4D Light FIeld Ophthalmoscope: A Study of Plenoptic Imaging for Retinal Imaging

The application of 4D Light Field technique to retinal imaging is proposed as a multi- modality imaging device. A feasibility study developed with numerical simulations is presente

Study of the dynamic tear film aberrations using a curvature sensing setup

The advancement in adaptive optics in recent years has increased the interest in the dynamic aberrations of the eye, including those introduced by the first optical surface provided by the tear film. A curvature sensing system to measure the dynamic topography of the tear film is described. This optical system was used to measure the aberrations of the tear film on 14 eyes. The evolution of this surface is monitored through videos of the tear film topography. The effect on optical quality is studied from the time-evolution of the RMS wavefront error showing non-negligible aberration variations attributed to the tear film layer; the effect of tear film break-up on the ocular optical quality is also discussed. Furthermore, the aberration maps are decomposed into their constituent Zernike components showing stronger contributions from 4th order terms, and also from those components with vertical symmetry which can be attributed to the effect of the eye lids on the tear film. Finally, the power spectra of the RMS wavefront error evolution show that the strongest contributions of the tear film aberrations are to be found at low frequencies, typically below 2Hz

Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye

A system to measure the topography of the first optical surface of the human eye noninvasively by using a curvature sensor is described. The static corneal topography and the dynamic topography of the tear film can both be measured, and the topographies obtained are presented. The system makes possible the study of the dynamic aberrations introduced by the tear film to determine their contribution to the overall ocular aberrations in healthy eyes, eyes with corneal pathologies, and eyes wearing contact lenses

New methodology to measure the dynamics of ocular wave front aberrations during small amplitude changes of accommodation

We present a methodology to measure the systematic changes of aberrations induced by small changes in amplitude of accommodation. We use a method similar the one used in electrophysiology, where a periodic stimulus is presented to the eye and many periods (epochs) of the stimulus are averaged. Using this technique we have measured changes in higher order aberrations from 0.006μm to 0.02μm and correlated them with amplitude changes of accommodation as small as 0.14D. These small changes would have been undetectable without epoch averaging. The correlation coefficients of Zernike terms with defocus were calculated, demonstrating higher values of correlation for epoch averaging. The accurate monitoring of defocus at the start of the accommodation response has shown some interesting trends that may be related with the mechanisms behind accommodation

Primary hyperparathyroidism : association of imaging and pathology

BACKGROUND: We studied a cohort of hyperparathyroid patients in order to elucidate their clinical, laboratory, radiological and histological findings; the role of diagnostic imaging and concomitant thyroid pathologies.METHOD: 48 patients met our inclusion criteria for hypercalcaemic primary hyperparathyroidism (pHPT). We documented patients’ demographic data, symptomatology, associated conditions and treatment and analysed the work-up, management and outcomes for each of these patients.RESULTS: pHPT patients had a median age of 62 years (range 20–79), median PTH of 145.5 pg/ml (range 27–4660) and mean serum calcium of 2.94 mmol/l (S.D.±0.33), while those operated (30/48, 62.5%) had a median age of 60 years (range 20–79), mean calcium of 3.02 mmol/l (S.D.±0.39) and a median PTH of 176 pg/ml (range 37–4660). Histology showed parathyroid adenoma in 16/30 (53.3%), hyperplasia in 8/30 (26.7%), parathyroid carcinoma in 1/30 and normal tissue in 5/30. 19 of the 30 operated patients had a positive sestamibi scan of which 14/19 (73.7%) had an adenoma, 3/19 (15.8%) had hyperplasia, 1/19 had a carcinoma, and 1/19 had normal histology. Out of the 11 patients who had a negative sestamibi scan, 8/10 also had a negative ultrasound (US) and histologically 2/11 (18.2%) had an adenoma, 5/11(45.5%) had hyperplasia and 4/11 (36.4%) had normal histology. Thyroid US showed a multinodular goitre in 12/41 (29.3%), solitary nodule in 5/41 (12.2%) thryoiditis in 4/41 (9.8%) and normal thyroid morphology in 20/41 (48.8%).CONCLUSION: Parathyroid adenoma is the commonest pathology in patients with positive parathyroid imaging while hyperplasia is commoner in scan negative patients. This study highlights the need to proceed with surgery even when imaging is negative if clinically indicated. It is important to investigate associated thyroid pathology prior to surgery though our data suggests similar incidence of thyroid pathology as documented in the general population.DECLARATION OF INTEREST: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.FUNDING: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.peer-reviewe

