Under ideal conditions, light that passes through the cornea and then the lens will come to a perfect focus on the retina. But vision rarely remains perfect throughout a lifetime. In some eyes, light comes to a focus in front of or behind retina. In other eyes, the light isn´t focused strongly enough.  In refractive surgery, a specially trained eye surgeon (an ophthalmologist) uses an extremely precise laser to reshape the cornea of the eye in order to bring the light into focus for most tasks.

To understand how refractive procedures work, it is important to understand how eyes with refractive errors differ from the emmetropic or "normal" eye.

To learn more about eye conditions that may be treated by refractive procedures, click on the appropriate entry.

Emmetropia is the ideal state of the eye in which no refractive error is present. Emmetropia occurs when the curvature of the cornea, the shape of the lens and their distances from each other and the retina are in harmony. The cornea and lens focus the rays of light from an object perfectly on the retina, creating a sharp image.


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