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Table 1 Visual, refractive and tomographic parameters of patients who were implanted with single ICRS (Group 1) and double ICRS (Group 2)

From: The number of intracorneal ring segments in asymmetric and central cones

  Preoperative Postoperative Changes induced by the surgery
Group 1 Group 2 P value Group 1 Group 2 P value Group 1 Group 2 P value
UDVA (Snellen lines) 0.11 ± 0.10 0.09 ± 0.09 0.67 0.41 ± 0.24 0.35 ± 0.23 0.34 0.31 ± 0.22 0.26 ± 0.25 0.45
CDVA (Snellen lines) 0.35 ± 0.20 0.29 ± 0.12 0.13 0.64 ± 0.25 0.56 ± 0.20 0.14 0.29 ± 0.21 0.27 ± 0.20 0.69
Spherical refraction (D) −2.48 ± 3.73 −4.19 ± 4.49 0.16 −1.76 ± 3.41 −2.69 ± 2.97 0.28 0.49 ± 2.70 1.39 ± 4.25 0.38
Cylindrical refraction (D) −4.98 ± 2.13 −5.68 ± 2.67 0.32 −2.12 ± 1.54 −2.39 ± 1.67 0.56 2.50 ± 2.17 3.52 ± 2.97 0.17
SE of refractive error (D) − 4.73 ± 4.31 −7.03 ± 4.06 0.05 −2.77 ± 3.64 −3.70 ± 3.18 0.32 1.74 ± 2.71 3.15 ± 4.31 0.18
SimKavg (D) 49.10 ± 3.67 51.37 ± 3.68 0.03* 47.13 ± 3.90 48.29 ± 3.08 0.21 −1.98 ± 1.90 −3.11 ± 2.05 0.04*
SimKf (D) 47.17 ± 3.93 48.78 ± 3.95 0.14 45.76 ± 3.72 47.19 ± 3.12 0.12 −1.40 ± 1.56 −1.51 ± 2.39 0.85
SimKs (D) 51.67 ± 4.41 54.30 ± 3.61 0.02* 48.61 ± 4.15 49.47 ± 3.19 0.38 −3.06 ± − 1.56 −4.83 ± 2.19 < 0.01*
Central pachymetry (μm) 461.73 ± 41.65 444.92 ± 47.91 0.18 479.0 ± 48.39 457.11 ± 50.09 0.11 17.27 ± 13.86 12.18 ± 18.75 0.28
Thinnest pachymetry (μm) 440.68 ± 44.27 432.82 ± 49.69 0.55 463.59 ± 46.53 434.82 ± 55.01 0.05 22.91 ± 17.39 2.00 ± 35.23 0.01*
Qant −0.91 ± 0.47 −1.12 ± 0.39 0.07 −0.61 ± 0.51 −0.57 ± 0.52 0.79 0.30 ± 0.22 0.56 ± 0.44 0.01*
Qpost −0.92 ± 0.46 −1.11 ± 0.56 0.19 −0.86 ± 0.43 −1.13 ± 0.56 0.07 0.06 ± 0.15 0.00 ± 0.50 0.64
ISV 95.41 ± 35.20 91.39 ± 28.93 0.64 75.18 ± 30.19 82.19 ± 29.87 0.40 −20.23 ± 13.67 −11.37 ± 21.53 0.09
IVA 0.99 ± 0.43 0.70 ± 0.39 0.01* 0.73 ± 0.41 0.72 ± 0.40 0.88 −0.25 ± 0.20 −0.01 ± 0.26 < 0.01*
KI 1.26 ± 0.12 1.20 ± 0.12 0.09 1.18 ± 0.12 1.13 ± 0.13 0.16 −0.08 ± 0.05 −0.10 ± 0.20 0.59
CKI 1.07 ± 0.05 1.09 ± 0.05 0.18 1.06 ± 0.05 1.10 ± 0.06 0.01* −0.01 ± 0.03 0.02 ± 0.19 0.93
IHA 19.06 ± 23.40 26.76 ± 20.96 0.20 22.22 ± 15.37 27.14 ± 19.50 0.32 3.16 ± 23.87 0.33 ± 23.84 0.59
IHD 0.14 ± 0.07 0.10 ± 0.07 0.05 0.10 ± 0.06 0.09 ± 0.05 0.78 −0.04 ± 0.03 −0.01 ± 0.04 0.01*
Rmin (mm) 5.98 ± 0.71 5.74 ± 0.61 0.18 6.22 ± 0.76 5.96 ± 0.56 0.14 0.24 ± 0.29 0.06 ± 0.89 0.36
TKC 2.68 ± 0.83 2.64 ± 0.58 0.85 2.44 ± 0.54 2.26 ± 0.55 0.28 −0.55 ± 0.50 −0.45 ± 0.79 0.61
ACD (mm) 3.61 ± 0.42 3.43 ± 0.39 0.10 3.46 ± 0.50 3.30 ± 0.39 0.18 −0.15 ± 0.25 −0.22 ± 0.57 0.60
ACV (mm3) 190.30 ± 47.84 177.05 ± 26.24 0.18 178.0 ± 31.30 174.86 ± 24.62 0.71 −52.76 ± 86.87 −43.61 ± 75.52 0.68
  1. * p < 0.05 indicating statistical significance
  2. UDVA= uncorrected distance visual acuity
  3. CDVA= corrected distance visual acuity
  4. SE= spherical equivalent
  5. SimKavg = average simulated keratometry
  6. SimKf = flat simulated keratometry
  7. SimKs = steep simulated keratometry
  8. Qant = anterior corneal asphericity
  9. Qpost = posterior corneal asphericity
  10. ISV= index of surface variance
  11. IVA= index of vertical asymmetry
  12. KI= keratoconus index
  13. CKI= central keratoconus index
  14. IHA= index of height asymmetry
  15. IHD= index of height decentration
  16. Rmin = radius of minimum axial/sagittal curvature
  17. TKC= topographic keratoconus classification
  18. ACD= anterior chamber depth
  19. ACV= anterior chamber volume