Leon Nicholas Davies

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PURPOSE To quantify changes in crystalline lens curvature, thickness, equatorial diameter, surface area, and volume during accommodation using a novel two-dimensional magnetic resonance imaging (MRI) paradigm to generate a complete three-dimensional crystalline lens surface model. METHODS Nineteen volunteers, aged 19 to 30 years, were recruited.(More)
PURPOSE To use anterior segment optical coherence tomography (AS-OCT) to analyze ciliary muscle morphology and changes with accommodation and axial ametropia. METHODS Fifty prepresbyopic volunteers, aged 19 to 34 years were recruited. High-resolution images were acquired of nasal and temporal ciliary muscles in the relaxed state and at stimulus vergence(More)
PURPOSE To assess the effect of ageing on in vivo human ciliary muscle morphology and contractility during accommodation. METHODS Seventy-nine subjects, aged 19-70 years were recruited. High-resolution images were acquired of nasal and temporal ciliary muscle in the relaxed state, and at stimulus vergence levels of -4 and -8 D, using anterior segment(More)
The aim of this work was to measure susceptibility to pattern glare within a stroke group, employing a direct method of assessment. Twenty stroke subjects, aged 38–85 years, were recruited, along with an age-matched control group (n = 20). Assessment of pattern glare susceptibility was undertaken using the pattern glare test. An abnormal degree of pattern(More)
Despite numerous investigations, the aetiology and mechanism of accommodation and presbyopia remains equivocal. Using Gaussian first-order ray tracing calculations, we examine the contribution that ocular axial distances make to the accommodation response. Further, the influence of age and ametropia are also considered. The data show that all changes in(More)
PURPOSE To investigate objectively and noninvasively the role of cognitive demand on autonomic control of systemic cardiovascular and ocular accommodative responses in emmetropes and myopes of late-onset. METHODS Sixteen subjects (10 men, 6 women) aged between 18 and 34 years (mean +/- SD: 22.6 +/- 4.4 years), eight emmetropes (EMMs; mean spherical(More)
PURPOSE To develop a questionnaire that subjectively assesses near visual function in patients with 'accommodating' intraocular lenses (IOLs). METHODS A literature search of existing vision-related quality-of-life instruments identified all questions relating to near visual tasks. Questions were combined if repeated in multiple instruments. Further(More)
BACKGROUND The binocular Esterman visual field test (EVFT) is the current visual field test for driving in the UK. Merging of monocular field tests (Integrated Visual Field, IVF) has been proposed as an alternative for glaucoma patients. AIMS To examine the level of agreement between the EVFT and IVF for patients with binocular paracentral scotomata,(More)
PURPOSE To determine the most appropriate analysis technique for the differentiation of multifocal intraocular lens (MIOL) designs by using defocus curve assessment of visual capability. METHODS Four groups of 15 subjects were implanted bilaterally with either monofocal intraocular lenses, refractive MIOLs, diffractive MIOLs, or a combination of(More)
Visual stress is a condition characterised by symptoms of eyestrain, headaches and distortions of visual perception when reading text. The symptoms are frequently alleviated with spectral filters and precision tinted ophthalmic lenses. Visual stress is thought to arise due to cortical hyperexcitability and is associated with a range of neurological(More)