Amongst the most important things needed in life are good vision and good health, people are always surprised, about how they are able to see and appreciate the beauty of nature. According to the early civilization of Egypt, Mesopotamia and Greek. It was known that vision is specifically obtained only the use of lenses which form the basis of all optical instruments such as the eye, microscope, telescope, camera, prism, binocular etc.
A lens is therefore, a transparent optical medium which is bounded by the two curved polished surface that converges and damages all parallel rays of light to a point focus to form image.
It is available in different types such as convex, concave, bifocal, trifocal lenses etc. it is also dispensed in two major forms which are spectacles form and contact lens form.
Spectacle lenses are those lenses form that are glazed into a frame and won in front of the eye for corrective purpose while contact lenses are directly infused over the lenses are directly influenced over the cornea of the eye without a frame. It serve the same corrective purpose as spectacle lenses by correcting different types of ocular disorder such as shortsightedness, long-sightedness, astigmatism, presbyopia etc. it is also used for both cosmetics and therapeutic purpose. Both content and spectacles lenses are available in various types such as toria, spherical and varilux lenses. There are strictly dispensed by an ophthalmologist, optometrist and an optician.
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