Table 2. Vector analysis of astigmatic correction at 6 months after small-incision lenticule extraction and photorefractive keratectomy using Alpins method.
| SMILE | PRK | P-value | ||
|---|---|---|---|---|
| TIA | Arithmetic mean ± SD (D) | 1.05 ± 0.46 | 0.92 ± 0.54 | 0.235 |
| Rangea (D) | 1.02 to 1.07 | 0.89 to 0.96 | ||
| SIA | Arithmetic mean ± SD (D) | 1.08 ± 0.43 | 1.26 ± 0.78 | 0.704 |
| Rangea (D) | 1.05 to 1.10 | 1.22 to 1.31 | ||
| DV | Arithmetic mean ± SD (D) | 0.20 ± 0.20 | 0.48 ± 0.44 | 0.005 |
| Rangea (D) | 0.19 to 0.22 | 0.45 to 0.51 | ||
| ME | Arithmetic mean ± SD (D) | 0.03 ± 0.22 | 0.34 ± 0.47 | 0.001 |
| Rangea (D) | 0.02 to 0.04 | 0.31 to 0.37 | ||
| Absolute AE | Arithmetic mean ± SD (°) | 5.0 ± 9.4 | 9.8 ± 13.6 | 0.040 |
| Rangea (°) | 4.5 to 5.6 | 9.0 to 10.7 | ||
| CI | Geometric mean ± SD | 1.02 ± 0.28 | 1.34 ± 0.86 | / |
| Rangea | 1.00 to 1.04 | 1.29 to 1.40 | ||
| FI | Geometric mean ± SD | 0.78 ± 0.88 | 0.90 ± 1.22 | / |
| Rangea | 0.73 to 0.83 | 0.83 to 0.97 | ||
| IOS | Geometric mean ± SD | 0.13 ± 0.31 | 0.48 ± 0.96 | / |
| Rangea | 0.12 to 0.15 | 0.42 to 0.53 |
SMILE = small-incision lenticule extraction; PRK = photorefractive keratectomy; AE = angle of error; CI = correction index; DV = difference vector; FI = flattening index; IOS = index of success; SIA = surgically induced astigmatism; TIA = target-induced astigmatism.
a95% confidence interval.