Past HDR Students

Damien Fisher | Rohan Hughes | Hamed Niyazmand | Seyed Hosein Hoseini-Yazdi | Sameneh Delshad | Sekar Ulaganathan | Beata Sander | Emily Woodman-Pieterse | Ranjay Chakraborty | Atanu Ghosh | Shila Roshani | Stephen Vincent | Garima Tyagi | David Alonso-Caneiro | Fan Yi | Alyra Shaw | Scott Read | Tobias Buehren | Wilfred Tang | Michael Sydenham | Thomas Tenkate

 

Damien Fisher

Thesis Title: Physiological corneal changes associated with scleral contact lens wear

Damien’s research examined the physiologic effects of scleral lenses on the cornea. While scleral lenses form a small percentage of contact lens usage, they still provide great visual benefit to those that suffer corneal irregularities.  Further understanding of corneal oedema and how this relates to various fitting parameters of scleral lenses was investigated. Various phases of Damien’s research examined the effects of altering central fluid reservoir thickness and lens central thickness on corneal oedema during open and closed eye conditions.  Another aspect of investigation involved a novel method utilising Pentacam Sheimpflug imaging to scrutinize tear dynamics within the fluid reservoir.

Damien Fisher received formal notification in July 2021 that he had completed all of the course requirements for the higher degree award of Doctor of Philosophy for his thesis entitled, ‘Physiological corneal changes associated with scleral contact lens wear.’

Publications (arising from thesis):

Fisher, DamienCollins, Michael J., & Vincent, Stephen J. (2021)  Conjunctival prolapse during open eye scleral lens wear. Contact Lens and Anterior Eye44(1), pp. 115-119.

Fisher, DamienCollins, Michael J., & Vincent, Stephen J. (2021) Fluid reservoir thickness and corneal oedema during closed eye scleral lens wear. Contact Lens and Anterior Eye44(1), pp. 102-107.

Fisher, DamienCollins, Michael, & Vincent, Stephen (2021) Fluid reservoir thickness and corneal oedema during closed eye scleral lens wear: Experimental and theoretical outcomes. Contact Lens and Anterior Eye44(1), pp. 124-125.

Fisher, DamienCollins, Michael J., & Vincent, Stephen J. (2020) Fluid reservoir thickness and corneal edema during open-eye scleral lens wear. Optometry and Vision Science97(9), pp. 683-689.

Fisher, DamienCollins, Michael J., & Vincent, Stephen J. (2020) Anterior segment optical coherence tomography scanning protocols and corneal thickness repeatability. Contact Lens and Anterior Eye43(5), pp. 433-440.

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Rohan Hughes

Thesis Title: Optics of the eye and refractive error development

Myopia commonly manifests and progresses throughout childhood. Excessive near work has been implicated as a risk factor, however the causative link between myopia and near work is yet to be established. In adults, ocular wavefront aberrations and the axial length of the eye are known to undergo transient changes during accommodation, however little is known about these changes during childhood; therefore, the optical and structural changes of the eye during accommodation in children is of significant interest. This program of research examined the short-term optical and structural changes in the eyes of children during accommodation by measuring ocular biometry and aberrations while varying the accommodative demand.

Rohan Hughes received formal notification in November 2020 that he had completed all of the course requirements for the higher degree award of Doctor of Philosophy for his thesis entitled, ‘Ocular Characteristics of Non-Myopic and Myopic Children During Relaxed and Active Accommodation.’

Publications (arising from thesis):

Hughes, Rohan P J, Read, Scott, Collins, Michael, & Vincent, Stephen (2020) Changes in ocular biometry during short‐term accommodation in children. Ophthalmic and Physiological Optics, 40(5), pp. 584-594.

Hughes, Rohan, Vincent, Stephen, Read, Scott, & Collins, Michael (2020) Higher order aberrations, refractive error development and myopia control: a review. Clinical and Experimental Optometry, 103(1), pp. 68-85.

Hughes, Rohan Phillip John (2020) Ocular characteristics of non-myopic and myopic children during relaxed and active accommodation. PhD thesis, Queensland University of Technology.

Hughes, Rohan P J, Vincent, Stephen, Read, Scott, & Collins, Michael (2019) Short-term changes in ocular biometry during accommodation in children. Investigative Ophthalmology and Visual Science, 60(9), Article number: 2745824 4360.

