Evaluation of corneal biomechanics in patients with graves' orbitopathy

Purpose: To investigate corneal biomechanical properties of Graves orbitopathy (GO) patients with clinical activity score (CAS) ≥ 3 and in age- and gender-matched healthy subjects using the Ocular Response Analyzer Method: Patients with Graves' orbitopathy who were referred from Dokuz Eylul University Faculty of Medicine, Endocrinology department to our Neuroophthalmology department to evaluate the ocular findings of Graves' disease and age- and sex-matched healthy individuals were included in the study between January 2018 and September 2020. Sixty-eight eyes of 34 GO patients with CAS≥3 and 107 eyes of 54 healthy individuals were enrolled in this study. Patients who have additional ophthalmological problems that effect vision and patients with systemic diseases other than diabetes and hypertension were excluded. After a full ophthalmological examination, all patients were measured with an Ocular Response Analyzer (ORA). Results: Mean age in group A was 54,8±12,2 years and in group B 53,5±11,5 years with no statistically significant difference between the groups (P > 0,05). Female rates were 79% and 80% in Group A and Group B. There was no statistically significant difference found between the two groups (p> 0.05). Goldmann applanation tonometry - mean intraocular pressure (IOPGAT), 16.04 ± 3.7mmHg in the Group A, 14.51 ± 3.4mmHg in the Group B. The mean Goldmann-correlated intraocular pressure (IOPg) was 16.58 ± 4.1mmHg in the Group A and 14.91 ± 3.9mmHg in the Group B; the mean cornea-compensated intraocular pressure (IOPcc) was 17.17 ± 3.6mmHg in the Group A and 15.23 ± 4.1mmHg in the Group B. As a result, IOP-GAT (p = 0.007), IOPg (p = 0.008) and IOPcc (p = 0.002) were found statistically significantly higher in active GO patients. The mean corneal hysteresis (CH) was 9.60 ± 1 in the Group A and 10.43 ± 2 in the Group B. The fact that it was detected lower in Group A compared to Group B was considered statistically significant. Conclusion: It was observed that CH was significantly decreased in patients with CAS≥ 3 when compared with the healthy control group. In addition, a statistically significant increase was found in IOPg, IOPcc and IOP-GAT compared to healthy individuals.