Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas

Figures & data

Figure 1 Raw data image as obtained by the Cassini multicolored-spot reflection topographer.

Notes: The septima sections are numbered sequentially, along with a cross indicating the prime orientation of the 100 spots within the section. The red dashed line indicates the steep axis; the blue dotted line, the flat axis.

Figure 2 Axial curvature maps.

Notes: In this example from the keratoconic group C, the same axial map is illustrated in three different color scales, according to (A) the oculus, (B) the KlyceUSS, and (C) the Normalized ISO 19980 color scale.
Abbreviations: D, diopters; OD, optical density.

Table 1 Descriptive statistics of flat and steep keratometry (diopters [D]), axis (°), form factor, surface regularity index (SRI), and surface asymmetry index (SAI) measurements for the control group and the three study groups

Group	K flat (D)	K steep (D)	Steep axis (°)	Form factor (k)	SRI	SAI
Control
Mean	42.83	44.35	91.85	0.96	0.91	0.61
SD	2.02	2.17	27.15	0.63	0.62	0.65
Min	32.36	33.48	0.15	−0.20	−0.46	−0.11
Max	50.94	54.01	179.86	6.30	3.01	5.38
Group A (LASIK)
Mean	38.20	39.50	87.78	2.62	1.60	1.01
SD	4.50	4.23	42.09	2.18	0.78	0.98
Min	23.93	25.28	4.42	0.07	−0.11	0.12
Max	45.57	47.04	179.75	10.61	3.52	6.31
Group B (keratoconus)
Mean	42.45	45.71	93.85	2.96	1.88	2.96
SD	3.90	3.65	46.78	1.96	0.71	2.89
Min	31.00	39.49	1.15	−0.05	−0.26	0.10
Max	53.98	58.07	179.79	10.47	3.60	20.47
Group C (Athens Protocol)
Mean	43.29	46.39	95.51	2.42	2.09	3.02
SD	4.22	4.72	39.43	1.91	0.63	2.33
Min	34.79	35.43	13.00	−0.84	0.13	0.18
Max	53.75	57.52	179.23	7.27	3.25	10.31

Abbreviations: LASIK, laser-assisted in situ keratomileusis; max, maximum; min, minimum; SD, standard deviation; K, keratometry; D, diopters.

Figure 3 Box plots illustrating steep and flat keratometry and axis measurement repeatability.

Notes: Group A, laser-assisted in situ keratomileusis (LASIK); Group B, keratoconus (KCN); Group C, Athens Protocol (AP); and Group D, control. Numerical indicators correspond to median values. (A) Comparative flat keratometry repeatabilty in all groups; (B) comparative steep keratometry repeatability in all groups; (C) comparative axis measurement repeatability in all groups.
Abbreviation: D, diopters.

Table 2 Repeatability of flat and steep keratometry (diopters [D]), axis (°), form factor, surface regularity index (SRI), and surface asymmetry index (SAI) measurements for the control group and the three study groups

Group	K flat (D)	K steep (D)	Steep axis (°)	Form factor (k)	SRI	SAI
Control
Mean	0.36	0.41	2.16	0.12	0.23	0.26
SD	0.46	0.50	1.39	0.15	0.16	0.30
Min	0.00	0.00	0.05	0.00	0.00	0.00
Max	2.71	3.51	5.86	1.06	0.75	2.39
Group A (LASIK)
Mean	0.74	0.64	3.45	0.29	0.22	0.33
SD	0.89	0.82	1.62	0.32	0.17	0.40
Min	0.03	0.01	0.38	0.00	0.01	0.01
Max	5.26	4.81	7.78	1.69	0.96	2.31
Group B (keratoconic)
Mean	0.88	0.89	4.12	0.42	0.20	0.39
SD	1.45	1.22	3.17	0.42	0.18	0.75
Min	0.00	0.02	0.02	0.00	0.00	0.00
Max	7.84	7.85	12.13	2.03	1.07	7.15
Group C (Athens Protocol)
Mean	0.71	0.93	3.20	0.46	0.13	0.43
SD	0.94	1.12	1.99	0.50	0.09	0.56
Min	0.02	0.04	0.17	0.02	0.00	0.05
Max	6.23	5.93	8.61	1.85	0.45	3.50

Abbreviations: LASIK, laser-assisted in situ keratomileusis; max, maximum; min, minimum; SD, standard deviation; K, keratometry; D, diopters.

Figure 4 Box plots illustrating form factor, surface asymmetry index (SAI), and surface regularity index (SRI) measurement repeatability.

Notes: Group A, laser-assisted in situ keratomileusis (LASIK); Group B, keratoconus (KCN); Group C, Athens Protocol (AP); and Group D, control. Numerical indicators correspond to median values. (A) Comparative form factor repeatability in all groups; (B) comparative SAI repeatability in all groups; (C) comparative SRI repeatability in all groups.