Evaluation of the corneal biomechanical properties and corneal thickness in patients with Graves' orbitopathy

Purpose To evaluate the corneal biomechanical properties and central corneal thickness in patients with Graves' orbitopathy (GO). Method A total of 132 eyes of 66 patients with GO and 108 eyes of 54 healthy subjects were enrolled. Eyes with GO were classified as high score clinical activity score (CAS, >= 3) (Group 1, n = 64) and low CAS score (< 3) (Group 2, n = 68). Corneal biomechanical parameters [corneal hysteresis (CH), corneal resistance factor (CRF)], Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) levels were measured with Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, NY) and compared between the groups. Results The mean CH values were found as 9.6 +/- 1 mmHg in Group 1, 10.2 +/- 0.9 mmHg in Group 2, and 11.4 +/- 1.7 mmHg in the Control Group (p < 0.001). In post hoc analysis the mean CH was significantly lower in Group 1 than Group 2 and Control Group (Group 1-Group 2, p < 0.001; Group 1-Control Group, p < 0.001). The mean CRF was found as 10.5 +/- 2.1 in Group 1, 10.4 +/- 2.2 in Group 2, and 10.43 ?+/- 2.0 in the Control group. There was no statistically significant difference between the groups in CRF measurements (p = 0.959). The mean IOPcc values were found as 17.1 +/- 3.6 mmHg in Group 1, 15.8 +/- 4.0 mmHg in Group 2 and 15.2 +/- 4.1 mmHg in the Control Group. The IOPcc and IOPg measurements between all groups were statistically significant (p = 0.009, p = 0.027, respectively). Conclusions Corneal biomechanical measurements were different in the GO patients with varying CAS scores compared to healthy individuals.