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Hamed Niyazmand

Thesis Title: Ocular changes associated with accommodation and convergence

Hamed’s doctoral research studies focused on the ocular changes associated with accommodation and convergence, with a primary focus on how the sclera (the white, outer coat of the eye) changes when near tasks are performed. As the sclera plays an important role in the determination of ocular size and shape, this research may provide new insight into the ocular changes associated with near work and the potential role of these changes in myopia development and progression. Therefore in the first phase of Hamed’s PhD research, the cornea, limbus, and anterior sclera were evaluated using the Eye Surface Profiler (ESP) while viewing targets requiring different levels of near focussing.

The Eye Surface Profiler is a newly released instrument based on Fourier transform profilometry and provides measurements of the ocular surface topography across a much wider area than was previously possible (out to a 16 mm diameter). Using the ESP instrument we are able now to measure the topographic parameters of the anterior sclera.  This technique uses two fringe pattern projectors to capture the anterior eye surface contour, and allows the changes in the anterior sclera with accommodation and convergence to be comprehensively assessed.

Publications (arising from thesis):

Niyazmand, HamedRead, ScottAtchison, DavidAlonso Caneiro, David, & Collins, Michael (2021) Anterior scleral thickness and shape changes with different levels of simulated convergence. Experimental Eye Research203, Article number: 108435.

Niyazmand, Hamed, Read, Scott A., Atchison, David A., & Collins, Michael J. (2020) Anterior eye shape in emmetropes, low to moderate myopes, and high myopes. Contact Lens and Anterior Eye.

Niyazmand, Hamed, Read, Scott A., Atchison, David A., & Collins, Michael J. (2020) Effects of accommodation and simulated convergence on anterior scleral shape. Ophthalmic and Physiological Optics, 40(4), pp. 482-490.

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Seyed Hosein Hoseini-Yazdi

Thesis Title: Spatial Characteristics of the Response of the Human Posterior Eye to Imposed Defocus

The growth of the eye is influenced by visual experience, specifically the level of blur detected by the retina. Extensive animal studies have shown that choroid plays an important role in the local ocular growth signalling cascade that determines the final status of ocular refraction. Indeed, choroidal thickness alterations form the early phase response of the eye to imposed blur conditions, with choroidal thinning/thickening occurring prior to the development of experimental myopia/hyperopia. Furthermore, these local mechanisms appear to respond differently to visual input in different retinal regions. However, only a limited number of studies have directly investigated the response to alterations in image focus in human eyes and these studies have been limited to small areas of the central retina (≈ 17˚), with the choroidal response to defocus beyond these central retinal regions remaining unexplored.

To improve the understanding of the mechanisms underlying refractive error development, Hosein’s PhD project examines alterations in central and peripheral choroidal thickness following the short-term exposure to myopic and hyperopic retinal image defocus of varying spatial patterns. For this purpose, he studies a wider area of the choroid employing the new technique of enhanced depth imaging wide-field optical coherence tomography (EDI-WFOCT) that provides choroidal thickness data across a 55˚ of the visual field (Figure 1). His early experiments on healthy adults have confirmed the repeatability of wide-field choroidal thickness via EDI-WFOCT imaging. Furthermore, in an attempt to provide a baseline data of central and peripheral choroidal thickness in healthy adults, he has subsequently investigated the wide-field choroidal thickness in a cohort of myopic and emmetropic healthy young adults and has found that the choroid undergoes a substantial peripheral thinning beyond the parafoveal zone and that significant differences in choroidal thickness associated with myopia are largely confined to the central 27˚ macular and near-peripheral zones (Figure 2). Following these baseline findings, he has then undertaken his major interventional experiments to study the influence of various spatial patterns of short-term imposed myopic and hyperopic optical defocus (including full-field, hemi-field and centre/periphery variations in defocus) on wide-field choroidal thickness of young healthy adults and his findings will be soon available.

Publications (arising from thesis):

Hoseini-Yazdi, HoseinVincent, Stephen J.Read, Scott A., & Collins, Michael J. (2020) Astigmatic Defocus Leads to Short-Term Changes in Human Choroidal Thickness. Investigative Ophthalmology & Visual Science61(8), Article number: 48.

