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Karin R Pillunat, Eberhard Spoerl, Lutz E Pillunat; Change in biomechanical parameters analyzed with the Corvis ST following trabeculectomy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3546. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate biomechanical changes after trabeculectomy using the Corvis Scheimpflug technology.
29 consecutive patients with open-angle glaucoma scheduled for primary trabeculectomy (TE) with mitomycin C were enrolled in this prospective case-control study. Biomechanical parameters were assessed with the Corneal Visualization Scheimpflug Technology (Corvis ST, Oculus, Wetzlar, Germany), immediately prior to and at least 6 months after uncomplicated TE. Main outcome measures were 10 parameters out of the 52 parameters of the new research-software (software version 102R1126): changes in IOP, pachymetry, maximal deformation amplitude, A2 time, HC time, A1 deflection amplitude, whole eye movement, deflection amplitude 2 ratio, CP-ratio and DA-ratio. SPSS and linear mixed models with IOP and CCT as covariates were used to compare the parameters before and after TE (means ± standard error).
IOP and pachymetry changed statistically significantly from 20.00±1.55 to 10.47±1.52 mmHg (P=0.001) respectively 544.0±5.37 to 521.1±1.52 µm (P=0.001).There was a strong correlation between IOP and pachymetry and most of the measured parameters. The adjusted maximal deformation amplitude (1.059±0.038 to 1.200±0.037 mm; P=0.014), the A1 deflection amplitude (0.102±00.3 to 0.089±0.003; P=0.018), the deflection amplitude 2 ratio (5.357±0.086 to 5.612±0.084; P=0.046) and the DA-ratio (1.592±0.008 to 1.617±0.008: P=0.034) changed statistically significantly whereas the CP-ratio (4.611±0.061 to 4.756±0.060; P=0.072) did not change statistically significantly.A2 time was only correlated with IOP but not with CCT and did not change statistically significantly (21.098±0.243 to 21.588±0.238 s; P=0.071).HC-time and whole eye movement showed no correlation with IOP and CCT and did not change statistically significantly after TE (HC-time: 16.202±0.189 to 16.234±0.189; P=0.908; whole eye movement: 0.309±0.016 to 0.309±0.016 mm; P=0.996).
Despite a marked IOP reduction and a weakening of the globe after trabeculectomy there are some biomechanical parameters as measured with the Corvis ST that change, whereas some do not change postoperatively. Maybe parameters that change do reflect ocular rather than corneal or orbital biomechanical characteristics.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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