Aldhafeeri, Raed
(2017)
Analysis of Scleral Buckling Surgery: Biomechanical Model.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The objective of this study was to analyze deformation and stresses and resultant refractive error of human eyes subjected to scleral buckling surgery by encircling band; and segmental buckle with encircling buckling. Experimental evaluation of buckling of the eye was conducted using animal model for evaluation of the axial length change and tilting of the cornea. For different segmental buckle widths and extents, the axial length increased and cornea tilt increased for all models. Axisymmetric and three-dimensional finite element models of the eye and buckles were constructed to calculate eye deformation. The analysis found that the change in the axial length, which is a factor in the myopia of the eye is mainly influenced by the amount of indentation. Steepening of the cornea and thus cornea and total eye power are mainly effected by the cornea thickness in addition to the indentation. The width of the band or buckle and band location have no effect on myopic shift. The reduction of the anterior chamber depth increased for band closer to limbus and with less cornea thinning where width of the band and the buckle and extent of the buckle had no effect. Additional types of refractive errors and deformation were encountered in buckled eye. The astigmatism of the cornea increased with increased indentation, corneal thinning and extent of the segmental buckle. Tilting of the cornea away from the center of the buckle was observed and it increased for higher indentation and decreased extent of the buckle. Greater indentation induced more displaced vitreous cavity volume and maximum stresses in the sclera. The maximum stress was located at the sclera-choroid interface and in at sclera surface close to the buckle edge contact location. Pressure-volume relationship was modeled for eyes with and without buckling by increasing the pressure and recording the added fluid volume and linear relationship was found for all models. The slope of the relationship can give rigidity factor for each model where the buckled eyes had less rigidity. The rigidity also showed decrease in thinner band, higher indentation, shorter buckle, thinner cornea and for band closer to the limbus.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
27 September 2017 |
| Date Type: |
Publication |
| Defense Date: |
21 July 2017 |
| Approval Date: |
27 September 2017 |
| Submission Date: |
24 July 2017 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
135 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Finite Element, Scleral Buckling, Eye, Biomechanical Model, Biomechanics |
| Additional Information: |
Alternative Email: raedalsuwait@gmail.com |
| Date Deposited: |
27 Sep 2017 19:22 |
| Last Modified: |
27 Sep 2018 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/32611 |
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