Journal of Refractive Surgery

Original Article 

Complications of LASIK Flaps Made by the IntraLase 15- and 30-kHz Femtosecond Lasers

Payman Haft, MD; Sonia H. Yoo, MD; George D. Kymionis, MD, PhD; Takeshi Ide, MD, PhD; Terrence P. O’Brien, MD; William W. Culbertson, MD

Abstract

Purpose:

To describe complications associated with femtosecond laser-assisted flap creation in LASIK surgery. The management and visual outcomes of femtosecond laser complications related to flap creation in LASIK patients are also described.

Methods:

All eyes that underwent LASIK with the IntraLase femtosecond laser from September 2003 to June 2006 at a university-based refractive center were included in this retrospective, noncomparative, interventional case series and IntraLase-related LASIK complications are described. All flaps were made with the 15- and 30-kHz IntraLase femtosecond laser.

Results:

Included in the study were 4772 eyes, of which 44 (0.92%) eyes had direct or indirect complications due to flap creation. Thirty-two eyes had indirect complications (diffuse lamellar keratitis [DLK] and transient light sensitivity)—20 (0.42%) eyes developed DLK (stage 1 to 2) and 12 (0.25%) eyes had transient light sensitivity syndrome. Twelve (0.25%) eyes had direct femtosecond laser flap-related complications—8 (0.17%) eyes had premature breakthrough of gas through the epithelium within the flap margins, 3 (0.06%) eyes had incomplete flaps due to suction loss, and 1 (0.02%) eye had irregular flap due to previous corneal scar.

Conclusions:

Less than 1% of eyes had direct or indirect complications due to femtosecond laser flap creation. Laser in situ keratomileusis complications specifically related to the IntraLase femtosecond laser did not cause loss of best spectacle-corrected visual acuity in any eyes.

Abstract

Purpose:

To describe complications associated with femtosecond laser-assisted flap creation in LASIK surgery. The management and visual outcomes of femtosecond laser complications related to flap creation in LASIK patients are also described.

Methods:

All eyes that underwent LASIK with the IntraLase femtosecond laser from September 2003 to June 2006 at a university-based refractive center were included in this retrospective, noncomparative, interventional case series and IntraLase-related LASIK complications are described. All flaps were made with the 15- and 30-kHz IntraLase femtosecond laser.

Results:

Included in the study were 4772 eyes, of which 44 (0.92%) eyes had direct or indirect complications due to flap creation. Thirty-two eyes had indirect complications (diffuse lamellar keratitis [DLK] and transient light sensitivity)—20 (0.42%) eyes developed DLK (stage 1 to 2) and 12 (0.25%) eyes had transient light sensitivity syndrome. Twelve (0.25%) eyes had direct femtosecond laser flap-related complications—8 (0.17%) eyes had premature breakthrough of gas through the epithelium within the flap margins, 3 (0.06%) eyes had incomplete flaps due to suction loss, and 1 (0.02%) eye had irregular flap due to previous corneal scar.

Conclusions:

Less than 1% of eyes had direct or indirect complications due to femtosecond laser flap creation. Laser in situ keratomileusis complications specifically related to the IntraLase femtosecond laser did not cause loss of best spectacle-corrected visual acuity in any eyes.

From Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Fla (Haft, Yoo, Kymionis, Ide, O’Brien, Culbertson); and Vardinoyannion Eye Institute of Crete, University of Crete, Medical School (Kymionis).

Dr Yoo is a speaker for AMO/IntraLase and receives direct funding, indirect donation, or provision of equipment. Dr Culbertson is a consultant for AMO/IntraLase and receives direct funding, indirect donation, or provision of equipment. Dr O’Brien is a consultant for AMO/VISX. Drs Haft, Ide, and Kymionis have no proprietary interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (P.H., S.H.Y., G.D.K., T.I., T.P.O., W.W.C.); data collection (P.H., S.H.Y., G.D.K., T.I.); interpretation and analysis of data (P.H., S.H.Y., G.D.K., T.I.); drafting of the manuscript (P.H., S.H.Y.); critical revision of the manuscript (S.H.Y., G.D.K., T.I., T.P.O., W.W.C.); obtained funding (S.H.Y.); administrative, technical, or material support (S.H.Y., T.P.O., W.W.C.)

