The cornea is a transparent layer located at the front of the eye and is responsible for focusing the rays reaching the eye onto the retina layer. If the rays entering the eye cannot be focused sharply on the retina layer due to irregularities in the shape of the cornea layer or the eyeball, the resulting image will be blurry.

These disorders in the focusing power of the eye are called refractive errors, and there are three basic refractive errors. These are myopia, hyperopia and astigmatism. Myopia: It is the condition where parallel rays coming to the eye focus in front of the retina. Myopes cannot see far away clearly. However, it is good for them to see up close.

Myopia

It occurs when the corneal layer is steeper than normal or the front-back diameter of the eye is larger than normal. Myopia up to 6 degrees is called simple myopia, and those higher are called high myopia. High myopia continues to increase after the age of 20 and results in thinning of the retina layer and decreased vision. Myopia is largely related to genetic structure. It is usually noticed in childhood, between the ages of 8-12. There may be no similarity in terms of myopia between family members.

Hypermetropia

It is a condition in which parallel rays coming to the eye focus behind the retina. Hypermetropia have difficulty seeing especially close-up vision. If the degree of hyperopia is high, these patients will have difficulty seeing far away. Hypermetropia occurs when the corneal layer is flat or the front-back diameter of the eye is small. The development of hypermetropia is largely hereditary. However, there may be no similarity in terms of hyperopia between family members.

Astigmatism

It is a condition in which a single focal point is not formed due to the eye refracting the rays differently in different meridians. These patients have problems with both distance and near vision. In hypermetropia, different axes of the corneal layer generally have different curvatures. Astigmatism can be seen together with myopia and hypermetropia. Astigmatism is also largely related to genetic structure. Again, there may be no similarity in astigmatism between family members. Presbyopia: In young people, the eye lens is soft and flexible. It easily changes its shape and allows us to focus on distant and near objects. However, the eye lens hardens and loses its flexibility after the age of 40. Due to loss of flexibility, near vision and reading become difficult. This normal condition is called presbyopia.

Refractive Surgery:Refractive surgery deals with the advanced diagnosis and treatment of diseases of the cornea, the most prominent transparent layer of the eye. The most appropriate method in refractive surgery varies from person to person and depending on many factors. Age, refractive error and degree, patient’s personality and expectation limits determine the type of surgery. Current refractive surgery techniques include:

• LASIK
• LASEK
• İLASİK
• PRK
• PTK
• WAVEFRONT