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Author Notes:

Manuel Ramirez-Garcia : mramire6@ur.rochester.edu, Full postal address: Department of Biomedical Engineering, 207 Robert B. Goergen Hall, University of Rochester, Rochester, NY 14627, USA.

Declarations of interest: none.

Subjects:

Research Funding:

This work was supported in part by the Fight for Sight Foundation [#FFS-SS-15–029]; and an internal University of Rochester Research Award.

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Ophthalmology
  • Corneal endothelium
  • Surgical trauma
  • Corneal endothelial cell density
  • Cataract surgery
  • Mechanical trauma
  • Corneal endothelial cell loss
  • DEPENDENT BIOMECHANICAL PROPERTIES
  • ASSISTED CATARACT-SURGERY
  • ANGLE-CLOSURE GLAUCOMA
  • PENETRATING KERATOPLASTY
  • DONOR TISSUE
  • INSERTION TECHNIQUES
  • GRAFT FAILURE
  • DAMAGE
  • INJECTOR
  • STROMA

Vulnerability of corneal endothelial cells to mechanical trauma from indentation forces assessed using contact mechanics and fluorescence microscopy

Tools:

Journal Title:

Experimental Eye Research

Volume:

Volume 175

Publisher:

, Pages 73-82

Type of Work:

Article | Post-print: After Peer Review

Abstract:

Corneal endothelial cell (CEC) loss occurs from tissue manipulation during anterior segment surgery and corneal transplantation as well as from contact with synthetic materials like intraocular lenses and tube shunts. While several studies have quantified CEC loss for specific surgical steps, the vulnerability of CECs to isolated, controllable and measurable mechanical forces has not been assessed previously. The purpose of this study was to develop an experimental testing platform where the susceptibility of CECs to controlled mechanical trauma could be measured. The corneal endothelial surfaces of freshly dissected porcine corneas were subjected to a range of indentation forces via a spherical stainless steel bead. A cell viability assay in combination with high-resolution fluorescence microscopy was used to visualize and quantify injured/dead CEC densities before and after mechanical loading. In specimens subjected to an indentation force of 9 mN, the mean ± SD peak contact pressure P 0 was 18.64 ± 3.59 kPa (139.81 ± 26.93 mmHg) in the center of indentation and decreased radially outward. Injured/dead CEC densities were significantly greater (p ≤ 0.001) after mechanical indentation of 9 mN (167 ± 97 cells/mm 2 ) compared to before indentation (39 ± 52 cells/mm 2 ) and compared to the sham group (34 ± 31 cells/mm 2 ). In specimens subjected to “contact only” – defined as an applied indentation force of 0.65 mN – the peak contact pressure P 0 was 7.31 ± 1.5 kPa (54.83 ± 11.25 mmHg). In regions where the contact pressures was below 78% of P 0 (<5.7 kPa or 42.75 mmHg), injured/dead CEC densities were within the range of CEC loss observed in the sham group, suggesting negligible cell death. These findings indicate that CECs are highly susceptible to mechanical trauma via indentation, supporting the established “no-touch” policy for ophthalmological procedures. While CECs can potentially remain viable below contact pressures of 5.7 kPa (42.75 mmHg), this low threshold suggests that prevention of indentation-associated CEC loss may be challenging.

Copyright information:

© 2018 Elsevier Inc. All rights reserved.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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