How Eyes Work

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	HOW OUR EYES WORK Our vision is something we all take for granted, but have you ever wondered how this miracle actually works? NUTS & BOLTS For something so small the eye is quite a complex organ, would you be surprised if we told you its made up of 15 sections? First up is the sclera, its job is to maintain the shape of the eye , its tough and is the outermost layer of the eye. Attached to the sclera is the extraocular muscles, they provide the power to move your eye around. The sclera is also home to the cornea, this is where light first passes when entering the eye. Next is the choroid (or uveal tract), the second layer of the eye. It contains the blood vessels that supply blood to other structures of the eye. Like the sclera, the choroid is home to two other structures of the eye, the cillary body and the iris. The cillary body controls the size of the lens for focusing by contracting and relaxing. The iris is the colored part of the eye. The color of your eye is determined by the amount of connective tissue and pigment cells in the iris, less pigment make the eye blue, less pigment makes the eye brown. The iris is an adjustable diaphragm around an opening called the pupil. The iris uses two muscles to control the amount of light that is allowed in to the eye. The dilator muscle makes the iris smaller and therefore the pupil larger, allowing more light into the eye; the sphincter muscle makes the iris larger and the pupil smaller, allowing less light into the eye. The pupil can expand from 2 millimeters to 8 millimeters, this expanding action means the eye can allow up to 30 times more light in to your eye. How cool! Deep inside your eye is the retina, the light-sensing portion of your eye. The retina contains two types of cells, rod cells which are responsible for vision in low light, and cone cells, which are responsible for color vision and detail. The cool thing about the retina is that it contains a chemical called rhodopsin, or "visual purple". Rhodopsin automagically converts light in to electrical impulses that your brain interprets as vision! The impulses travel to your brain courtesy of the optic nerve, a collection of nerve fibers at the back of your eye. MORE INFORMATION LIKE THIS.... SUNGLASSES GUIDE For such a simple idea, the sunglass can come in huge variety of shapes, styles and materials making picking the right pair far from simple. Get some top tips with our handy sunglass guide. THE HISTORY OF SUNGLASSES We've all worn a pair and we've all benefitted from their sun stopping power, but have you ever stopped to wonder where the sunglass came from? PRESCRIPTION SUNGLASSSES Many of us need a little help in the sahpe of prescription lenses to keep our vision nice and sharp. But this can make purchasing sunglasses a little tricky. Find out what you need to know.