Mario Giardini

Clinical validation of a smartphone-based adapter for optic disc imaging in Kenya

IMPORTANCE Visualization and interpretation of the optic nerve and retina are essential parts of most physical examinations. OBJECTIVE To design and validate a smartphone-based retinal adapter enabling image capture and remote grading of the retina. DESIGN, SETTING, AND PARTICIPANTS This validation study compared the grading of optic nerves from smartphone images with those of a digital retinal camera. Both image sets were independently graded at Moorfields Eye Hospital Reading Centre. Nested within the 6-year follow-up (January 7, 2013, to March 12, 2014) of the Nakuru Eye Disease Cohort in Kenya, 1460 adults (2920 eyes) 55 years and older were recruited consecutively from the study. A subset of 100 optic disc images from both methods were further used to validate a grading app for the optic nerves. Data analysis was performed April 7 to April 12, 2015. MAIN OUTCOMES AND MEASURES Vertical cup-disc ratio for each test was compared in terms of agreement (Bland-Altman and weighted κ) and test-retest variability. RESULTS A total of 2152 optic nerve images were available from both methods (also 371 from the reference camera but not the smartphone, 170 from the smartphone but not the reference camera, and 227 from neither the reference camera nor the smartphone). Bland-Altman analysis revealed a mean difference of 0.02 (95% CI, -0.21 to 0.17) and a weighted κ coefficient of 0.69 (excellent agreement). The grades of an experienced retinal photographer were compared with those of a lay photographer (no health care experience before the study), and no observable difference in image acquisition quality was found. CONCLUSIONS AND RELEVANCE Nonclinical photographers using the low-cost smartphone adapter were able to acquire optic nerve images at a standard that enabled independent remote grading of the images comparable to those acquired using a desktop retinal camera operated by an ophthalmic assistant. The potential for task shifting and the detection of avoidable causes of blindness in the most at-risk communities makes this an attractive public health intervention.

A smartphone based ophthalmoscope.

A low-cost alternative to the direct ophthalmoscope, a simple optical adapter for a smartphone, is described. It can overcome many of the technical challenges of fundoscopy, providing a high-resolution view of the retina through an un-dilated pupil. This can be used in locations with limited diagnostic resources to detect conditions such as glaucomatous optic neuropathy. Comparison of optic nerve images from commercial retinal screening cameras with the smartphone adapter demonstrates strong evidence for no difference in performance in glaucomatous disc grading (p=0.98, paired student t test, n=300).

A hybrid organic semiconductor/silicon photodiode for efficient ultraviolet photodetection

A method employing conjugated polymer thin film blends is shown to provide a simple and convenient way of greatly enhancing the ultraviolet response of silicon photodetectors. Hybrid organic semiconductor/silicon photodetectors are demonstrated using fluorene copolymers and give a quantum efficiency of 60% at 200 nm. The quantum efficiency is greater than 34% over the entire 200-620 nm range. These devices show promise for use in high sensitivity, low cost UV-visible photodetection and imaging applications.

OPTICAL COHERENCE TOMOGRAPHY

The 1990s saw a parallel growth of intravascular ultrasound (IVUS) and stent implantation, heralded and explained by the seminal observations that stents implanted at low pressure under angiographic guidance alone are frequently underdeployed and have higher risk of thrombosis ([1][1]). With a high

Home respiratory muscle training in patients with chronic obstructive pulmonary disease

Objective and background:  The benefits of inspiratory muscle strength training in decreasing symptoms, disability or handicap of patients affected by COPD are not well established. The objective of this study was to assess the efficacy of the constant use of a new flow‐volumetric inspiratory exerciser, named Respivol™, in improving respiratory functional parameters in COPD patients.

Ellipsometric characterization of amorphous and polycrystalline silicon films deposited using a single wafer reactor

The optical functions of amorphous and polycrystalline silicon thin films deposited on single oxidized silicon substrates by chemical vapor deposition in a wide range of deposition temperatures have been determined using spectroscopic ellipsometry. The data analysis is performed by direct inversion of the experimental spectra, therefore, obtaining results independent of any film modeling. The optical results indicate that the film structure changes as the deposition temperature increases from amorphous to polycrystalline with different grain size and distribution.

Frequency dependence of the dielectric and electro-optic response in suspensions of charged rod-like colloidal particles

We have performed an experimental investigation on the electrokinetic properties of charged rod-like fluorinated latex colloids. Systematic measurements of electrophoretic mobility, dielectric constant and electric birefringence have been performed as a function of the concentration of added nonionic surfactant and salt. In the investigated range of parameters, the zeta potential is a strongly decreasing function of the concentration of nonionic surfactant, while it is basically independent from ionic strength. We have obtained the frequency dependence of dielectric constant and Kerr constant as a function of zeta-potential and ionic strength. We observe the transition from a low frequency behavior, where both the dielectric constant and the Kerr constant are enhanced by the presence of the double layer, to a high frequency behavior, where both quantities take the value expected for unchanged particles in an insulating medium. The shape of the frequency dispersion of the Kerr constant coincides with that of the dielectric constant, but the cut-off frequencies are the same only when the zeta-potential of the particles is low.

The Kerr effect in aqueous dispersions of anisotropic and electrically charged latex particles

Static and dynamic electric birefringence measurements are performed on dispersions of electrically charged fluorinated latex spheres. It is shown that the Kerr constant is made up of three contributions: the first depends on the intrinsic and form anisotropy of the particle; the second arises from the presence of a slowly fluctuating electric dipole which should be originated by the statistics of the surface charge distribution, and the third is connected with the cloud of dissociated counter-ions. This latter contribution shows a non-Lorentzian frequency dispersion, and its amplitude is strongly dependent on the particle concentration and on the ionic strength.

A Raman spectroscopy bio-sensor for tissue discrimination in surgical robotics

We report the development of a fiber-based Raman sensor to be used in tumour margin identification during endoluminal robotic surgery. Although this is a generic platform, the sensor we describe was adapted for the ARAKNES (Array of Robots Augmenting the KiNematics of Endoluminal Surgery) robotic platform. On such a platform, the Raman sensor is intended to identify ambiguous tissue margins during robot-assisted surgeries. To maintain sterility of the probe during surgical intervention, a disposable sleeve was specially designed. A straightforward user-compatible interface was implemented where a supervised multivariate classification algorithm was used to classify different tissue types based on specific Raman fingerprints so that it could be used without prior knowledge of spectroscopic data analysis. The protocol avoids inter-patient variability in data and the sensor system is not restricted for use in the classification of a particular tissue type. Representative tissue classification assessments were performed using this system on excised tissue.

How the smartphone is driving the eye-health imaging revolution

The digitization of ophthalmic images has opened up a number of exciting possibilities within eye care such as automated pathology detection, as well as electronic storage and transmission. However, technology capable of capturing digital ophthalmic images remains expensive. We review the latest progress in creating ophthalmic imaging devices based around smartphones, which are readily available to most practicing ophthalmologists and other medical professionals. If successfully developed to be inexpensive and to offer high-quality imaging capabilities, these devices will have huge potential for disease detection and reduction of preventable blindness across the globe. We discuss the specific implications of such devices in high-, middle- and low-income settings.