Papers by Elizabeth Irving
Ophthalmic and Physiological Optics, Feb 26, 2007
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Ophthalmic and Physiological Optics, May 1, 2010
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ACM transactions on computing for healthcare, Dec 20, 2021
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Journal of Vision, Jul 15, 2022
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Investigative Ophthalmology & Visual Science, Jul 13, 2018
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Investigative Ophthalmology & Visual Science, May 1, 2004
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Optometry and Vision Science, 2012
A significant number of patients return to optometric practice dissatisfied with their spectacles... more A significant number of patients return to optometric practice dissatisfied with their spectacles. An important question is whether any of these cases are preventable. There are several different clinical maxims that are used to modify the subjective refraction when determining the refractive prescription. These maxims aim to improve patient comfort and adaptation and thereby reduce patient dissatisfaction with new spectacles. They are not based on research evidence, but rather on expert opinion gained from clinical experience. The aim of this study was to retrospectively analyze a large number of case records of dissatisfied patients to assess the possible usefulness of the prescribing maxim "if it ain't broke, don't fix it." Three hundred eighteen non-tolerance cases from a university-based Canadian optometric clinic were categorized by a focus group of optometrists. Three prescribing categories were defined and comprised cases in which application of the proposed maxim may have prevented the recheck eye examination; a more limited application of the maxim for one working distance may have been appropriate; and finally scenarios in which the maxim did not work in that the practitioner was judged to have initially followed the maxim, yet patient dissatisfaction was still reported. The remaining unallocated records comprised prescribing situations outside the scope of this study. Approximately 32% of non-tolerance cases were judged to have been preventable by use of the proposed maxim. Furthermore, an additional 10% reduction in recheck cases may have been possible by a more liberal interpretation of the maxim. Conversely, 4% of cases were deemed to comprise scenarios in which the maxim was followed yet the patient returned later to report problems with their spectacles. The prescribing maxim "if it ain't broke,…
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Brain Research, Feb 1, 2009
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Gaceta óptica: Órgano Oficial del Colegio Nacional de Ópticos-Optometristas de España, 2010
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PubMed, 2012
Myopia is characterized by an increase in axial length of the eye, but the reasons for the axial ... more Myopia is characterized by an increase in axial length of the eye, but the reasons for the axial elongation are still unknown. Higher intraocular pressure (IOP) has been associated with myopia and could be involved in eye enlargement. The purpose of this study was to investigate the effect of intraocular pressure on the geometry of the chick eye and to investigate whether an increase in IOP could cause the elongation of the eye. The IOP of ten 7-day old chick eyes was raised by injecting fluid into the eyes and the resulting deformation of the eyes was measured using digital cameras. In-vitro pressure-volume curves were obtained. The axial and equatorial strains (deformation normalized to the original dimension) were calculated. Our results showed that IOP increased exponentially with increasing injected volume. About 25 D myopia could be induced by the axial elongation created with an increase in IOP by 100 mmHg. As pressure increased from 0 to 140 mmHg, the chick eye elongated in the axial direction and initially contracted in the equatorial direction. The natural tendency of chick eyes is to elongate as IOP increases and this suggests that from a mechanical perspective IOP could play a role in myopia onset and progression. The results also suggest that oblate eyes might have higher risk of developing myopia.
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Ophthalmic and Physiological Optics, Jul 26, 2017
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Computer Methods in Biomechanics and Biomedical Engineering, Feb 1, 2012
The geometry of anatomical specimens is very complex and accurate 3D reconstruction is important ... more The geometry of anatomical specimens is very complex and accurate 3D reconstruction is important for morphological studies, finite element analysis (FEA) and rapid prototyping. Although magnetic resonance imaging, computed tomography and laser scanners can be used for reconstructing biological structures, the cost of the equipment is fairly high and specialised technicians are required to operate the equipment, making such approaches limiting in terms of accessibility. In this paper, a novel automatic system for 3D surface reconstruction of the chick eye from digital photographs of a serially sectioned specimen is presented as a potential cost-effective and practical alternative. The system is designed to allow for automatic detection of the external surface of the chick eye. Automatic alignment of the photographs is performed using a combination of coloured markers and an algorithm based on complex phase order likelihood that is robust to noise and illumination variations. Automatic segmentation of the external boundaries of the eye from the aligned photographs is performed using a novel level-set segmentation approach based on a complex phase order energy functional. The extracted boundaries are sampled to construct a 3D point cloud, and a combination of Delaunay triangulation and subdivision surfaces is employed to construct the final triangular mesh. Experimental results using digital photographs of the chick eye show that the proposed system is capable of producing accurate 3D reconstructions of the external surface of the eye. The 3D model geometry is similar to a real chick eye and could be used for morphological studies and FEA.
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Journal of Cataract and Refractive Surgery, Feb 1, 2004
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Movement Disorders Clinical Practice, Nov 20, 2016
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Experimental Eye Research, Jun 1, 2019
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Vision Research, May 1, 1995
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A number of experiments have demonstrated that it is possible to induce ametropias in the eyes of... more A number of experiments have demonstrated that it is possible to induce ametropias in the eyes of young animals by distorting early visual experience. Much of the work has involved the use of chicks (Gallus gallus domesticus) because of their precocial nature and because they grow and develop rapidly. The earlier studies generally involved depriving the retina of a clear image by either suturing the eyelids together or applying some kind of translucent or light scattering device over the eye during development (e.g., Pickett-Seltner, et al., 1987). This kind of treatment invariably leads to varying levels of myopia, often referred to as form deprivation or experimental myopia, through the axial elongation of the eye.
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Over the past three decades, refractive errors have been induced in a variety of vertebrate speci... more Over the past three decades, refractive errors have been induced in a variety of vertebrate species by various methods. By manipulating the visual environment during early visual experience, hyperopia, myopia, and astigmatism have been induced. When using defocus to induce refractive error, the error results from an adjustment in the emmetropization process in order to compensate for the induced blur. The rationale associated with lid suture, form deprivation, dark rearing, continuous light exposure, and dim light exposure is less clear.
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Optometry and Vision Science, Feb 1, 1991
Experiments were conducted to characterize the distribution of the monocular components of fixati... more Experiments were conducted to characterize the distribution of the monocular components of fixation disparity, i.e., ascertain whether or not the fixation disparity measured by nonius alignments is equally divided between the two eyes or has an unequal distribution. Computer generated nonius lines were used to measure the monocular components of the forced vergence fixation disparity curve (FDC) for subjects with normal binocularity. Thirty-three percent of all subjects tested showed unequal distribution of their monocular components. The composite FDC's for subjects with unequal distribution of the monocular components tended to have steeper slopes than those with equally distributed components. It was concluded that equally divided monocular components are not a prerequisite for good binocularity.
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Optometry and Vision Science, May 1, 1999
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Papers by Elizabeth Irving