Intralase All-Laser LASIK Fact vs. Fiction

The widely advertised Intralase "All-Laser" LASIK (or "Bladeless LASIK) procedure is not in fact performed entirely with a laser. The procedure involves using a laser to create non-connecting spots in the cornea (in a pattern analogous to the perforations on an old-fashioned postage stamp). Because the spots do not fully connect, a dull blade must be used to finish creating the flap by hand. While this technique works and is approved by the FDA, there are downsides to its use.

There are several important issues involving the Intralase femtosecond laser for creating the corneal flap in LASIK surgery. While vision care professionals and consumers have been bombarded with marketing-related information about the laser, an analysis using evidence based medicine can help separate Intralase fact from fiction.

As you may be aware, Intralase was approved more than two years ago by the FDA as an alternative to traditional mechanical microkeratomes. While the company, Intralase Corp., is attempting to promulgate its technology as the standard of care, the reality is that less than 15% of all flaps in the world are created with an Intralase laser. In fact, more than 85% of surgeons, including some of the most prolific and respected refractive surgeons in the US, still consider the mechanical microkeratome as a state-of-the-art technology that represents the standard of care. While the Intralase laser clearly works, I have seen no convincing evidence that it represents an improvement over more traditional keratome technology.

Many ophthalmologists who have considered using Intralase have concluded that at present, the Intralase technology is best suited to those surgeons who are very inexperienced, and have difficulty with the flap creation part of the LASIK procedure. Consistent with this view, there is a growing consensus among the majority of experienced surgeons that the Intralase laser may actually represent a step backward in performing safe, effective LASIK.

This view is substantiated by a significant body of clinical evidence. Since its introduction, many adverse events with the Intralase have been reported to the FDA’s Manufacturer and User Facility Device Experience (MAUDE) Database Website
- enter “Intralase” in the search field and click on “Search” to see the many adverse events which have been reported).

Following is Dr. Dougherty's summary of marketing-inspired myths about the Intralase laser, followed by references at the end of the summary:

MYTH: Intralase enables surgeons to perform “All-Laser LASIK”
REALITY: In an attempt to recreate what is performed with a traditional microkeratome, the Intralase technique disrupts corneal stroma in a spot fashion¹. Unfortunately, the spots don’t connect, so the technique essentially creates a swiss-cheese pattern in the stroma, with attachments between the bed and the flap. These attachments must be torn away with a hand-held instrument². Because these flaps are harder to lift than standard flaps, Intralase can cause an increase of higher order aberrations that is higher than that of a conventional microkeratome³. So rather than performing “all-laser LASIK,” Intralase in essence performs “manual LASIK,” with an important step of the process performed by hand (much like RK was performed by hand).
MYTH: Intralase creates better stromal beds for laser treatment.
REALITY: The flaps created by Intralase can be compared to postage stamps that are incompletely perforated. Just like Intralase flaps, manually tearing a postage stamp results in rough edges when separated. Intralase performs an incomplete keratectomy that requires manual dissection, and thus creates beds that are very rough, by both gross inspection and electron microscopy⁴.
MYTH: Intralase allows for better post-operative visual outcomes.
REALITY: Due to the irregular beds described above, visual recovery with Intralase flaps may be delayed⁵. In addition, there is good evidence that Intralase visual outcomes are no better than those achieved with a conventional microkeratome^6,7,8 -- and may in fact be inferior⁹.
MYTH: Intralase creates more accurate flaps.
REALITY: While the company claims that the accuracy of flap thickness is +/- 5 microns (the typical mechanical flap is +/- 15 to 20 microns), Binder¹⁰ reported that in clinical practice, Intralase flaps have a standard deviation of +/- 18.5 microns. This consistency of flap thickness is nearly identical to the +/- 20 micron flaps that I create with my mechanical microkeratome, the BD K-3000/4000^11,12. In addition, Intralase creates thousands of cavitation bubbles in the cornea, which remove corneal tissue instead of separating it. This makes the flap smaller than the stomal bed^2,13, which can cause flap folds and loss of BCVA⁵.
MYTH: Intralase creates flaps more safely than mechanical microkeratomes.
REALITY: Like any surgical procedure, there are risks associated with creating Intralase flaps. Because the Intralase process requires a step involving manual keratectomy, there have been documented cases of perforated and/or ripped flaps⁵. Flap stria, flap edema and irregular astigmatism with loss of BCVA from the flap with Intralase have also been reported^5,14. In contrast, the risks of intra-operative flap problems of any variety with the newer mechanical microkeratomes such as the BD is extremely low^{9,11,12,15,16}. Additionally, the rate of DLK (diffuse lamellar keratitis) is higher with Intralase, with up to 19% of eyes developing this complication^17,18. This is likely due to either the laser energy or the manual keratectomy. In addition, cases of bilateral DLK with irregular astigmatism and loss of BCVA have been reported⁵. Finally, there is an Intralase study¹⁸ that has reported a very high incidence of both post-operative flap edema (23%) and peripheral epithelial ingrowth (23%).
MYTH: Patient acceptance is higher with Intralase.
REALITY: Because of both the slow visual recovery and the increased incidence of pain compared to traditional keratomes, patient acceptance of Intralase may in fact be lower. A syndrome of late-onset severe pain and photophobia that can last for up to six months. Known as track-related iridocyclitis and iritis (TRISC), this syndrome has been described following the Intralase procedure¹⁹. This syndrome occurs in just under 1% of patients¹⁸. TRISC is often disabling for the patient, and usually requires treatment with high dose topical steroids. Because of the pain and inflammation associated with Intralase, a more prolonged use of post-operative steroids is required^20,21 compared to the typical 2 to 4 day course after standard keratectomy, even in the absence of TRISC. The use of steroids after LASIK can result in significant elevation of the IOP that can be missed because of fluid accumulation under the flap that falsely lowers IOP. Such cases can result in serious loss of vision after LASIK²².

