrylic groups. Decentration in all 3 groups increased significantly postoperatively but virtually returned to preoperative levels by 10 days. No significant difference was observed among the 3 groups. Higher-order irregularity significantly increased after surgery in all 3 groups. The higher-order irregularity in the PMMA group persisted for up to 1 month, while that in the silicone and acrylic groups returned to preoperative levels by 4 days, resulting in significant differences between these groups 10 days and 1 month after IOL implantation.

CONCLUSION

Irregular astigmatism, both the decentration and higher-order irregularity components, increased significantly after 3 types of scleral tunnel incisions for silicone, acrylic, or PMMA IOL implantation but returned to preoperative levels soon after surgery except for the higher order irregularity after PMMA IOL implantation.