Lasers have revolutionized ophthalmic surgery. Today lasers are used extensively in eye surgery for vision correction where it has considerably increased the safety and predictability of refractive surgeries. Patients now have the option of discarding glasses and contacts. The major credit for such startling developments must go to the latest marvel of laser technology-the excimer laser.

The laser treatment of myopia has considerably advanced over the last 15 years with the introduction of the advanced excimer laser. The surgical treatment of astigmatism and hyperopia is also possible with this laser. Excimer laser has changed the face of refractive surgery like no other technology since the dawn of ophthalmic surgery. It allows a level of precision in surgery that was not attainable earlier. This precision overcomes to a large extent one weakness of earlier eye surgeries, which was a lack of predictability.

Use of the excimer laser treatment in low, moderate, and high myopia is now well established. It can also remove superficial anterior corneal scars and make hyperopic and astigmatic corrections.

But there is still some way to go. Despite its considerable contributions in corneal reshaping, the excimer laser still cannot produce the perfect results expected with robotic laser surgery. For that, surgical skills will need to be honed further.

Lasik eye surgery

Lasik stands for laser in situ keratomileusis. It is a very common corneal refractive procedure used for correcting a wide variety of refractive errors, including, near and far sightedness and astigmatism. It can also be used in combination with other surgical procedures in extreme complications.

Successful LASIK treatment requires an excimer laser and a medical device, known as, the microkeratome. The surgery consists of formation of an anterior epithelial-stromal flap of the cornea that is left attached to the periphery of the cornea by a small-uncut tissue. The flap is lifted and a high-energy excimer laser is used to sculpt the stromal surface to get the required correction. The flap is then replaced over the cornea without sutures.

All patients have to undergo a pre-operative screening. The minimum age for LASIK is typically 18 years. Refraction stability of the patient is important as it influences the long-term stability of the correction. Patients also have to undergo a complete eye examination. Lasik surgery is not advised in pregnant or lactating patients, and in patients with dry eyes, inadequate corneal thickness, corneal and some systemic diseases.

Advantages of LASIK are the ability to treat a wide variety of refractive errors, short recovery time, less discomfort and less intense healing response. There are risks of serious but manageable complications, such as, losing best spectacle corrected vision. Most complications are flap related. Laser related complications, like, over and under corrections, occur due to machine malfunctioning or inappropriate parameters. They are preventable.

Lasek eye surgery

LASEK stands for laser subepithelial keratomileusis. It has been designed to avoid the flap complications of LASIK and the drawbacks in PRK. In practice, it lacks consistency, though early results look promising.

In LASEK, dilute ethanol is applied on the epithelial area marked for flap formation and a hinged epithelial flap is created by peeling the loosened epithelium as a sheet. After application of excimer laser, the flap is replaced over the ablated stroma.

LASEK, unlike LASIK can treat thin corneas without any risk. Other indicators for LASEK are LASIK complications in the predisposition to trauma, low myopia, irregular astigmatism and glaucoma suspects. Patients have to undergo similar pre-operative evaluation as in LASIK.

The main disadvantages of this procedure remain the unpredictable postoperative pain and epithelial healing.

PRK eye surgery

Photorefractive keratectomy or PRK was the first laser refractive procedure used for correcting myopia.

In PRK, the epithelium is removed from the center of the cornea and excimer laser is applied on the stromal bed to reshape the cornea. PRK has proved very effective in myopia, with a good risk to benefit ratio. Currently it is an established procedure for myopia. But PRK has lagged behind other refractive procedures in hyperopia treatment. While regression is a problem with PRK, in hyperopia the incidence of regression is higher. PRK is more successful in treating low to moderate hyperopia.

As in the above procedures, patients have to go through a pre-operative screening. The disadvantages of PRK are mainly relatively more pain during operation and delayed recovery.

Conclusions

The advent of lasers, especially excimer lasers, has significantly improved the chances of resolving eye problems, intractable till recently. Improved technology and surgeon skills should see further improvements in laser eye treatments.