July 30, 2009 
Dream lens, dream vision and ortho-k, these terms are used to delineate orthokeratology, which is firm gas-permeable contact lenses, usually worn during the night to enhance or improve eyesight or vision by reshaping one’s cornea…
Instead of having eyeglasses, wearing contact lenses throughout the day or undergoing refractive surgery, you can use this method to achieve a clear vision enough to perform your responsibilities during the day. Eye doctors actually discovered the reshaping of the cornea eye treatment by using glass lenses during the 1940s. The early designs of ortho-k exhibited irregular and unpredictable outcomes, resulting to the belief of many that this process is not effective. But now that computers and measuring instruments are widely available, the theory of special overnight lenses in reshaping the cornea created new designs that present effective and repeatable results.
Most people assume that the special overnight lenses utilized in ortho-k reshape the eye’s cornea by budging the epithelial cells that envelop the cornea’s surface. Several studies suggest that the epithelial cells pack together in some regions and may also be repositioned. One of the usual misconceptions in the special overnight lenses design is that they force down on the cornea and eventually flatten the eye. In real fact, the idea that the compelling forces produced by the reverse curve result to the epithelial cells redistributions and not pressure on the eye. An appropriate design of lenses should not be in contact with the patient’s cornea.
Orthokeratology lenses are being manufactured by many companies, through the facilitation of one of two Food and Drugs Administration’s (FDA) approved technologies. All of which, make use of special gas-permeable eye lenses to reshape the cornea. The material used in the lens is a vital factor for keeping the eye’s condition and health during the treatment term.
It’s important to note that there are only few brands of ortho-k special lenses that have been authorized by the FDA to be worn overnight. Eye doctors may devise the shape of the lens using the principles of ortho-k. This is made possible by different systems and software packages, which help in designing the lenses while creating the appropriate changes on the eye.
Though many people have been taking advantage of this eye treatment especially those who have Myopia or nearsightedness, there are some side-effects the lenses can give the wearer like blinding complications. These most of the time happen because of the patient’s failure to strictly follow the use of tap water when rinsing and not performing proper hygiene. Other health complications may take place because of lack of oxygen in the eye or relative corneal hypoxia brought about by prolonged use or the lenses were made from wrong or inappropriate materials.
When using orthokeratology for eye vision problems like Myopia or nearsightedness, it’s important to check if the lenses are made from high oxygen-permeable materials, which lessen hypoxia. This will also prevent users from experiencing other side effects due to overly huge pupil size such as double vision, ghosting, star bursting and contrast quandaries particularly during night time.
Takren from: http://www.ezinearticles.com