Corneal astigmatism, high order aberrations, and optical quality after cataract surgery: microincision versus small incision.

PURPOSE

To compare the astigmatism, high order aberrations, and optical quality of the cornea after microincision (approximately 1.7 mm) versus small incision approximately 3.2 mm) cataract surgery at Eye Center, Zhejiang University, Hangzhou, China.

METHODS

This prospective, randomized clinical study included microincision cataract surgery and small incision cataract surgery performed on 60 eyes. Corneal astigmatism and higher order aberrations to the sixth order were measured using the NIDEK OPD-Scan aberrometer/topographer 1 month after surgery. To evaluate the optical quality of the cornea, the 0.5 modulation transfer function (MTF) value and 0.1 MTF value within a 5-mm pupil were calculated using OPD-Station software. Statistical analysis assessing the difference between groups was carried out using the independent t test.

RESULTS

The mean corneal astigmatism was significantly lower after microincision cataract surgery compared with small incision cataract surgery (0.78+/-0.38 diopters [D] vs 1.29+/-0.68 D, respectively; P=.001). No significant differences were found between the two groups for the root-mean-square value of total high order aberrations or individual high order aberrations for spherical aberration, coma, and trefoil. However, eyes that underwent microincision cataract surgery showed statistically significantly better optical performance with a 0.5 MTF value than eyes that underwent small incision cataract surgery (3.13+/-0.30 cycles per degree [cpd] vs 2.75+/-0.63 cpd, respectively; P=.005). The 0.1 MTF values for the two groups were 9.37+/-3.72 cpd for microincision cataract surgery and 7.24+/-3.43 cpd for small incision cataract surgery, which was not significantly different (P=.136).

CONCLUSIONS

Microincision cataract surgery generates statistically significantly less corneal astigmatism and better optical quality of the cornea by MTF evaluation compared with small incision cataract surgery. However, microincision cataract surgery shows no significant advantage in reducing corneal high order aberrations over small incision cataract surgery.