Laser Eye Surgery

Laser eye surgery (also called refractive eye surgery) is any eye surgery that uses lasers to reshape the cornea for the purpose of improving the patient’s vision and reducing his or her dependency on glasses or contact lenses. Successful laser eye surgeries can help correct or partially correct common vision problems such as myopia, hyperopia, and astigmatism.

Myopia (also known as nearsightedness) is a refracted defect in the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed. Those with myopia can typically see nearby objects clearly; however, objects that are far away appear blurred. Myopia occurs when the cornea is too flat or the eye is too short.

Hyperopia (also known as farsightedness) is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or the lens cannot become round enough) that causes inability to focus on near objects and, in extreme cases, causing the sufferer to be unable to focus on objects at any distance. The eye must increase power as an object moves closer toward the eye in order to keep it on the retina. If the power of the eye cornea and lens are insufficient, as with hyperopia, the image will appear blurred.

Astigmatism is when an optical system has different foci for rays that propagate in two perpendicular planes. If an optical system that has astigmatism is used to form an image of a cross, for example, the lines on the vertical and horizontal planes will be in sharp focus at two different distances.

The retina is a thin layer of neural cells that lines the back of the eyeball. This layer of cells processes images much like the film in a camera.

The cornea is the transparent front part of the eye the covers the pupil, iris, and anterior chamber, providing most of the eye’s optical power.

Accommodation is the process by which the eye increases optical power to maintain focus on the retina. The principal focusing ability of the eye is due to the difference in refractive index between air and the curved cornea, but the curvature of the lens is also a factor and allows for an additional adjustment.

Definitions