Figure 5
Spatial variation of Brillouin frequency value across corneas. (A–C) Lateral variation of Brillouin shifts in: (A) normal subjects, (B) stage-I KC patients, (C) stage-II KC patients. Circles and shaded regions represent average and SD of 4 to 16 maps. (D–F) Pairwise comparison of Brillouin values in corneal centers or cones to Brillouin values in peripheral regions, for (D) normal subjects (n = 16, 39 ± 10 y/o, 25% female): 5.738 ± 0.010 GHz (center) vs. 5.737 ± 0.011 GHz (peripheral), (E) Stage I-II KC: 5.716 ± 0.020 GHz (cone) vs. 5.726 ± 0.020 GHz (outside cone), (F) Stage III-IV KC patients: 5.677 ± 0.024 (cone) vs. 5.728 ± 0.032 GHz (outside cone). **p < 0.01, ***p < 0.001, by paired t-test. (G) Difference in Brillouin shift measured in the outside-cone (peripheral) versus cone (central) regions for KC and normal (N) groups. n.s.: non-significant, **p < 0.01, ***p < 0.001, by unpaired t-test.
