The most common of visual disorders, refractive errors describe the eye's inability to bring light into sharp focus on the retina. In the past, glasses or contact lenses provided the only means to optimize visual acuity. With the advent of laser vision correction, a laser can now gently and painlessly reshape the cornea, the tough, resilient clear membrane that is the outermost part of the eye and does 80% of the focusing for the eye at distance, in order to decrease or eliminate the need for glasses or contact lenses altogether.
There are three basic types of refractive errors:
Nearsightedness, where the eye is a bit longer than it should be
(axial myopia),
or where the cornea is excessively curved (curvature myopia)
Farsightedness, where the eye is a bit shorter than it should be (axial hyperopia), or where the cornea is not sufficiently curved (curvature hyperopia)
Astigmatism, where the cornea is shaped more like a football than a baseball, resulting in two, or multiple focal lines that focus in front, or behind, or on the retina.
Reading Vision
Inside the eye, beneath the cornea, the pupil and the iris, the eye's
natural lens is responsible for bringing the focus in to near so that we may read. The lens has a muscle that surrounds it and can squeeze it to make it more convex and bring the focus in to near. As we reach our forties and fifties, this mechanism will fail to function properly and patients will notice an inability to focus up close. The condition is called
presbyopia. For those where the vision at distance is still good, reading glasses will now be required. For those who also have difficulty at distance, progressive lenses, bifocals or trifocals may be called for. Laser vision correction can also be used to treat presbyopia and turn back the clock to restore near vision and socially unburden patients.
