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Evaluation of Corneal Deformation Parameters Provided by the Corvis ST Tonometer After Trabeculectomy

Zong, Yuan MD; Wu, Na MD, PhD; Fu, Zhixuan MD; Kong, Xiangmei MD, PhD

doi: 10.1097/IJG.0000000000000590
Original Studies

Purpose: The aims of this study were to evaluate how the corneal deformation parameters provided by the Corvis ST tonometer (CST) were influenced by pressure-lowering ocular surgery, and to determine the correlations of intraocular pressure (IOP) and axial length (AL) with CST corneal deformation parameters.

Methods: This prospective 1-month study enrolled 22 subjects (22 eyes) who underwent trabeculectomy combined with mitomycin C. The corneal deformation parameters were measured using the CST. IOP was measured before and after surgery by a Goldmann applanation tonometer and the CST. The central corneal thickness and AL were also recorded. The correlations of the corneal deformation parameters with central corneal thickness, AL, and IOP changes were determined by linear regression analysis.

Results: IOP decreased significantly after surgery. AL was significantly shorter at 1 week after surgery. There were significant changes in the CST parameters time 1, velocity 1, velocity 2, peak distance highest concavity, and deformation amplitude highest concavity at 1 week and 1 month after surgery and in time highest concavity at 1 week after surgery. The change in time 1 was significantly correlated with preoperative IOP and the IOP reductions, and was positively correlated with the decrease in AL at 1 week. The increase in velocity 1 was negatively correlated with preoperative IOP, and IOP reductions. The change in time highest concavity was negatively correlated with IOP before surgery and the decrease in IOP at 1 week.

Conclusion: CST is a good choice for measuring IOP, especially when aiming for normalization of IOP after glaucoma surgery.

*Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University

Key Laboratory of Myopia, Ministry of Health

Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China

Supported by the National Major Scientific Equipment program (No. 2012YQ12008003, China), the New Technology Research Project, Shanghai Municipal Commission of Health and Family Planning (No.SHDC12014114 and 2013SY058), and the Shanghai Natural Science Foundation (No.14ZR1405400).

Disclosure: The authors declare no conflict of interest.

Reprints: Xiangmei Kong, MD, PhD, Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, 83 Fenyang Road, Shanghai 200031, China (e-mail:

Received November 18, 2015

Accepted October 25, 2016

Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.