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Comparative rheological studies of the vitreous body of the eye.
- Format:
- Book
- Thesis/Dissertation
- Author/Creator:
- Lee, Belinda.
- Language:
- English
- Subjects (All):
- Biomedical engineering.
- Physiology.
- 0433.
- 0541.
- Penn dissertations--Bioengineering.
- Bioengineering--Penn dissertations.
- Local Subjects:
- Penn dissertations--Bioengineering.
- Bioengineering--Penn dissertations.
- 0433.
- 0541.
- Physical Description:
- 302 pages
- Contained In:
- Dissertation Abstracts International 53-05B.
- System Details:
- Mode of access: World Wide Web.
- text file
- Summary:
- The rheological (viscoelastic) properties of the vitreous gel are a function of composition and may differ among species and vary regionally within the vitreous. These properties are essential to the mechanical functioning of the eye. Although there are gross, qualitative data on the vitreous available, quantitative measurement of species and other differences is important for understanding the role of the vitreous in eye dysfunction due to age and disease.
- Samples of vitreous from pigs, cows, and humans, each sectioned into anterior, central and posterior regions, were tested. The viscoelastic behavior was measured in terms of a three or four parameter model of the creep compliance. The concentrations of those macromolecular components (collagen and hyaluronic acid) and electrolytes (Na$\sp+,$ Ca$\sp{2+},$ K$\sp+,$ Cl$\sp-)$ that are believed to be key determinants of vitreous rheology were also measured.
- Significant differences, both regionally and interspecific, were found in both rheological and chemical properties of the vitreous samples. Previously observed differences in the gross "thickness" of vitreous samples from difficult species arise from variations in the viscous or energy dissipating components of the gel, whereas the elastic or energy storing properties do not differ to a great extent. For example, both the unrecoverable and internal viscosity parameters of compliance are a factor of three or more greater for cows than for humans, explaining why cow vitreous appears to be grossly 100% gel while human vitreous appears to be between 40 and 80% gelled. In these samples, no significant differences in macromolecular concentrations were found. However, there were highly significant differences in Na$\sp+$ and Ca$\sp{2+}.$ Detailed statistical analyses (ANOVA, MANOVA, and Canonical Correlation) revealed other significant relationships between species and regions. Since the human samples were predominantly from elderly donors, whereas the animal samples were from juveniles, the results suggest that age is an important factor in vitreous rheology, and that more detailed studies of the role of vitreous physico-chemistry in age and disease are needed.
- Notes:
- Thesis (Ph.D. in Bioengineering) -- Graduate School of Arts and Sciences, University of Pennsylvania, 1992.
- Source: Dissertation Abstracts International, Volume: 53-05, Section: B, page: 2427.
- Supervisors: Mitchell Litt; Gershon Buchsbaum.
- Local Notes:
- School code: 0175.
- Access Restriction:
- Restricted for use by site license.
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