Optometry and Vision Science

An Exploration into the lens paradox: in-vivo observation

Supervisor

Dr Ehsan Vaghefi
Mr Wilson Pan

Discipline

Optometry

Project code: MHS010

Lens paradox is a phenomenon that the curvature of the crystalline lens increases with age, yet most human eye do not become more powerful or myopic, as they get older. Previous in-vitro investigations suggest this is owing to the change of gradient of refractive index (GRIN) of the lens, one of the important aspect of lens physiological optics. Due to lack of technology, the linkage between GRIN and lens paradox has not been studied in-vivo. Our group has been developed magnetic resonance imaging (MRI) protocol to non-invasively measure the lens GRIN and advance optical modelling approach to evaluate lens optics. In this project, we aim to use these techniques to explore the “lens paradox” using our in-vivo data. Specifically, we will investigate how the effects of geometry and GRIN on the lens power, and further investigate their age-related trends. The significance of this project is to provide experimental evidences into previous idea and new insights into “lens paradox”.

The ideal candidate should have understanding of the human eye optics. Candidate will be trained to use ZEMAX, an optical modelling software, in this project. This project suits student with background in optometry, physics or biomedical engineering.

The role of the ‘diving reflex’ in controlling the thickness of the ocular choroid

Supervisor

Dr John R Phillips
Dr Safal Khanal

Discipline

Optometry

Project code: MHS049

The ocular choroid is the vascular bed supplying blood to the photoreceptors of the retina: it is thinner than normal in ischemic retinal diseases such as Age-related Macular Degeneration and Diabetic Retinopathy. The choroid has the capacity to rapidly change its thickness and blood perfusion in response to a variety of factors including exercise, accommodation and retinal defocus etc. Temperature also seems to be important in controlling choroidal thickness and blood flow, although little is known about this function. For example, it is not known whether temperature is sensed by thermo-receptors in the eye and/or those in facial skin (which initiate the diving reflex). The aim of this project is to investigate the choroidal response (change in thickness) to imposed warming and cooling applied to the eye or facial skin with a simple heating/cooling device. Choroidal thickness will be measured non-invasively using Optical Coherence Tomography (OCT) in human volunteers.
Skills
Conducting OCT scans. Recruiting research participants and conducting experiments. Interpretation and analysis of OCT images. Analysis of the relevant literature.

Localisation of atropine in the chick model of myopia inhibition using MALDI

Supervisor

Dr John R Phillips
Dr Monica Acosta
Dr Gus Grey

Discipline

Optometry

Project code: MHS060

The most effective current method for inhibiting the progression of myopia (worsening of short-sight) in children involves the nightly instillation of atropine eye drops. However, atropine does not halt myopia progression completely and its use can produce undesirable side effects. Importantly, it is unclear how and exactly where in the eye atropine exerts its anti-myopia effects. An understanding of how and where atropine acts to inhibit myopia would advance attempts to produce more effective anti-myopia therapies with reduced side-effects.

The aim of this project is to use MALDI (Matrix-Assisted Laser Desorption Ionization) imaging mass spectrometry techniques to localise atropine in the eye tissues of Chicks in which experimental myopia has previously been induced and in which eye tisues have then been incubated with atropine.

Skills: cryosectioning, MALDI mass spectrometry, image analysis, report writing

Depth perception in mantis shrimps

Supervisor

Dr Misha Voronyev

Discipline

Optometry

Project code: MHS215

Mantis shrimps have remarkable vision. They have 12-dimensional colour vision, can see polarisation and are the only animals that can perceive circular polarization.

The aim of this project is to understand how mantis shrimps use their eyes for depth perception. We will study optics of the mantis shrimp eyes using microscopy and model the accuracy of depth perception by mantis shrimps.

Behavioural experiments will be performed to estimate the accuracy of depth perception in monocular and binocular conditions.

The effect of myopia control contact lenses on the choroid

Supervisor

Dr Philip Turnbull
Dr John Phillips
Safal Khanal

Discipline

Optometry

Project code: MHS177

The choroid is a vascular layer positioned between the retina and sclera, which is able to rapidly change its thickness based on the sign of optical defocus on the retina. It thins in response to stimuli which encourage myopia, and thickens in response to stimuli which are known to protect against myopia. Because of this, it has become an attractive target for measuring the effectiveness of myopia control therapies. One of these therapies is dual focus contact lenses, which reduce the rate of myopia progression, but their mechanism of action remains poorly understood. This project aims to measure the choroidal response to wearing dual focus contact lenses, compared to regular contact lenses.

The ideal student for this project would be familiar with, or willing to learn, concepts of myopia control, refraction, contact lenses, and optical coherence topography (OCT) based ocular biometry.

There will be some capacity to learn MATLAB skills for image processing, although this would not be essential. The project will take place in the Auckland Myopia Lab.