Sporting embodiment: sports studies and the (continuing) promise of phenomenology

Whilst in recent years sports studies have addressed the calls ‘to bring the body back in’ to theorisations of sport and physical activity, the ‘promise of phenomenology’ remains largely under-realised with regard to sporting embodiment. Relatively few accounts are grounded in the ‘flesh’ of the lived sporting body, and phenomenology offers a powerful framework for such analysis. A wide-ranging, multi-stranded, and interpretatively contested perspective, phenomenology in general has been taken up and utilised in very different ways within different disciplinary fields. The purpose of this article is to consider some selected phenomenological threads, key qualities of the phenomenological method, and the potential for existentialist phenomenology in particular to contribute fresh perspectives to the sociological study of embodiment in sport and exercise. It offers one way to convey the ‘essences’, corporeal immediacy and textured sensuosity of the lived sporting body. The use of Interpretative Phenomenological Analysis (IPA) is also critically addressed. Key words: phenomenology; existentialist phenomenology; interpretative phenomenological analysis (IPA); sporting embodiment; the lived-body; Merleau-Pont

A simple digital-optical system to improve accuracy of hot-wire measurements

A high precision traverse mechanism with micro-resolution was designed to capture accurately the velocity profile of the very thin turbulent attachment line on a swept body. To ensure that the traverse mechanism could position the hot wire reliably, a simple digital optical system was designed to check the performance of the traverse by measuring the displacement of the hot wire: a vertical displacement of 2.4µm was achievable and this could be further reduced to 0.6µm using micro-stepping. Due to the simplicity of the set-up it was equally useful for probe wall positioning and the velocity profiles captured clearly demonstrated that the optical set-up helped in resolving the near wall flow more accurately, regardless of the thinness of the boundary layer. The captured data compare well with the results from similar investigations, with arguably higher precision achieved

Feminist phenomenology and the woman in the running body

Modern phenomenology, with its roots in Husserlian philosophy, has been taken up and utilised in a myriad of ways within different disciplines, but until recently has remained relatively under-used within sports studies. A corpus of sociological-phenomenological work is now beginning to develop in this domain, alongside a longer standing literature in feminist phenomenology. These specific social-phenomenological forms explore the situatedness of lived-body experience within a particular social structure. After providing a brief overview of key strands of phenomenology, this article considers some of the ways in which sociological, and particularly feminist phenomenology, might be used to analyse female sporting embodiment. For illustrative purposes, data from an autophenomenographic project on female distance running are also included, in order briefly to demonstrate the application of phenomenology within sociology, as both theoretical framework and methodological approach

The effects of ocular magnification on Spectralis spectral domain optical coherence tomography scan length

Purpose The purpose of this study was to assess the effects of incorporating individual ocular biometry measures of corneal curvature, refractive error, and axial length on scan length obtained using Spectralis spectral domain optical coherence tomography (SD-OCT). Methods Two SD-OCT scans were acquired for 50 eyes of 50 healthy participants, first using the Spectralis default keratometry (K) setting followed by incorporating individual mean-K values. Resulting scan lengths were compared to predicted scan lengths produced by image simulation software, based on individual ocular biometry measures including axial length. Results Axial length varied from 21.41 to 29.04 mm. Spectralis SD-OCT scan lengths obtained with default-K ranged from 5.7 to 7.3 mm, and with mean-K from 5.6 to 7.6 mm. We report a stronger correlation of simulated scan lengths incorporating the subject’s mean-K value (ρ = 0.926, P < 0.0005) compared to Spectralis default settings (ρ = 0.663, P < 0.0005). Conclusions Ocular magnification appears to be better accounted for when individual mean-K values are incorporated into Spectralis SD-OCT scan acquisition versus using the device’s default-K setting. This must be considered when taking area measurements and lateral measurements parallel to the retinal surface