Laser subepithelial keratomileusis (LASEK)

Overview

Nowadays, excimer laser surgery is one of the most popular ophthalmic procedures. Thousands of patients are operated on each year in the United States to correct various refractive errors. Laser Epithelial Keratomileusis, or LASEK, is a vision correction procedure very similar to LASIK. 

 

What is LASEK?

Laser Assisted Epithelial Keratomileusis (LASEK) is a popular alternative to LASIK surgery that can treat all common refractive errors such as myopia (short vision), hyperopia (long vision), and astigmatism. It is still one of the safest methods of laser eye surgery. Once the eye has been reshaped and the refractive error has been corrected, the flap is repositioned.

LASEK works by precisely changing the shape of your cornea — the dome-shaped transparent tissue at the front of your eye — with a special type of laser to improve vision.

Images are normally clearly focused on the retina in the back of your eye because light rays are properly bent to contact the retinal surface. Short-sightedness (myopia), long-sightedness (hyperopia), or astigmatism cause the light to be bent incorrectly and focus elsewhere, resulting in blurred vision. Blurred vision is traditionally corrected by bending (refracting) light rays with glasses or contact lenses. However, reshaping the cornea will also provide the required refraction.

 

What are the Benefits of LASEK?

• The procedure is quick and painless, lasting less than 5 minutes per eye.
• Excellent outcomes, with patients frequently seeing improvement within a few days.
• Clinically proven treatment - According to research, 97% of patients achieve their desired vision and complete satisfaction after LASEK treatment.
• Because no flap is created during surgery, it is appropriate for patients with dry eyes, thin corneas, or who participate in contact sports.
• The surgery is very comfortable, with very little touch involved.
• There are no stitches required.
• If necessary, additional adjustments can be made in the future to correct vision.

 

Disadvantages of LASEK

One of the most significant disadvantages of LASEK is that recovery is somewhat slower than recovery from LASIK. In addition, LASEK recovery is typically more painful than LASIK recovery.

Furthermore, there is the possibility of subepithelial haze, which is the formation of a haze that can obscure vision. This usually goes away with time, but it can rarely cause long-term vision problems.

When compared to other refractive surgery options, LASEK is also associated with a higher risk of persistent epithelial defect and infection. It also carries many of the same risks as other types of eye surgery.

 

How is LASEK performed?

LASEK involves creating an epithelial detachment on the cornea by applying a diluted alcohol solution (18-20%). After rinsing off the alcohol, the epithelium is scraped. The epithelium is folded on a nasal or superior hinge to form an epithelial flap. On the bed, laser ablation is then performed. The epithelium on the stroma is replaced with special care to ensure proper alignment and avoid future complications. Finally, topical steroids and antibiotics are applied, followed by the insertion of a soft contact lens. After complete re-epithelialization, the soft contact lens is removed (typically 3 or 4 days post op).

 

Surgical Techniques

The LASEK procedure is described in several ways, the most common of which are described below.

• Camellin Technique

Following the administration of topical ophthalmic anesthesia, an epithelial incision is made with a notched micro-trephine (with a 90° hinge at 12:00). For 20 seconds, an 18% ethanol solution (diluted with distilled water rather than balanced salt solution) is applied over an 8.5 mm diameter area.

The eye's surface is then rinsed with diclofenac sodium. The flap edge is detached and advanced to the 12:00 position. After laser ablation, the epithelium is repositioned and a soft contact lens is placed on the cornea for 3 to 4 days. Following surgery, antibiotic and cortisone eye drops are given for a few days, and a mild cortisone treatment is given for up to a month.

When this method was first reported, 76 eyes were treated, with a mean refractive error of -11.00 +/- 3.00 D (range -8.00 to -22.00). Visual stability was observed approximately 60 days after surgery. Sixty-two percent of patients reported no post-operative pain. In 95% of the eyes, no significant subepithelial haze was observed. Thus, the study concluded that, when compared to LASIK, LASEK had the advantage of being able to treat a larger diameter ablation zone in thinner corneas without stromal flap problems. In these cases, the advantage of LASEK over PRK was less post-operative pain and less subepithelial haze.

• Azar Technique

A lid speculum is used after applying topical 0.05% proparacaine and 4% tetracaine (formulated in the Massachusetts Eye and Ear Infirmary pharmacy). The cornea is then marked with overlapping 3mm circles that form a floral pattern around the corneal periphery. The reservoir for 18% alcohol is an alcohol dispenser made up of a customized 7 or 9mm semi-sharp marker attached to a hollow metal handle. After 25-30 seconds, the ethanol is absorbed with an aspiration hole and dry sponges.

