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Refractive Surgery — Other Procedures
Astigmatic Keratotomy (AK)
AK is used for the correction of severe to extreme astigmatism as it may occur after a corneal transplant or after perforating eye injury. The curvature of the cornea is reduced by placing small, arch-shaped incisions at the cornea.
Indication
— Astigmatism exceeding 3 diopter
Properties
— sensitivity and slight pain may occur after surgery
— correction outside of the optic center
— immediate effect
— vision fluctuations may occur for several weeks
— irreversibility of the effect
— enhancement corrections are difficult
The procedure
Ideally the curvature of the cornea is as even as the surface of a ball. If the curvature is uneven at different areas of the cornea, this is referred to as astigmatism. The corneal surface seems more like an egg than like a ball.
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During AK, incisions using a diamond blade are placed at the steeper axis of the astigmatism (at the more narrow "part of the egg"), which allows the surface to flatten, therefore resembling more the curvature of the ball. |
AK originated from the radial keratotomy (RK), the so-called "Russian blade technique" by Professor Fjodorov. Today, RK is obsolete due to a high rate of serious complocations.
