Myopia, also called nearsightedess, is a condition where close objects can be seen clearly but distant objects cannot. Myopia is increasing in the population at an alarming rate. According to the National Institutes of Health in 1972, the frequency of myopia was 25% in Americans aged 12 to 54. By 2004, it had increased to 41.6%. (Roan,2010).
Myopia ocurrs when the eyeball is too long or the cornea has too much curvature. When this happens, the light entering the eye is not focused properly, resulting in blurry vision. Myopia may be hereditary or it may occur spontaneously.
Even worse than the increasing frequency of myopia is that for affected individuals it has a tendency to get worse over time. This means that an individuals eyeglasses prescription will increase over time and the individual will become more dependant on eyeglasses, contact lenses or other forms of vision correction. Corrective lenses may fix a myope's blurry vision but myopia is far more dangerous than blurry vision.
Myopia can lead to blindness due to the adverse ocular changes associated with it. Myopia causes abnormal stretching or elongation of the eye which can cause thinning and weakening of the retina (the thin membrane at the back of the eye that contains the cells that send visual information to the brain). This elongation may pull on the vitreous (the gel substance that fills the eye) which in turn pulls on the retina. This proces can cause a retinal detatchment - a medical emergency requiring immediate surgery. A detached retina can lead to blindness.
Another problem associated with myopia is glaucoma. Moderate to highly myopic people are twice as likely to develop glaucoma. (Mitchell 2000). Threfore, it is important for myopic individuals to see thier optometrist regularly to ensure that glaucoma is not developing.
Because of the dangers of myopia, scientists have been working on ways to stop myopia progression. Orthokeratology is one solution that has been shown to be effective in a number of studies from around the world. Orthokeratology is a treatment where the patient wears a night-time retainer lens while sleeping. The retainer changes the shape of the cornea so that the patient experiences clear vision during the day. In addition to being an alternative to glasses, contacts and laser surgery, orthokeratology retainers can slow or stop the progression of myopia.