Mapping the visual cortex under free-viewing and resting conditions

Supervisor

Sam Schwarzkopf
Simon Rushton (Cardiff, UK)
Jane Harding
Ben Thompson (Waterloo, Canada)

Discipline

Optometry

Project code: MHS031

The human visual cortex is organised into a topographic visual field maps. Functional MRI can reveal this architecture non-invasively. However, such retinotopic mapping experiments require stable fixation and repetitive visual stimulation without cognitively engaging the participant. This renders such experiments tedious even for healthy normal adults and severely complicates their use in patient populations or children. It further precludes such mapping experiments entirely when the participant’s eyes are closed.
However, recent advances in imaging analysis enable us to construct a map of functional connectivity between brain areas. In this project we will use data from resting state scans as well as images acquired while participants freely view movies to test whether such "connective field maps” enable us to reconstruct the retinotopic organisation without the use of explicit mapping stimuli. First, we will compare this approach with traditional mapping in normal healthy adults. Then we will seek to apply this method to resting-state data from a population of children who were born pre-term.

The Digital Synoptophore for vision training

Supervisor

Tina Gao
Phil Turnbull
Joanna Black

Discipline

Optometry

Project code: MHS055

Virtual reality, 3D displays, and eye trackers have great potential for the delivery of vision testing and training in clinical and home-based settings, and these electronics are now widely available and economical. Vision training or “eye exercises” are used to treat a variety of oculomotor disorders. Training is usually done at home with simple tools like a pencil or printed cards, or with specialised equipment such as synoptophores in-office. However, it can be difficult to maintain motivation and treatment adherence for the durations required for training to be effective.

In this project we wish to develop a digital suite of diagnostic vision tests and vision training programs for oculomotor disorders, which can be deployed in clinics or at home. These programs will utilise consumer-grade 3D or VR displays, and use eye tracking to objectively measure eye movements and provide real-time feedback to patients on their training.

The ideal student for this project would be comfortable with Matlab and be keen to learn how to code eye tracking protocols and visual stimuli.

Understanding the mechanisms of suppression in amblyopia

Supervisor

Tina Gao
Ben Thompson
Joanna Black

Discipline

Optometry

Project code: MHS056

Amblyopia (“lazy eye”) is a visual neurodevelopmental disorder that affects about 3% of people, and is associated with unbalanced interocular suppression. Even after standard therapies like patching or atropine, this binocular imbalance often persists and may limit the recovery of binocular visual functions such as stereopsis (3D vision). Our previous work using Continuous Flash Suppression found a type of generalised, completely orientation-independent suppression in some patients with amblyopia, in contrast to the feature-selective suppression found in controls. It is unknown if these characteristics of amblyopic suppression can be simulated in visually-normal subjects, for example by wearing a neutral density filter over one eye. If so, this would imply that similar mechanisms of suppression are present in both amblyopic and normal vision, and that a simple re-balancing of binocular input could be an effective treatment strategy for ameliorating binocular deficits in amblyopia.

In this project, the student will screen participants for eligibility, perform clinical and psychophysical measures of interocular suppression, analyse results, and present results through a written report and an oral presentation.

This project will suit a student with a clinical background in optometry/medicine, or in vision science and psychology.

Ocular manifestations in Alzheimer’s disease and vascular dementia

Supervisor

Joanna Black
Monica Acosta
Lily Chang

Discipline

Optometry

Project code: MHS191

Dementia is a health priority. With population ageing worldwide, every 1 in 9 people aged 65 and over is affected. As the eyes are sensory extensions of the brain, ocular changes such as thinning in the optic nerves and deficit in contrast sensitivity may be reflecting neurodegenerative changes in the brain. However, ocular signs and symptoms in various types of dementia have not yet been widely investigated. It is therefore unknown if unique ocular changes are indicative of a specific type of dementia.

The aim of the project is to identify unique ocular characteristics in Alzheimer’s disease and Vascular dementia (the two most common causes of dementia), with the long-term goal of improving sensitivity and specificity of dementia diagnosis.

The student will collect clinical data, including imaging of the eye and ocular electrophysiology, and develop important skills such as academic writing, data extraction and analysis.

The goal of this studentship is to prepare an article for publication in peer-reviewed international journal.

Measuring the impact of Aniseikonia on binocular visual function

Supervisor

Joanna Black
Jay South
Tina Gao

Discipline

Optometry

Project code: MHS192

Aniseikonia is the perception of different image size or shape between the eyes, often caused by the optical effects of spectacles or by inter-ocular variability in eye size. Aniseikonia is known to have a detrimental effect on the ability of the visual system to combine information under binocular conditions, and can cause reduced stereopsis (3D vision).
In this project subjective (clinical and psychophysical tests) and objective (electrophysiological) tests will be used to measure the effect of aniseikonia on binocular visual function in human subjects with normal visual function.

This project will involve recruiting participants, and running a series of tests with different levels of simulated aniseikonia. The ideal student will be familiar with vision testing and interested in learning specialist techniques in the area of psychophysics and visual electrophysiology.