Where can I buy all-plastic or MRI safe prescription glasses in the UK.

July 9, 2009 3:26 PM

Where can I buy all-plastic or MRI safe prescription glasses in the UK?

I work in and around an MRI scanner and I wear glasses.

I've been into the scanner countless number of times in my current glasses right upto and inside the bore with no problem.

The other day I was at the back of the bore when I moved my head and suddenly one arm of my glasses snapped clean off and flew into the bore. I think it was probably from one of the screws as I'd tested the glasses previously with a magnet and they seemed fine.

Anyway I managed to get a replacement pair but I'm nervous now of going into the scanner so I've been trying to find some MRI safe glasses which I can wear when I'm in the scanner.

Most high street shops sell plastic glasses but they always have metal screws. Even titanium glasses which are MRI safe have screws which might contain iron or steel.

So is it possible to buy all-plastic or other MRI safe prescription glasses anywhere in the UK?

Thanks in advance for any/all suggestions.

posted by empedia to grab bag (7 comments total)

If I were you, I'd buy some cheap plastic frame glasses with reasonably chunky arms, then remove the hinge/screws and superglue the arms in place - chunky arms help here by increasing the surface area over which the glue can stick.

Leave your glasses at work, wear your ordinary ones home, then change when you get back in to work the next day.
posted by Nice Guy Mike at 3:52 PM on July 9 [1 favorite]

What about getting plastic glasses and replacing the screws with brass or some other non-magnetic material? I'm not sure how eyeglass screws are sized, but you can get some pretty tiny brass screws from McMaster-Carr.
posted by pombe at 4:06 PM on July 9

I wouldn't assume that even brass screws would be safe. See "eddy current".
posted by Chocolate Pickle at 4:19 PM on July 9 [1 favorite]

There are plastic safety glasses and goggles claimed to have no metal parts, for use in electrical environments. Google "plastic safety goggle prescription".
posted by TruncatedTiller at 4:54 PM on July 9

I figured that if there are MRI-safe titanium glasses then probably eddy currents weren't that much of a concern. But agreed, no metal is probably best.
posted by pombe at 5:15 PM on July 9

Here's an example of a wooden eyeglass frames manufacturer, via google. In this case, the hinge is made from wood, with a (unknown) metal pin. Some of the other manufacturers use metal hinges.

I mention wood frames for the sake of completeness.

I'd get some plastic or TI frames and have brass screws put in. McMaster-Carr won't ship to the UK, but online (?ebay.co.uk?)/ the glasses shop/ a ?watch repair shop?/ a model engineering shop will have them. If that's too much bother, replace the screw with a pin and then glue or epoxy them.

Eddy currents aren't going to be a problem with non-ferromagnetic materials (like TI implants), they're more like drag than "yank towards a pole of the magnet". (Check that the brass is brass, however.)

Finally, you may want to bring a small rare-earth magnet along when frame and screw shopping.
posted by sebastienbailard at 8:19 PM on July 9

Thanks for all your suggestions. I googled some more and found www.safetyspecs.co.uk who do prescription safety glasses.

They do two pairs which seem to be all made of plastic so I've ordered one of those - for reference its the Peltor Eagle or the Bolle Premium which seem to be best suited to the task.
posted by empedia at 12:31 AM on July 11