During extra-vehicular activities (EVAs) or space walks astronauts over use their fingertips under pressure inside the
confined spaces of gloves/space-suite. The repetitive hand motion is a probable cause for discomfort and injuries to the
finger-tips. We describe a new wireless fiber-optic probe that can be integrated inside the astronaut glove for non-invasive
blood perfusion measurements in distal finger tips. In this preliminary study, we present blood perfusion
measurements while performing hand-grip exercises simulating the use of space tools.
We have developed a non-invasive diagnostic instrument based on a scanning fluorophotometer integrating autofluorescence and dynamic light scattering techniques. The device makes a scan along the optical axis of the eye. In a DLS measurement, it is extremely important to precisely define the position of the volume-under-test inside the eye and its effective volume. In this work, a specific optical computer aided design tool based on the Navarro's model of the human eye is used to simulate the optical path of the DLS laser beams and to calculate position and size of the volume-under-test.
Pigment dispersion syndrome and pigmentary glaucoma are
investigated by a scanning instrument based on dynamic light
scattering technique. The measurements are oriented to evaluate
the various conjectures about the pathogenesis of pigmentary
glaucoma and to establish a diagnostic tool that may be used for
an early detection of this type of glaucoma.
A digital control unit for use with a new integrated instrument for dynamic light scattering and natural fluorescence measurements is presented. This unit, based on a microcontroller (Microchip PIC16F877), process signals from an optical head and controls instrument functions. The microcontroller internal counters are used to perform real- time photon counting measurement by processing the TTL signals obtained from the photodetectors. The new system provides reliable and simultaneous DLS and AF measurements from the same ocular volume located from the cornea to the retina.
Dynamic light scattering (DLS) and autofluoresence (AF) are two promising optical diagnostic techniques for use in ophthalmology. In this paper the DLS and AF are integrated in one instrument and applied to study healthy and pathological ocular tissues to detect changes at the molecular level. Measurements performed on 17 patients (age range 20-80 years) are presented. Out of these, 7 patients were healthy normals, 10 had glaucoma and the two oldest patients had both glaucoma and cataracts.
Dynamic light scattering (DLS) and autofluorescence (AF) are non-invasive diagnostic techniques that can monitor changes at the molecular level in ocular tissues. In the present study, we demonstrate as simultaneous measurements of autofluorescence and dynamic light scattering on the corneal tissues can be performed using a novel specifically designed instrument. The integrated instrument takes advantage of the singular techniques by improving the measurement quality and the reliability of the diagnosis. Preliminary tests on volunteers show promise in relation to possible use in the clinical practice.
Over the past two decades, great efforts have been made in ophthalmology to use optical techniques based on dynamic light scattering and tissue natural fluorescence for early (at molecular level) diagnosis of ocular pathologies. In our previous studies, the relationship between the corneal AF and DLS decay widths of ocular tissues were established by performing measurements on diabetes mellitus patients. In those studies, corneal AF mean intensities were significantly correlated with DLS decay width measurements for each diabetic retinopathy grade in the vitreous and in the cornea. This suggested that the quality of the diagnosis could be significantly improved by properly combining these two powerful techniques into a single instrument. Our approach is based on modifying a commercial scanning ocular fluorometer (Fluorotron Master, Ocumetrics Inc., CA, USA) to include both techniques in the same scanning unit. This configuration provides both DLS and AF real time measurements from the same ocular volume: they can be located in each section of the optical axis of the eye from the cornea to the retina. In this paper, the optical setup of the new system is described and preliminary in-vitro and in-vivo measurements are presented.
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