Vision Correction Technology
Photorefractive Keratectomy (PRK)
Laser Assisted in Situ Keratomileusis (LASIK)
Laser Epithelial Keratomileusis (LASEK)
A Comparison of Vision Correction Procedures

Vision Correction Technology

Duke surgeons use the safest and most advanced technologies available for vision correction, including flap creation with the femtosecond laser, wavefront analysis, CustomVue customized treatments, iris registration, and the latest advances in high-frequency pupil tracking.

In the skilled hands of a Duke laser surgeon, you can be confident you are receiving the best of today's technology combined with decades of experience and leadership in the field of ophthalmology.

The Optimal Environment -- Safe, Consistent, Reliable

Many LASIK shops use a rented, mobile laser transported and delivered monthly for use in an uncontrolled environment -- a room used for other activities and procedures throughout the remaining month.

At Duke, all procedures are performed with an on-site, dedicated laser in a controlled environment that is monitored for consistent temperature and humidity to ensure reliable results.

Our ability to provide a controlled, consistent environment means that whether it's a cold, dry day in January or a hot, humid day in August, you will have the same excellent results. This consistency reduces our enhancement rate, that is, the likelihood you will need a future adjustment in your treatment.

While Duke offers the most comprehensive scope of available procedures, LASIK and surface ablation PRK comprise the vast majority of procedures performed.

Photorefractive Keratectomy (PRK)

PRK is an FDA-approved procedure that uses the excimer laser to precisely remove tissue and reshape the corneal surface to match the curvature and power of a properly fit contact lens.

PRK has evolved substantially over the past 25 years, taking full advantage of advances made in laser technology, wound healing, and patient comfort.

Confusion arises from several different names used to designate this procedure, including: epi-LASIK, e-LASIK, LASEK, ASA, advanced surface ablation, to name a few. PRK is essentially a LASIK procedure without a corneal flap and is often the procedure of choice for patients with unusually thin corneas, very small corrections, or dry eyes.

What to Expect with PRK

• The entire procedure takes less than 10 minutes per eye. With the newer, faster lasers, the actual laser application is usually under a minute. Oral diazepam (Valium) and topical anesthetic make this procedure completely painless.
• At the completion of the procedure, a soft contact lens is inserted, serving as a bandage for comfort and protection as the surface heals naturally. Patients are seldom aware that the contact lens is present, and it is removed once the surface heals -- usually three to five days after surgery.
• Vision begins to clear after three to four days, with final acuity achieved over the next several weeks.
• PRK produces a mild inflammatory reaction; therefore, it is important to use a topical steroid drop for several weeks after surgery to reduce inflammation and prevent the development of corneal scarring or haze.

As a precautionary measure, UV-protective sunglasses are recommended in the short term for comfort and even long term when significant sun exposure may occur. There are rare anecdotes of patients developing corneal scarring after intense, prolonged unprotected outdoor UV exposure.

Laser Assisted in Situ Keratomileusis (LASIK)

LASIK remains our most popular procedure primarily because it offers the most rapid recovery of vision, allowing you to return to work and daily activities.

Over the past two decades, millions of LASIK procedures have been performed, leading to substantial experience and added measures of safety. The success of LASIK as a surgical procedure results primarily from combining two very successful and safe procedures.

First, flap creation takes advantage of the principles of partial thickness corneal surgery which began over a century ago. This surgery evolved into mechanized surgery with a microkeratome and is now performed entirely by a femtosecond laser for the safest, most consistent and reliable procedure available.

Second, the actual ablation under the flap uses the excimer laser –- the most precise laser in all of medicine. Each pulse "etches" the surface, removing only 1/100,000^th of an inch of tissue. High-frequency eye tracking precisely directs each pulse, reshaping the corneal surface to match the curvature and power of a properly fit, customized contact lens.

All of this is offered at the Duke Center for Vision Correction using the very latest in laser hardware and software for unprecedented precision and safety.