Hoseini Yazdi, Seyed Hosein, Vincent, Stephen, Collins, Michael, Read, Scott, & Alonso-Caneiro, David (2019) Wide-field choroidal thickness in myopes and emmetropes. Scientific Reports, 9(1), Article number: 3474 1-10.

Hoseini Yazdi, Seyed Hosein, Vincent, Stephen, Collins, Michael, Read, Scott, & Alonso-Caneiro, David (2019) Impact of image averaging on wide-field choroidal thickness measurements using enhanced-depth imaging optical coherence tomography. Clinical and Experimental Optometry, 102(3), pp. 320-326.

Hoseini Yazdi, Seyed Hosein, Vincent, Stephen, Collins, Michael, & Read, Scott (2019) Regional alterations in human choroidal thickness in response to short-term monocular hemifield myopic defocus. Ophthalmic and Physiological Optics, 39(3), pp. 172-182.

Hoseini Yazdi, Seyed Hosein, Vincent, Stephen, Collins, Michael, Read, Scott, & Alonso-Caneiro, David (2019) Repeatability of wide-field choroidal thickness measurements using enhanced-depth imaging optical coherence tomography. Clinical and Experimental Optometry, 102(3), pp. 327-334.

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Samaneh Delshad

Thesis Title: Temporal Dynamics of the Eye’s Response to Blur

Awarded: Executive Dean’s Commendation in the Faculty of Health 2019 Outstanding Doctoral Thesis Award

Emmetropization is the process by which the growing eye matches its length to its optical power, so that the images of distant objects are focused on the retina. Evidence from animal models of eye growth show that ocular growth during the emmetropization process is visually guided. The visual cues that drive the emmetropization process in humans are complex, since the retina does not experience stationary blur, but blur that changes as the eyes change fixation. Thus, the required visual information for eye growth control can only be obtained through continuous temporal averaging of blur. Animal model studies of eye growth suggest a non-linear model of integration of the visual signals. 

To date, it is not clear whether the same non-linearity in the temporal integration of visual signals found in animals also exists in human eyes. This PhD research is aimed to assess the model of temporal integration of defocus blur in human eyes, through a series of experiments examining the short term response of the human eye to blur. Knowledge from this project may ultimately contribute towards a better understanding of methods for myopia control.

In this program of research, a binocular beam splitter periscope system was used to provide constant exposure to defocus and maintain distance fixation during Lenstar biometry. Human eye elongates faster in response to hyperopic defocus than it shortens in response to myopic defocus, during 60 minutes imposed defocus. Following cessation from defocus, the effects of myopic defocus persisted longer than the hyperopic defocus effects, during the recovery.

Publications (arising from thesis):

Delshad, SamanehCollins, Michael J.Read, Scott A., & Vincent, Stephen J. (2021) Effects of brief periods of clear vision on the defocus-mediated changes in axial length and choroidal thickness of human eyes. Ophthalmic and Physiological Optics41(4), pp. 932-940.

Delshad, Samaneh, Collins, Michael J., Read, Scott A., & Vincent, Stephen J. (2020) The time course of the onset and recovery of axial length changes in response to imposed defocus. Scientific Reports, 10(1), Article number: 8322.

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Sekar Ulaganathan

Thesis Title: The influence of light and seasonal changes on the daily variation of ocular biometrics and eye growth in young adults

Awarded: QUT Outstanding Thesis Award for 2018

Sekar’s PhD research aims to explore the relationship between ambient light exposure and ocular changes associated with myopia in young adults. Animal studies, and studies in children have shown that ambient light exposure plays an important role in the control of eye growth and in the development of myopia. There is also evidence from animals that daily oscilations in eye biometrics are linked to eye growth and the development of refractive error.  However, there is limited research in young adults examining the role of light exposure, and ocular diurnal rhythms in the regulation of human eye growth, and the interaction between these factors is not well understood. Therefore, this research is utilising objective light exposure measurement techniques, coupled with high resolution ocular imaging to explore the relationship between ambient light exposure, short term diurnal variations and longer term eye growth in young adults.

Publications (arising from thesis):

Ulaganathan, Sekar, Read, Scott A., Collins, Michael J., & Vincent, Stephen J. (2019) Daily axial length and choroidal thickness variations in young adults: Associations with light exposure and longitudinal axial length and choroid changes. Experimental Eye Research, 189, Article number: 107850.

