Many people experience vision problems are a result of eye conditions. The four main eye conditions are very common and vision can easily be corrected with glasses or contact lenses. It is important to note that your vision changes through your lifetime and while some eye conditions are hereditary others can develop as a result of your lifestyle, health and the natural process of ageing.
Eye conditions are the result of refractive errors. For perfectly clear vision, the image of a viewed object is focused onto the retina at the back of your eye. The lens, as well as other parts of your eye, refracts light onto the retina like a camera refracts light onto film. If the image is not focused exactly on the retina then the image will be blurred just like an out-of-focus photograph.
There are four major refractive errors: