Refractive Surgery (Lasik / PRK Surgery):

Lasik (laser assisted in situ keratomileusis) is a type of refractive surgery for correcting myopia, hyperopia and astigmatism.

How is Lasik eye surgery performed?

First a flap of corneal tissue is created. This flap consists of the surface layer of cells, the epithelium, plus a thin layer of the underlying cornea, the stroma. Flap creation is done by placing a suction ring on the eye for about 20 seconds and using either a mechanical microkeratome (using a metal blade), or a femtosecond laser (Zeimer or Intralase in the US), the latter of which creates a series of tiny closely arranged bubbles within the cornea. We use the Zeimer femtosecond laser, which gives excellent safety, accuracy and comfort with the least amount of energy applied to the tissue.

Many people are surprised to learn that the flap created is permanent and can be lifted later without recutting. However, due to the geometry of modern flaps and some unique properties of the cornea, dislocation of the flap after the early postoperative periord is rare.

After the flap is created, it is lifted and flipped back out of the way on its hinge, so that the stromal part of the cornea is exposed and can be shaped by a second laser, the excimer laser. The excimer laser vaporizes the water in the cornea, which is 90% of the stroma, along with other components. When it does so, you might smell the keratin which is the major structural protein of the cornea, like that in your hair. After the reshaping is complete, the flap is laid back down, checking for proper positioning, smoothness and debris. Vision is noticeably better right after the procedure, with some fogginess that improves over the next few hours as the saline used as a rinse is absorbed by the tissue.

It is unusual for people not to feel comfortable driving the next day.

Who performs Lasik surgery and where is it done?

Lasik surgery is performed by an ophthalmologist. This procedure is done in the office while the patient is awake using anesthetic drops. A mild sedative such as valium is usually offered to patients prior to the surgery.

PRK (Photorefractive Keratectomy) is another type of refractive surgery that corrects myopia, hyperopia and astigmatism.

How is PRK performed?

PRK eye surgery is performed via the removal of the outer layer of the cornea (the epithelium), which then allows the cells to regenerate after the surgery. The outer layer of the cornea is a soft, rapidly regrowing layer that can completely replace itself within a few days. After removal of the epithelial cells, the excimer laser is applied to the stroma to reshape the cornea. After the reshaping is complete, a clear contact lens bandage is placed over the eyes for a few days until the outer layer of the cornea has healed.

The PRK eye procedure is distinct from Lasik eye surgery in that the epithelial surface cells are removed and have to grow back under the bandage contact lens. However, no flap is created. PRK is used when the adequacy of the corneal thickness is borderline, or when patients do not want a flap due to an occupation/hobby, like military personnel or professional fighters.

The US armed forces have varying requirements (Lasik vs PRK) for refractive surgery, but generallly the newer femtosecond laser flaps are accepable to most. There are extensive data confirming the stability and safety of the femtosecond laser flaps from US Air Force studies in pilots that paved the way for the acceptance of this technology.

What are the pros and cons to Lasik vs. PRK?

Lasik requires less down time and activities can be resumed the very next day. There is a permanent flap with Lasik though. Because of the flap, careful consideration should be taken if your profession or hobby might increase possible injury to the eye.

PRK has a longer healing time than Lasik, with variable vision over the approximately 4 days the contact lens is in place. Daytime driving may be affected, and night time driving is not advised. The day after the bandage contact lens is removed, the vision is notably better. However, the vision continues to fluctuate for several more weeks.

The advantage to PRK is that less corneal tissue is used, which typically allows more room for a touchup (enhancement) should one be needed in the future. There is no permanent flap involved in this eye surgery. The same visual outcome is expected with both procedures.

Complications associated with Lasik:

Dryness **
Under or over correction that might necessitate an enhancement
Visual acuity fluctuations
Halos or starbursts around lights
Light sensitivity
Ghosting or doubled images
Wrinkles in the flap
Debris under the flap
Dislocation of the flap
Infection
Thin flaps
Epithelial erosion

**There are recent studies which indicate that the problem with dryness after deeper Lasik flaps, created with the mechanical keratome, are NOT as much a long term issue with the thinner, femtosecond laser-created flaps.

Complications associated with PRK:

Dry eyes
Longer healing period
Slight discomfort
Glare, halos and starbursts around lights
Under or over correction
Corneal haze, a rare problem now with the use of dilute mitomycin C applied briefly at the end of the case

To date, Dr. Smith has performed over 11,000 refractive surgeries.

Please contact our refractive coordinator to schedule your FREE Lasik evaluation. 919.256.2500