Ulaganathan, Sekar, Read, Scott, Collins, Michael, & Vincent, Stephen (2019) Influence of seasons upon personal light exposure and longitudinal axial length changes in young adults. Acta Ophthalmologica, 97(2), e256-e265.

Ulaganathan, Sekar, Read, Scott, Collins, Michael, & Vincent, Stephen (2017) Measurement duration and frequency impact objective light exposure measures. Optometry and Vision Science, 94(5), pp. 588-597.

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Beata Sander

Sander, Beata P. (2017) The influence of the autonomic nervous system on the human choroid. PhD thesis, Queensland University of Technology.

Thesis research concentrated upon defining the role of muscarinic signaling in myopia development. Using a high-speed, high axial resolution, three-dimensional OCT system to acquire chorioretinal images, it has been demonstrated that muscarinic blockers can influence choroidal thickness at least in the short-term, and the blockage of muscarinic signaling can prevent short-term choroidal thinning effect of negative lenses, but doesn’t enhance the effect of positive lenses on choroidal thickness. It has been shown that low-dosage atropine (0.01% atropine) can prevent choroidal thinning in response to negative lenses but its effect is about 50% weaker than 2% homatropine.

Publications (arising from thesis):

Asejczyk-Widlicka, Magdalena, Krzyzanowska-Berkowska, Patrycja, Sander, Beata, & Iskander, D. Robert (2015) Age-related changes in ocular blood velocity in suspects with glaucomatous optic disc appearance. Comparison with healthy subjects and glaucoma patients. PLoS One, 10(7), pp. 1-12.

Sander BP, Collins MJ, Read SA. (2014) The effect of topical adrenergic and anticholinergic agents on the choroidal thickness of young healthy adults. Experimental Eye Research. 30;128:181-9

Read, Scott A., Collins, Michael J., & Sander, Beata (2010) Human optical axial length and defocus. Investigative Ophthalmology and Vision Science, 51(12), pp. 6262-6269.

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Emily Woodman-Pieterse

Woodman, Emily Claire (2015) Ocular changes associated with accommodation in myopes and emmetropes. PhD thesis, Queensland University of Technology.

This thesis examines the short-term changes occurring in a number of the eye’s structures during reading tasks, and explores how these changes differ between normal eyes, and those with short-sightedness (myopia). This research revealed changes in the shape and thickness of a number of the eye’s structures during near work, and aspects of these changes showed differences associated with myopia. These findings have potentially important implications for our understanding of the role of near work in the development and progression of myopia.

Publications (arising from thesis):

Woodman, Emily, Read, Scott A., & Collins, Michael J. (2012) Axial length and choroidal thickness changes accompanying prolonged accommodation in myopes and emmetropes. Vision Research: an International Journal for Functional Aspects of Vision72, pp. 34-41.

Woodman-Pieterse, Emily C., Read, Scott A., Collins, Michael J., & Alonso-Caneiro, David (2015) Regional changes in choroidal thickness associated with accommodation. Investigative Ophthalmology and Visual Science56(11), pp. 6414-6422.

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Ranjay Chakraborty

Chakraborty, Ranjay (2013) Diurnal variation of ocular biometrics under natural and defocused conditions. PhD thesis, Queensland University of Technology.

Awarded: QUT Outstanding Thesis Award for 2013

This thesis examines the diurnal variations in axial length in young normal eyes, the contributing components, and the influence of optical stimuli on these changes.  The results show that axial length undergoes significant diurnal variation in young adult human eyes, and has shown that the natural diurnal variations in choroidal thickness and IOP are significantly associated, and may underlie these diurnal fluctuations in axial length.  This work also demonstrates for the first time that exposing young human eyes to monocular myopic and hyperopic defocus leads to a significant disruption in the normal diurnal rhythms of axial length and choroidal thickness.  These changes in axial length with defocus may reflect underlying mechanisms in the human eye that are involved in the regulation of longer term eye growth.

Publications (arising from thesis):

Chakraborty, Ranjay, Read, Scott A., & Collins, Michael J. (2013) Hyperopic defocus and diurnal changes in human choroid and axial length. Optometry and Vision Science90(11), pp. 1187-1198.

Chakraborty, Ranjay, Read, Scott A., & Collins, Michael J. (2012) Monocular myopic defocus and daily changes in axial length and choroidal thickness of human eyes. Experimental Eye Research103, pp. 47-54.