If necessary, the ethanol application can be repeated for another 10-15 seconds. To delineate the epithelial margin and fashion a hinged epithelial flap, an arm of modified Vannas scissors is used. The modified Vannas scissors also enable the LASEK incision to be customized for different corneal types. Following the removal of the epithelial flap, the underlying stromal bed is ablated with an excimer laser.

An anterior chamber cannula is used after ablation to hydrate the stroma and float the epithelial flap over a layer of balanced salt solution. The epithelial flap is then replaced, with careful attention paid to realigning the epithelial flap margins using the previous marks. After that, the epithelial flap is allowed to dry for 2-5 minutes. Topical steroids and antibiotics are applied, and a bandage contact lens is inserted. After complete reepithelialization, the bandage contact lens is removed (generally postoperative day 3 or 4).

• Vinciguerra (Butterfly Technique)

In this technique, a thin abrasion is performed on the paracentral cornea with a Vinciguerra spatula from the 8:00 to 11:00 positions, and 20% alcohol in BSS is placed in contact with the cornea for 5-30 seconds. The epithelium is separated from Bowman's layer using the same spatula on both sides, moving from center to periphery.

The Vinciguerra LASEK butterfly protector/retractor is used to move and hold the two sheets of loose epithelium sideways toward the limbus. Excimer laser ablation is performed after the surface has been dried. Smoothing with a hyaluronic acid masking solution is then performed, followed by repositioning the stretched epithelial flaps with overlapping margins.

• McDonald Technique

This is a no-alcohol technique. After marking the epithelium, GenTeal® gel is applied. After that, the cornea is trephinated. A 2.25 rounded knife is used to score the epithelium down to Bowman's layer (a distance of 1-2 mm). To stiffen the epithelium, ten drops of 5% NaCl ophthalmic solution are applied to the corneal epithelium and then blotted dry with eye spears. A microkeratome head is placed on the eye (upside down), and the stalk/stem is held by a surgical assistant (because the surgeon needs both hands to continue operating); suction is then applied.

After that, a cannula is inserted beneath the epithelium and used as a fulcrum to sweep and loosen the epithelium. After releasing the suction, GenTeal® gel is injected beneath the loosened epithelium. The Vinciguerra butterfly technique is then used to create a LASEK flap. A cut is made through the center of the sheet of epithelium with Vannas scissors, and the two halves of the sheet are reflected to the side. Alternatively, the epithelium sheet could be quadrisected rather than bisected. Bowman's gel is then removed with an eye spear, and excimer laser ablation is performed. After that, the epithelium is replaced, and a bandage contact lens is placed.

 

What to Choose: LASIK or LASEK?

LASEK and LASIK are procedures that are very similar, with the main difference being whether or not a flap is created. Both procedures involve the removal of corneal tissue after the cornea has been prepared. The more tissue that must be removed, the greater the refractive error. To be safe, the corneal thickness must be measured prior to surgery to ensure that there is enough tissue left after surgery.

When compared to LASEK, the flap in LASIK compromises extra tissue. As a result, some people with thin corneas and/or high refractive error may be LASEK candidates but not LASIK candidates. 

Benefits of LASIK

• Fast healing time
• Quick vision recovery
• Minimally invasive
• Minimal discomfort
• Fewer complications

 

LASEK Eye Surgery Recovery & Aftercare

As the anesthesia wears off, your eye may feel uncomfortable for a few days as it heals in the early stages. Although it may itch, it is critical to avoid touching the eye as much as possible.

Discuss with your doctor the level of discomfort you can expect and potential solutions to deal with it without interfering with your healing. Your doctor may prescribe antibiotic or anti-inflammatory eye drops for the first week or so. This helps to avoid complications as your eye's protective layer regenerates.

It is normal for your vision to gradually improve during the first few weeks of healing. Discuss with your doctor when you can expect your final level of visual acuity, which most patients achieve after about three months.

Make sure to follow all of your doctor's instructions and to see them for any follow-up visits they recommend. They will monitor your progress and ensure that your eye heals properly. Contact them right away if you notice any strange changes in your vision or unusual levels of discomfort or pain.

 

LASEK Eye Surgery: What to Expect?

Before 

To determine whether you are a good candidate for LASEK eye surgery, your eye surgeon will perform a thorough eye exam as well as a general health check. Many eye surgeons will only recommend LASEK if you are not a candidate for LASIK.

