Tag Archives: ophthalmology

Blast from the past

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A semi-regular round-up of some technolgy stories I’ve written about recently:

Curiosity continues to trundle across Mars, and another article about its on-board laser is here on Optics.org. As always with space applications, it’s the timescales that surprise but probably shouldn’t. ChemCam is the first planetary application of laser-induced breakdown spectroscopy, an attention-grabbing media-friendly experiment to zap bits of Martian geography, and a landmark experiment in every sense. Thales Optronics were told “Nice laser; now make it 95 percent lighter and need no cooling,” and achieved it within a couple of years. It’s state of the art – for 2003, when the design was locked down. Although some of the smaller sensor components developed for ChemCam have gone on to Earth-bound uses in the decade since, the new class of laser that Thales designed has not found its way into commercially viable applications because it’s remained stubbornly too expensive. It’s a relic from the past, currently engaged in one of the most futuristic experimental scenarios on the books.

My grasp of gene sequencing tends to be a consistent three years out of date, so it’s only when studies like ENCODE prompt round-ups of where things stand that the vast scale of the topic comes into focus. But now, a decade and a bit into the human genome project, there are some promising practical applications becoming commercially viable. A children’s hospital in Kansas believes it can sequence enough of the genome of a sick child to identify some life-threatening hereditary conditions in a short enough time to start meaningful treatment, through a combination of a custom-built piece of software and a sequencing machine designed to get the job done as fast as reasonably possible. That involves elegant use of a fluorescence-tagging technique that’s been around for a while, but in Kansas they pressed the accelerator. Potentially, clinicians could get results in their hands in as little as 50 hours, although the trial hit some logistical issues that got in the way of that nice round number.

Adaptive optics is a feature of some astronomical telescopes, compensating for natural atmospheric disturbances by deliberately deforming a mirror very, very rapidly with mechanical actuators to counteract the interference. Ophthalmologists face similar problems when trying to get a good look at the retina to spot the onset of certain retinal diseases, but deformable mirror technology was never quite good enough to pull off the same trick dealing with the wide array of optical distortions found in human eyes. Imagine Eyes think they’ve cracked it, in a system that should mark the first reasonably practical transfer of adaptive optics into a normal clinical environment – practical, in that the machine to do the job isn’t the size of a small car.

Vision things

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Two holdovers from my trip to Baltimore for SPIE DSS 2012 have appeared on Optics.org:

Since shining a laser pointer in the general direction of an aircraft pilot seems to be the jape that won’t go away, optical filters that can limit the dazzle are in demand, and the military are just as interested in them as commercial airlines – probably more. Filters usually work by blocking the particular laser wavelengths used in your average pointer, but a better approach might be to block incident light based on its power instead. KiloLambda showed off a wide-band filter that uses a layer of carefully manufactured nanostructures and exploits their non-linear optics to block laser light when it passes a designated power threshold. Below that, the filter stays clear at all wavelengths; above it, transmission is either limited to a certain value or blocked completely.

Nanstructures are also the key to a scintillator material made by the applied research arm of Georgia Tech, a cerium-doped gadolinium halide material cast in a glass that scintillates when hit by incoming gamma-rays. If the nanoparticles used can be held below a certain size, and about 20 nanometers or so seems to do it, then the scattering of the scintillated light which can bedevil any kind of accurate reading is drastically reduced. Plus a glass or glass-ceramic material is much easier to handle than a fragile scintillation crystal. Plenty of room for improvement in the resolution, though.

And away from DSS: further work on retinal implants, a topic that has now entered the watch-lists of TV news producers everywhere. The principle of restoring sight to someone suffering from a condition like age-related macular degeneration hinges on the fact that it’s the photoreceptors in the retina that have died, not the neurons behind them. Implants to take over the job of the receptors and fire the neurons when light hits the retina are well past the status of pipe dreams, but there are a wealth of problems – not least among them, how to power the array of photoreceptors while it goes about its business. A group from Stanford University, applying scrupulous logic, think the answer may be to build an implant which draws its power from the same incoming infra-red light which brings the visual data, and their lab trials suggest that they’re on the right lines. Not quite a solar-powered retinal implant, but not too far off. Not a bionic eye either, although Steve Austin is the gift that keeps on giving for headline writers on a deadline.