Chakraborty, Ranjay, Read, Scott A., & Collins, Michael J. (2014) Diurnal variations in ocular aberrations of human eyes. Current Eye Research39(3), pp. 271-281.

Chakraborty, Ranjay, Read, Scott, & Collins, Michael (2011) Diurnal variations in axial length, choroidal thickness, intraocular pressure, and ocular biometrics. Investigative Ophthalmology and Visual Science52(8), pp. 5121-5129.

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Atanu Ghosh

Ghosh, Atanu (2012) Optical and biomechanical factors, associated with near work and myopia. PhD thesis, Queensland University of Technology.

This thesis is primarily concerned with investigating the changes in the eye during near work in downward gaze under natural viewing conditions.  The findings of these experiments collectively show the dynamic characteristics of the optics and biometrics of the eye in downward gaze during a near task, over time.  These were small but significant differences between myopic and emmetropic eyes in both the optical and biomechanical changes associated with shifts of gaze direction.  These differences between myopes and emmetropes could arise as a consequence of excessive eye growth associated with myopia.  However, the potentially additive effects of repeated near work activities employing inferonasal gaze could also act to promote elongation of the eye.

Publications (arising from thesis):

Ghosh, Atanu, Collins, Michael, Read, Scott, Davis, Brett, & Iskander, Robert (2011) Measurement of ocular aberrations in downward gaze using a modified clinical aberrometer. Biomedical Optics Express2(3), pp. 452-463.

Ghosh, Atanu, Collins, Michael, Read, Scott, Davis, Brett, & Iskander, Robert (2011) The influence of downward gaze and accommodation on ocular aberrations over time.Journal Of Vision11(10), pp. 1-13.

Ghosh, Atanu, Collins, Michael J., Read, Scott A., & Davis, Brett A. (2012) Axial length changes with shifts of gaze direction in myopes and emmetropes. Investigative Ophthalmology and Visual Science53(10), pp. 6465-6471.

Ghosh, Atanu, Collins, Michael J., Read, Scott A., Davis, Brett A., & Chatterjee, Payel (2014) Axial elongation associated with biomechanical factors during near work.Optometry and Vision Science91(3), pp. 322-329.

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Shila Roshani

Roshani, Shila (2011) The effect of ocular surface conditions on blink rate and completeness. Masters by Research thesis, Queensland University of Technology.

The experiments described in this thesis have attempted to investigate show of the basic eye gaze factors that influence natural blinking patterns and the interaction between various types of contact lenses and these natural blinking patterns.  As direction of gaze shifted from downward gaze to updward gaze, the number of blinks and percentage of incomplete blinks increased significantly in the bare eye.  Rigid contact lens wear caused a significant increase in the blink rate in unadapted wearers, but no significant changes were found in blink rate, blink completeness, open palpebral aperture and percentage of incomplete blinks after fitting with soft contact lenses.

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Stephen Vincent

Vincent, Stephen James (2011) Ocular characteristics of anisometropia. PhD thesis, Queensland University of Technology.

Awarded: QUT Outstanding Thesis Award for 2011

This thesis investigated a range of biometric, optical and mechanical properties of anisometropic eyes (with and without amblyopia) with the aim of improving our current understanding of asymmetric refractive error development.  The results show that a high degree of symmetry exists between the fellow eyes on non-amblyopic myopic anisometropes for a range of biomechanical, biometric and optical parameters for different levels of accommodation and following near work.  These findings suggest that further research into the association between ocular dominance, choroidal thickness and higher-order aberrations with ansiometropia may improve our understanding of refractive error development.

Publications (arising from thesis):

Vincent, Stephen, Collins, Michael J., Read, Scott A., Carney, Leo G., & Yap, Maurice (2011) Interocular symmetry in myopic anisometropia. Optometry and Vision Science88(12), pp. 1454-1462.

Vincent, Stephen J., Collins, Michael J., Read, Scott A., & Carney, Leo G. (2012) Monocular amblyopia and higher order aberrations. Vision Research66, pp. 39-48.

Vincent, Stephen J., Collins, Michael J., Read, Scott A., Carney, Leo G., & Yap, Maurice K.H. (2013) Corneal changes following near work in myopic anisometropia. Ophthalmic And Physiological Optics33(1), pp. 15-25.

