History of Laser Vision Correction
Are You a Good Candidate?
Photorefractive Keratectomy (PRK)
Laser Assisted in Situ Keratomileusis (LASIK)
Laser Epithelial Keratomileusis (LASEK)
Comparison of Vision Correction Procedures

History of Laser Vision Correction

The development of the excimer laser introduced technology that was unmatched with respect to surgical precision. Adding computerized control, this became the most precise laser in all of medicine.

The laser has the ability to sculpt and reshape the cornea with sub-micron precision. These advances set a new, higher standard for all vision correction procedures.   

Consider that each pulse of the laser accurately removes 1/100,000th of an inch of tissue in 12 billionths of a second. When followed by normal healing, this degree of precision routinely leads to a remarkable improvement in unaided vision.

The first laser vision correction surgery system was based on lasers originally developed by IBM to etch computer microprocessing chips. The system was first produced in 1986. That same year, the first FDA clinical site was established and the first human eyes were treated with a VISX laser.

Released in 1995, the VISX Star was the first laser system approved in the United States for the treatment of both nearsightedness and astigmatism. It currently possesses the potential to treat almost all degrees of nearsightedness, farsightedness, and astigmatism.

Duke and Laser Vision Correction Technology

The latest version of the VISX laser is used at Duke. It utilizes all of the latest advances including WaveFront technology, CustomVue™ customized treatments, iris registration, and the latest version of pupil-tracking.

The addition of the new 400 Hz Alcon-Wavelight Allegretto Wave excimer laser has further enhanced our range and precision of correction while reducing our retreatment rate to 1 to 2 percent even with higher corrections.

These excimer lasers remove tissue by delivering energy that separates molecular bonds making this essentially a non-thermal (no tissue burning) mechanism for removing tissue at a subcellular level. 

Duke remains committed to its position at the forefront of technological advances in the field. The IntraLase femtosecond laser allows us to provide the most advanced care to our refractive patients by making LASIK a blade-free, all-laser procedure. This innovative technology creates a more precise, consistent, and safer approach for flap creation in preparation for LASIK.

Are You a Good Candidate?

To be a successful candidate for vision correction, you should:

• Be at least 18 years of age. PRK below 18 year of age and LASIK below 21 years of age is considered “off label” by the FDA because the original approval process did not look at patients below those respective ages.
• Have a stable refractive prescription. When possible, we want to review your previous records to evaluate and confirm stability in your prescription.
• Have no significant disease of the eye that would interfere with the surgical procedure or affect your long term outcome. These include keratoconus and herpes simplex viral keratitis.
• Have no systemic autoimmune diseases such as systemic lupus erythematosis, scleroderma, dermatomyositis, or severe rheumatoid arthritis.

Note: Eye surgery is not recommended for pregnant or nursing women.

Photorefractive Keratectomy (PRK)

Photorefractive Keratectomy (PRK) is an FDA-approved procedure that uses the excimer laser to precisely remove tissue from the cornea, reshaping the surface to match the curvature and the power of a properly fit contact lens.

During PRK, the cornea is prepared for the laser treatment by gently removing the surface layer of the cornea (epithelium) centrally over a circular area. The laser is then applied to the surface, creating a newly contoured surface, painlessly and in less than a minute in most cases.

At the completion of the procedure, a soft bandage contact lens is inserted for usually two to five days for comfort and to protect the cornea as it heals naturally. Vision begins to clear after three to four days with the final acuity achieved over the next several weeks. 

PRK produces a mild inflammatory reaction, and 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. Significant scarring is rare; however, it has been reported in patients who have prolonged, unprotected ultraviolet injury to the eye. 

For that reason, we recommend using sunglasses when outside on bright days or while boating. Loss of vision resulting from corneal haze is extremely rare thanks to newer laser technology, UV protection, and a course of intraocular topical steroid drops. Your series of post-operative checkups monitor the healing process along with the recovery of vision and need for topical medication drops.

Laser Assisted in Situ Keratomileusis (LASIK)

Laser Assisted in Situ Keratomileusis (LASIK) combines nearly a century of experience with lamellar or partial thickness corneal flap surgery with the unprecedented precision of the laser hardware and software used with PRK (photorefractive keratectomy).

In LASIK, a protective corneal flap is created that is about one-tenth of a millimeter thick. Once the corneal flap is lifted, a precise laser treatment is applied to the bed before returning the flap to its original position.

The amount of tissue removed is usually very small measuring close to the thickness of a single red blood cell for each half diopter of refractive correction.

Among the most important considerations when evaluating patients for LASIK is making sure that the cornea offers adequate tissue in the remaining corneal stromal bed to avoid the development of progressive thinning (ectasia) of the cornea.

In addition, it's important that your eye has adequate tear production since most patients develop a temporary dryness after LASIK that may last for several weeks before returning to baseline. Patients with severe dry eyes resulting in an inability to wear contact lenses are often better treated with surface ablation PRK.

LASIK may also aggravate the dry eye that is caused by some medications, systemic autoimmune diseases, and hormonal status, so these are important consideration to address in the evaluation before your surgery.

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. 

CustomVue™ LASIK Surgery

Among the many advances in the field of laser vision correction surgery, our ability to individualize or customize your surgical treatment is perhaps the most exciting. Our ability to match our treatment specifically and uniquely to your eye rather than simply to your prescription makes us a leader in respect to vision correction.

Prior to 2003, two patients with the same prescription received similar laser treatments. With customized laser surgery, this is no longer the case. Advances in WaveFront technology, computerized corneal topography, and sophisticated laser tracking of the eye during surgery, allow Duke surgeons to use data that is unique to your eye to guide a laser treatment that is specifically designed for your eye.

Our ability to treat so called “higher-order” optical aberrations allows us to correct even those distortions of vision which are not correctable by glasses or contact lenses. This customized approach to laser vision correction has also been shown to reduce vision problems associated with glare and night driving.

Tracking your eye using iris registration has further refined and enhanced our treatment aimed at achieving the best possible outcome. Customized laser surgery requires a series of measurements prior to surgery, and consultation with your Duke surgeon and staff is necessary to make sure that you qualify for this advanced procedure.

Bladeless LASIK

The new IntraLase femtosecond laser represents the latest innovation and technological advance that has replaced the mechanical micorkeratome at Duke making LASIK an all-laser, bladeless procedure.

This latest generation of laser creates a precise, predictable, reliable, reproducible flap in 19 seconds without any of the mechanical concerns associated with a surgical blade. This new method gives confidence to patients who have been waiting to undergo the procedure out of fears associated with the “surgical” aspects of vision correction.

This technology also allows patients who were previously considered suboptimal candidates for LASIK to reconsider this option by safely creating a thinner flap than occurs with the blade microkeratome, allowing a faster recovery of the ocular surface and also leaving more tissue in the bed of patients with thin corneas. 

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 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 may be best for them.

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