Abstract
Purpose :
Thyroid eye disease (TED) is an inflammatory disease characterized by remodeling of peri/orbital tissue associated with increased intraocular pressure (IOP). Corneal tissue stiffness and increased IOP was noted in TED compared with normal subjects. Corneal Visualization Scheimpfug Technology (Corvis ST; Oculus GmbH,Wetzlar,Germany) objectively measures changes in ocular biomechanics (orbital compliance after IOP adjustment)
In this retrospective in vivo study, we compared pre and post operative changes of biomechanical properties (measured with Corvis ST) in subjects who underwent orbital decompression and anterior blepharotomy.
Methods :
We enrolled 83 and 45 eyes in the orbital decompression and anterior blepharotomy groups, respectively.The baseline and postoperative ocular biomechanical changes (at 3 and 6 months) were measured with Corvis ST. Measurements included applanation (A1 and A2) lengths and velocities, highest concavity (HC) radius, deformation and deflection amplitude, deformation amplitude (DA) ratio, stiffness parameter applanation 1(SPA1), maximum whole eye movement (WEM), central corneal thickness (CCT), and biomechanically corrected IOP(bIOP).
Results :
Compared to before surgery, the orbital decompression group had a significantly lower SPA1 reduced from 112.5 ± 13.7 mmHg/mm to 108.2 ± 17.5 mmHg/mm(P=0.039) along with a shorter A2 length(P=0.009) suggesting reduced corneal stiffness postoperatively. bIOP was more associated with reduction of SP-A1(β=1.885, P=0.012) after controlling for age, gender, CCT, and axial length in the multivariate linear regression. Post anterior blepharotomy group had a significantly higher WEM increased from 0.20 ± 0.05 mm to 0.24 ± 0.06 mm(P=0.003) indicating higher orbital compliance attributed to the release of the force on the eyeball by the fibrotic levator palpebrae muscle. Myopic eyes were more associated with WEM (β = -0.005, P=0.029) in the multivariate linear regression model. Both groups had no significant bIOP change after the surgery.
Conclusions :
Post-orbital decompression surgery with low IOP eyes had reduced corneal stiffness, while post-anterior blepharotomy myopic eyes showed restoration of orbital compliance. These results help us understand the pathogenesis and improve the management of TED.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.