Hans Vellara, Richard Hart, Akilesh Gokul, Charles McGhee, Dipika Patel
Purpose: To compare the ocular biomechanical properties in patients with thyroid eye disease (TED) and healthy participants using a non-contact Scheimpflug based tonometer (CorVis ST,CST).
Methods: All eyes were examined by slit lamp biomicroscopy, corneal tomography, and the CST. This study compared the outputs from CST such as deformation amplitude (DA) and additionally derived parameters including maximum orbital deformation (MOD); between healthy participants and patients with TED. CST parameters and MOD were compared between groups using a student’s t-test. Furthermore, a multiple linear regression analysis was utilized to control for various factors known to influence the ocular biomechanical response.
Results: This study included 20 TED patients and compared them to a cohort of 152 healthy participants. The mean age of TED patients were 46.7±19 and the mean age of healthy participants were 35.9±13.8 years (P=0.03). There were no significant differences in gender distributions between both groups (P>0.05). Several CST parameters were significantly different between groups (P<0.05). Of note, however, MOD was significantly lower in TED patients (0.16±0.04 mm) compared to the healthy participants (0.25±0.05 mm, P<0.001). This dissimilarity remained even after controlling for the various co-factors. Receiver operating characteristic analysis revealed an area under the curve of 0.91±0.04 (95% CI 0.84-0.98, P<0.001) for MOD.
Conclusions: The in vivo ocular biomechanics as measured by the CST reflects a reduced orbital compliance. This method of ocular biomechanical assessment may aid in the categorization of TED severity, assist in monitoring, and/or diagnosing TED.