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Contact lens

Contact lenses are used primarily to replace glasses as a way to adjust someone’s vision. The contact lens fits over the cornea of the eye and becomes nearly invisible.

Many people prefer to use contact lenses (also referred to as "contacts") instead of glasses for many reasons: they are nearly invisible, offer a better field of vision, do not fog up in humid conditions.

Adolf Eugen Fick (1829-1901) from Germany invented the first contact lens prototype in 1887.  A thick contact shell made of glass was initially made to rest on the tissue around the cornea. A solution of grape sugar filled the space between the glass and the cornea. After successful testing, he was able to produce a glass-blown version of his invention to correct his own myopia in 1888.

This kind of contact lens was used until the 1930s, before perspex / plexiglas (PMMA) versions were introduced. The fist contact lenses to fit directly over the cornea only appeared in the 1950s. Ten years later, production technology gave contact lenses a much more precise fit and better comfort, which lead to a great increase in their popularity.

Oxygen permeable contacts appeared in the 1980s but they were still made with rigid materials. Soft lenses were already used since the 1960s but it took many years before polymer materials used in these contact lenses for better oxygen permeability.

Silicone-based hydrogel contact lenses were introduced at the end of the 1990s and offered better oxygen permeability and overnight wear.

Rigid contact lenses offer the advantage of correcting vision for people suffering from astigmatism or distorted cornea, since these contact lenses can be made to give the proper shape which is not naturally present.

The latest silicone hydrogels, with extremely high oxygen permeability, have helped the development of extended wear periods that can now reach a month. These lens are getting more popular for their simple, easy to use characteristics.

However, corneal infections are more common in extended wear contact lenses, mostly because of improper care. For this reason, some people prefer single-use contact lenses.

People suffering from astigmatism can be prescribed with toric lens, a type of contact lens which is made specifically to correct both spherical and cylindrical anomalies. Toric lens have different shape at the top and bottom so they must be worn only in a specific orientation. Acuvue contact discount lens.

Prescription of contact lenses are prepared by an optometrist (or ophthalmologist in some European countries). The prescription includes information about the brand, center thickness, base curve radius, cylinder axis, material and optical power.  

These days cosmetic cheap contact lenses, used mostly to give a special look to the eyes, are extremely popular.  There are the colored contact which can change the natural color of the eye but also create special designs with crazy styles and strange colors. 

Almost 10% of contact lens users will suffer from various wear problems. These complications may include eyelid ptosis, some forms of conjunctiva and corneal abrasion and erosion, among others. Fungal eye infections – especially with extended wear lenses – are also problematic.

The best way to avoid infection is to make sure your hands are properly cleaned and disinfected before touching your contacts. As for cleaning and disinfecting the contact lenses, many different kind of solutions are available: daily cleaner, enzymatic cleaner, daily cleaner, hydrogen peroxide solution, saline solution and multipurpose solution.

Major manufacturers of contact lenses are Bausch & Lomb, CooperVision, CIBA Vision and Johnson & Johnson. Some of the most popular contact name brands are Acuvue (with Advance and Oasys lines with Ultraviolet (UV) protection), 02 Optix, PureVision, Focus, Soflens and Biomedics.

 

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