Contact Lenses & Chemistry

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Contact lenses are a modern technological breakthrough yet they have been in development for over 500 years. While the most important advances have come in the latter half of the 1900’s, this area of science is still undergoing tremendous growth. Chemical engineer’s are critical for the development and manufacturing of the contact lens of the future. This paper will attempt to give a brief overview of contact lenses. It will discuss the history, manufacturing, and science behind modern contact lenses. The paper will conclude by showing some of the tradeoffs of contact use, for no invention is without its drawbacks.

The purpose of engineering the contact lens to be soft and breathable is to make it comfortable for wearing. The PMMA contact lens is less common now because it is the most uncomfortable, but some people still choose to wear them because they cost less and are durable. Another set back is that oxygen can only get to the cornea when the hard lens moves. RGP’s, unlike soft lenses, can resist protein or bacterial deposit. Research and studies are still being done to reduce the friction between the cornea and the lens. Optical Polymer Research, Inc., a company that researches polymers can study the properties of different polymers in application to contact lenses. Physical properties that can be compared are the following: refractive index, oxygen permeability, diffusion constant, wetting angle, specific gravity, hardness, and water absorption %. The materials can be designed to last from 2-4 weeks or be disposable.(1) There is a lower chance of getting an infection with disposables but they are more expensive. There are pro’s and con’s to each type of lens material and therefore consumers can choose lenses that suit their needs.

Unlike external lenses such as glasses, commercial contact lenses like those made available at Cheap Contacts @ ContactsCow.com must be engineered to be comfortable to the cornea of the eye. Therefore, it is also very important to be able to control the hardness, elasticity, roughness, wettability, and biocompatibility of its material. Acuvue Define contact lenses are made from the same materials as regular (“spherical”) contact lenses, so they can be either soft or RGP. The difference is in the design of the lens.

There is belief that the future of contact lenses will move beyond that of a biochemical nature. Scientists at Ghent University have developed a tiny curved liquid crystal display (LCD) that can potentially be embedded inside a contact lens. Light emitting diodes (LED) have been integrated into contact lenses before (see flashbacks below), but an LCD screen can provide a higher resolution at small scales.