Table 3
Comparison of topographic patterns, in relation to astigmatism and quantitative indices
| Topographic pattern | Refractive astigmatism (D) Mean (SD) | Keratometric astigmatism (D) Mean (SD) | Topographic astigmatism (simk) Mean (SD) |
SRI Mean (SD) |
SAI Mean (SD) |
|---|---|---|---|---|---|
| I Non-astigmatic | 1.67 (0.76) | 1.17 (0.99) | 1.61 (0.85) | 0.82 (0.39) | 0.60 (0.27) |
| II Regular astigmatism | 4.20 (2.98) | 5.08 (3.21) | 5.93 (3.92) | 1.63 (1.26) | 0.97 (0.61) |
| Oval | 2.17 (1.22) | 2.96 (3) | 2.70 (1.97) | 1.61 (1.32) | 1.06 (0.49) |
| PSBT | 4.09 (1.81) | 7 (2.57) | 8.18 (4.63) | 1.82 (1.04) | 1.01 (0.54) |
| PABT | 4.41 (3.50) | 5.45 (2.76) | 6.22 (3.28) | 2.07 (1.48) | 1.20 (0.76) |
| OSBT | 4.81 (2.99) | 4.63 (3.70) | 6.82 (5.79) | 1.08 (0.59) | 0.73 (0.59) |
| OABT | 4.62 (2.79) | 5.65 (3.17) | 5.72 (2.88) | 1.49 (1.24) | 0.90 (0.38) |
| III Irregular astigmatism | 3.37 (2.38) | 4.03 (2.87) | 3.98 (2.47) | 2.06 (1.67) | 1.44 (0.88) |
| Prolate irregular (PI) | 4.61 (2.49) | 5.37 (3.14) | 5.20 (2.49) | 1.78 (1.25) | 1.09 (0.57) |
| Oblate irregular (OI) | 5.46 (1.51) | 6.47 (2.07) | 5.70 (2.64) | 2.50 (2.21) | 1.22 (0.98) |
| Mixed | 4.22 (2.92) | 5.56 (3.66) | 4.83 (2.73) | 1.96 (1.82) | 1.19 (0.77) |
| Steep/flat (SF) | 2.39 (1.62) | 2.87 (1.39) | 3.43 (1.87) | 1.96 (1.79) | 1.70 (0.99) |
| Localised steep (LS) | 2.50 (1.77) | 3.02 (2.14) | 3.34 (2.57) | 2.10 (1.57) | 1.68 (0.82) |
| Triple | 3.78 (2.95) | 2.91 (0.61) | 2.70 (1.54) | 1.11 (0.38) | 0.94 (0.47) |
| Horseshoe | 2.08 (1.61) | 2.20 (0.82) | 2.26 (1.25) | 0.97 (0.54) | 0.97 (0.42) |
| Unclassified | 3.37 (2.35) | 4.58 (3.91) | 4.23 (2.43) | 3.19 (1.92) | 1.78 (1.12) |