Correspondence: Sonia H. Yoo, MD, Bascom Palmer Eye Institute, 900 NW 17th St, Miami, FL33136. Tel: 305.326.6322; Fax: 305.326.6337; E-mail: syoo@med.miami.edu

Received: June 19, 2008
Accepted: October 29, 2008
Posted Online: November 13, 2009

Corneal flap creation by the femtosecond laser has emerged as a new option in LASIK. The femtosecond laser applies patterned pulses of ultrashort wavelength energy at many intrastromal points at a predetermined depth. Each laser pulse generates a small amount of microplasma without affecting anterior tissues, which results in an interface of microscopic gas bubbles and flap interface creation.1 The relative lack of energy imparted to the cornea helps minimize collateral tissue damage.1,2

Femtosecond laser–assisted flap creation has rapidly gained popularity. This technology offers many advantages over the microkeratome, including improved uniformity of the flap, better predictability of flap thickness,3–5 and increased safety of the procedure.6 Also, flap creation by the femtosecond laser is more predictable and reliable than traditional microkeratomes.7–9 Furthermore, flap creation by the femtosecond laser has been shown to produce similar outcomes compared to the microkeratome in terms of high contrast visual acuity, manifest refractive error, contrast sensitivity, and patient preference. There are, however, potential problems with the femtosecond laser, including complications associated with corneal flap creation such as suction loss, vertical gas epithelial breakthrough,10 anterior chamber gas bubbles,11,12 and irregular or decentered flaps. Diffuse lamellar keratitis (DLK)13 and transient light sensitivity syndrome14,15 are examples of indirect laser complications.

Patients and Methods

All patients (4772 eyes) undergoing LASIK from September 2003 to June 2006 at a university-based refractive center were included in this retrospective, noncomparative, interventional case series designed to quantify the rates and types of complications using a femtosecond laser to create the corneal flap.

All procedures were performed by five different attending surgeons (S.H.Y., T.P.O., W.W.C., C.K., Y.L.) at the Bascom Palmer Eye Institute (Miami and Palm Beach Gardens, Fla locations) using flaps made with the 15- and 30-kHz IntraLase femtosecond laser (model number 1, software version 2.44; Abbott Medical Optics Inc [AMO], Santa Ana, Calif). The machine settings for the 15-kHz laser were: flap diameter 8.7 to 9.1 mm, flap thickness 110 to 120 μm, side-cut energy 3.0 mJ, raster energy 2.7 mJ, and raster spot and line separation 12 μm and 11 μm, respectively. The flap side-cut angle was 70°, and the hinge angle was 45° of arc. The hinge position was set to 12 o’clock (90° hinge position). The settings for the 30-kHz laser were: flap diameter 8.7 to 9.1 mm, flap thickness 100 to 120 μm, side-cut energy 2.3 mJ, raster energy 1.9 mJ, and raster spot and line separation 11 μm and 9 μm, respectively. The flap side-cut angle was 70°, and the hinge angle was 45° of arc. The hinge position was set to 12 o’clock (90° hinge position). Ultrasound pachymetry measurements were taken using the Advent pachymeter (Accutome Inc, Malvern, Pa), which was done just prior to flap creation. Ultrasound pachymetry of the stromal bed was also performed just after the flap was lifted.

Data were analyzed to determine the types of complications and to quantify the incidence rate of the various complications.

Results

Of the 4772 eyes, 44 (0.92%) eyes had direct or indirect complications due to flap creation (rate of total complications). The main types of indirect complications were diffuse lamellar keratitis (DLK) and transient light sensitivity syndrome. Direct complications of femtosecond laser–assisted LASIK occurred during flap creation. Thirty-two eyes had indirect complications and 12 eyes had direct complications (Table).

