What is LASIK ?

LASIK is an acronym that stands for Laser in-Situ Keratomileusis. It is the most popular surgical option for correction of refractive errors like myopia (shortsightedness), astigmatism and hyperopia today worldwide.

This day-surgery procedure takes about 10 minutes per eye to perform and is done with topical anaesthesia via eyedrops. It first involves the creation of a thin corneal flap which is reflected. The exposed underlying corneal stroma is then re-shaped using a computer guided excimer laser system. The reflected corneal flap is then replaced. The reshaping of corneal tissue causes the centre of the cornea to flatten in the correction of nearsightedness, steepen in the correction of farsightedness, or selective flattening in the correction of astigmatism, and thereby changing the focusing power of the cornea and improving unaided vision.

Types of Refractive Errors

1. Myopia
   This is the most common refractive error in Singapore. Here, the eye is either too long or the cornea too steep or both such that distant objects are focused in front of the retina. Myopic individuals see distant objects blurred.
   
   
2. Hyperopia
   In hyperopia, the eye is either too short or the cornea is too flat or both resulting in blurred near and distant objects as objects are focused behind the retina.
   
   
3. Astigmatism
   Here the cornea is unequally curved i.e. it is more curved in one direction and lees so in another. Imagine a rugby ball. Individuals with astigmatism will see objects blurry or shadowed. Astigmatism can co-exist with myopia or hyperopia.
   
   
4. Presbyopia
   This is an age related phenomenon in which eyes lose the ability to accommodate and lose the focusing ability for near objects. This is naturally occurring and tends to affect all individuals after the age of 40, be they myopic, hyperopic or astigmatic.
   
   
   

Options for refractive errors

Spectacles and contact lenses are the most common non-surgical methods of correcting nearsightedness, farsightedness and astigmatism. They are good alternatives to LASIK. Other alternatives include photorefractive keratectomy (PRK) and phakic intraocular lens implantation. Refractive surgery is continually evolving and other procedures may be available as an alternative to LASIK in the future.