If you wear contact lenses, your doctor will usually tell you to stop wearing them for a while before having laser eye surgery because contacts can alter the natural shape of your cornea.

You will need to arrange for someone to drive you home from the surgery because you will be unable to drive yourself. You'll also need to plan time off work — usually around a week — as your eyes heal and your vision improves.

 

During

Your eye is first numbed with anesthetic drops. Then, with a fine blade, your surgeon makes a circular cut in the corneal epithelium (trephine). The trephine leaves a small arc-shaped area of the circle uncut, allowing the created epithelial "flap" to remain attached to the eye. For about 30 seconds, a diluted alcohol solution is placed over the eye, loosening the edges of the epithelium and allowing the surgeon to gently push the loosened flap of epithelium to the side.

After that, the excimer laser is used to reshape the corneal stroma and correct your vision. Following the completion of the laser treatment, the epithelial flap is repositioned on the eye. A special contact lens is then placed over your eye to act as a protective bandage.

LASEK eye surgery is a walk-in, walk-out procedure that should take about 15 minutes per eye. You will be awake during the procedure and should not experience any pain, but your surgeon may administer a mild sedative to help you relax.

 

After

Following LASEK surgery, you will be able to return home after a brief period of rest. Most people report mild to moderate discomfort in the days following LASEK. You will need to wear the "bandage" contact lens for four days while the surface epithelial cells heal and regenerate. In order to aid healing and reduce the risk of infection, your doctor will also prescribe topical steroids and antibiotics for at least three weeks.

Visual recovery after LASEK (and epi-LASIK) is generally slower than after LASIK and frequently slower than recovery after PRK. With LASEK, initial visual recovery can take up to a week (as opposed to 24 hours in typical LASIK cases), and final results can take anywhere from a few weeks to several months.

The outcomes of LASEK and PRK are comparable to those of LASIK. After laser eye surgery, the majority of people achieve 20/20 vision, and nearly all achieve 20/40 visual acuity or better. You may still need to wear eyeglasses or contact lenses depending on your degree of refractive error, but the prescription will be significantly lower.

LASEK eye surgery, like LASIK and PRK, is not always a cure for presbyopia, a natural age-related loss of near vision. Your doctor will be able to tell you if you are a good candidate for presbyopia surgery instead.

 

Side Effects & Risks of LASEK

A small number of LASEK surgeries result in the formation of a subepithelial haze, which can cause permanent or long-term astigmatism due to incorrect eye healing.

Microbial infection is a risk with LASEK surgeries. If left untreated, this infection, known as microbial keratitis, can cause permanent damage to your eye. Fortunately, most eye infections are treatable with antibiotics if caught early.

LASEK, like LASIK, has risks such as dry eyes, eye irritation, undercorrection, overcorrection, and halos around lights. While LASEK, like any surgery, has risks, it is not a particularly dangerous procedure. A total loss of visual acuity is possible, but extremely rare.

 

LASEK Eye Surgery FAQs

1. Is LASEK better than LASIK?

LASIK is far more common than LASEK. Because of its faster recovery time, it is usually the preferred option. When someone has a weak or thin cornea, LASEK is usually the better option.

    2. Is LASEK safer than LASIK?

Both LASEK and LASIK are thought to be safe procedures. Because LASIK heals faster, it is generally preferred when both surgeries are available.

   3. Is LASEK more painful than LASIK?

Yes, LASEK may be more uncomfortable and painful than LASIK. The recovery time is also longer.

   4. How does LASEK differ from LASIK?

The main distinction between the two surgeries is how the surgeon gains access to the part of the eye that needs to be reshaped. LASEK is based on a solution detaching the epithelium and then medically scraping it with another tool. LASIK involves the use of a precise blade or laser to cut a flap into the eye, which is then moved to allow access to the cornea for reshaping.

   5. How long does LASEK take?

A LASEK procedure takes under an hour, usually less than 20 minutes. 

   6. How long do the results of LASEK last?

The results of the surgery are permanent once a patient has completely healed in about three months. Unless your vision deteriorates due to another cause, such as age-related vision loss, your visual acuity will remain constant.

 

Conclusion

LASEK treatment entails lasering the surface of the cornea beneath the epithelium, your eye's transparent layer. LASEK can treat a variety of refractive issues, such as near-sightedness, far-sightedness, and astigmatism, but it is especially appropriate if you have thinner corneas and participate in contact sports like rugby or martial arts.