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Fashion industry is brimming with new trends one of them is the use of contact lenses. Youngsters today prefer varied eye colors for different appearances. This has created a strong demand for disposable contact lenses or soft lenses in the market. Disposable lenses come in variety of replacement options. Replacement refers to how frequently the contact lenses could be changed. Daily disposable lenses are to be changed daily. Disposable (daily wear) have a replacement duration of 14 days or two weeks. Seven day extended wear lenses are to be replaced after a week . Planned or frequent replacement lenses are to be changed after one or more months depending upon the brand. The conventional contact lenses are replaced after an year. These replacement durations are very general n nature and vary according to the amount of lipid; the proteins; produced by the eyes.

Earlier cleaning of lens was a tedious job with various solutions. With passage of time lens manufacturers developed better quality lenses and lens solutions that are easier to use. Lenses protect eyes from UV rays of sun. UV rays from the sun are associated with formation of cataracts. Excessive exposure to UV rays leads to photokeratitis. It is a condition in which the sun burn is caused to cornea of eye leading to temporary vision blindness known as “snow blindness”. It is easy to find whether a lens is UV blocker or not. UV protection layer is clearly visible on a lens. Also, the packaging of the lens clearly states if the lens is UV protected or not. However, these lenses only cover the cornea of the eye for protecting the other parts of eye from sun it is essential to make use of sunglasses.

Also, the 30 day continuous wear lenses are back in market. They are made up of better material than they were earlier. They allow a lot more amount of oxygen to reach the eye even when you are wearing the lenses. Thereby making them much safer and convenient to use. A few manufacturers are also making bifocal & toric lenses in disposable styles in addition to the conventional styles that last from one to several years.

The replacement schedule of a lens depends on whether i can be worn during sleep or not. There are lenses that have the caliber of correcting vision. This is known as corneal refractive therapy. Under this therapy special contact lenses are worn during night when you sleep. These lenses reshape the eyes in order to improve your vision. As a result you can see even when you are not wearing them.

The concept of lenses made from silicone hydrogel was first proposed over 20 years ago. The potential benefits were clear but the technological challenge was as difficult as needing to combine oil and water to produce an optically clear product. Researcher organizations have to date invested considerable academic and financial resources to achieve the high performance soft lenses of today. They have done this quite simply because they see this material as the way forward and the ultimate standard of the future.

At the time of writing, silicone hydrogel lenses are available in the USA from four manufacturers: “Night & Day” and “O2OPTIX” from CIBA Vision, “Pure Vision” from Bausch & Lomb, and “Acuvue OASYS” and “Advance” from J&J Vision Care.

OXYGEN TRANSPORT

So what’s so special about silicone hydrogel as a lens material? Essentially, the great benefit of this material is it’s ability to transport oxygen to the eye and thus maintain proper eye health. Modern contact lens technology is all to do with oxygen permability, which is measured using the “Dk” index. And for optimal oxygen transmission, this must be as high as possible.

The Dk of traditional, non-silicone based hydrogel lenses is directly related to the amount of water that the material can hold, since oxygen dissolves into the water-component of the material and thus diffuses through the lens. The Dk in fact increases logarithmically with increasing water content. Water itself has a Dk of only 80, thus placing a ceiling on the Dk of convential materials, and the original soft contact lens material, polyHEMA, possesses a Dk of only around 10 (with a water content of about 38%).

However, in silicone hydrogels, the relationship between Dk and water content is the opposite. Here higher water content implies lower Dk. With these lenses Dk increases significantly as the silicone content – not water content – of the lens increases. The Dk values of silicone hydrogel contact lenses are much higher than those of older soft lens materials.

SLEEPING IN CONTACT LENSES

According to market data from CIBA Vision, 84% of soft contact lens wearers occasionally sleep with their lenses in, and one-third admit to doing this regularly. 25% of wearers of one to two-week disposable lenses with low oxygen transmissibility occasionally or routinely sleep in their lenses overnight. And 72% of soft contact lens wearers said they would prefer to be allowed to wear their lenses overnight provided it was safe.

Thus the demand for lenses with the capablities of silicone hydrogels is evidently very high with almost three-quarters of soft lens wearers wanting to be able to sleep in their lenses.

