Clear vision in the normal eye is due to light rays falling on the eye and passing through the cornea, pupil and lens and focusing the image on the retina
When the eye is too long, light focuses in front of the retina causing myopia (Short Sight). When the eye is too short, light rays focus behind the retina causing hyperopia (long sight). When the cornea is shaped like the back of a spoon, light focuses on more than one point and a blurred image is formed on the retina and this is known as astigmatism (Cylindrical power) and is often associated with short sight or long sight.
Normal Eye : Rays of light refocused on the Retina (FOVEA)
Hypermetropia : Light rays are focused behind the Retina
Myopia : Light rays are focused in front of the retina.
This is the most common temporary solution to correct refractive errors because of easy maintenance and low cost. The drawbacks of spectacles are obvious-they interfere with activities and change a person's appearance. Additionally, spectacles also reduce the peripheral vision.
Contact lenses are a popular alternative to spectacles. They provide excellent peripheral vision and permit a wider range of activities than spectacles. Contact lenses do not alter a person's appearance. Problems with contact lenses include their recurrent costs, maintenance hassles and possibility of infection and intolerance due to sensitivities.
In Lasik, the corneal surface is reshaped using a laser beam. It corrects vision by altering refractive power of the eye by a calculated change in the corneal curvature. The image of the outside world is now focused sharply on the retina.
Wavefront Lasik or Customized Lasik is the result of a quantum leap in technology of sight restoration and enhancement. This Wavefront guided Lasik is a giant step forward from conventional Lasik. Optical aberrations (imperfections) inherent in the eye may adversely affect the visual acuity and the optical performance of the eye. Conventional Lasik can only correct the spectacle power & not these subtle optical aberrations. With Wavefront guided Lasik, it is now possible to reduce these aberrations and enhance vision much above the normal levels. Custom Vue (VISx star S4 from AMO) is the procedure available for customized Lasik.