Table 5. Anterior corneal measurement estimations of total corneal astigmatism by steepness of corneal meridian.
| Overestimated | Underestimated | No influence | Total | |||
|---|---|---|---|---|---|---|
| n, % | Mean±SD (D) | n, % | Mean±SD (D) | n, % | n, % | |
| WTR | ||||||
| ±10° | 28, 71.79% | 0.29±0.17 | 5, 12.82% | 0.16±0.09 | 6, 15.38% | 39, 100% |
| ±20° | 48, 73.85% | 0.27±0.16 | 9, 13.85% | 0.21±0.16 | 8, 12.31% | 65, 100% |
| ±30° | 55, 68.75% | 0.27±0.18 | 16, 20% | 0.21±0.13 | 9, 11.25% | 80, 100% |
| ATR | ||||||
| ±10° | 1, 4.17% | 0.1 | 22, 91.67% | 0.5±0.35 | 1, 4.17% | 24, 100% |
| ±20° | 1, 2.38% | 0.1 | 39, 92.86% | 0.43±0.30 | 2, 4.76% | 42, 100% |
| ±30° | 1, 1.85% | 0.1 | 48, 88.89% | 0.41±0.28 | 5, 9.26% | 54, 100% |
| Obl | 8, 24.24% | 0.13±0.05 | 21, 63.64% | 0.24±0.13 | 4, 12.12% | 33, 100% |
| Total | 64 | 0.25±0.18 | 85 | 0.33±0.24 | 18 | 167, 100% |
WTR = with the rule; ATR = against the rule; Obl. = oblique; SD = standard deviation.
WTR ± 10° = steep meridian of 80°–100°; WTR ± 20° = steep meridian of 70°–110°; WTR ± 30° = steep meridian of 60°–120°; ATR ± 10° = steep meridian of 0°–10° and 170°–180°; ATR ± 20° = steep meridian of 0°–20° and 160°–180°; ATR ± 30° = steep meridian of 0°–30° and 150°–180°; Obl. = steep meridian of 30°–60° and 120°–150°.