Put down the One Two in front of you and stare at the wall. You have just been accommodating. No; doesn't mean you've done us any favours, it's how sciency types describe focusing your eyes, the subject of this month's OTT medical titbit.

Your eye, each one, is spherical, not Callard and Bowser toffee-shaped as the eyelids, covering two thirds of it, might lead you to believe. A lens is held in place and changed in shape, by a ring of muscle called the ciliary. It's this shape shifting that allows you to focus on the sound man at the back of the hall or the music in front of you and is known as accommodation.

The image produced falls, upside down, on the retina at the back of the eye. This layer, a mere 1/50in thick, converts light into electrical signals lead via the optic nerves to the brain. It's the brain which mentally (how else) sorts out the image to appear the right way up to your senses. Optic nerves plot an involved route through the brain and that's a handy cheat for doctors who can track down faults in different sections of the grey matter by analysing the resultant eye problems... window of the soul, and all that.

However, this does mean that everything to your right is 'seen' by the left hand side of your brain, and vice versa — supposedly an explanation for why drummers cross their hands (right on hi-hat, left on snare). Thus we have a more direct link between the muscles on the right hand side of your body, through the left eye, to the right hand side of the brain. No proof, but its A GREAT STORY.

We all know the iris reacts to light, enlarging or shrinking the pupil, but did you know that the small, pink, fleshy bit in the corner of the eye, next to the nose, is the remnant of your third eyelid; abandoned by man, still used by some animals. And you're probably smart enough to remember the retina is covered in cones, which 'see' colour and are concentrated in the centre (the macula) and rods, better at picking up dimmer (if colourless) images, and spread around the edges. That's why you catch (faint) things out of the corner of your eye — the bass player's annual offer to buy a drink, the gate money, etc.

While we're here, let's kill off a few myths about the mince pies. Your eyesight usually gets worse as you get older because past the age of 40, the lens starts to harden and the ciliary muscle grows tired... result, it's more of an effort to focus. You can't wear your eyesight out by, say, too much close work, neither can you preserve it by reading only one book every five years. Dim light won't damage it, neither will TV, though there is a caucus of medical opinion that considers the VDU screen to be unusually tiring on the spheroids. But we await positive proof. Wearing glasses won't weaken your eyes, NOT wearing them when you should in order to make your eyes tough little critters who can stand on their on two stalks, will probably reward you with headaches, and little else.

Everyone has one blind spot in each eye, it's where the optic nerve (a bundle of more than a million nerve fibres yet only 1/10in across) exits the retina, hence no rods or cones at the door. We all cry. Tear fluid is mildly antiseptic and continually drains into the eye, through channels in the upper lid, to keep it clean. These channels also pass through the nose, which is why the conk runs during bursts of sobbing. And do not believe uncles, grannies or other relatives who tell you the doctor took their eye out of its socket and rested it on their cheek in order to carry out an optical-type operation. Rubbish. What's supposed to happen to the nerves and muscles that hold it tightly in place during these occasions? Here's looking at you.