TABLE 1.
Median (95% Confidence Interval) of Clinical and Custom-Derived Indices in Normal and Keratoconus Eyes
| Normala | Keratoconusa | |
|---|---|---|
| Age (y) | 24 (22–28) | 25 (24–26) |
| K1 (D) | 42.6 (42.3–43.0) | 46.9 (46.0–48.2) |
| K2 (D) | 43.6 (43.1–44.2) | 51.7 (49.8–53.6) |
| Kmax (D) | 44.1 (43.6–44.6) | 58.7 (56.6–59.6) |
| Kmean (D) | 43.2 (42.6–43.5) | 49.4 (47.2–50.4) |
| Minimum corneal thickness (μm) | 522 (516–528) | 443 (436–455) |
| Central corneal thickness (μm) | 526 (520–536) | 454 (446–467) |
| Root mean square of second-order PZA Zernike coefficients (μm) | 15.76 (14.84–16.31) | 24.24 (23.78–25.48) |
| Root mean square of third-order PZA Zernike coefficients (μm) | 1.39 (1.09–1.67) | 5.62 (4.38–6.36) |
| Root mean square of higher-orderb PZA Zernike coefficients (μm) | 1.42 (1.17–1.97) | 7.29 (4.73–9.18) |
| Root mean square of second-order anterior corneal wavefront Zernike coefficients (μm) | 0.77 (0.67–0.89) | 3.78 (3.24–4.58) |
| Root mean square of third-order anterior corneal wavefront Zernike coefficients (μm) | 0.15 (0.13–0.20) | 1.91 (1.59–2.33) |
| Root mean square of higher-order anterior corneal wavefront Zernike coefficients (μm) | 0.47 (0.42–0.52) | 0.94 (0.87–1.06) |
| Axial curvature CLMI of anterior surface (D) | 0.53 (0.43–0.66) | 7.83 (6.03–10.78) |
| Axial curvature CLMI of posterior surface (D) | 0.15 (0.12–0.18) | 1.91 (1.52–2.35) |
| Tangential curvature CLMI of anterior surface (D) | 1.62 (1.31–1.99) | 12.36 (10.55–13.50) |
| Tangential curvature CLMI of posterior surface (D) | 0.28 (0.18–0.57) | 2.75 (2.22–3.16) |
CLMI = cone location magnitude index; D = diopter; K1 = flat axis keratometry; K2 = steep axis keratometry; Kmax = maximum keratometry; Kmean = mean keratometry; PZA = pachymetry Zernike analysis.
a
All variables were statistically significant between normal and keratoconus eyes with P < .0001. A P value < .05 was considered statistically significant.
b
Zernike order 4 and greater.