Tuesday, March 25, 2014

3D PRINTING OF OPHTHALMICS

How long will it be before eyeglass lenses are 3D printed?

About a year ago I visited 3D printer manufacturer Stratasys to investigate the possibility of printing ophthalmic lenses. What I found was the printing process using materials used to print with can't be made transparent. The best that can be done so far is a translucency not suitable for optical applications. Due to the printing process (melting of polymer threads fed onto the printing stage) the printed structure results in a lot of internal scatter.

Here's a good video from Stratasys showing translucent 3D printed parts.



For those readers not familiar, here's a video demonstrating current ophthalmic lens manufacturing. (Skip past the first 30 seconds)



If you compare current ophthalmic lens manufacturing to the 3D printing process its easy to see the savings. The most apparent is material waste. An ophthalmic lens blank comes in standard sizes and then has to be generated, polished and edged to fit in a frame. Depending on the prescription and frame size and shape, the material cut away and discarded may be over 80% of its original blank size.


Other major savings will include equipment, floor space for that equipment, water, power, and waste removal. These savings are more than significant. And depending on the size of the printer labs can print several pair at a time.

Once 3D printing has advanced to the point where transparent parts can be printed it won't be long before full pairs of glasses are printed, frames and all.

Going further still, as the technology progresses glasses can be printed not only with frames but with optical density in a wide range of colours for sunglasses (tints) and possibly with AR coatings. A welcome bonus will be printing lenses in 'tinted' colours will ensure the colour chosen by the customer matches the colour they've actually chosen at the store (I know all too well how frustrating this can be!).

Objet Eden500V 3D printer from Stratasys.com
As far as AR printing is concerned, currently the tolerancing for 3D printing is on the order of ± 16 microns (for the printer pictured at left). To print AR coatings that tolerancing has to come down to ± 1 nanometer.

As I see it the future of ophthalmic lens manufacturing will be a lab with one or more 3D printers connected to the internet taking prescription orders for specific frame styles including tints for sunglasses and fashion.

I am happy to say my job as a coating process specialist is safe for the foreseeable future.

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