A contact lens is a lightweight corrective, cosmetic or healing device that is usually placed directly onto the cornea of the eye. Contact lenses have many benefits for wearers, including appearance and practicality.
Many people choose to wear contact lenses as opposed to spectacles because they do not steam up, they give you a wider field of vision, and they are more suitable for a number of sporting activities.
Contact lenses vary according to construction materials, wear time, replacement schedule, and design. In the United States, contact lenses are considered medical devices and require a prescription by a qualified eyecare practitioner. If you're looking for contact lenses in Toronto, you can browse various online sources.
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First Contact Lens Designs
Although we think of contact lenses as a modern invention, this concept was first developed by Leonardo da Vinci. Five hundred years ago, he drew a diagram showing how the eye's refractive power can be changed by direct contact with water.
Years later, the inventor thought of putting the glass on the eye to change the way our eyes are focused. their ideas may far ahead have their own materials and manufacturing methods are available for those we have today.
About 120 years ago scientists in Germany made the first contact lenses of glass. They are called scleral lenses because they just do not sit on the cornea, the clear dome-like structure at the front of the eye, but on the whole the white part (sclera) of the eye.
Rigid lenses
Around 1940, he developed the first plastic lens which sits just on the cornea. This plastic is made of PMMA (polymethyl methacrylate).
Because the lens is very small, it seems to be more comfortable. These lenses do not allow oxygen to pass through as well and in the 1970's rigid gas permeable designed to address this problem.