Table 2.
Corneal densitometry (CD) after SMILE and FS-LASIK.
| CD (GSU) | Anterior layer | Central layer | Posterior layer | Total thickness | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0–2 mm | 2–6 mm | 6–10 mm | 0–2 mm | 2–6 mm | 6–10 mm | 0–2 mm | 2–6 mm | 6–10 mm | 0–2 mm | 2–6 mm | 6–10 mm | ||
| Pre-op | SMILE | 25.24 ± 3.83 | 23.29 ± 3.48 | 23.49 ± 4.48 | 16.87 ± 2.13 | 15.49 ± 1.90 | 16.22 ± 2.62 | 14.46 ± 2.07 | 13.67 ± 1.89 | 15.21 ± 2.39 | 18.87 ± 2.61 | 17.49 ± 2.37 | 18.30 ± 3.07 |
| FS-LASIK | 27.26 ± 3.26 | 24.90 ± 2.80 | 24.22 ± 2.72 | 18.04 ± 1.80 | 16.43 ± 1.51 | 16.76 ± 1.43 | 15.30 ± 1.85 | 14.49 ± 1.60 | 16.16 ± 1.48 | 20.19 ± 2.22 | 18.60 ± 1.89 | 19.04 ± 1.71 | |
| P§ | 0.051 | 0.09 | 0.50 | 0.04|| | 0.06 | 0.42 | 0.13 | 0.12 | 0.12 | 0.06 | 0.08 | 0.33 | |
| Post-op month 6–12 |
SMILE | 25.85 ± 4.93 | 24.12 ± 4.40 | 23.08 ± 4.65 | 17.09 ± 2.78 | 15.71 ± 2.28 | 16.18 ± 2.83 | 14.36 ± 2.65 | 13.95 ± 2.35 | 15.70 ± 3.06 | 19.11 ± 3.42 | 17.93 ± 2.98 | 18.32 ± 3.45 |
| Change | 0.33 ± 4.31 | 0.57 ± 3.81 | −0.91 ± 3.52 | −0.02 ± 2.30 | −0.01 ± 1.89 | −0.40 ± 1.82 | −0.36 ± 2.37 | 0.04 ± 2.10 | 0.20 ± 2.12 | −0.02 ± 2.94 | 0.19 ± 2.58 | −0.36 ± 2.41 | |
| FS-LASIK | 26.23 ± 2.87 | 24.61 ± 2.80 | 22.97 ± 2.87 | 16.82 ± 1.79 | 15.81 ± 1.59 | 16.19 ± 1.62 | 13.99 ± 1.73 | 14.00 ± 1.47 | 15.96 ± 1.43 | 19.02 ± 1.98 | 18.15 ± 1.84 | 18.38 ± 1.82 | |
| Change | −1.40 ± 4.39 | −0.50 ± 3.77 | −1.83 ± 3.73# | −1.37 ± 2.48# | −0.74 ± 2.02 | −0.92 ± 2.09# | −1.47 ± 2.52# | −0.53 ± 2.13 | −0.16 ± 2.03 | −1.39 ± 3.03# | −0.59 ± 2.56 | −0.97 ± 2.48# | |
| ΔChange§ | −1.01 | −0.48 | −0.58 | −0.99 | −0.45 | −0.35 | −0.76 | −0.26 | −0.12 | −0.90 | −0.39 | −0.36 | |
| 95% CI§ | (−4.32, 2.30) | (−3.36, 2.39) | (−3.04, 1.88) | (−2.75, 0.76) | (−1.86, 0.96) | (−1.63, 0.93) | (−2.57, 1.04) | (−1.83, 1.31) | (−1.58, 1.33) | (−3.14, 1.35) | (−2.32, 1.54) | (−2.02, 1.30) | |
| Post-op year 5 |
SMILE | 18.95 ± 5.10 | 17.69 ± 4.81 | 18.26 ± 5.48 | 12.28 ± 3.30 | 11.40 ± 2.95 | 12.60 ± 3.42 | 9.92 ± 2.78 | 9.77 ± 2.60 | 11.55 ± 2.90 | 13.71 ± 3.56 | 12.96 ± 3.34 | 14.13 ± 3.85 |
| Change | −5.85 ± 5.13* | −5.17 ± 4.76* | −5.22 ± 4.66* | −4.32 ± 3.11* | −3.84 ± 2.79* | −3.60 ± 2.70* | −4.38 ± 3.36* | −3.74 ± 2.99* | −3.57 ± 2.65* | −4.86 ± 3.66* | −4.25 ± 3.37* | −4.12 ± 3.21* | |
| FS-LASIK | 18.49 ± 5.43 | 17.18 ± 4.89 | 16.82 ± 4.38 | 11.86 ± 3.49 | 11.13 ± 3.11 | 11.82 ± 2.99 | 9.80 ± 3.06 | 9.64 ± 2.78 | 11.18 ± 2.79 | 13.38 ± 3.83 | 12.65 ± 3.45 | 13.28 ± 3.27 | |
| Change | −8.87 ± 5.61# | −7.79 ± 5.09# | −7.44 ± 4.72# | −6.22 ± 3.72# | −5.33 ± 3.35# | −4.94 ± 3.11# | −5.52 ± 3.54# | −4.86 ± 3.24# | −4.99 ± 3.04# | −6.87 ± 4.15# | −5.98 ± 3.77# | −5.78 ± 3.51# | |
| ΔChange§ | −3.04† | −2.66† | −2.25† | −1.90† | −1.49† | −1.35† | −1.14 | −1.10 | −1.41† | −2.01† | −1.74† | −1.66† | |
| 95% CI§ | (−5.35, −0.73) | (−4.83, −0.49) | (−4.40, −0.10) | (−3.25, −0.55) | (−2.73, −0.26) | (−2.57, −0.12) | (−2.74, 0.46) | (−2.51, 0.30) | (−2.63, −0.19) | (−3.61, −0.42) | (−3.20, −0.28) | (−3.10, −0.23) | |
||
P < 0.05, significantly different in preoperative values between SMILE and FS-LASIK group.
*
P < 0.05, significantly different from the preoperative values in the SMILE group.
#
P < 0.05, significantly different from the preoperative values in the FS-LASIK group.
†
P < 0.05, a greater change in FS-LASIK group than SMILE group.
§
Estimated from the linear mixed model with subject ID as the random intercept.
Δ
Change = difference in the changes between the two groups; CI = confidence interval; GSU = grayscale units.