Table 5.
Descriptive statistics and inter-day repeatability of measurements using a mean of four replicates in subjects with keratoconus and healthy controls.
| Variable | Group | Mean (SD)a | Min‒Maxa | Sw (95% CI) | CV% | Repeatability | ICC (95% CI) |
|---|---|---|---|---|---|---|---|
| 0‒2 mm | |||||||
| Anterior | Keratoconus | 28.0 (2.1) | (23.6‒32.9) | 0.58 (0.42‒0.75) | 2.07 | 1.62 | 0.93 (0.84‒0.97) |
| Control | 22.8 (4.2) | (17.1‒29.3) | 0.61 (0.44‒0.78) | 2.68 | 1.69 | 0.98 (0.95‒0.99) | |
| Middle | Keratoconus | 17.1 (1.1) | (15.0‒19.1) | 0.30 (0.22‒0.39) | 1.75 | 0.84 | 0.93 (0.84‒0.97) |
| Control | 14.4 (2.4) | (11.2‒18.2) | 0.32 (0.23‒0.40) | 2.22 | 0.88 | 0.98 (0.96‒0.99) | |
| Posterior | Keratoconus | 12.8 (0.9) | (10.9‒15.0) | 0.34 (0.24‒0.43) | 2.66 | 0.94 | 0.87 (0.72‒0.94) |
| Control | 11.8 (1.3) | (9.9‒13.9) | 0.41 (0.30‒0.53) | 3.47 | 1.14 | 0.91 (0.80‒0.96) | |
| Total | Keratoconus | 19.3 (1.2) | (16.8‒21.9) | 0.34 (0.25‒0.44) | 1.76 | 0.95 | 0.92 (0.83‒0.96) |
| Control | 16.3 (2.6) | (12.6‒20.4) | 0.41 (0.30‒0.52) | 2.52 | 1.14 | 0.98 (0.95‒0.99) | |
| 2‒6 mm | |||||||
| Anterior | Keratoconus | 24.4 (1.6) | (20.7‒28.4) | 0.46 (0.34‒0.59) | 1.89 | 1.29 | 0.92 (0.84‒0.97) |
| Control | 20.5 (3.7) | (15.4‒25.8) | 0.55 (0.39‒0.70) | 2.68 | 1.51 | 0.98 (0.95‒0.99) | |
| Middle | Keratoconus | 15.0 (0.8) | (13.3‒16.6) | 0.25 (0.18‒0.32) | 1.67 | 0.70 | 0.91 (0.81‒0.96) |
| Control | 13.0 (2.0) | (10.4‒15.7) | 0.30 (0.22‒0.38) | 2.31 | 0.83 | 0.98 (0.95‒0.99) | |
| Posterior | Keratoconus | 12.2 (0.8) | (11.0‒14.5) | 0.23 (0.17‒0.30) | 1.89 | 0.64 | 0.93 (0.84‒0.97) |
| Control | 11.1 (1.3) | (9.4‒13.9) | 0.36 (0.26‒0.45) | 3.24 | 0.99 | 0.92 (0.84‒0.97) | |
| Total | Keratoconus | 17.2 (1.0) | (15.0‒19.8) | 0.28 (0.20‒0.35) | 1.63 | 0.77 | 0.93 (0.85‒0.97) |
| Control | 14.9 (2.3) | (11.7‒18.0) | 0.38 (0.27‒0.48) | 2.55 | 1.04 | 0.97 (0.94‒0.99) | |
| 6‒10 mm | |||||||
| Anterior | Keratoconus | 22.6 (2.7) | (17.5‒26.6) | 1.21 (0.87‒1.54) | 5.35 | 3.35 | 0.81 (0.63‒0.91) |
| Control | 19.0 (3.9) | (14.4‒29.2) | 0.68 (0.49‒0.87) | 3.58 | 1.88 | 0.97 (0.93‒0.99) | |
| Middle | Keratoconus | 15.3 (1.9) | (12.2‒19.2) | 0.50 (0.36‒0.63) | 3.27 | 1.38 | 0.93 (0.85‒0.97) |
| Control | 13.3 (2.5) | (9.9‒20.3) | 0.43 (0.31‒0.54) | 3.23 | 1.18 | 0.97 (0.94‒0.99) | |
