Focus Correction of the Eye

The cornea is the clear window, which forms the front surface of the eye. The main function of the cornea is to focus light onto the back of the eye. In order to form a clear image there must be a balance between the curvature of the cornea and the focal length of the eye.

The internal lens of the eye also contributes to focus. It allows us to adjust focus from distance to near, as when reading.

Shortsightedness Myopia – Shortsightedness Shortsightedness is due to the corneal curvature being too steep for the focal length of the eye. The excimer laser corrects this by flattening the curvature of the cornea.

Farsightedness Farsightedness Farsightedness is due the corneal curvature being too flat for the focal length of the eye. The excimer laser corrects this by steepening the curvature of the cornea.

Astigmatism Astigmatism Astigmatism is due to an oval shape of the cornea (like a rugby ball), being too flat in one direction and too steep in the other direction. The excimer laser reshapes the cornea to correct the curvature.

Presbyopia Presbyopia Presbyopia is an ageing change whereby the internal lens loses its ability to adjust focus from distance to near. This results in people needing reading glasses after the age of 45. Laser does not correct presbyopia and people in this age group will still need reading glasses after the surgery.