Contact lenses are medical devices that rest on the eyes directly to provide better vision, which is a tremendous scientific accomplishment when you think about it. Contact lens technology has evolved so much that wearers only have to choose between daily vs. monthly contacts, disposable vs. non-disposable, daily wear vs. extended wear, among other types of contacts.
Contact lenses were not always this easy to use, and like other health products, they have undergone centuries of evolution and improvement to become the convenient, comfortable medical devices they are today.
History of Contact Lenses
It is challenging to credit a single individual with inventing contact lenses. However, we can trace the history of contact lenses to famous Italian mathematician and inventor Leonardo da Vinci whose early illustrations in his 1508 "Codex of the Eye" suggested that the human eye could be altered by placing the cornea in a bowl of water.
He created a glass lens with a funnel on one side so that water could be poured into it. Da Vinci's model was impractical and probably ridiculous at the time, but it was the beginning of something revolutionary.
French scientist Rene Descartes reviewed da Vinci's work in 1638 and proposed placing a glass tube filled with liquid in direct contact with the cornea. Contact lenses get their name from this idea as they make direct contact with the eye's surface. Descartes' model improved vision but made blinking impossible. The works of Leonardo da Vinci and Rene Descartes were the springboards for subsequent contact designs 200 years later.
In 1801, English scientist Thomas Young, attempting to improve Descartes' idea, reduced the glass tube size to a quarter of an inch and used wax to stick the water-filled lenses to his eyeballs. Young's attempt was also impractical and did not improve vision.
Another Englishman, Sir John Herschel, was the first to conceptualize a practical contact lens design when he posited that contact lens designs that take the shape of the cornea might improve vision. However, available technology then made it impossible for Herschel to test his hypothesis.
The First Functional Contact Lenses
With improving technology towards the end of the 19th century, designs for contact lenses that could fit the eye and allow blinking began to materialize. Advances in glass cutting and production made the manufacture of thin lenses that could improve vision with minimal discomfort.
Swiss doctor Adolf Fick described contact lenses with refractive power for visual improvement in 1888. Fick was the first to fit contact lenses using blown glass successfully.
These glasses could only be worn for a few hours daily and were twice the size of modern contacts. The blown glass materials were heavy and uncomfortable, and they also covered the entire eye, making it impossible for oxygen to get into the eye.
German artificial eye-maker F.A Muller corrected his myopia with the first scleral lenses. Muller's lenses were lighter than Fick's and also covered the entire eye.
The oxygen supply problems to the eyes remained until the 1920s when advances in material manufacture fostered the development of lenses that allowed oxygen permeability. The creation of malleable, lightweight plastic materials led to the development of highly functional contact lenses.
In 1948, English optical technician Kevin Touhy became the first to introduce contact lenses similar to modern gas permeable lenses. Touhy's lenses were known as corneal contact lenses as they were smaller than other types of contacts and covered only the clear front surface of the eye.
The 1950s and 1960s saw the creation of thinner lenses. These lenses, despite their improvements, still did not allow sufficient oxygen into the eye, so wearers could not use them for extended periods.
The Development of the Modern Contact Lens
Today's contact lenses allow an unhindered oxygen flow into the eyes and can be worn for days to weeks continuously. The development of modern contacts began with the discovery of hydrogel plastic by Czech chemists Otto Wichterle and Drahoslav Lim. This plastic was soft and pliable when wet, and its potential for contact lens manufacture was quickly recognized.
Bausch and Lomb obtained the patent to hydrogel plastic in 1965, and using a refined casting technique, they developed a consistent lens surface and devised a system for mass production.
In 1971, the FDA approved hydrogel soft contact lenses for sale in the United States. Rigid gas permeable lenses, extended-wear contacts, and bifocal contact lenses followed in subsequent years, and by 1987, disposable contact lenses had launched on the market.
In 1998, the first silicone hydrogel lenses were released by Ciba Vision in Mexico. Silicone hydrogel offers improved oxygen permeability and is more comfortable than hydrogel lenses. These lenses entered the American market in 2002, and in the same year, overnight orthokeratology (ortho-k) came to the fore.
Ortho-k is the fitting of special gas permeable lenses worn overnight to reshape the cornea for improved vision after removing the lenses. It corrects refractive errors and slows the progression of childhood myopia.
The Future of Contact Lenses
As technology continues to improve, the future of contact lenses holds a lot of promise. Diagnostic biomarkers in tears can point to specific diseases like diabetes, cancer, glaucoma, and Alzheimer's disease. Contact lenses of the future will contain sensing technologies that would increase the potential for early disease detection and improve patient outcomes.
Drug-releasing contact lenses will also be used to administer medications for ocular disease with more precision than eye drops. They will address challenges of patient compliance with ocular disease treatments that require frequent dosing and eliminate problems associated with eye drops such as tear dilution and non-specific absorption.
The contact lenses of the not-too-distant future will integrate optical components that will allow them to be used for other non-medical reasons. Think of a contact lens that doubles as a screen providing real-time information right in front of your eyes. These smart contacts will be able to detect road signs and display them clearly to users.
Smart contact lenses are likely first to be applied as visual aids to people with poor vision, but they will also join the range of consumer wearable smart devices for navigation, entertainment, social media, and instant messaging.
* This is a contributed article and this content does not necessarily represent the views of sciencetimes.com
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