Influence of corneal biomechanical properties on intraocular pressure measurement in different types of Graves’ orbitopathy.

Background/aims: To compare the ocular biomechanical properties of inactive Grave's orbitopathy (GO) patients and healthy subjects and to evaluate the influence of severity and phenotype of GO on these parameters.

Methods: This was a cross-sectional study. All included inactive GO patients and healthy controls underwent complete ocular examination, including Goldman applanation tonometry (GAT), corneal biomechanical analysis using Ocular Response Analyser (ORA), and corneal epithelial thickness analysis using Optovue. Patients with inactive GO were classified based on the severity and orbital phenotype (predominantly myogenic or lipogenic). Comparison among groups was performed.

Results: 60 eyes from 30 inactive GO patients and 30 healthy eyes were examined. Corneal hysteresis (CH) was significantly lower in inactive GO patients (9.6 [p25 8.1; p75 11.2]) compared to controls (10.4 [9.8; 11.5]) ( = 0.012). In GO patients, cornea compensated intraocular pressure (IOPcc) was significantly higher than Goldman applanation tonometry IOP (IOP-GAT) ( = 0.001). A total of 13.3% GO patients were initially classified as having ocular hypertension (OHT; defined as IOP > 21 mmHg with no signs of glaucomatous optic neuropathy) based on IOP-GAT measurement. According to IOPcc, 27.8% of GO patients were classified as OHT. In GO patients, no differences were found in corneal bimechanical properties according to the disease severity or orbital phenotype.

Conclusions: CH is significantly lower in inactive GO patients compared to healthy subjects. ORA corrected IOP was significantly higher in GO patients compared to IOP-GAT. No differences in corneal biomechanical properties between mild and moderate-to-severe GO disease and between myogenic and lipogenic orbitopathy were found.