JONNY PHILLIPS:

Did you know that the average human eyeball is two and a half centimeters wide, by two and a half centimeters deep, by a fraction over two centimeters tall.  Now that's not the kind of information you're gonna need every day, unless of course, you make them for a living.

NARRATOR:

This medical laboratory has been producing artificial eyes since World War 1.  Back then, they were known as the army spectacle depot, but they've come a long way since then.  Now they look after over 40,000 patients and they make over 6,000 eyes a year.

Every single eye is made by hand to an exact order.  A wax pattern of the patient's eye socket is sent here to the lab in Blackpool and a plaster of Paris cast is made.  This produces a mould that is the exact shape of the eye that they're going to manufacture.

The iris --  or coloured part of the eye -- is painted onto a flat plastic disc which is measured to the size of the patient's remaining Iris.  Each Iris is hand-painted using oil-based paints and the technicians work from either a digital photo or a previously painted eye to make sure that it will match the other eye.

After 18 hours, the Iris paint is dry and it gets pressed into a button-shaped disc.  This puts a curve on top of the Iris so that it will be flush on top of the round eye.

The Iris is placed upside down in a mould and the white of the eye is made.  It's made out of polymethyl methacrylate; a medical grade acrylic plastic similar to the material that's used to make false teeth.

Once prepared, it's squashed down into the cast of the top of Iris, and the whole mould goes into an oven for two and a half hours. The eye is now starting to take shape.  The excess acrylic material is trimmed away on a grinding wheel and the eye gets stained and veined.

The average human eye isn't snow white, so a bit of watercolour paint is dabbed around the edges depending on the patient's natural colour.

This embroidery silk is used to replicate the veins of the eye.  The thread is separated into individual fibres and applied with an acrylic varnish.  Just 1 centimeter of this thread will provide enough fibres to make over 100 eyes.

A coat of clear acrylic varnish is applied over the top of the eye and It gets oven cured to seal it.  Finally, a buff and polish gives it a nice glossy finish and the appearance of a living eye.

The expected lifespan of an artificial eye is around 6 years, as long as it gets looked after properly.  And the end result is pretty amazing.  Meet Pavel, he's been wearing an artificial eye since an accident when he was 15.  Can you tell which one it is?  Are you looking hard?  No I can't tell either. Ok, it's actually the one on the right of the frame.  Thanks Pav.