All ETDs from UAB

Advisory Committee Chair

Thomas T Norton

Advisory Committee Members

Qiang Ding

Michael R Frost

Roderick J Fullard

Kent T Keyser

Joanne E Murphy-Ullrich

Document Type

Dissertation

Date of Award

2014

Degree Name by School

Doctor of Philosophy (PhD) School of Optometry

Abstract

The sclera is a target tissue that receives signals that are initiated in the retina, cascade through retinal pigment epithelium (RPE) and choroid, and cause scleral extra cellular matrix remodeling. Biomechanical alterations of the sclera are produced by these biochemical changes, and in turn control the axial length of the eye. This dissertation project examined scleral gene expression changes in mRNA level of juvenile tree shrews. Three specific aims were investigated: specific aim one tested the hypothesis that three different GO visual conditions that all produce axial elongation and myopia: minus-lens wear, form deprivation, and continuous darkness, will produce similar gene expression signatures in sclera. Recovery (STOP) occurs in response to the myopia that is produced by discontinuing minus-lens wear. The axial elongation rate slows and the induced myopia dissipates. Scleral responses in STOP were examined in specific aim two to compare with GO conditions. A very similar refractive myopia can also be produced by having normal juvenile eyes wear convex lenses. This treatment produces very little refractive change (IGNORE). In specific aim three, we compared the scleral response to IGNORE conditions with the STOP response. In all three specific aims, scleral mRNA levels for 55 candidate genes were measured in treated and control eyes and compared between groups of tree shrew (n = 7 per group) exposed to GO, STOP, and IGNORE conditions. Normal interocular differences were also measured. In specific aim one, the gene expression in tree shrew sclera was very similar in the three different GO conditions, a GO signature. Specific aim two found a STOP response signature that included some bi-directionally-regulated genes, but the expression of other genes differed only in GO or STOP. Although plus-lens wear did not produce significant refractive changes in specific aim three, the IGNORE gene signature showed that signals arrive at the sclera produce a pattern that is similar to STOP signature with distinguishable differences in normal sclera.

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Optometry Commons

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