Pearson’s correlation coefficient between the intrapatient differences for each index with the intrapatient differences in spectacle corrected visual acuity (n = 50)
| Index | Pearson’s correlation |
|---|---|
| Coefficients were calculated using data collected from patients designated as having bilateral keratoconus. Patients with apical corneal scarring in either eye were excluded from the analysis. Significance is denoted by *p = 0.05 and **p = 0.01. | |
| Standard deviation of power (SDP) | −0.76** |
| Average corneal power (ACP) | −0.75** |
| Keratoconus prediction index (KPI) | −0.73** |
| Central corneal power (K) | −0.69** |
| Differential sector index (DSI) | −0.6** |
| Inferior minus superior power (I–S) | −0.67** |
| Opposite sector index (OSI) | −0.64** |
| Surface regularity index (SRI) | −0.57** |
| Surface asymmetry index (SAI) | −0.57** |
| Irregular astigmatism index (IAI) | −0.51** |
| Centre surround index (CSI) | −0.50** |
| Corneal eccentricity index (CEI) | −0.36* |
| Area analysed (AA) | 0.21 |