Table 4. Mean preoperative and postoperative RMS values and Zernike aberrations (µm) in the posterior corneal surface over a 6.0 mm diameter central area in 3 groups.

Parameters	12 o'clock incision group			9 o'clock clear corneal incisions			BENT incision group
	Preop.	Postop.	P	Preop.	Postop.	P	Preop.	Postop.	P
Total RMS	0.757±0.177	0.902±0.343	0.023	0.672±0.200	0.770±0.154	0.001	0.754±0.198	0.951±0.291	0.002
tLOA	0.735±0.176	0.869±0.328	0.025	0.645±0.205	0.734±0.155	0.003	0.730±0.196	0.917±0.284	0.002
tHOA	0.180±0.037	0.238±0.115	0.012	0.181±0.031	0.225±0.062	0.000	0.183±0.046	0.247±0.083	0.003
Z (3, -3)	0.020±0.032	0.036±0.061	0.240	-0.013±0.033	-0.014±0.047	0.876	0.026±0.041	0.023±0.061	0.810
Z (3, -1)	0. 003±0.055	-0.062±0.095	0.001	0.029±0.060	0.005±0.122	0.184	-0.005±0.048	-0.059±0.083	0.002
Z (3, 1)	0.003±0.308	0.006±0.051	0.718	0.001±0.043	0.045±0.063	0.000	0.009±0.033	0.034±0.058	0.016
Z (3,3)	-0.0004±0.024	0.000±0.055	0.656	0.006±0.028	0.003±0.048	0.733	-0.003±0.031	-0.020±0.073	0.258
Z (4, -4)	0.014±0.027	0.032±0.062	0.081	0.000±0.044	-0.005±0.068	0.655	0.006±0.031	0.011±0.100	0.789
Z (4, -2)	0.002±0.017	0.000±0.025	0.808	-0.003±0.018	0.010±0.028	0.021	0.004±0.030	0.018±0.034	0.070
Z (4, 0)	-0.136±0.038	-0.147±0.039	0.024	-0.125±0.037	-0.135±0.033	0.033	-0.131±0.027	-0.144±0.033	0.008
Z (4, 2)	-0.023±0.027	-0.007±0.034	0.029	-0.056±0.080	-0.040±0.033	0.330	-0.023±0.030	-0.015±0.043	0.269
Z (4,4)	-0.040±0.033	-0.024±0.078	0.292	-0.037±0.029	-0.001±0.051	0.000	-0.033±0.046	-0.044±0.049	0.360
Coma	0.006±0.062	-0.056±0.122	0.008	0.114±0.681	0.050±0.150	0.604	0.004±0.062	-0.025±0.096	0.018
Trefoil	0.016±0.043	0.036±0.084	0.243	-0.019±0.267	0.017±0.060	0.493	0.023±0.058	0.003±0.104	0.353
Tetrafoil	-0.026±0.046	0.007±0.100	0.057	-0.220±0.374	-0.006±0.091	0.005	-0.028±0.055	-0.033±0.102	0.835
Secondary astigmatism	-0.021±0.029	-0.007±0.036	0.035	-0.027±0.154	-0.031±0.048	0.895	-0.019±0.026	0.002±0.054	0.055

RMS: Root mean square; tLOA: Total low order aberration; tHOA: Total high order aberration; Z: Zernik; Coma: Z₃⁻¹ and Z₃¹; Trefoil: Z₃⁻³ and Z₃³; Tetrafoil: Z₄⁻⁴ and Z₄⁴; Secondary astigmatism: Z₄⁻² and Z₄². The terms of coma, trefoil, tetrafoli and secondary astigmatism indicate the RMS values of the 2 Zernike aberration, P<0.05; P<0.01; P<0.001.