Someone with myopia is near sighted

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Myopia Introduction

Myopia is one of the two most frequently experienced of eye problems. Myopia is known as nearsightedness. The disorder is caused by refractive errors of the eye which means that the eye cannot focus correctly.

Refractive disorders of the eye

When the eye fails to refract light properly for focusing on the fovea of the retina it is commonly called a refractive disorder. In medical eye care terms it refers to the thickness of the eye lens.

Refraction takes place when light travels through a medium of greater density. Normally light travels in a straight line however when it hits a flat surface, such as the cornea lens, it travels at an angle.

When light travels into the cornea, the difference in density between the outside air and the cornea of your eye causes the light to refract. The lens of the eye accordingly adjusts in order to focus the refracted light from various distances and objects and focus it onto the retina.

The eye lens

The refractive power of an eye lens is calculated in dioptres (D).

There are mainly two groups of lenses:

  • A 'plus' lens is convex and focuses light inwards to the retina
  • A 'minus' lens is concave and sheds light outwards away from the retina

The higher the calculation of the dioptre of a lens, the stronger is its power in either plus or minus count.

Myopia or Shortsightedness

Myopia is measured in minus counts as the eye’s focusing power is stronger than needed and is bending light inwards towards the retina. Hence, the eye power must be corrected with minus power lenses. Severe myopia can lead to severe complications like retinal detachment and injury.

Clinical signs of myopia

A swelling or bulging of the eyeball marks myopia. This is called the development of the myopic crescent. Aside from nearsightedness this irregularity of the eyeball and lens can also signified chorioldal and retinal degenerative transformation, glaucoma, staphyloma and detached retina.

Different types of myopia

There are three categories of Myopia:

  1. Low Myopia also known as =2D Myopia. This type is also called School or Physiological Myopia.
  2. Moderate myopia also known as the 2–6D type
  3. High Myopia which is also known as the >6D type or high myopia. It is also sometimes termed as pathological myopia.

Physiological or school myopia

If myopia is caused by stress it is called is called Physiological or School or =2D type Myopia. This low myopic condition is the most commonly diagnosed type of near sightedness. It is often caused by stressful habits like excessive reading from an early age. Statistics show that over sixty percent of the medical school students experience this type of myopia.

However, your disposition towards developing this type of low myopia might depend on race and ethnicity. Research indicates that it is more common in Asians and Jews. Often it is both a combination of genetics and stress that result in near sightedness.

Treatment for myopia

The treatment of myopia necessitates refractive correction of the cornea Wearing bifocals is the most common solutions. Sometimes atropine eye drops are used to correct severe cases. Contact lenses and laser technology that alters the shape of the eyeball can also be employed for treatment of myopia.

Pathological myopia or high myopia

This is the other less common kind of myopia that is also known as the >6D type or high myopia. Certain studies have revealed that two to three percent of the population suffer from this form of nearsightedness.