Vincent, Stephen J., Collins, Michael J., Read, Scott A., & Carney, Leo G. (2013) Retinal and choroidal thickness in myopic anisometropia. Investigative Ophthalmology and Visual Science54(4), pp. 2445-2456.

Vincent, Stephen J., Collins, Michael J., Read, Scott A., & Carney, Leo G. (2014) Myopic anisometropia : ocular characteristics and aetiological considerations. Clinical and Experimental Optometry97(4), pp. 291-307.

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Garima Tyagi

Tyagi, Garima (2011) Ocular surface changes with short-term contact lens wear. PhD thesis, Queensland University of Technology.

This thesis presents a series of experiments that investigate the mechanical and physiological effects of the short-term use of contact lenses on anterior and posterior corneal topography, corneal thickness, the eyelids, tarsal conjunctiva and tear film surface quality.  These experiments showed that a variety of changes can occur in the anterior eye as a result of the short-term use of a range of commonly used contact lens types.  These short-term changes in the anterior eye are potential markers for further long term changes and the relative differences between lens types that we have identified provide an indication of areas of contact lens design and manufacture that warrant further development.

Publications (arising from thesis):

Tyagi G, Collins M, Read S and Davis B (2010). Regional changes in corneal thickness and shape with soft contact lenses. Optometry and Vision Science, 87(8):567-575.

Tyagi, Garima, Alonso-Caneiro, David, Collins, Michael J., & Read, Scott A. (2012) Tear film surface quality with rigid and soft contact lenses. Eye and Contact Lens38(3), pp. 171-178.

Tyagi, Garima, Collins, Michael J., Read, Scott A., & Davis, Brett A. (2012) Corneal changes following short-term rigid contact lens wear. Contact Lens and Anterior Eye35(3), pp. 129-136.

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David Alonso-Caneiro

Alonso-Caneiro, David (2010) Non-invasive assessment of tear film surface quality. PhD by Publication, Queensland University of Technology.

Awarded: QUT Outstanding Thesis Award for 2010

This thesis aimed to improve techniques for the assessment of tear film surface quality (TFSQ) by means of high-speed videokeratoscopy (HSV).  A set of novel image and signal processing techniques are proposed to quantify different aspects of the tear film assessment, analysis and modelling.  This technique could be a useful clinical tool to assess tear film surface quality in the future.

Publications (arising from thesis):

Alonso-Caneiro, David, Iskander, D. Robert, & Collins, Michael J. (2008) Estimating corneal surface topography in videokeratoscopy in the presence of strong signal interference. IEEE Transactions on Biomedical Engineering55(10), pp. 2381-2387.

Alonso-Caneiro, David, Iskander, Robert, & Collins, Michael J. (2009) Assessment of tear film surface quality using dynamic-area high-speed videokeratoscopy. IEEE Transactions on Biomedical Engineering56(5), pp. 1473-1481.

Alonso-Caneiro, David, Iskander, Robert, & Collins, Michael J. (2009) Tear film surface quality with soft contact lenses using dynamic-area high-speed videokeratoscopy. Eye and Contact Lens: Science and Clinical Practice35(5), pp. 227-231.

Szczesna, Dorota, Alonso-Caneiro, David, Iskander, D. Robert, Read, Scott A., & Collins, Michael J. (2010) Lateral shearing interferometry, dynamic wavefront sensing, and high-speed videokeratoscopy for noninvasive assessment of tear film surface characteristics : a comparitive study. Journal of Biomedical Optics15(3), 037005-1.

Szczesna, Dorota, Alonso-Caneiro, David, Iskander, D. Robert, Read, Scott A., & Collins, Michael J. (2011) Predicting dry eye using non-invasive techniques of tear film surface assessment. Investigative Ophthalmology and Visual Science52(2), pp. 751-756.

Alonso-Caneiro, David, Turuwhenua, Jason, Iskander, D. Robert, & Collins, Michael J. (2011) Diagnosing dry eye with dynamic-area high-speed videokeratoscopy. Journal of Biomedical Optics16(7), 076012.

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Fan Yi

Yi, Fan (2010) Wavefront aberrations and the depth of focus of the human eye. PhD thesis, Queensland University of Technology.

