Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Nystagmus is an eye movement pattern that consists of a drifting gaze component, known
as the slow phase, followed by a corrective quick phase component. The presence of
nystagmus or the lack thereof under certain conditions can be used for various diagnostic
purposes including the diagnosis of physiological, pathological and neurological conditions.
The angular velocity of the quick phase can make the detection of nystagmus a challenging
task for the untrained eye, since the quick phases are usually comparable with saccadic eye
motions. The goal is thus to develop a fully automated diagnostic tool that can identify
the presents of nystagmus in a patient’s eye motions.
In this thesis, an appropriate eye tracking method was selected from a number of eye
tracking methods that are commonly implemented in the literature. A video-oculography
goggle concept was chosen based on criteria such as invasiveness, sampling rate, accuracy
and telemedicine capability, amongst other nystagmus related necessities. A binocular
video-oculography concept was chosen that satisfied the technical requirements and
provided a cost-effective design. An automated analysis algorithm was developed for
automatic nystagmus identification from eye motion data. The algorithm was validated
by testing the performance of the algorithm on an optokinetic nystagmus signal. It
proved to provide a reliable automatic identification of nystagmus beats, even in signals
that contained nystagmus as well as random motion components. A statistical analysis
showed that the algorithm provided a sensitivity of 91.8% and a specificity of 96.5% for
pure nystagmus signals, and a sensitivity and specificity of 87.8% and 91.1% respectively
for mixed signals. / AFRIKAANSE OPSOMMING: Nystagmus is ’n oogbewegingspatroon wat bestaan uit ’n dwalende tuurkomponent, wat
die stadige fase genoem word, gevolg deur ’n vinnige korrigereringsbeweging wat bekend
staan as die vinnige fase. Die teenwoordigheid van nystagmus, of afwesigheid daarvan
in sekere gevalle, kan gebruik word in ’n verskeidenheid diagnostiese toepassings, onder
andere die diagnose van fisiologiese-, patalogiese- en neurologiese kwale. Die hoeksnelheid
van die vinnige fase lei daartoe dat nystagmus dikwels moeilik is om te bespeur vir
ongeöefende oë, aangesien dit vergelykbaar is met saccade bewegings. Die doel van hierdie
navorsing is dus die ontwikkeling van ’n stelsel wat ’n volledige automatiese identifisering
van nystagmus kan behartig.
’n Gepaste oogvolgtegniek was gekies vanuit ’n aantal verskillende oogvolgmetodes
wat dikwels in die praktyk gebruik word. Die finale keuse was ’n skermbril, video-oogvolgmetode
wat gekies was op grond van kriteria soos onder andere, invallendheid,
meetfrekwensie, akkuraatheid en geskiktheid vir telemedisyne toepassings. Die ontwikkelde
brilkonsep bied ’n koste-effektiewe oplossing, met die moontlikheid om albei oë
te volg en bevredig al die bogenoemde tegniese spesifikasies. ’n Geoutomatiseerde
nystagmus identifiseringsalgoritme is ontwikkel. Die algoritme se effektiwiteit is getoets
op optokinetiese nystagmusseine. Betroubare resultate is vekry vanaf die algoritme, selfs
in die geval van gemengde seine wat bestaan uit arbritrêre- en nystagmus komponente.
Statistiese analiese het gewys dat die algoritme ’n sensitiwiteit van 91.8% en ’n spesifisiteit
van 96.5% kon behaal vir seine met slegs nystagmus inhoud. Vir gemengde inhoud seine
het die algoritme ’n sensitiwiteit van 87.8% en spesifisiteit van 91.1% behaal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/18019 |
| Date | 12 1900 |
| Creators | Swart, Wayne |
| Contributors | Scheffer, C., Schreve, K., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 122 p. : ill. |
| Rights | Stellenbosch University |
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