Summer students present projects at inaugural NZ NEC symposium
From left: Raj Maiti, Jian Li, Ankita Umapathy, Erin Tan, Will Ikink, Sophie Chan, Brian Granger with Trevor Sherwin who organised the event
“It has been a bumper year for students in our labs,” enthused Professor Trevor Sherwin who chaired the event. “The students have been an absolute pleasure to be around; they have been hardworking, intelligent and industrious.
“It is appropriate that now we have the NZ NEC well established and a considerable number of students in the programme that we hold a symposium to give the students an opportunity to present what they’ve been doing all summer.”
Professor Charles McGhee and A/Professor Rob Jacobs judged the presentations based on clarity, content and style.
“The first summer student symposium was really excellent,” said Professor McGhee. “All the speakers were entertaining and the projects were so diverse. It’s a real testimony to the benefits of bringing the professions and disciplines together and it was therefore very difficult in deciding on a winner. In the end, however, we did come to a unanimous decision, Ankita Umapathy.
“From this symposium we can see that some of these projects will turn into bigger projects and several will ultimately turn into scientific papers. I believe we’re seeing the future of ophthalmology, optometry, and visual sciences here today.”
Following is a brief synopsis of each of the student’s projects:
Ankita Umapathy Molecular Vision Laboratory
Cystine Supplementation – can it reduce oxidative damage to cataractous rat lenses?
Supervisors: Dr Julie Lim, Professor Paul Donaldson
Age related nuclear cataract is the leading cause of blindness in the world and is associated with oxidative damage to the lens. In the young lens, such damage is minimised by high levels of antioxidants. However, with increasing age there is a significant depletion of antioxidants specifically in the lens centre making proteins in this region especially susceptible to oxidative damage. The aim of my project was to determine whether supplementation of cystine to the rat lens was protective against oxidative stress and therefore effective as an antioxidant. I developed an in vitro model of nuclear cataract by incubating rat lenses in sodium selenite supplemented with or without cystine. My results revealed that with the addition of cystine, there was not only a reduction in lens opacity but also a 28.6% decrease in malondialdehyde, an end product of lipid peroxidation suggesting that cystine was protective against oxidative damage.
Brian Granger Department of Ophthalmology
Connexin 43 expression in the optic nerve head following retrobulbar optic nerve injury
Supervisor: Professors Helen Danesh-Meyer and Colin Green
My research investigated how traumatic optic nerve injury leads to changes in the histology of the optic nerve head. This involved using two rodent models of optic nerve injury developed previously by graduate students in the Department of Ophthalmology – Dr Taras Papchenko and Dr Shenton Chew.
We were interested in seeing what if any changes were occurring in the nerve head region, given its known importance in non-traumatic optic neuropathies such as glaucoma. We found that there are are indeed reactive changes in astrocytes (the inflammatory cells of the central nervous system) within the head region of the optic nerve far removed from the local changes which occur at the site of injury. These changes are mediated by gap junctions between astrocytes containing the protein Connexin 43, which is the target of the novel anti-inflammatory agent Nexagon developed by Professor Green in previous work investigating central nervous system injury.
Erin Tan Department of Optometry & Vision Science
Blurring the boundaries: taking aim at myopia
Supervisors: Drs Simon Backhouse and Ben Thompson, Andrew Collins
We investigated the effect of differing visual demands on the blur adaptation response of myopic and emmetropic subjects. Participants were binocularly blurred by +1.00D for one hour while playing either an action video game (visually demanding) or a non-action video game (less demanding). Sinusoidal grating and Bailey-Lovie logMAR acuity measures were made before and after the adaptation period. Blur significantly decreased logMAR acuity in both groups (greater decrease in myopes). Both groups showed equal blur adaptation over one hour (improvement in logMAR acuity). On removal of the blur myopes returned to baseline acuity while emmetropes showed a blur after-effect (logMAR acuity significantly better than baseline). The type of video game had no significant effect, and there were no changes in grating acuity. The failure of emmetropisation in myopes may be related to the differential logMAR blur adaptation response of this group.
Sophie Chan Department of Ophthalmology
Understanding angiogenesis in the cornea
Supervisor: Associate Professor Trevor Sherwin
We aimed to determine the angiogenic growth factor/inhibitor profile for the peripheral cornea and limbal transition zone in normal human tissue, and to compare it with neovascularised human cornea.
