Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet

The ability of the human lens to accommodate is mediated by the ciliary muscle and zonule; the manifest optical power changes depend on the shape and material properties of the lens. The latter are difficult to measure with accuracy and, given the dynamic aspects of accommodation and the ageing of cells and tissues, the biomechanics of the lens is neither fixed nor constant. A range of techniques have been developed to measure both ageing trends and spatial variations in the mechanical properties and these have yielded a diverse array of findings and respective conclusions. The majority of quasi-static measurements, where the observation time is in minutes or hours, indicate that the stiffness of the lens increases with age at a faster rate in the lens centre than in the periphery. Dynamic measurements show that lens material properties are dependent on the loading frequency. Recent in vivo analyses suggest that, along the optic axis, profiles of elastic moduli are very similar to profiles of refractive index. This review assesses the advantages and limitations of different measurement techniques and consequent variations in elastic moduli that have been found. Consideration is given to the role of computational modelling and the various modelling methods that have been applied. The changes in mechanical properties of the lens associated with ageing and pathology and future implications for implant design are discussed.

Mobile and tablet apps, ubiquitous and pervasive computing, wearable computing and domotics for health.

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height.

Objective The emergence of evidence suggests that student nurses commonly exhibit concerns about their lack of knowledge of organ donation and transplantation. Formal training about organ donation has been shown to positively influence attitude, encourage communication and registration behaviours and improve knowledge about donor eligibility and brain death. The focus of this study was to determine the attitude and behaviour of student nurses and to assess their level of knowledge about organ donation after a programme of study. Design A quantitative questionnaire was completed before and after participation in a programme of study using a pretest–post-test design. Setting Participants were recruited from a University based in Northern Ireland during the period from February to April 2011. Participants 100 preregistration nurses (female : male=96 : 4) aged 18–50 years (mean (SD) 24.3 (6.0) years) were recruited. Results Participants’ knowledge improved over the programme of study with regard to the suitability of organs that can be donated after death, methods available to register organ donation intentions, organ donation laws, concept of brain death and the likelihood of recovery after brain death. Changes in attitude postintervention were also observed in relation to participants’ willingness to accept an informed system of consent and with regard to participants’ actual discussion behaviour. Conclusions The results provide support for the introduction of a programme that helps inform student nurses about important aspects of organ donation.