Table 2.

Patient characteristics of the study groups

Variable	Adult group (n = 33 eyes)	Pediatric group (n = 14 eyes)	P -value
Age (y), Mean ± SD Median (Range)	29.97 ± 5.84 31 (20 to 41)	16.36 ± 0.93 17 (14 to 17)	< 0.001
Sex (Male / Female), n (%)	18 (54.5) / 15 (45.5)	7 (50.0) / 7 (50.0%)	0.78
Preoperative A-K KCN grading Grade 1 (24 eyes) / Grade 2 (23 eyes), n (%)	18 (54.5) / 15 (45.5)	6 (42.9) / 8 (57.1)	0.46

Abbreviations: n, numbers; y, years; SD, standard deviation; KCN, keratoconus; µm, micrometers. Note: Adult group included patients aged ≥ 18 years with intolerance to spectacles and gas permeable contact lenses (GPCL), stable KCN for at least one year (Kmax remained < 1 diopter [D]), grade 1 and 2 Amsler – Krumeich classification (A-K; Kaverage ≤ 48 D with < - 5 D myopia and astigmatism, 48 – 53 D with 5 – 8 D myopia and astigmatism, respectively) [13]. The cone asymmetry was type 1 and type 2 (100% and 80% of the cones were on one side of the steepest meridian, respectively), and the thinnest corneal thickness (TCT) should be > 380 μm; Pediatric group included patients aged 14 – 17 years with intolerance to spectacles and GPCL, grade 1 and 2 A-K classification [13], type 1 and 2 cone asymmetry, TCT > 380 μm, and the spherical equivalent of the refractive error worse than - 4 D.