| Posterior | Keratoconus | 13.9 (1.9) | (10.8‒19.6) | 0.46 (0.33‒0.58) | 3.31 | 1.27 | 0.95 (0.88‒0.98) |
| Control | 12.3 (2.0) | (9.5‒18.2) | 0.42 (0.31‒0.54) | 3.41 | 1.17 | 0.96 (0.91‒0.98) | |
| Total | Keratoconus | 17.3 (2.0) | (14.2‒21.0) | 0.62 (0.45‒0.80) | 3.58 | 1.73 | 0.90 (0.80‒0.96) |
| Control | 14.9 (2.8) | (11.2‒22.6) | 0.48 (0.35‒0.61) | 3.22 | 1.33 | 0.97 (0.93‒0.99) | |
| 10‒12 mm | |||||||
| Anterior | Keratoconus | 32.4 (6.4) | (23.1‒46.2) | 2.99 (2.16‒3.82) | 9.23 | 8.28 | 0.80 (0.61‒0.91) |
| Control | 27.6 (7.6) | (16.5‒48.1) | 2.21 (1.60‒2.83) | 8.01 | 6.14 | 0.92 (0.83‒0.96) | |
| Middle | Keratoconus | 22.0 (3.4) | (16.2‒29.1) | 1.16 (0.84‒1.49) | 5.27 | 3.23 | 0.89 (0.77‒0.95) |
| Control | 18.6 (3.9) | (13.0‒28.2) | 1.04 (0.75‒1.33) | 5.59 | 2.89 | 0.93 (0.85‒0.97) | |
| Posterior | Keratoconus | 19.5 (3.5) | (13.3‒25.8) | 0.73 (0.53‒0.93) | 3.74 | 2.02 | 0.96 (0.91‒0.98) |
| Control | 16.0 (3.5) | (11.3‒25.5) | 0.94 (0.68‒1.20) | 5.88 | 2.60 | 0.93 (0.85‒0.97) | |
| Total | Keratoconus | 24.5 (3.9) | (18.6‒34.2) | 1.66 (1.20‒2.12) | 6.78 | 4.60 | 0.84 (0.67‒0.92) |
| Control | 20.7 (4.5) | (13.6‒33.4) | 1.34 (0.97‒1.72) | 6.47 | 3.72 | 0.92 (0.82‒0.96) | |
| Total | |||||||
| Anterior | Keratoconus | 25.7 (1.9) | (22.8‒30.2) | 0.58 (0.42‒0.75) | 2.26 | 1.62 | 0.91 (0.81‒0.96) |
| Control | 21.6 (4.0) | (16.2‒30.1) | 0.61 (0.44‒0.78) | 2.82 | 1.68 | 0.98 (0.95‒0.99) | |
| Middle | Keratoconus | 16.6 (1.1) | (14.4‒18.5) | 0.33 (0.24‒0.43) | 1.99 | 0.92 | 0.92 (0.82‒0.96) |
| Control | 14.3 (2.4) | (10.9‒19.1) | 0.44 (0.32‒0.57) | 3.08 | 1.23 | 0.97 (0.93‒0.99) | |
| Posterior | Keratoconus | 14.0 (1.1) | (12.4‒16.2) | 0.53 (0.38‒0.67) | 3.79 | 1.46 | 0.81 (0.61‒0.91) |
| Control | 12.5 (1.8) | (9.9‒16.7) | 0.53 (0.38‒0.68) | 4.24 | 1.47 | 0.92 (0.83‒0.96) | |
| Total | Keratoconus | 18.8 (1.3) | (16.8‒21.4) | 0.38 (0.28‒0.49) | 2.02 | 1.07 | 0.91 (0.81‒0.96) |
| Control | 16.1 (2.7) | (12.3‒22.0) | 0.51 (0.37‒0.65) | 3.17 | 1.41 | 0.96 (0.92‒0.98) | |
aSubject mean. The values are presented in greyscale units. Standard deviation (SD), Sw (Within-subject standard deviation, CI (confidence intervals), CV% (coefficient of variation), ICC (Intraclass correlation coefficient).