Faculty of Medical and Health Sciences


NZ-NEC events

Coordinators

Hutokshi Chinoy

Hutokshi Chinoy

NZ-NEC Chief Administrator
Department of Ophthalmology
Phone +64 9 373 7599 ext 86712 

Sue Raynel

Sue Raynel

NZ-NEC Research and Development Manager
Department of Ophthalmology
Phone +64 9 373 7599 ext 86337 

 

 

2018 NZ-NEC Seminar Series


alcon

 

The 2018 NZ-NEC Seminar Series is kindly sponsored by Alcon.

Spatial Tuning Properties of Human Visual Cortex in Normal and Atypical Vision - Associate Professor Sam Schwarzkopf, School of Optometry and Vision Science.

Functional MRI can estimate non-invasively the spatial tuning properties (population receptive fields) of human visual cortex. We quantified the reliability of such pRF measures and how they relate to visual perception. We further investigated the spatial tuning properties of visual cortex in autism spectrum disorders and schizophrenia. This revealed a dissociation between these conditions even though they have been linked with similar atypical perceptual processes. Finally, in a currently ongoing study we investigate how spatial tuning may differ in amblyopia.

Monday 10 September 2018, 4-5pm

Conference Room, Domain Lodge, 1 Boyle Crescent.

   

Water transport in the lens: The relative contributions of the water channels AQPO and AQP5 - Dr Rosica Petrova, Postdoctoral Research Fellow, Molecular Vision Laboratory.

Results from the Molecular Vision Laboratory have shown that the removal of water from the lens actively controls its optical properties. Aquaporin (AQP) 0 and AQP5, two water channels with very different properties contribute to the water permeability of lens fibre cells. Using immunolabeling studies I have found that in peripheral fibre cells of the rodent lens AQPO is always found in the plasma membrane, while AQP5 appears to be predominantly located in a cytoplasmic pool, but becomes inserted into the membranes of fibre cells as they differentiate. In peripheral fibre cells AQP5 can also be dynamically inserted into the plasma membrane, suggesting that the water permeability of these cells is regulated. To further understand the functional contribution of each AQP channel in different regions of the lens I have developed two different approaches to measure the water permeability of lens cells. In this seminar I will describe the development of these techniques and discuss how the differential regulation of lens water permeability contributes to the overall transport of water and therefore the optical properties of the lens.

Translating Objective Measures of Visual Field Using Eye Movement From Lab to Clinic - Soheil Mohammadpoor, PhD candidate, School of Optometry and Vision Science.

Diagnosis of conditions such as glaucoma rely on assessment of functional vision across the field but mirco­perimetry is hampered by a reliance on the patients' subjective judgement of presence/absence of a stimulus and by the high demands (in terms of time and attention) that this places on them. We determined the feasibility of using changes in an objective measure of an involuntary eye movement (optokinetic nystagmus, OKN) to quantify concomitant field loss. To this end, first, we measured how various measures of OKN depend on the extent of simulated visual field loss (SVFL). Second, we are measuring OKN in both eyes of patients with unilateral visual field loss due to glaucoma. I will present the results of SVFL experiment, and the preliminary results from patients.

Presented 22 August 2018.

   

Assessment, Simulation and Correction of Binocular Vision Impairment - Professor Peter Bex, Professor of Psychology Northeastern University, Boston.

Current clinical binocular assessment methods depend primarily on insensitive tests of stereoacuity (e.g. Stereo Fly), suppression (e.g. Worth 4 dot) and ocular alignment (e.g. Cover Test). Recent virtual reality-based approaches to the treatment of binocular vision impairment have enabled much greater control of therapeutic stimuli but require more sensitive assessments of their efficacy over current treatments. We have developed a range of novel tests that quantify the spatial frequency-dependence of binocular contrast sensitivity, inter-ocular suppression and stereo-acuity; and the eye posture-dependence of ocular alignment. These tests take less than 5 minutes each to complete yet show high sensitivity and reliability. We show that treatments based on interocular manipulations of blur, contrast and luminance have profound consequences for oculomotor control and depth perception. Furthermore, these approaches do not address ocular misalignment that may limit treatment outcomes. We show that dichoptic eye movement adaptation can transiently induce and reverse interocular alignment and alter depth perception. This work aims to provide a comprehensive framework for the assessment and correction of binocular vision deficits.

Presented 19 July 2018.

   

Age Related Eye Diseases: Roles for the Lens - Professor Paul Donaldson, Director Molecular Vision Laboratory, Department of Physiology, School of Medical Sciences.