LENS HANDLING

Silicone hydrogel lenses are significantly more rigid than their conventional counterparts, due to the presence of silicone. This increased rigidity does possess some advantages, making the lenses markedly easier to handle and thus the ideal choice for wearers with a less delicate touch. There is a downside to this however in that the rigidity makes the lenses less prone to adopting the shape of the eye so readily, resulting in the possibility for some of reduced comfort.

REDUCED DEPOSITIONS

Historically, the deposition of proteins and lipids has been a problem with contact lenses. The amount of depositions is essentially linked to the duration of wear, the lens material and the tear composition of each individual wearer. With traditional lenses, a frequent replacement schedule greatly reduces the buildup of harmful deposits.

Silicone hydrogel contact lenses have been proven to offer major benefits in the reduction of protein and lysozyme deposition. Indeed, combined with the correct replacement schedule and appropriate care system, problems associated with protein deposition have become almost a thing of the past.

DRY EYES

A problem frequently encountered by wearers of traditional soft contact lenses is one of a feeling of discomfort and “grittiness” in the eyes towards the end of the day. It has been reported that after one week wearing silicone hydrogel lenses, the quantity of regular soft lens wearers in a particular study group who previously suffered significantly from end-of-day dryness, was reduced dramatically to only 13% of the sample.

LIFESTYLE BENEFITS

Silicone hydrogel contact lenses also provide some benefits that conventional lenses don’t. Continuous wear contact lenses can be particularly beneficial for use by members of certain professions, such as medical workers, police, the armed forces and firefighters who frequently work unpredictable and long hours.

Furthermore, an increasing numbers of contact lens wearers can now enjoy active outdoor lifestyles, enjoying pursuits such as camping and hiking where it is often difficult to handle and disinfect the lenses with the appropriate level of hygiene.

THE FUTURE FOR CONTACT LENSES

There is much evidence to suggest that, owing to their significant benefits over conventional soft lenses, silicone hydrogel lenses will ultimately, and sooner rather than later, displace other types of contact lens as the prefferred choice for both daily and overnight wear for the majority of contact lens wearers. Silicone hydrogel lenses provide a much improved physical performance, excellent handling properties and greater comfort. They might be considered as the ideal lens for general purpose use that exists today and are likely to become the new everyday standard.

Every first timer who makes use of contact lenses for eyes goes through a series of questions. “ Are lenses suitable for me ? ” or “ How do I wear them ? “ or “ How do I clean my lenses” these are just a few of numerous queries that people have related to the use of lenses. Once you have made your mind in favor of contact lenses the very first step that you must take is to visit your ophthalmologist. An ophthalmologist is commonly known as an “ Eye Specialist”. He would thoroughly check your eyesight and prescribe the perfect set of lenses for your beautiful eyes. In addition to the prescription he would also guide you through use , replacement, cleaning and protection of lenses. He is your best judge in adoption & replacement of lenses.

When wearing contact lenses for the first time you might be amused thinking about which side is the correct one to wear. If you are among the lucky few who can read the laser imprint you would not require a guide to help you through the process. But if your lens has not got a laser imprint over it then the easiest way to locate the wearable side of the contact lens is to hold it on your finger tip. Make sure you wash your hands thoroughly every time before touching your lenses this secures them from unnecessary harmful deposits. When held over finger tip if the contact lens forms a “U” shape with the edges extended outwards its inside out. You must reverse it before wearing. A contact lens if worn from the wrong side would not do any harm but would be uncomfortable. A contact lens wearable side is when it forms a simple “U” shape with it edges not flaring outwards.

A wide range of contact lenses is available in market. You can expect to have a hard time deciding. All the contact lenses can be condensed under categories depending upon various factors like wear ability, replacement and composition. Based on composition contact lenses come in two broad categories namely soft and rigid gas permeable. Soft lenses are easy to adapt and wear as they contain 25 % to 80% water but are not usually durable. Rigid gas permeable lenses on the other hand are more durable however it takes time to adapt to them. Rigid lenses in some cases offer better vision to individuals than soft contact lenses. There upright payment is mostly higher as they can be used for several years. In case of soft lenses they can be replaced on daily, weekly, monthly and after 1 year. Contact lenses in which one can sleep are known as extended wear lens others are daily wear.