What do you know about ‘CONTACT LENSES’?

If you put your face in the water, you would see things differently.  Interestingly, Leonardo Da Vinci published this idea in his manual on manipulating cornea’s power in 1509. Then 300 years later the concept of correcting vision through wearable contact lenses emerged.  The Idea was nice, but technology was not available (scientists at that time tried several crazy methods involving ‘animal jelly’ as well). Finally in 1887, some glass shells were invented by Adolph Fick with an aim to treat patients with Keratoconus (cone-shaped cornea). But these glass shells had two problems, it was too big and eyes could not get oxygen through glass. (That is why glass should be used as windows to block wind, and not something you put in your eyes!)

But hey, did you know contact lenses were originally invented for medical use? A year after Pakistan’s independence, PMMA (hard) contact lenses were accidently discovered and designed by Kevin Tuohy, still with an aim to treat eyes with Keratoconus. The material was not yet ideal (no oxygen transmittability), but the size was smaller and it certainly appealed to the market. In 1954 a British man Woodly started to use it not just for treatment purpose but also cosmetic purpose!

The trend of using contact lenses to improve appearance propelled the invention of a new type of lenses in 1971. This breakthrough was softlens, made from hydrogel material. It was more comfortable than hard lenses. Scientists who manufactured hard lenses in response developed a range of new material which allowed more oxygen to penetrate the structure of chemical composition. And these lenses are now called Rigid Gas Permeable (RGP) lenses, approved by FDA in 1978.  Technology continued to improve, in 1981 and 1986, FDA approved extended wear (overnight wear) of soft lenses and RGP lenses. It means that people had the option to sleep with their lenses!

Being a relatively younger product than hard contact lenses, soft contact lenses have become a more popular choice for refractive correction. The reason for that mainly due to the immediate comfort and the natural feeling whereas a short adaption period is required for hard/RGP lenses. The soft lenses users also increase with the invention of decorative lenses, which are used to change iris colors for festivals or cosmetic reasons.

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But has hard lenses lost its market? Not at all.  Although soft contact lenses are comfortable, they may not be healthy for your eyes. Your eyes need oxygen (remember the crazy glass shells invented by Fick?). There are countless options of lenses even within one company with different pricing strategy, but the most important thing is to know the designed wearing schedule. For instance, if a lens is designed to be disposed after two-week, you are risking your health if you intentionally or unintentionally extended the replacement schedule. And the most common mistake is forgetting to take out lenses before sleep, such consecutive wear can cause hypoxia (lack of oxygen for eyes). In long term your eyes may become too sensitive or dry, and you will not be able to tolerate even wearing soft contact lenses.   There are many adverse events on usage of soft contact lenses such as infection, allergy, dryness, inflammation, ulcer, neovascularization, or giant papillary conjunctivitis due to careless instruction at over-the-counter sale.

Hard/RGP lenses is a better solution in long term. The benefits include higher gas permeability rate which provide adequate oxygen to your cornea for your eye to be healthy, control of myopia progression which stops you eyesight getting worse, correction of high astigmatism or refractive error due to irregular corneas, safety for kids younger than 13, better vision quality, less allergic problem, easier to maintain, longer useful life than soft lenses, and in the case of overnight ortho-k lenses (also a type of RGP lenses), there is a temporary reduction of myopia after 8 hours wear during sleep for 100% freedom from glasses or lenses during the day.

The concept of Orthokeratology (ortho-k), a corneal reshaping treatment emerged in 1960s. The idea was to flatten the cornea to achieve a temporary 6/6 vision. But PMMA was the only available material at that time, and is was till the arrival of new technology that made this vision reshaping treatment more effective and predictable. Ortho-k can now reduce upto -6.00D without performing a surgery. FDA approved this treatment in 1994 before laser surgery was approved, and in 2002 again for overnight wear.

In summary, soft lenses is more for cosmetic use, but it is not good for long term and can cause complication. Hard contact lenses was created for medical use, and for myopic people who don’t like wearing lenses during the day, there is overnight ortho-k treatment, which indeed is a safer and healthier solution for long term.

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soft lenses

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