| K | Central K reading. Calculates the difference in steepness between the inferior and superior cornea at a distance of 3 mm from the apex | <47.2 D or >7.2 mm |
| I-S | The inferior-superior dioptric asymmetry | <1.4 |
| ACP | Average corneal power | 40.5 to 46.7 D |
| CEI | Corneal eccentricity index or global shape factor. Positive for a prolate surface and negative for an oblate surface | −0.114 to 0. 806 |
| SDP | Standard deviation of the power. Increased when there is a wide range of dioptric power within the cornea | 0.37 to 1.33 |
| DSI | Differential sector index. Reports the greatest difference in average power between any two sectors | 0.21 to 3.51 |
| OSI | Opposite sector index. Represents the greatest difference of average power in opposite sectors | −0.55 to 2.09 |
| CSI | Centre surround index. The difference in the average area corrected corneal power between the central corneal zone 3 mm in diameter and a 3 mm annulus surrounding the central area | −0.28 to 0.80 |
| IAI | Irregular astigmatism index. Reports the average inter-ring variation in power along semi-meridians | 0.19 to 0.49 |
| AA | Area analysed. The ratio of the area used for calculation compared to that covered by image of the concentric rings | 0.70 to 0.94 |
| SAI | Surface asymmetry index. Detects alteration of corneal symmetry—for example, off centre keratoconus apices by comparing areas of the cornea 180° apart | 0.10 to 0.42 |
| SRI | Surface regularity index. Values can be used to predict the optical outcome that might be expected based on corneal topography | 0.0 to 0.56 |