Laser subepithelial keratomileusis, LASEK in short, as the name suggests is a laser-assisted surface ablation surgery for vision correction. LASEK is a close competitor of its two refractive surgery counterparts of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). In fact, LASEK came about as an attempt to improve on laser surgical techniques.

All three procedures, however, are fairly effective and consistent surgical techniques for correcting myopia (nearshightedness) and hyperopia (farsightedness) with or without mild or moderate astigmatism.

Diagnostic overview

The main indications for LASEK are:

• Thin corneas.
• Inclination towards flap trauma especially related to professional exposure (for instance in the military) or lifestyles such as contact sports etc.
• Mild myopia with a lesser risk for subepithelial haze.
• Epithelial disorders (M/D/F changes).
• LASIK complications in the contralateral eye.
• Irregular astigmatism (corneal topographical defects excluding keratoconus).
• Potential glaucoma cases.

LASEK contraindications include fear of post-operative pain, glaucoma, pregnancy and hyperopia and hyperopic astigmatism.

Preoperative Screening

Preoperative evaluation is vital to ensure optimum results from any kind of laser surgery for the eye. Clinical tests conducted for LASEK are similar to that for the other refractive surgical methods. These tests are:

• Uncorrected visual acuity (UCVA).
• Best-corrected visual acuity (BCVA).
• Manifest and cycloplegic refraction.
• Ocular dominance.
• Keratometry.
• Tonometry.
• Pachymetry.
• Slit-lamp screening.
• Aberrometry.
• Computerized videokeratography

Surgical preparation

The pre-surgical preparatory steps include:

• Application of trimethoprim sulfate 1?mg/ml, polymyxin B 10,000?U/ml or ciprofloxacin to the eye thirty minutes before the operation.
• Sterile dressing of the eye.
• Application of one drop each of topical 0.5% proparacaine and 4% tetracaine.
• Application of lid speculum.

Operative procedures

Briefly, LASEK is a surgery that involves three major steps:

1. The creation of a hinged epithelial flap by peeling the loosened epithelium as a sheet (after treatment with 18% alcohol for 25 seconds)
2. Laser ablation.
3. Replacement of the flap over the ablated stroma.

Several surgical approaches are prevalent with modifications here and there. Those proposed by Camellin, Cimberle, Vinciguerra and Epstein] have all reported effective results.

Postoperative steps

After the surgery, patients are advised to take the following measures:

• Use of oral analgesics but strictly when needed.
• Application of tobramycin-dexamethasone ointment four times a day for a week and prednisolone acetate 1% four times a day for 2 weeks.
• Use of artificial tears when required.

Removal of the bandage contact lens generally takes place after complete epithelial recovery, generally on the 3th or 4th postoperative day. Removal of the contact lens prior to that involves the risk of detaching the epithelial flap along with the contact lens.

Comparison with other refractive surgeries

In PRK, the central corneal epithelium is detached and stromal tissue is removed from the stromal bed with an excimer laser. In LASIK, an epithelial–stromal flap is created with a microkeratome, and a portion of the stromal surface is removed with an excimer laser. In LASEK, an epithelial flap is created with the help of dilute ethanol and special apparatus. Thereafter the stromal tissue is removed from the stromal surface with an excimer laser. Generally the epithelium in replaced in LASEK. Sometimes when it is lost then the process becomes almost identical to PRK.

Advantages of LASEK

It has been claimed that LASEK ensures faster visual restoration, lesser postoperative discomfort and lesser chances for haze than with PRK. What’s more, theoretically LASIK-type flap complications can be avoided with LASEK. LASEK derives its basic benefits from the characteristics of the epithelial sheet and its adhesion capability.

Complications with LASEK are generally similar to those with PRK, although incidence of slow epithelial recovery is higher in LASEK.

There have also been studies based on the degree and type of errors. For instance, it has been suggested that for patients with around 6-10 D myopia, LASIK is the preferred choice over PRK or LASEK, considering consistency of outcome and rate of vision rehabilitation.

It has also been advised that LASIK should not be the choice in patients with thin corneas (though there is a dispute among surgeons about corneal thickness) and low-to-medium dry eyes. In such cases, PRK or LASEK should be the preferred option.

The drawbacks of LASEK are as of now restricted to research conducted on a very small population because of its somewhat limited indications. As of now, its primary disadvantages remain its inconsistency in terms of postoperative pain and epithelial recovery. But since postoperative pain is a major problem of PRK, speedy epithelial healing is vital for at least some degree of postoperative relief to the patient. Though, LASEK is said to address these issues, there is not consistency in this regard.