Globally, 285 million people are visually impaired, of whom 39 million are blind due to age related eye diseases, and with a rapidly ageing population the extent of this burden is only expected to rise. A considerable fraction of age-related eye disease is associated with pathologies of the crystalline lens. This seminar will outline our recently submitted HRC programme application that endeavours to bring together an international team of laboratory and clinical researchers to study not only the lens specific pathologies, presbyopia and cataract, but also to investigate potential roles played by the lens in the initiation of other age related eye diseases. It will highlight lessons learnt from the process and will encourage discussion on how to improve the re-submission.

Presented 16 July 2018.

   

Aqp0a Regulates Suture Stability in the Zebrafish Lens - Dr Irene Vorontsova, Postdoctoral Scholar, University of California.

Aquaporin 0 (AQPO) is essential for lens development and transparency. However, mammalian AQPO has multiple cellular functions including water transport and adhesion, which have been difficult to study individually. Due to the ancestral teleost genome duplication, zebrafish have two AQPO genes, aqp0a and aqp0b, which appear to have functionally diverged such that water transport is an essential characteristic of Aqp0a, but not of Aqp0b. Previous knock-down experiments show that both proteins are essential for embryonic lens transparency (Clemens, IOVS 2013). In this study, we show that loss-of-function mutations in Aqp0a and/or Aqp0b generated by CRISPR-Cas9 also result in an increased frequency of embryonic cataracts. While the lenses of single mutants in either gene recover transparency in juveniles, double mutants retain dense nuclear cataracts, indicating partially redundant functions. We show that the zebrafish lens nucleus moves posteriorly toward the centre in both WT and aqp0b-/- adult fish, from an initial location near the anterior pole in juveniles. But in double mutants and aqp0a-/- lenses, the nucleus fails to centralize and remains shifted anteriorly. In addition, the anterior sutures of aqp0a-/-, but not aqp0b-/-, adult lenses are unstable, characterized by fiber cell tip disorganization leading to anterior polar opacity. Aqp0b, but not Aqp0a, has adhesive properties in an in vitro adhesion assay. Both Aqp0s localize to finger-like-projections (FLPs), membrane subdomains on fiber cells that are thought to facilitate water transport in young fiber cells during differentiation and maturation. FLPs grossly elongated in aqp0a-/- and double mutants, similar to mouse AQPO mutants (Lo, IOVS 2014). These data suggest that water transport activity of Aqp0a, potentially via FLPs, is required for stable suture formation and integrity, which in turn is required for nucleus centralization and lens optics. Next, we will test the ability of Aqp0 constructs lacking residues thought to be essential for water transport or adhesion, driven by a BB1 crystallin promoter, for their ability to rescue sutural defects and restore lens nucleus centralization when injected into Aqp0 mutants.

Presented 10 July 2018.

   

Seeing through retinal ganglion cells: New insights into human pattern vision - Dr MiYoung Kwon, Assistant Professor, Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham.

The integration of visual information over space is a critical step in human pattern recognition. In the human visual system, the retinal ganglion cells (RGCs) are the output neurons of the retina, and human pattern recognition is built from the neural representation of the RGCs. Despite its significance, very little attention has been paid to understanding the role of RGCs in human pattern vision. Here I will present our recent work demonstrating how a loss of RGCs due to either normal aging or pathological conditions such as glaucoma undermines human pattern vision and alters spatial integration properties. I will also discuss the mechanism (i.e., an increase in internal noise, a decrease in the sampling efficiency or both) by which a loss of RGCs impairs visual sensitivity. In this talk, I will further highlight the role of the RGC density in determining the spatial extent over itch visual inputs are combined. By linking the sampling density of retinal ganglion cells (RGCs) to psychophysically-defined spatial integration zone, I will demonstrate that the ROC density largely accounts for the visual-field dependence of Ricco's area (luminance detection) and crowding zone (object recognition). Taken together, our findings suggest that understanding the structural and functional integrity of RGCs may help better characterize visual deficits associated eye disorders, but also reveal the important computational constraint set by the RGCs during the early encoding stage of visual input.

Presented 21 June 2018.

   

The Perceptual and Visuomotor Consequences of Myopia - Dr Guido Maiello, Justus-Liebig-Universität GieBen, Germany.

Humans continuously refocus their eyes to inspect objects at different depths. Whereas objects fixated with the high-resolution fovea are sharply focused, objects at different depths in the visual periphery are blurred. The amount of defocus blur depends on the depth structure of the visual scene and on the shape of the retina. Myopic eyes are elongated relative to emmetropic eyes, which thus affects the distribution of retinal blur in real scenes. Using depth maps of natural images, we demonstrate that the different topography of outdoor and indoor natural environments produces greater levels of defocus blur in the peripheral retinae of myopic than emmetropic model eyes. These differences exist regardless of foveal optical correction. These computational data predict a myopic loss in peripheral contrast sensitivity, which we confirm with functional measurements in human myopes and emmetropes. Additionally, myopes exhibit a monocular impairment in blur sensitivity that improves under binocular conditions. Yet myopia interacts with binocularity, since both vergence and accommodation in virtual reality systems are less stable in myopes compared to emmetropes. These observations have important implications in the development of myopia because eye growth is governed by the pattern of retinal blur across the retina and time spent outdoors is protective against myopia. Overall, our findings suggest that myopia might be driven by patterns of retinal blur that do not conform to those expected in outdoor natural scenes.