Using angiogenesis antibody arrays which screen 43 angiogenic molecules, significantly greater levels of angiogenin (P < 0.044) and interleukin-8 (P < 0.044) were demonstrated in the neovascularised cornea compared to normal limbal and peripheral cornea. Interestingly, no significant differences (P < 0.05) were found between levels of the factors screened for in normal limbus compared to normal peripheral cornea. With immunohistochemical staining, angiogenin and vascular endothelial growth factor were strongly positive in vascular endothelial cells, and weakly positive in stromal keratocytes and corneal epithelium.
Our results suggest that drugs that block a range of angiogenic molecules, including angiogenin and interleukin-8, may be the future of anti-angiogenic therapy for corneal neovascularisation.
Luzinda Lo Department of Optometry & Vision Science
The effect of infection-sensitised hypoxia on pre-term fetal sheep retina
Supervisors: Drs Ellen Knapp and Monica Acosta, Professors Alistair Gunn and Laura Bennett
In an effort to investigate the impact of environmental toxins on fetal pre-term retina, the eyes of fetal sheep exposed to simultaneous damage from asphyxia and lipopolysaccharide (LPS) were obtained. The central retina surrounding the optic nerve, being rich in blood vessel supply, was the first area analysed. Visually we have seen through immunocytochemistry that Glial Fibrillary Acidic Protein (GFAP) is less upregulated in our experimental model compared with studies featuring LPS bolus alone, suggesting that reactive gliosis caused by LPS is occurring to a lesser degree in our experimental model. The results indicate that no other morphological changes affect central retina in the animal model of complications of prematurity.
Jian Li Department of Ophthalmology
Mutations in the VSX1 gene in a New Zealand Dystrophy Population
Supervisor: Dr Andrea Vincent
The VSX1 gene, a transcription factor, has been implicated in the pathogenesis of Keratoconus (KC) and Posterior Polymorphous Corneal Dystrophy (PPCD). Although initial studies found mutations in this gene in PPCD and KC, an equal number of studies have failed to detect mutations in these disorders. The study aim was to determine the genetic contribution of VSX1 in KC and PPCD in our New Zealand cohort; a total of 58 patients (Keratoconus=43, PPCD=10) underwent VSX1.screening by High Resolution Melting and DNA sequencing. 1 previously reported mutation was identified in a Keratoconus patient (2.3%). This mutation was previously reported in keratoconus. 4 other non-disease causing changes were also found. Therefore VSX1 plays a minor role in the pathogenesis of KC and PPCD in a New Zealand, and therefore is consistent with other studies suggesting there is a population specific contribution of VSX1 to disease.
Raj Maiti Department of Optometry & Vision Science
Colour vision of bees
Supervisor: Dr Misha Vorobyev
Do honeybees use chromatic or achromatic vision to find their hive? Using a Y-tube entrance hive entrance, we trained honeybees to discriminate dark yellow (entrance open) from light blue (entrance closed). We then tested the bees with light yellow and dark blue colours. We calculated quantum catches of the honeybee photoreceptors and predicted that, in the test, the bees would prefer light yellow if they relied on chromatic cues and dark blue if they relied on achromatic cues. Bees preferred light yellow, indicating that they used chromatic vision. In additional experiment, we tested whether the bees preferred light yellow or dark yellow after being trained to dark yellow against light blue. Interestingly, the bees preferred light yellow indicating that bees prefer colours with high luminance.
Will Ikink Department of Ophthalmology
The role of corneal topography in the clinical diagnosis of Marfan syndrome
Supervisor: Dr Andrea Vincent
The aim of our research was to determine the corneal thickness, curvature and anterior chamber depth (ACD) in patients with known and suspected Marfan syndrome, use the Orbscan and Pentacam. An abnormally flat cornea is a minor criterion in the current diagnostic criteria for Marfan syndrome, a connective tissue disorder affecting primarily the cardiovascular, skeletal and ocular systems.
Despite this, corneal curvature is not effectively used in clinical practice as a definite cut-off value indicative of Marfan syndrome has not been clearly established.
Preliminary results from Orbscan System readings show that the average corneal curvature in patients from our study with a definitive diagnosis of Marfan syndrome was 40.95 diopters (D) as compared with 42.89D in the control group, which was statistically significant (p=0.0007). Mean ACD and thickness were similarly decreased however this was not statistically significant.
These findings suggest keratometry should be a routine examination in the ophthalmic work up of suspected Marfan patients.
