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iPhone OCT?

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A convergence of mobile and cloud-computing technology with new diagnostic techniques for glaucoma has the potential to greatly improved access to expert clinical opinion for glaucoma patients in remote parts of the world, and their capabilities will only expand as the technology improves, according to presentations at the 11th Congress of the European Society of Glaucoma in Nice.

Already there are mobile phone attachments available which can provide a sharp fundus image that can then in turn be uploaded to a database from where it can be assessed by specialists anywhere in the world. Moreover, there is nothing currently standing in the way of creating an optical coherence tomography (OCT) attachment for smartphones that can be used in a similar way, said Prof Rainer A Leitgeb MD, PhD, University of Vienna, Austria.

“Basically all the necessary technology is available today to create a mobile phone based OCT. They only need to be optimised and put together,” he said.

He noted, for example, that the miniaturised integrated interferometer optics necessary for a smartphone-based OCT system are already available. The same is true of the small scanners suitable for such devices, which are available with Micro-Electro-Mechanical Systems (MEMS) technology. Small and efficient light sources have also been developed that would be suitable for use as part of a smartphone-based OCT device.

And finally the data reduction techniques necessary with a smartphone-based system are available in the form of sparse imaging. In a manner similar to JPEG image compression, sparse imaging compressive sampling and then reconstruction of the image provides a good preservation of image quality, he added.


Visual fields through the cloud

The electronic digital interconnectedness of modern society also raises the prospect of perimetry being performed in the practice or even at a patient’s home, said W Blair Donaldson MD, managing director of IbisVision, Aberdeen, Scotland, UK.

He noted that he and his associates have developed a perimetry system called RingOfSight™ that only requires some special software, a laptop computer connected to a standard television set and a Wacom tablet and pen, and a camera to measure the direction of gaze.

The test normally takes just over two minutes, making it much faster than standard 24/2 perimetry but provides similar results, he said. Other advantages include significant advantages in cost because it only requires very conventional hardware.

In addition, the software for conducting the test and assessing and comparing the results is not installed on the laptop connected to the wide-screen TV. Instead it is installed on a remote server.

There are two tests available with the new system, a full threshold test and a supra threshold test. The full threshold test involves the patient viewing the screen and moving a ring-shaped cursor over darkening spots that appear at various points in a random manner. The spots are first a very light grey and then gradually darken.

When the patient moves the ring over the target spot a new target spot appears on the screen and the patient moves the ring to the new spot as soon as they become aware of it . The sooner the patient covers the spot , the higher the sensitivity score. The patient repeats the exercise 52 times to build up a visual field.

The supra threshold test comes into play if the patient does not initially see the target. In those cases the spot moves closer to the last ring’s target until the patient registers its position by moving the ring over it.

“This gives an accurate distance of the scotoma from fixation, which is obviously useful in assessing the progress of the disease,” Dr Donaldson said.

Dr Donaldson and his associates have conducted a feasibility study with the RingOfSight system as part of the Northern Finland Birth Cohort Study. The study involved 131 patients, all of whom were tested with both the RingOfSight and the Humphrey perimeter, and 95 per cent of patients said that they preferred the RingOfSight, he noted.

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