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Info on Epi-LASIK

Epi-LASIK: The Thinking Man’s LASIK

The LASIK Revolution

LASIK has become the new catchphrase for the new and informed generation, becoming the permanent and much embraced solution to one’s dependence on glasses or contact lenses. The “cut, flap and zap” procedure, fast painless recovery and predictable results have delighted the public, so much so that worldwide, about 15 million LASIK procedures have been performed and the numbers are soaring.

The LASIK Procedure

LASIK, by far, is the most common form of refractive surgery performed in Singapore. Conventional LASIK involves the use of a microkeratome (a sophisticated surgical blade) to cut a flap on the front surface of the cornea. Excimer laser is then used to ablate or laser the tissue at the central portion of the cornea. The cornea flap is subsequently replaced, healing with natural adhesion.

Epi-LASIK – A Surface Procedure


Epi-LASIK		Epi-LASIK Surface Procedure

Epi-LASIK is a surface based procedure. This means that the laser tissue sculpting that is done to correct the eye power is at the level of the glassy smooth cornea bed surface called the Bowman’s membrane. This membrane layer lies just beneath the superficial epithelial layer.

To prepare the treatment surface, a blunt device that does not cut into the cornea is used to separate or lift up the epithelium from the Bowman’s layer (see the above diagram).

Epi-LASIK Treatment Surface versus LASIK Treatment Surface



For Epi-LASIK, laser tissue sculpting is done on the glassy smooth cornea bed (bowman’s membrane after the surface epithelium is lifted off. This epithelium will regenerate itself in 3 to 5 days.		Unlike Epi-LASIK, LASIK cuts a cornea flap & laser tissue sculpting is done on the residual cornea bed surface that is not entirely smooth (see above picture). This can adversely affect the result of wavefront laser treatment.

Why True Wavefront Laser Treatment is only possible with Epi-LASIK?


Aberrometer		Wavefront Technology

Much has been written about “customised wavefront” laser treatment. This is a procedure where special machines called aberrometers are used to map the patient’s unique refraction ‘fingerprint’, in addition to standard optical measurements. The information is then transferred to the laser computer and laser tissue sculpting on the cornea is performed taking into consideration these findings.

In theory, this should produce better visual outcomes than a procedure relying solely on conventional measurements. The reality however, is that if LASIK is done, cutting the cornea flap will induce new optical abnormalities that may negate the potential benefits derived from wavefront treatment. With Epi-LASIK however, since no cut is made into the cornea and the treatment is done one a smooth cornea bed, true wavefront treatment can finally be approached.

Drawbacks of LASIK


Thin Cornea		Dry Eyes		High Myopia

While LASIK is a fuss free, painless procedure for permanent vision correction, not all individuals are suitable candidates. Approximately one in six are turned away, mostly due to thin corneas, high myopia, dry eyes or a combination thereof. But thanks to Epi-LASIK, a procedure evolved from LASIK, many individuals previously unsuitable for LASIK now have renewed hope. With Epi-LASIK, a “no-cut”, tissue-sparing procedure suitable for even those with high degrees of myopia, the breakthrough procedure is proving to be the “no-cut” LASIK surgery for just about anyone.

The “No Cut” Difference


LASIK Flap Wrinkles		DLK		Button-Hole Flap

Laser cut or blade cut, LASIK suffers from the drawbacks of cornea flap creation and healing. These run the gamut of partially cut flaps, decentred flaps, button-hole flaps, free caps, epithelial in-growth, flap infection, trapped debris and DLK or ‘sands’ that is a sterile inflammation of the flap interface. An abbreviation for Diffused Lamellar Keratitis, DLK is a cornea inflammation caused by debris or chemicals which are trapped in between the flap interface. If not treated promptly with medications, DLK can lead to reduced vision. As no flap is created in Epi-LASIK, there is no risk of DLK occurring. Cutting the flap in LASIK also means that less cornea bed is available for tissue sculpting and if the patient’s cornea is naturally thin or the power to be corrected high, the patient will be an unsuitable candidate. In Epi-LASIK, at least 100 microns of cornea tissue is saved as only a superficial layer of epithelium is moved aside for lasering beneath the bed. In LASIK, because significant cornea tissue is lost during the process of flap creation, individuals with high myopia who undergo the procedure risk the development of keratoectasia, a condition whereby the removal of excessive cornea tissue causes the cornea to become so eroded that it begins to bulge. For those with pre-existing dry eye problems, cutting the flap means cutting the nerve endings and this could severely aggravate the problem.

In fervent support of the Epi-LASIK procedure is senior eye surgeon, Dr. Tony Ho, who possesses over a decade of experience in laser refractive surgery: “The risks involved in refractive surgery have been greatly minimized with Epi-LASIK, and I am convinced that Epi-LASIK will be the future of refractive surgery.”

New Hope With Epi-LASIK

By doing away with flap creation, Epi-LASIK offers safe, predictable vision correction for just about everyone. It may still not be routinely recommended over LASIK because the downtime for vision recovery is longer, taking three to five days as opposed to the overnight recovery for LASIK. In addition, significant discomfiture may be experienced by the Epi-LASIK patient during the recovery period. In some patients, particularly those treated for high myopia, cornea hazing may be present. Usually this is not visually symptomatic but the risk of such an occurrence is certainly higher than that present following a LASIK procedure. However, for many patients who otherwise cannot have LASIK, who are fearful of flap complications, who suffer from severe dry eye, who desire to achieve true wavefront vision correction or who are simply afraid to have their corneas cut, Epi-LASIK is the way to go.

The Trend Towards Epi-LASIK

More veteran surgeons are switching to perform Epi-LASIK over conventional LASIK. Renowned expert in refractive surgery, Dr. Marguerite McDonald, M.D. who performed the world’s first excimer laser treatment for the correction of refractive errors in 1987, and who performed the world’s first excimer laser for long-sightedness in 1993, expressed her views to the American Academy of Ophthalmology audience on the benefits of Epi-LASIK with respect to its safety, reliability in producing superior visual outcomes, and greater patient suitability, stating that she has “hung up her microkeratome” for surface ablation.

Dr. Tony Ho is likewise embracing Epi-LASIK as the surgery of choice for the correction of refractive errors, recognizing the risk/benefit ratio to be in favour of Epi-LASIK over conventional LASIK.

	Published in "Today" Newspaper - Wed June 1, 2005




	Epi-lasik, unlike lasik, can be used on almost all patients

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