Since the beginning of the 70s there are surgical procedures for changing the refractive power of the eye. (refractive surgery.) Perfect vision without glasses or contacts can be achieved. There are procedures corcerning the cornea (LASIK, PRK, intracorneal ringsegments (ICRS), other procedures concern the lens of the eye. We will try to give you a general idea about the optical fundamentals of the eye and the possible methodes for changing the refractive power of the eye as we are offering them to you in our clinic.

What is a refractive error?


The emmetropic eye:
Light is transmitted through the cornea (1) and the lens (2) and ist converged in one point (3, so called focal point) so as to create a sharp picture of the outside world.

In the normal sound eye lightrays are refracted by the cornea and the lens in such a way that they converge in a single point on the retina. (focal point. See image) This is not the case in an eye with a refractive error. In the myopic eye the focal point is situated in front of the retina, in the hyperope eye the focal point lies behind the retina. Consequently vision is blurred. In an astigmatic eye vision is distorted. An eye that is too short or too long causes a refractive error, as does an astigmatism. The next images will clarify to you the kind of visual image that is caused by an uncorrected refractive error.

Myopia: The image of the nearby book is sharp, the background is blurred. The patient needs glasses for ths distance. The patient is myope.. Example >

Hyperopia: The image of the book is blurred, the background is sharp. The patient needs reading glasses. The patient is hyperope. Example >

Astigmatism: The book and the distance both are distorted. The patient has trouble seeing nearby as well as in the distance. The patient needs glasses for near and distant vision. Example >

Up to recent times the correction of a refractive error was performed with glasses or contact lenses. Performing a surgical correction of the corneal shape, or by implanting an additional lens into the eye enables us today to compensate for the refractive error completely and permanently.

How about presbyopia?

Presbyopia is a perfectly natural effect of aging. Normally the lens gradually looses the main part of its elasticity from the age of 40. The ability to focus on near objects is lost. The ability to read without glasses is reduced. Reading glassses or bifocals respectively multifocals are necessary to facilitate reading. Because none of the procedures described in the following takes any influence on the lens of the eye, patients that underwent these treatments in their younger years will experience presbyopia later in life. They will need reading glasses.