The Role of the crystalline lens in ametropia

When examining the dimensions of the crystalline lens, it is found that some may vary with different types of refractive error. The effects of several of these variations on refractive error are investigated in this thesis. To examine whether lens thickness was significantly different in youth-onset myopes compared with emmetropes, a structural model was developed and tested. No substantial difference was found between the two groups. In both groups of eyes, increased lens thickness was found to contribute significantly to the refractive state of the eye; a thicker lens effectively being a stronger lens. The crystalline lens may play a different role in early adult-onset myopia which develops after normal growth has ceased compared to its role in youth-onset myopia. Cross-sectional data from early adult-onset myopes, youth-onset myopes and emmetropes were evaluated to determine whether lens thickness differed among the refractive error groups. No significant differences were found. However, some early adult-onset myopes and youth-onset myopes were re-evaluated three years after the initial data were collected and a significant increase in mean lens thickness was, found in the group of early adult-onset, myopes. No significant mean lens thickness increase occurred in the group of youth-onset myopes. To evaluate further the contribution of the crystalline lens dimensions to the refractive state of the eye, radii of curvature and. lens thicknesses of a group of anisometropes were examined. Radii were found not to be consistently flatter or steeper in the relatively, more myropic eye compared with the relatively less myopic eye and there was also no significant difference between mean lens thickness of the relatively more myopic eye compared to mean lens thickness of the relatively less, myopic eye. Crystalline lens thickness and radii of curvature were therefore found to play only a minor role in refractive error development, Deeper vitreous chambers and steeper corneal curvatures were found to be the major contributors to myopia.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Optometry

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

1993

Author dc:creator

• Scott, Rolene

Advisors dc:contributor.advisor

• Dr M K Yap
• Prof L F Garner

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2292/3220

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/3220