LASIK: Revolutionising correction of refractive errors

Dr Niteen C Dedhia

LASIK, an unprecedented advancement in eye care, offers people a safe and simple opportunity to see the world clearly, minus the inconvenience or discomfort of scratched or lost contact lenses, or the blocked side vision of spectacles. In simple term LASIK is a revolutionary laser technique for correction of refractive errors.

Refractive errors may be in the form of Myopia (short-sightedness), Hyperopia (long-sightedness) or Astigmatism. Correction of refractive errors is possible with the use of Excimer Laser, which is a class of lasers with output in the UV range of the electromagnetic spectrum. This type of Laser produces a reaction on the surface of the cornea, which gradually causes graded removal of the surface tissue and ultimately reshapes the cornea to make it of normal curvature.

Excimer Laser & LASIK

The introduction of Excimer Laser has brought a level of precision and predictability to Refractive surgery. Excimer Laser is of two types viz. PRK (Photo Refractive Keratomy) and LASIK (Laser in Situ Keratomileusis). PRK being a conventional Laser technique which destroys the Bowman's layer (a sheen that is located just below the corneal surface). It led ophthalmologists world over to make the technique safer, more refined and accurate without compromising on any generic technological parameter. This led to the invention of LASIK technique. In contrast, LASIK technique is more advanced and accurate, where laser treatment is given under a hinged corneal flap and this flap is placed back after the laser procedure. This flap is self-healing and does not require any stitches. In this procedure, the Bowman's layer of the cornea is left intact making this technique safe and more predictable. The corneal flap is made with the help of a special instrument called the 'Microkeratome'. The entire procedure takes 20 minutes with the actual laser time varying between 15-145 seconds. The procedure is done under topical anesthesia (use of drops) and it is virtually painless. The patient does not have to stay in the clinic and can resume work after three days.

Eligibility: Anyone above 18 years of age can undergo this laser procedure that have stable refraction (no change in number) since past six months.

Besides a thorough checking of the refractive error, they are subjected to certain diagnostic tests, namely the 'Topography' test to map the surface of the cornea and the 'Pachymeter' test to measure the corneal thickness.

In cases, where laser surgery techniques cannot be performed effectively, implantable contact lenses (Phakic IOL implantation) is effective in correcting the vision errors, for very high glasses numbers specially.

In this procedure, a lens of specific power is implanted permanently infront of the patient's iris (coloured part of the eye) which provides patients with excellent vision. Thus, the future of refractive surgery is enormous.

The writer is medical director with Laser Eye Surgery Centre, Mumbai.
Email: ndedhia@vsnl.com