June 2013
Volume 54, Issue 15
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ARVO Annual Meeting Abstract  |   June 2013
Local Stiffness of Rat Trabecular Meshwork
Fan Yuan; Lucinda Camras
Author Affiliations & Notes
  • Fan Yuan
    Biomedical Engineering, Duke University, Durham, NC
    Ophthalmology, Duke University, Durham, NC
  • Lucinda Camras
    Biomedical Engineering, Duke University, Durham, NC
  • Footnotes
    Commercial Relationships Fan Yuan, None; Lucinda Camras, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 75. doi:
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      Fan Yuan, Lucinda Camras; Local Stiffness of Rat Trabecular Meshwork. Invest. Ophthalmol. Vis. Sci. 2013;54(15):75.

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Abstract
 
Purpose
 

Stiffness of trabecular meshwork (TM) may play an important role in regulating outflow resistance in healthy and glaucomatous eyes (Last et al., 2011; Camras, et al., 2012). To investigate its effects on pathogenesis of glaucoma in rodent models, we developed a technique to determine TM stiffness in rat eyes using atomic force microscopy (AFM).

 
Methods
 

Rat eyes were enucleated immediately after death and perfused with Evans Blue dye (0.5 mg/mL) for 15 min. The dye perfusion allowed us to better visualize TM location in subsequent tissue dissection and tissue assignment with the AFM probe. Incisions were made in the posterior sclera to remove the iris, lens, choroid, and retina leaving only the ocular shell (cornea, sclera, and TM) intact. The shell, with the TM facing upwards, was flat mounted to a petri dish using glass coverslips. Histological examination was performed to check any damages of TM caused by tissue dissection. A probe with gold-coated colloid (5 µm in diameter) was used to indent the cornea, sclera, and TM at a velocity of 5 µm/sec. The Hertz equation was used to calculate the Young’s modulus (E) of tissues.

 
Results
 

The average Young’s modulus of TM was 91.4 ± 0.6 Pa, which was lower than the stiffness of cornea and sclera measured in the same eye. Histological examination confirmed that TM structures were still intact post-dissection. Additional studies are being conducted to determine the accuracy of measurements and regional variation of E in the ocular shell.

 
Conclusions
 

A rat model was developed for investigation of TM stiffness and its effects on outflow resistance. The enabling technique developed in this study will allow investigators to use the rat model to evaluate mechanisms of TM stiffness changes related to aging or pathogenesis of glaucoma. It can also be used to study efficacies of interventions and drug treatments that are designed to modulate TM stiffness.

 
Figure 1. Location of AFM probe. The triangle probe was placed on top of the TM that is indicated by the blue color from Evans blue dye.
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Figure 1. Location of AFM probe. The triangle probe was placed on top of the TM that is indicated by the blue color from Evans blue dye.
 
Figure 1. Location of AFM probe. The triangle probe was placed on top of the TM that is indicated by the blue color from Evans blue dye.
Figure 1. Location of AFM probe. The triangle probe was placed on top of the TM that is indicated by the blue color from Evans blue dye.
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Figure 2. Typical curves of force versus separation distance. Two curves are shown here. One was measured when the AFM probe approached to TM; another was done during probe retraction from the TM sample.
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Figure 2. Typical curves of force versus separation distance. Two curves are shown here. One was measured when the AFM probe approached to TM; another was done during probe retraction from the TM sample.
 
Figure 2. Typical curves of force versus separation distance. Two curves are shown here. One was measured when the AFM probe approached to TM; another was done during probe retraction from the TM sample.
Figure 2. Typical curves of force versus separation distance. Two curves are shown here. One was measured when the AFM probe approached to TM; another was done during probe retraction from the TM sample.
View OriginalDownload Slide
 
Keywords: 735 trabecular meshwork • 633 outflow: trabecular meshwork  
© 2013, 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 © 2024 Association for Research in Vision and Ophthalmology.
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