This thesis consists of two parts: a report on the use of a binocular Shack-Hartmann (SH)
sensor to study the dynamic correlation of ocular aberrations; and the application of an
adaptive optics (AO) system to investigate the effect of the manipulation of aberrations
on the accommodation control.
The binocular SH sensor consists of one laser source and one camera to reduce
system cost and complexity. Six participants took part in this study. Coherence function
analysis showed that coherence values were dependent on the subject, aberration and
frequency component. Inter-ocular correlations of the aberration dynamics were fairly
weak for all participants. Binocular and monocular viewing conditions produced similar
wavefront error dynamics.
The AO system has a dual wavefront sensing channel. The extra sensing channel
permits direct measurement of the eye¿s aberrations independent of the deformable
mirror. Dynamic correction of aberrations during steady-state fixation did not affect the
accommodation microfluctuations, possibly due to the prior correction of the static
aberration level and/or the limited correction bandwidth. The inversion of certain
aberrations during dynamic accommodation affected the gain and latency of
accommodation response (AR), suggesting that the eye used the aberrations to guide its
initial path of accommodative step response. Corrections of aberrations at various
temporal locations of AR cycle produced subject- and aberration-dependent results. The
gain and phase lag of the AR to a sinusoidally moving target were unaffected by
aberration correction. The predictable nature of the target had been suggested as the reason for its failure to produce any significant effect on the AR gain and phase lag.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4291 |
| Date | January 2009 |
| Creators | Chin, Sem Sem |
| Contributors | Mallen, Edward A.H., Hampson, Karen M. |
| Publisher | University of Bradford, Bradford School of Optometry and Vision |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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