Customized LASIK surgery refers to a specific, individualized treatment that represents a significant advance to help patients with aberrations specific to the treated eye obtain the benefits of high-frequency eye tracking in addition to wavefront analysis.

Each procedure is uniquely designed, similar to a fingerprint, and is capable of treating even the "high order" optical aberrations that remain untreated by spectacles or soft contact lenses. As your vision is improved under both daytime and nighttime conditions, your need for spectacles is further reduced.

Bladeless surgery is another advantage offered by the Duke program. Since the addition of the latest generation femtosecond laser, this all-laser procedure removes any potential blade-related complications and adds an unprecedented level of precision, accuracy, reproducibility, and long-term stability.

Thinner flaps appear to offer a faster recovery from postoperative dryness and also allow an extra margin of safety for patients starting out with thinner corneas. While all patients experience some dryness after LASIK, most recover within a few weeks.

Those with severe dryness and inability to wear contact lenses should consider surface ablation PRK or spectacles.

All patients receive an FDA pamphlet reviewing medications that may impact surgical outcome. Some medication that contribute to dryness after surgery include amiodarone and Imitrex, as well as some allergy and psychiatry medications.

LASIK Recovery

Since the tissue removal is relatively small compared to the dimensions of the overall cornea, returning the flap to its original position leads to a rapid recovery without sutures or significant discomfort. We recommend patients avoid eye rubbing for at least a week after surgery to avoid injury to the flap.   

LASIK offers the most rapid recovery of vision among the available laser procedures. The protective corneal flap lends comfort to corneal nerve endings and offers less irritation than other procedures that involve the corneal surface, such as PRK or incisional surgery. This protective flap further reduces the potential for corneal haze seen more commonly in patients undergoing high degrees of correction with PRK.

Topical eye drops (antibiotic and steroid) are used during the initial four days following surgery and are usually not required after that. Nonpreserved artificial tears are also helpful as a lubricant immediately after surgery and in the early postoperative period when patients experience temporary dryness.

Laser Epithelial Keratomileusis (LASEK)

Laser epithelial keratomileusis (LASEK) -- also called epi-LASIK, e-LASIK, ASA, or advanced surface ablation -- is a relatively new procedure offered at Duke since 2001 that combines some of the elements of both LASIK and PRK.

The procedure is technically similar to LASIK except that the flap is much thinner, measuring only 1/20^th of a millimeter, since it incorporates only the epithelial surface cell layer. This provides an additional margin of safety for thin corneas compared to LASIK; however, the healing and overall recovery resembles that of PRK.

Preservation of the epithelial cell layer in a flap layer may provide additional benefit by preventing long-term haze, and patients with borderline tear production do not appear to have the dryness seen in the early postoperative period experienced by LASIK patients.

LASEK in some ways is technically more demanding than LASIK or PRK and requires an experienced surgeon. Fortunately, doctors at Duke have performed this procedure since its development and are among the most experienced in this type of surgery, having been involved with instrument design and research in this area.

LASEK also requires more frequent follow-up care in the early postoperative period, making this procedure less attractive to high-volume and discount-oriented facilities. At Duke there is no additional charge for LASEK.

The staff and doctors at Duke evaluate each patient to determine whether or not he or she is a candidate for laser vision correction surgery and determine which procedure is the best for each patient.

For those patients who are excellent candidates for both LASIK and LASEK, the more popular procedure remains LASIK due to the faster recovery, the ability to treat both eyes at the same time, the greater comfort immediately after surgery, the shorter duration of medication drops, and the ability to perform a retreatment or enhancement procedure more efficiently.

A Comparison of Vision Correction Procedures

Learn more about LASIK and refractive surgery:

• The Duke Difference and Common Conditions
• Pros and Cons of Vision Correction Surgery
• Preparing for Vision Correction Surgery
• LASIK Glossary
• Patient Forms