June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Change in corneal biomechanical parameters following trabeculectomy
Author Affiliations & Notes
  • Karin R Pillunat
    Dept of Ophthalmology, Univ Clinic Carl Gustav Carus Dresden, Dresden, Germany
  • Eberhard Spoerl
    Dept of Ophthalmology, Univ Clinic Carl Gustav Carus Dresden, Dresden, Germany
  • Naim Terai
    Dept of Ophthalmology, Univ Clinic Carl Gustav Carus Dresden, Dresden, Germany
  • Lutz E Pillunat
    Dept of Ophthalmology, Univ Clinic Carl Gustav Carus Dresden, Dresden, Germany
  • Footnotes
    Commercial Relationships Karin Pillunat, None; Eberhard Spoerl, None; Naim Terai, None; Lutz Pillunat, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 2025. doi:
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    • Get Citation

      Karin R Pillunat, Eberhard Spoerl, Naim Terai, Lutz E Pillunat; Change in corneal biomechanical parameters following trabeculectomy. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2025.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Aim of the study was to evaluate corneal biomechanical changes after trabeculectomy and the impact on intraocular pressure (IOP) measurements.

Methods: 30 consecutive patients with open-angle glaucoma scheduled for trabeculectomy (TE) with mitomycin C were enrolled in this prospective case-control study. Corneal biomechanical parameters were assessed with the Ocular Response Analyzer (ORA, Reichert Inc. Depew, New York,USA) immediately prior and at least 6 months after uncomplicated TE. Main outcome measures were changes in corneal hysteresis (CH) and corneal resistance factor (CRF). IOP was measured with Goldmann applanation tonometry (GAT) and with the ORA: IOPg (Goldmann correlated) and IOPcc (corneal compensated). SPSS and linear mixed models with IOP as covariate were used to compare the parameters before and after TE.

Results: After correcting for IOP dependency CH (before TE 8.00±1.35 mmHg; after TE 7.12±1.36 mmHg, P=0.011) and CRF (before TE 8.59±1.64 mmHg; after TE 7.49±1.67 mmHg, P=0.015) were statistically significantly lower after TE. IOP dropped statistically significantly: GAT from 21.7±11.3 mmHg to 9.6±2.6 mmHg (P=0.001), IOPg from 23.7±14.9 mmHg to 9.4±4.6 mmHg (P=0.001) and IOPcc from 26.9±15.2 mmHg to 13.2±4.8 mmHg (P=0.001). Preoperatively IOPcc was 20% higher than GAT (P=0.001) and 15% higher than IOPg (P=0.001). Postoperatively IOPcc was 37% higher than GAT (P=0.001) and 40% higher than IOPg (P=0.001).

Conclusions: Despite a marked IOP reduction IOP-adjusted CH and CRF do not increase after TE but rather decrease. The elastic capacity and viscous damping after TE are affected in such a way that the stress and strain relationship changes to a level where stress can be compensated by strain again. It is very much likely that we underestimate GAT measurements especially after surgery.

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