Presented 19 June 2018.

   

Keratoconus in Down Syndrome: Much More Common Than Anticipated! - Joyce Mathan, Doctoral Candidate, Department of Ophthalmology.

Keratoconus affects approximately 0.05% of the general population. Limited evidence suggests a greater prevalence, between 0.5-30%, in individuals with Down Syndrome (DS). This study investigated the prevalence of keratoconus in athletes with DS at the 2017 New Zealand Special Olympics National Summer Games. Participants were screened using corneal topography (TMS-4, Toiney, USA). Two independent quantitative criteria and qualitative assessment by three ophthalmologists were utilised to diagnose keratoconus, the prevalence of confirmed keratoconus cases identified by each method were compared. Of 110 participants screened, 98 were included in analyses. Twelve participants met quantitative criteria 1, keratoconus was confirmed by qualitative review in 10 of these participants (10%). Keratoconus was indicated in 63 participants by quantitative criteria 2 and was confirmed by qualitative review in 38 (39%) participants. Depending on criteria, this pilot indicates a prevalence of keratoconus of 10-39% in DS, up to 700x higher compared to the general population.

Effect of Ageing on the Physiological Optics of the Lens - Alyssa Lie, Doctoral Candidate, School of Optometry and Vision Science.

The crystalline lens is a transparent biological tissue essential for the overall focussing of the eye. A gradient of refractive index (GRIN), determined by the concentration and distribution of water and protein within the lens, contributes to its optical performance. Regulatory water transport pathways which have been identified in the lens of animal models are thought to maintain lens transparency and GRIN. We hypothesise that these pathways are relevant to the human lens, and that ageing causes a decline in lens water transport resulting in the opacification of the lens known as cataract. This study aims to utilise clinical MRI techniques to monitor for changes in lens water transportation parameters (such as water content, water-to-protein ratio) with age, and to compare them between cataractous and non-cataractous lenses.

Presented 13 June 2018.

   

Endophthalmitis - Clinical Associate Professor Philip Polkinghorne, Vitreo-Retinal Consultant, ADHB.

Intra-ocular infections are uncommon causes of ocular morbidity but can be devastating when they occur. Endophthalmitis is the term that describes this set of clinical features and in Auckland we manage about a case a month, mostly occurring as a complication following cataract surgery or intravitreal injections. In this talk I will describe what we have learnt in terms of establishing the diagnosis, managing the entity and future research plans.

Presented 14 May 2018.

   

Pharmacological Regulation of the Lens Internal Water Content and Its Effects on Physiological Optics - Yadi Chen - Doctoral Candidate, Department of Physiology.

Age-related changes to the optical properties of the ocular lens cause refractive errors, presby­opia and ultimately cataract. The Molecular Vision Laboratory has shown that lens optical power and vision quality are maintained by the active removal of water from the lens core. This lens internal water movement has also been shown to generate a hydrostatic pressure gradient which is subjected to a dual feedback regulation. However, the interaction between lens cellular physiology and its optical properties still remains unclear. In this current study, we aim to investigate the bovine lens optical changes elicited in response to regulation of the lens pressure gradient at the cellular level by using a microelectrode/pico-injector-based pressure measurement system and a laser ray tracing imaging system. Insights into the mechanisms responsible for the onset of optical changes will inform the development of novel pharmacological therapies to maintain vison quality in the elderly.

Cell-penetrating Peptide for Ocular Drug Delivery - Frazer Coutinho - Doctoral Candidate, Department of Ophthalmology.

Choroidal neovascularisation (CNV) is the hallmark of neovascular AMD, where the haemorrhage of leaky blood vessels in the choroid creates an inflammatory environment resulting in hemichannel mediated cell death including the loss of retinal pigment epithelial (RPE) cells which maintain blood retinal barrier integrity and rod/cone function. Current treatments do not address the self-perpetuating, hemichannel mediated inflammatory and hypoxic environment underlying disease cause. The Connexin43 (Cx43) hemichannel specific intracellular acting peptide, Gap 19, can reduce hemichannel mediated cell death in response to inflammation and ischemia but has low cell permeability requiring high concentrations to achieve efficacy. By fusing Gap19 to the cell penetrating peptide, Xentry, we have developed an intracellular acting Cx43 hemichannel blocking fusion peptide, XG19, which enables low dose delivery yet treatment efficacy. Xentry interacts with cell surface expressed Syndecan-4, which we have found is highly expressed in hypoxic retinal cells. This means that XG19 preferentially targets hypoxic cells and can be delivered systemically as it is not sequestered by red blood cells. Our in vitro and in vivo studies have shown that this fusion peptide has therapeutic potential to shut down the inflammatory cycle and repair vascular damage that occurs with CNV as well as other inflammatory and hypoxic-ischemic diseases of the body.