It is important to separate Intralase fact from fiction in order to provide our patients with the best, most appropriate care possible. Despite all of the marketing hype surrounding “all laser LASIK,” the medical evidence suggests that the latest generation of mechanical microkeratomes may provide a better, safer option than the current generation of femtosecond lasers.

Sincerely,
Paul J. Dougherty, M.D.

References

Sugar A. Ultrafast (femtosecond) laser refractive surgery. Curr Opin Ophthalmol. 2002; 13:246-249.
Goldberg DB. The IntraLASIK learning curve. Cataract & Refractive Surgery Today. 2004:4:24-28.
MacRae SM, Porter J, Yoon G-Y, et al. Causes of the increase in higher-order aberrations after LASIK. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery Symposium. San Diego, CA. May, 2004
Solomon R, Donnenfeld ED. Flap Bed Smoothness in LASIK. Presented at the American Academy of Ophthalmology Annual Meeting, New Orleans, LA, November, 2004.
FDA Manufacturer and User Facility Device Experience (MAUDE) Database Website
Cox IG. The Hansatome versus the femtosecond laser: Equivalent results after LASIK [white paper]. Bausch & Lomb; April 2004.
Gupta P, Netto MV, Dupps W, et al. Femtosecond laser: myths and truths. Analysis of our first 400 cases. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery. Washington DC. May, 2005.
Chalita R, Netto M, Dupps W, et al. Comparison of custom LASIK outcomes with femtosecond and conventional microkeratomes. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery. Washington DC. May, 2005 and ASCRS 2005 Update; Femtosecond vs. conventional. Primary Care Optometry News. June 2005:20.
Woodhams T. Does a better flap improve outcomes? Ophthalmology Management May 2004.
Binder, PS. Flap Dimensions Created with the Intralase FS Laser. Journal of Cataract and Refractive Surgery 2004;30(1):26-32.
Dougherty, PJ. Thin Flap LASIK. Clinical and Surgical Ophthalmology (The Journal of the Canadian Society of Cataract and Refractive Surgery) 2003;1/21(8):326-330.
Dougherty, PJ. The thin flap LASIK technique. Journal of Refractive Surgery 2005;21(5S):84-87.
Donnenfeld ED. FS Laser: Not ready for prime time. Ophthalmology Management. 2004; 8(suppl):10-12.
Biser SA, Bloom AH, Donnenfeld ED, et al. Flap folds after femtosecond LASIK. Eye Contact Lens 2003;29:252-254.
Dougherty, PJ. Reliability and Safety of the BD K-4000 Microkeratome in LASIK. Presented at the American Society of Cataract and Refractive Surgery Annual Meeting, San Francisco, California, April 2003.
Carillo C, Chayet A, Dougherty PJ, et al. Incidence of complications during flap creation in LASIK using the Nidek MK-2000 microkeratome in 26,600 cases. Journal of Refractive Surgery 2005;21(5S).
Meltzer, J in Kent, C. Microkeratomes vs. the Femtosecond Laser. Ophthalmology Management 2003;7(9):71-79.
Gupta P, Netto MV, Dupps W, et al. Femtosecond laser: myths and truths. Analysis of our first 400 cases. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery. Washington DC. May, 2005
Will BR. Track-related iridocyclitis and sceritis associated with the Intralase for LASIK. Presented at the ASCRS Symposium on Cararact, IOL and Refractive Surgery Symposium. San Diego, CA. May, 2004.
Kezerian GM, Stonecipher KG. Comparison of the Intralase femtosecond laser and mechanical keratomes for laser in situ keratomileusis. Journal of Cataract and Refractive Surgery 2004;30:804-811.
Controversies in Flap Creation: Hansatome Versus Intralase. Cataract and Refractive Surgery Today (suppl.). November/December 2004:3-10.
Artola A, Galal A, Alio J, et al. Pseudo-DLK secondary to post-LASIK steroid induced elevation of IOP. Submitted for publication in the Journal of Refractive Surgery, 2005.

Dr. Paul Dougherty is a Los Angeles Laser Eye Surgery specialist who also is an expert with the Crystalens and Staar Visian ICL Implantable Contact Lens.
When you think of Los Angeles LASIK Surgery, think of Dougherty Laser Vision Correction.

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