Presbyopia is an age-related problem where the eye progressively loses its ability to focus on near objects. It can be treated by optically extending the range of focus of the human eye. This PhD research investigated the range of focus in both young and old eyes and its relationship with the optical qualities of the eye. The research has led to new optical designs that show promise for providing better corrections for presbyopia.

Publications (arising from thesis):

Yi, Fan, Iskander, D. Robert, & Collins, Michael J. (2010) Estimation of the depth focus from wavefront measurements. Journal of Vision10(4), pp. 1-9.

Yi, F., Robert Iskander, D., & Collins, M. J. (2011) Depth of focus and visual acuity with primary and secondary spherical aberration. Vision Research51(4), pp. 1648-1658.

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Alyra Shaw

Shaw, Alyra J. B. (2009) Eyelid pressure on the cornea. PhD thesis, Queensland University of Technology.

Awarded: QUT Outstanding Thesis Award for 2009

The findings of this thesis have shown that the pressure exerted by the eyelids can influence the regularity of the corneal surface and the eye’s optics.  Novel methods were developed to quantify the contact region and pressure distribution between the cornea and eyelids.  The findings of this thesis are important for our understanding of the eyelids role in tear film distribution and the interaction between the eyelids and contact lenses on eye.

Publications (arising from thesis):

Shaw, Alyra J., Collins, Michael J., Davis, Brett A., & Carney, Leo G. (2008) Corneal refractive changes due to short-term eyelid pressure in downward gaze. Journal of Cataract and Refractive Surgery34(9), pp. 1546-1553.

Shaw, Alyra J., Collins, Michael J., Davis, Brett A., & Carney, Leo G. (2009) Eyelid pressure: inferences from corneal topographic changes. Cornea28(2), pp. 181-188.

Shaw, Alyra J., Davis, Brett A., Collins, Michael J., & Carney, Leo G. (2009) A technique to measure eyelid pressure using piezoresistive sensors. IEEE Transactions on Biomedical Engineering56(10), pp. 2512-2517.

Shaw, Alyra J., Collins, Michael J., Davis, Brett A., & Carney, Leo G. (2010) Eyelid pressure and contact with the ocular surface. Investigative Ophthalmology and Visual Science51(4), pp. 1911-1917.

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Scott Read

Read, Scott A. (2006) Corneal topography and the morphology of the palpebral fissure. PhD thesis, Queensland University of Technology.

Awarded: QUT Deans Commendation for Outstanding Thesis for 2006

This thesis shows that the cornea changes as a result of eyelid forces occurring in the majority of young subjects tested over the course of a normal working day.  The morphology of the palpebral fissure, and central and peripheral corneal topography was defined for a large population of young subjects, revealing significant associations between corneal astigmatism and the morphology of the palpebral fissure.  While the results of this thesis support a model of corneal astigmatism development based on eyelid morphology, they do not prove causation.  Further research investigating eyelid pressure and corneal rigidity is necessary to understand the exact aetiology of the magnitude and axis of corneal astigmatism.

Publications (arising from thesis):

Read, Scott A., Collins, Michael J., & Carney, Leo G. (2005) The diurnal variation of corneal topography and aberrations. Cornea24(6), pp. 678-687.

Read, Scott A., Collins, Michael J., Carney, Leo G., & Franklin, Ross J. (2006) The topography of the central and peripheral cornea. Investigative Ophthalmology and Visual Science47(4), pp. 1404-1415.

Read, Scott A., Collins, Michael J., Carney, Leo G., & Iskander, D. Robert (2006) The Morphology of the Palpebral Fissure in Different Directions of Vertical Gaze. Optometry and Vision Science83(10), pp. 715-722.

Read, Scott A., Collins, Michael J., & Carney, Leo G (2007) A review of astigmatism and its possible genesis. Clinical and Experimental Optometry90(1), pp. 5-19.

Read, Scott A., Collins, Michael J., & Carney, Leo G. (2007) The Influence of Eyelid Morphology on Normal Corneal Shape. Investigative Ophthalmology and Visual Science48(1), pp. 112-119.

Read, Scott A., Collins, Michael J., & Carney, Leo G (2007) A review of astigmatism and its possible genesis. Clinical and Experimental Optometry90(1), pp. 5-19.

Read, Scott A., Collins, Michael J., & Carney, Leo G. (2007) The Influence of Eyelid Morphology on Normal Corneal Shape. Investigative Ophthalmology and Visual Science48(1), pp. 112-119.

