Clinicians are becoming increasingly aware of the effect of various
pathologieso n the characteristicso f saccadice ye movements.A s such, an efficient
and non-invasivem eano f measuringe ye-movementisn a clinical environmenti s of
interest to many. The aim of this thesis is to investigate the clinical application of a
non-invasive eye movement recording technique as a part of a clinical examination.
Eye movements were measured using an IRIS 6500 infrared limbal eye
tracker, which we customized for the direct recording of oblique eye movements as
well as horizontal and vertical. Firstly, the eye-tracker itself was assessed. Visually
normal observers made saccadic eye movements to a 10' stimulus in eight directions
of gaze. Primary (ANOVA) and secondary analyses (mean error less than 5%)
resulted in acceptance that averaging four measurements would give a representative
measurement of saccadic latency, peak velocity, amplitude and duration. Test-retest
results indicated that this technique gives statistically (± 1.96*STDEVDifference)
repeatable responses.
Severalf actors that could potentially influence clinically basedm easureso f
eye-movementsw ere examined. These included, the effect of ageing, viewing
distances, dioptric blur and cataract. The results showed that saccadic latency and
durationa re significantly (p< 0.05) longer in older (60-89 years)o bserversc ompared
to younger (20-39 years). Peak velocity and amplitude were not significantly
affectedb y the age of the observer.A ll saccadicp arameters( SP) were significantly
affected by direction (Chapter 5). The compact nature of this eye movement
methodology is obtainable since there is no significant effect on viewing distance
(300 cm vs. 49 cm) (Chapter 6). There is also no significant effect of dioptric blur
(up to +LOODS) on any of the four SP. In contrast, a higher level of defocus
(+3.O ODS)h as a larger probability of interfering with the measurementso f peak
velocity and duration (Chapter 7). Saccadice ye-movementsw ere also recorded
whilst normally sighted subjects wore cataract simulation goggles. The results
suggested that the presence of dense cataract introduces significant increases in
saccadic latencies and durations. No effect was found on the peak velocities and
amplitudes.T he effect of amblyopiao n SP was also investigatedin order to examine
if this methodologyi s able to detectn ormal from abnormalr esponses(i . e. increased
saccadicla tencies).T his set of data (Chapter9 ) showedt hat using IRIS 6500, longer
than normal latencies may be recorded from the amblyopic eye but no consistent
effect was found for the other SP (peak velocity, amplitude, duration).
overall, the results of this thesis demonstrateth at the IRIS 6500 eye-tracker
has many desirable elements (it is non-invasive; comfortable for the observers and
gives repeatable and precise results in an acceptable time) that would potentially
make it a useful clinical tool as a part of a routine examination.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/3577 |
| Date | January 2005 |
| Creators | Kavasakali, Maria |
| Contributors | Douthwaite, William A., Hazel, Charlotte, Bloj, Marina |
| Publisher | University of Bradford, Department of Optometry |
| 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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