imaging and machine vision europe october/november 2011
www.imveurope.com
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medical applications
update rate of the system is more than 30Hz. The uninterrupted display produces the so-called immersion effect, in which the user no longer perceives the difference between reality and simulated images.
Dry eye syndrome Vision technology is being used to achieve accurate diagnosis of dry eye syndrome (or keratoconjunctivitis sicca), the fifth largest eye problem in the world, and one that is most prevalent in Asia. The condition means the eyes do not make enough tears, or the tears evaporate too quickly. As a consequence, the eyes dry out or become inflamed. It tends to affect people above the age of 60, and although not usually a serious condition, it can be uncomfortable and, in some cases, can affect vision. Around four years ago, two Japanese doctors
(Dr Reiko Arita and Dr Shiro Amano) began a collaboration with TopCon to develop a vision- based process that would help diagnose the cause of dry eyes, and therefore assist in deciding the most appropriate course of treatment. Often, the root cause of dry eyes can be traced
to the meibomian glands, which are located on the inside of the eyelids; there may be more than 60 of these glands in each eye. The meibomian glands produce lipids, which are an essential component in keeping the surface of the eye moist. If the lipids produced are too ‘sticky’, they cannot get out of the gland. Also, the opening of the gland may be too small. Henry Claessens, product manager at TopCon, explains: ‘In 2009, TopCon Tokyo developed a
JAI’s AT-200GE Medical, which has colour management qualities making it particularly suitable for use in the medical market
system using a Sony infrared camera and infrared illumination, which enabled medical teams to see the condition of these meibomian glands. We’ve spent the past couple of years modifying the system for use in the European market. The system uses a slit lamp, which is a biomicroscope specially adapted for viewing the eye by means of a very narrow illuminated slit. It works like an optical knife, slicing through the cornea and into the eye. ‘We’ve been using Sony’s analogue infrared cameras for a long time in our retina imaging
‘Standard colour cameras use interpolation, whereas this unit uses true colours’
systems, so we were familiar with the camera’s quality and also the ease with which it connected to our software.’ TopCon’s system first makes the meibomian
glands visible, allowing medical teams to view the exact nature of the condition. ‘We are looking to see if the glands are blocked,’ says Claessens, ‘or if the mouths of the glands are too small. If neither of those appears to be the problem, we look for the presence of the tear meniscus, which will tell us whether or not there is a problem with the aqueous layer on the eye. Once we’ve checked all those conditions and seen no problems, we can deduce that the cause of the dry eyes lays in the absence of necessary proteins in the eyes. At the moment, we can’t yet measure these proteins in isolation, although research is going on to make that possible.’ From this, treatment is then offered, which
Using TopCon’s system, medical teams can spot differences between normal meibomian glands in the eyelid (top) and abnormal ones (bottom)
can include heat treatment if the issue is sticky lipids, or the use of a device to open the mouths of the glands further. ‘The system is used again a few months later to check on the progress of the treatment,’ says Claessens. TopCon’s system was recently unveiled to
the market, and Claessens has been delighted with the response. ‘We’ve been overwhelmed with enquiries, so we are struggling to find the necessary parts to fulfil the orders,’ he says. ‘And following feedback from that launch, we are looking to improve the image quality that the system provides, as this will really help with diagnosis.’
Blood analysis The use of colour has also had an impact on medical imaging applications, particularly in microscopic applications, such as blood analysis. JAI has recently introduced the AT-200GE Medical, a new 3-CCD digital progressive scan camera aimed specifically at this market. It has been developed to provide accurate, high resolution images under low light conditions, and is particularly relevant to blood analysis, because of its colour management capabilities. It features approximately five times the
resolution compared with ordinary 3-CCD analogue PAL cameras often used in the medical field, and the precisely-aligned three CCDs on the prism block generate true image colours through JAI’s original colour matrix circuit. Users have the possibility to obtain not only the RGB digital data, but also sRGB or Adobe RGB video directly from the camera to calibrate it with connected devices like monitors or printers. ‘The camera features true RGB,’ says JAI’s
Michael Lund. ‘Standard colour cameras use interpolation, whereas this unit features true colours, which can be very important in medical applications. The portability of these true colours is also important, as it ensures no loss of colour quality between devices.’ JAI’s true colour management system in combination with Megapixel resolution gives clear and natural images of skin, blood, eye iris and other biological objects being viewed, providing users with a better foundation in relation to patient diagnostics and patient treatment, as well as in medical research studies.
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