LASIK Treatment Types

Nearsightedness (Myopia)

With myopia, the cornea is too steeply curved and too much focusing power is produced. This makes distant objects blurry, because light is focused in front of the retina. Near objects remain clear.

When LASIK is performed for myopia, most of the laser pulses are applied to the central cornea. This flattens the cornea, reduces its focusing power and allows light to focus further back in the eye. Imagine making a mountaintop flatter.

Farsightedness (Hyperopia)

With hyperopia, the cornea does not bend incoming light enough, so light focuses behind the retina. Hyperopia causes blurry vision up close. Hyperopia must be distinguished from presbyopia, which is the inability of the eye to focus sharply on nearby objects, resulting from loss of elasticity of the crystalline lens with advancing age.

When LASIK is performed for hyperopia, most of the laser pulses are applied to the peripheral cornea. This is like removing a “doughnut” of corneal tissue, making the cornea steeper, increasing its focusing power and allowing light to focus more toward the front of the eye.

Astigmatism causes light entering the eye at different axes to be focused at different amounts. For example, light entering vertically (from 12 o’clock to 6 o’clock) may be focused more than light entering horizontally (from 9 o’clock to 3 o’clock). In an eye without astigmatism, light is focused the same amount in each axis.

The net result of astigmatism is blurred vision. Often letters appear slanted or with “tails” coming off of them. Sometimes the affected eye sees double.

When LASIK is performed for astigmatism, the laser pulses are applied to the axes that are too steep; or applied to flat axes, therefore steepening them; or a combination of both.

Monovision is correcting one eye for distance vision and the other eye for near vision. LASIK cannot correct presbyopia so that one eye can see at both distance and near. However, LASIK can be used to correct one eye for distance and the other for near. If you can adjust to this correction, it may eliminate or reduce your need for reading glasses. In some instances, surgery on only one eye is required.