May 2005
Volume 46, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2005
Histological Evaluation of Poly(Ethylene Glycol)–Poly(Acrylic Acid) (PEG–PAA) Double Network Hydrogel Corneal Implant
N. Farooqui; D. Myung; M. Masek; R. Dalal; W. Koh; S. Gupta; J. Noolandi; C. Frank; C.N. Ta
Author Affiliations & Notes
  • N. Farooqui
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
  • D. Myung
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
    Department of Chemical Engineering, Stanford University, Palo Alto, CA
  • M. Masek
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
  • R. Dalal
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
  • W. Koh
    Department of Chemical Engineering, Stanford University, Palo Alto, CA
  • S. Gupta
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
  • J. Noolandi
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
    Department of Chemical Engineering, Stanford University, Palo Alto, CA
  • C. Frank
    Department of Chemical Engineering, Stanford University, Palo Alto, CA
  • C.N. Ta
    Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA
  • Footnotes
    Commercial Relationships  N. Farooqui, VISX, Incorporated F; D. Myung, VISX, Incorporated F, P; M. Masek, None; R. Dalal, VISX, Incorporated F; W. Koh, VISX, Incorporated F, P; S. Gupta, VISX, Incorporated F; J. Noolandi, VISX, Incorporated F, P; C. Frank, VISX, Incorporated F, P; C.N. Ta, VISX, Incorporated F, P.
  • Footnotes
    Support  VISX, Incorporated
Investigative Ophthalmology & Visual Science May 2005, Vol.46, 873. doi:
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      N. Farooqui, D. Myung, M. Masek, R. Dalal, W. Koh, S. Gupta, J. Noolandi, C. Frank, C.N. Ta; Histological Evaluation of Poly(Ethylene Glycol)–Poly(Acrylic Acid) (PEG–PAA) Double Network Hydrogel Corneal Implant . Invest. Ophthalmol. Vis. Sci. 2005;46(13):873.

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Abstract

Abstract: : Purpose:Due to their unique composition, physiologic properties, and high water content, many hydrogel scaffolds are unable to be successfully processed for histological evaluation using routine tissue processing methods. Our goal is to adapt novel methods for hydrogel processing to successfully prepare a PEG–PAA double network (DN) hydrogel for histological analysis. Methods:Three methods were assessed for their ability to produce accurate light microscopy analysis. A modified protocol for glycol methacrylate (GMA) resin was used. The specimen, consisting of a PEG–PAA hydrogel (water content 80%) implanted within the stroma of a bovine cornea, was fixed overnight using 2.5% glutaraldehyde–2% paraformaldehyde. Pre–infiltration was achieved with increasing concentrations of GMA every hour under vacuum pressure. The Technovit 7100 kit recommendations call for dilution of the GMA monomer with ethanol. Due to the high water content of the PEG–PAA hydrogel and to preserve the morphology, ethanol was substituted with deionized water. Infiltration was performed overnight under vacuum with 100ml 100% GMA monomer and 1g Hardener I (dibenzoylperoxide). The sample was embedded in gelatin capsules and polymerized at room temperature, using 15:1 of pre–infiltration solution and Hardener II (dimethylsulfoxide). Thin sections (2 microns) were taken using a glass knife. Sections were taken off of a water bath and placed directly onto a dry slide and stained with toluidine blue. Bovine corneas with PEG–PAA implants were also processed by using frozen section and the standard TEM epoxy methods as bases for comparison. Results:Slides processed using the GMA method were evaluated under a light microscope, and the implant was clearly visible and intact within the stroma, with excellent preservation of both tissue and hydrogel morphology. Frozen sectioning of the implanted tissue resulted in loss of the hydrogel due to ice crystal formation of the water in the hydrogel. Hydrogels embedded in epoxy resin showed gross distortion of morphology due to the high ethanol concentrations required in the process. Conclusions: The GMA method is successful in yielding light microscopy sections for the histological evaluation of a PEG–PAA corneal implant. It proves to be a promising method for further evaluation of our hydrogel implants in their various applications.

Keywords: keratoprostheses • cornea: epithelium 
© 2005, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2025 Association for Research in Vision and Ophthalmology.
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