Presented 11th April 2018.

   

Pathophysiology of Presbyopia and Ocular Trauma - Dr Matthew Reilly, Department of Biomedical Engineering & Ophthalmology, Ohio State University.

Presbyopia is the most common vision disorder, resulting in compromised near-vision for nearly all individuals over the age of 50. The mechanism(s) by which the eye becomes presbyopic remain poorly understood, though most indications point to natural aging processes in the lens, including growth, remodeling and stiffening. These changes, which occur in parallel, result in an altered balance of residual stresses between the lens and its capsule in the accommodated state. However, their respective contributions to presbyopia are as yet unknown. I will discuss the potential roles of biomechanics and mechanobiology in ocular development, refractive development, and pathophysiological changes following the onset of presbyopia and cataract extraction.

Ocular trauma is increasingly common in both military and civilian sectors, is the most common vision-related cause of hospitalization, and the fourth-most common type of battlefield injury. The increased use of improvised explosive devices (IEDs) is thought to be the main contributing factor to military eye injuries and may indicate that the eye is particularly susceptible to blast. We have developed experimental and computational models of blast injury to the eye to understand the mechanical injury mechanisms, offer improved diagnosis, and suggest preventative measures. Most recently, we developed a novel animal model for traumatic optic neuropathy which will be used to develop diagnostic criteria and test candidate treatments for this vision-threatening condition.

Presented 28th March 2018.

   

Shifting the Paradigms of Ophthalmic Drug Delivery - Professor Heather Sheardown, Department of Chemical Engineering, McMaster University, Canada.

Delivery of drugs to the eye remains the most significant challenge in ophthalmology, requiring new delivery paradigms. This talk will discuss a novel mucoadhesive micelle based system which has the potential to remain on the ocular surface for prolonged periods and has the potential to act as a better method of delivering drugs to the front of the eye in dry eye applications. In addition, novel injectable systems which gel in situ following injection and have the potential to last for periods of up to 6 months in the back of the eye have been developed. In vivo testing of the systems as well as methods of prolonging drug release from the systems will be discussed.

Presented 12th March 2018.

   

Inflammation of the Eye Leading to Cell Death: Gaining Insight Into a Range of Pathologies - Dr Monica Acosta, Senior Lecturer, School of Optometry and Vision Science.

The eye provides an excellent paradigm for examining mechanisms that lead to cell death with remarkable similarities with other organs. Among the 13 subroutines of regulated cell death that can be found in the human body, at least five of these mechanisms are implicated in vision loss in retinal pathologies.

My laboratory initiated studies on the mechanisms of cell death in the retina in 2009, having identified at least two pathways in light-induced photoreceptor damage and metabolic changes that precede apoptosis in the ischaemia/reperfusion retina, as well as specific cell death modalities in genetic models of photoreceptor degeneration. Of particular interest in our research is that most of the cellular processes involved in ocular pathologies suggest that inflammation, mediated by macrophages in the choroid and microglia in the retina, triggers unique cell death modalities in the eye. This inflammatory-mediated process of cell death is particularly intriguing in the context of diabetic retinopathy (DR), a disease which was originally thought of as a purely vascular disease but is increasingly considered to be a chronic inflammatory disease with inflammation leading to changes in the retinal microvasculature.

Similarly, the aetiology of Age-related Macular Degeneration (AMD) remains elusive despite the characterization of many factors in the early stages of the disease contributing to the disease late-stage phenotypes. While it is clear that these processes ultimately result in degeneration of retinal pigment epithelium and photoreceptor, the prevalent type of cell death contributing to the various phenotypes is unknown.

In this seminar I will attempt to reconcile factors identified in human donor tissues and to integrate these data with pathology modelled in cell cultures and animal models. These studies have led to collaborative research to trial intervention strategies that are now in clinical trial stages.

Presented 15th February 2018.

   

A Computational Approach (Pattern Recognition) in Disease Diagnosis/Management - Professor Michael Kalloniatis Director, Centre for Eye Health, University of New South Wales, Sydney.

Pattern recognition has been useful to analyse satellite images and also applied in medical diagnosis. We have applied this methodology to determine ganglion cell iso-density contours (structure) and contrast sensitivity iso-contours (function) derived from OCT and visual field data. By combining these contours we are beginning to obtain useful insights on structure-function correlations, hemifield testing in glaucoma and identifying clinical signs in intermediate AMID, including automated progression and regression analysis.

Presented 9th February 2018.