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Tobias Buehren

Buehren, Tobias F. (2003) Corneal topography, near work and eyelid forces. PhD thesis, Queensland University of Technology.

Subtle changes in corneal shape can cause substantial changes in the optical characteristics of the eye.  This thesis has investigated the optical effects of corneal distortions caused by eyelid forces and demonstrated that several corneal higher and lower order Zernike wavefront aberrations can change following reading.  The changes in corneal shape following reading appear to be different in myopic versus emmetropic refractive error groups.

Publications (arising from thesis):

Buehren, Tobias F., Lee, Brenden J., Collins, Michael J., & Iskander, D. Robert (2002) Ocular microfluctuations and Videokeratoscopy. Cornea21(4), pp. 346-351.

Buehren, Tobias F., Collins, Michael J., & Carney, Leo G. (2003) Corneal Aberrations and Reading. Optometry and Vision Science80(2), pp. 159-166.

Buehren, Tobias F., Collins, Michael J., Loughridge, James S., Carney, Leo G., & Iskander, D. Robert (2003) Corneal topography and accommodation. Cornea22(4), pp. 311-316.

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Wilfred Tang

Tang, Wilfrid (2001) The relationship between corneal topography and visual performance. PhD thesis, Queensland University of Technology.

The work reported in this thesis is primarily related to the analysis of corneal topography in groups with wide ranging corneal shapes and the relationship between corneal shape and visual performance.  Topographic data was fitted with Zernike polynomials, and corneal measurements were also used to derive the total residual refractive power of the cornea using a root mean square (RMS) index.  RMS was found to be significantly correlated with visual performance in these subjects.

Publications (arising from thesis):

Tang, Wilfred, Collins, Michael J., Carney, Leo G., & Davis, Brett A. (2000) The Accuracy and Precision Performance of Four Videokeratoscopes in Measuring Test Surfaces. Optometry and Vision Science77(9), pp. 483-491.

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Michael Sydenham

Sydenham, Michael Matthew (1995) The measurement of ultraviolet radiation at the surface of the eye. PhD thesis, Queensland University of Technology.

While there is a clear role for ultraviolet (UV) radiation in the pathogenesis of certain ocular disorders, the relative amount of UV radiation which reaches the eye, and its relationship to the site and incidence of UV-induced ocular pathology is less clear.  The aim of this thesis was to develop a contact lens dosimeter for the assessment of ocular UV radiation exposure.  Two polysulphone contact lens designs are proposed for ocular UV dosimetry, which will provide a new research tool for ocular UV dose assessment.

Publications (arising from thesis):

Sydenham, Michael M., Collins, Michael J., & Hirst, Lawrence (1994) The effectiveness of poly(allyl diglycol carbonate(CR39) for low-dose solar ultraviolet dosimetry. Photochemistry and Photobiology59, pp. 58-65.

Sydenham, Michael M., Collins, Michael J., & Hirst, Lawrence W. (1997) Measurement of ultraviolet radiation at the surface of the eye. Investigative Ophthalmology and Visual Science38(8), pp. 1485-1492.

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Thomas Tenkate

Tenkate, Thomas Daniel (1994) Ultraviolet radiation exposure of welders. Masters by Research thesis, Queensland University of Technology.

Ultraviolet radiation is a by-product of the welding process, and can produce acute and chronic effects on the eyes and skin.  The personal ultraviolet radiation exposure levels of a group of welders and nearby workers was estimated using a photosensitive polymer film (polysulphone) which was attached to eye protection, worker’s clothing, and throughout the work area.  The results of this study suggest that welders require ocular protection in addition to welding helmets, and that all exposed skill surfaces of workers in a welding environment should also be protected.

Publications (arising from thesis):

Tenkate, Thomas D. & Collins, Michael J. (1990) A survey of symptoms and eye safety practices among welders. Clinical and Experimental Optometry73(3), pp. 79-85.

Tenkate, Thomas D. & Collins, Michael J. (1997) Personal ultraviolet radiation exposure of workers in a welding environment. American Industrial Hygiene Association Journal58(1), pp. 33-38.

Tenkate, Thomas D. & Collins, Michael J. (1997) Angles of entry of ultraviolet radiation into welding helmets. American Industrial Hygiene Association Journal58(1), pp. 54-56.

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