Nearsightedness (myopia) is a vision ability to clearly see objects up close but not those at a distance. Myopia is very common. It affects children and adults equally. Myopia occurs when the eyeball is slightly longer than usual from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on its surface, your vision becomes blurred.

There are three levels of nearsightedness:

• Mild myopia - less than - 3.00 diopters
• Moderate myopia - 3.00 to 6.00 diopters
• High myopia - 6.00 diopters and up

There are many factors that cause the development of nearsightedness:

• too much close work can cause nearsightedness
• genetic factors
• weakened sclera that can't resist the excessive growth of the eye

When the muscle that control accomodation is not fully developed, its overtension can lead to development of myopia. As usual nearsightedness appears in childhood and increases as the eye grows in length during puberty. Myopia affects the far vision and the night vision equally. The treatment for nearsightedness includes contact lenses or glasses. But glasses can't stop progressing of nearsightedness, they only correct the process of refraction. Those who become myopic may develop myopia and feel ''handicapped'' by the need to wear glasses. It means that nearsightedness gets progressively greater over time. This occurs because the eyeball is too long and progressing myopia requires surgical treatment.

Myopia treatment

• scleroplasty - plastic surgery of the sclera, stops progressing of nearsightedness
• prevention of possible complications (laser treatment that helps strengthen the retina)
• refractive surgery can reduce or even eliminate your need for glasses or contacts. The most common procedures are performed with an eximer laser (PRK- photorefractive keratectomy. LASIK - laser-assisted in situ keratomileusis)

LONGSIGHTEDNESS

Longsightedness (hypermetropia) is a defect of vision caused by an imperfection in the eye, causing inability to focus on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any distance.

Longsightedness is often present from birth, but with aging the eye grows. There is normal variation in eyeball length. But when the eye stops to grow, its length is too short and a person becomes hyperopic. This type of hypermetropia is called axial.

But in some cases the cornea and the lens are too weak to refract the light. This causes light to come to a focus behind the retina. This type of hypermetropia is called refractive.

There are three levels of longsightedness:

• Mild - less than 3 dioptres
• Moderate - 3-6 dioptres
• High - more than 6 dioptres

A little hypermetropia is not a problem because the eye can compensate easily. Young people are often able to see clearly because their eyes can accomodate to increase the eye's focusing ability. Older people or people with significant hypermetropia often have problems because focusing requires more effort and they usually need spectacles or contact lenses. But hyperopic people may get tired eyes after a lot of visual work. Hyperopic people have problems with stereoscopic vision, they are at risk of developing a squint and vision loss.

Hypermetropia treatment

• refractive surgery can correct hypermetropia. It may reduce or eliminate your need to wear glasses or contact lenses
• prevention and treatment of complications after hypermetropia - squint, ambliopy (different kinds of stimulation etc)
• surgical correction of squint