Types of refractive surgery

Surgical procedures to improve the focusing power of the eye are called refractive surgery. Here are some of the common types :

RK or Radial Keratotomy - a very sharp knife is used

PRK or Photorefractive Keratectomy - Excimer laser is used

LASIK  or Laser-ASsisted In-situ Keratomileusis -Excimer laser is used

LTK  or Laser Thermokeratoplasty  - holmium YAG laser is used

In earlier days, eye surgery was done using a knife and then laser was used for sculpting and still later LASIK was developed. Often for both PRK and LASIK the same type of laser is used.

The major difference between the two surgeries, PRK and LASIK, is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stromal layer underneath. In LASIK, a flap is cut in the stromal layer and the flap is folded back.

Another type of refractive surgery is Thermokeratoplasty in which heat is used to reshape the cornea. The source of the heat can be a laser, but it is a different kind of laser than is used for LASIK and PRK.

Other refractive devices include corneal ring segments that are inserted into the stroma. ICRS - Intrastromal Corneal Ring Segments (INTACS) are Non-Laser Surgical Products.