Associate Professor Katrina Schmid
Professor David Atchison
Adjunct Professor Brian Brown
Professor Leo Carney
Dr Jennifer Chen
Associate Professor Michael Collins
Dr Robert Iskander
Professor Joanne Wood
Darren Brinkworth
Dr Sanjeev Kasthurirangan
International Collaborators
Professor Marion Edwards (Hong Kong Polytechnic University)
Professor Robert Hess (McGill, Montreal)
Dr Niall Strang (University of Aston)
Dr Christine Wildsoet (University of California, Berkeley)
Research Students
Hui-Ying (Eve) Kuo
Chien-Chun (Joe) Peng
Srikant Tripathy
Background
Myopia (short-sightedness) is the most common refractive problem. It usually
results when the axial length of the eye is too long for the eye’s power. This
means that images of distant objects are focussed in front of the retina (the
light-detecting layer of the eye) and appear blurred. While spectacles, contact
lenses and laser surgery can optically correct the myopia, there is no treatment
that is effective in preventing the development of myopia. As the myopic eye
is enlarged, the risk of eye diseases such as glaucoma and retinal detachment
may be increased. A treatment to prevent or at least slow myopia development
is thus much sought after.
The Centre for Health Research (Optometry) is involved in many research projects, with many collaborators, investigating how eye growth is regulated and why myopia develops in some individuals. We are using both human based and animal based studies to shed light on different aspects of this complicated problem. Our future studies are aimed at adding further to our knowledge of this area.
Human Based Research
Our human based research predominantly revolves around the hypothesis that myopia
development is due to the presence of image blur. We are investigating this
by studying the dynamics of the accommodation system and the visual system's
sensitivity to image blur. We are also comparing the visual performance of myopes
with that of non-myopes.
| The length of a person's eye can be measured using A-scan ultrasonography. Here Dr Schmid measures the axial length of a patient attending our clinic for full myopia assessment and advice. |  |
Recent projects in this area include:
- Comparison of accommodation stimulus response curves of myopes and emmetropes.
- Hyperopia is predominantly axial in nature.
- Refractive error changes of optometry students.
- The effect of myopia on the retinal nerve fibre layer around the optic
nerve head using the GDx.
| In her PhD project, Jennifer Chen investigated whether an imbalance in the autonomic nervous system, which controls accommodation, is responsible for myopia development. Her work involved monitoring the accommodation system using the Canon infrared autorefractor. |  |
Animal Based Research
Here we use the chick as a model for eye growth regulation. Eye growth is monitored
using A-scan ultrasonography and refractive error changes using retinoscopy.
Our two main areas of interest include:
- determining how the eye guides its growth using visual feedback,
- investigating how different drugs alter eye growth.
Dr Schmid’s work investigating what aspects of the visual image are important
for the emmetropization process has recently received ARC Large funding. We
are also currently working on the role of the dopaminergic, muscarinic and serotonin
systems in eye growth regulation.
An important question is what retinal transmitters may be involved in eye growth
and how the signal to speed up or slow down growth gets from the retina, where
it is thought to be generated, to the sclera, which ultimately has to change
in size. Both the dopaminergic and muscarinic systems appear to have a role
in this process. Their effects are not additive, but neither do they work in
isolation (see diagram below).
Some of our recent projects in this area include:
- Effects on the compensatory responses to positive and negative lenses of intermittent lens wear and ciliary nerve section in chicks.
- Contrast and spatial frequency requirements for emmetropization in chicks.
- Inhibitory effects of stroboscopic light on form-deprivation and lens-induced myopias show different frequency tuning and patterns of axial change in chick.
- Apomorphine inhibits lens-induced myopia but not lens induced hyperopia in chick.
- The inhibitory effect of apomorphine and atropine on form-deprivation myopia are not additive in chick.
- Eye drops that lower intraocular pressure do not prevent myopia development in chick.
- Sharp vision - a prerequisite for compensation to myopic defocus in the chick?
- Imposed retinal image size changes - do they provide a cue to the sign of lens-induced defocus in chick?
- Influence of controlled viewing conditions on emmetropization to imposed myopic defocus in the chick.