Topographic and surgical risk factors for high postoperative residual astigmatism after small incision lenticule extraction in patients with different degrees of myopia: a retrospective cohort study

Table 1 Preoperative features of the study population

Features (mean ± SD)	Low myopia group (N = 80)	High myopia group (N = 150)	P
Age	31.91 ± 6.76	32.71 ± 6.43	0.380
Sex (male: female)	17: 23	28: 47	0.692
Cycloplegic refraction
SE	-4.07 ± 0.83	-7.35 ± 1.49	< 0.001*
Sphere	-3.58 ± 0.79	-6.78 ± 1.37	< 0.001*
Cylinder	-0.98 ± 0.73	-1.12 ± 0.86	0.222
IOP	18.03 ± 2.59	18.32 ± 2.52	0.405
BCVA	0.99 ± 0.04	0.99 ± 0.04	0.923
Manifest refraction
SE	-4.12 ± 0.89	-7.18 ± 1.37	< 0.001*
Sphere	-3.64 ± 0.79	-6.67 ± 1.28	< 0.001*
Cylinder	-0.95 ± 0.74	-1.03 ± 0.79	0.477
Steep stimulated keratometry	44.02 ± 1.53	44.08 ± 1.60	0.785
Flat stimulated keratometry	42.51 ± 1.41	42.69 ± 1.47	0.377
Topographic cylinder	1.51 ± 0.76	1.40 ± 0.72	0.248
CCT
Apex	557.25 ± 26.03	569.35 ± 28.69	0.002*
Thinnest	549.90 ± 25.48	563.08 ± 27.81	0.001*
Difference	7.35 ± 6.20	6.27 ± 4.33	0.124
ISV	20.38 ± 5.52	24.01 ± 6.31	0.117
IHD	0.008 ± 0.004	0.007 ± 0.006	0.817
Angle Kappa	0.23 ± 0.14	0.26 ± 0.15	0.794
Lenticule thickness	101.90 ± 12.11	136.68 ± 25.66	< 0.001*
Optic zone	6.64 ± 0.21	6.41 ± 0.22	< 0.001*
Incision length	3.73 ± 0.27	3.76 ± 0.28	0.534

BCVA: best-corrected visual acuity, CCT: central corneal thickness, IHD: index of height decentration, IOP: intraocular pressure, ISV: index of surface variance, N: number, SD: standard deviation, SE: spherical equivalent
* Denotes a significant difference between groups

ISSN: 1471-2415