Complications in 4772 Eyes that Underwent LASIK with Femtosecond Laser Flap Creation

Table: Complications in 4772 Eyes that Underwent LASIK with Femtosecond Laser Flap Creation

Indirect Complications

Twenty (0.42%) eyes developed DLK (stage 1 to 2) after LASIK. All patients had clinically evident DLK on the first postoperative day. All patients were treated with an intensive course of topical steroids. Twelve (0.25%) eyes had transient light sensitivity syndrome. No surgical intervention (eg, flap lift) was needed in any of these cases. At 1-year follow-up, no eyes lost lines of best spectacle-corrected visual acuity (BSCVA).

Direct Complications

Twelve (0.25%) eyes developed femtosecond laser flap–related complications. Eight (0.17%) eyes had premature breakthrough of gas through the epithelium within the flap margins. Three (0.06%) eyes had incomplete flaps due to suction loss. One (0.02%) eye had an irregular flap due to previous corneal scar. In the 8 eyes that had premature breakthrough of gas through the epithelium, all had their procedure completed without further complication. In the 3 eyes that had incomplete flaps due to suction loss, all were treated simultaneously with a second femtosecond laser pass at the same level. The remainder of the procedure in these patients was completed without consequence. The only procedure that could not be completed was the case with the 1 eye that had an irregular flap due to previous corneal scar. The 0.5-mm diameter corneal scar was in the superficial anterior stroma of the patient’s right eye and was located in the pupillary axis. The flap thickness was set to 120 μm. The tear was noticed upon lifting of the flap and the procedure was aborted. The patient declined retreatment and had no loss in BSCVA.

Overall, LASIK complications specifically related to the IntraLase femtosecond laser did not cause loss of BSCVA in any of the study eyes.

Discussion

Because femtosecond laser technology is a relatively new development in the armamentarium of the refractive surgeon, relatively few studies examining the incidence of complications are available in the literature. Although these complications may be rare and usually do not affect final BSCVA, our study was able to elucidate the types of complications associated with femtosecond laser flap creation in LASIK and strategies to manage these complications. Complications of flap creation in femtosecond LASIK can be grouped into indirect and direct complications. The primary indirect complications are DLK and transient light sensitivity syndrome. Some of the more common direct complications include suction loss, epithelial breakthrough, gas bubbles in the anterior chamber, and irregular flaps.

Indirect Complications

Diffuse lamellar keratitis (ie, Sands of the Sahara) is a syndrome that can result in diffuse haze of the interface (Fig 1).13 Treatment includes topical steroids, oral steroids (in more severe cases), and lifting of the flap and irrigating the stromal bed with balanced salt solution. Binder16 reported moderate DLK in the first 20 (19.4%) eyes in a series of 103 eyes operated with the IntraLase 6-kHz femtosecond laser. Javaloy et al17 reported stage 1 to 3 DLK in 17 (17%) of 100 eyes using a 15-kHz femtosecond laser. Gil-Cazorla et al18 reported 5 cases of stage 2 to 3 DLK in 1000 eyes operated with the IntraLase 15-kHz laser. The lower incidence of DLK in the IntraLase group in that study may be explained by the more intense anti-inflammatory therapy (8 times daily in the femtosecond group instead of 4 times daily) during the first postoperative week.

Diffuse Lamellar Keratitis. Note the Typical Diffuse Inflammation and Granular, “sandy” Opacification (arrow).

Figure 1. Diffuse Lamellar Keratitis. Note the Typical Diffuse Inflammation and Granular, “sandy” Opacification (arrow).

Total laser energy imparted to the tissue may be an important factor in the pathogenesis of DLK. One of our cases of postoperative stromal inflammation (Fig 2) supports this theory. This case showed peripheral stromal haze at the edges of the flap cut, where the side-cut was performed with higher energy settings. In our study, 20 (0.42%) eyes developed DLK (stage 1 to 2) after LASIK. This occurred using the 15-kHz laser in 15 eyes and in 5 eyes with the 30-kHz laser. All patients had clinically evident DLK on postoperative day 1, and all were treated with an intensive course of steroids. No surgical intervention was needed (eg, flap lift). At 1-year follow-up, none of these patients had loss of BSCVA.

Focal Stromal Inflammation at the Flap Edge. Haze Is Primarily Seen at the Flap Edge (arrow), Likely Due to the Higher Laser Energy Settings Needed for the Side Cut.

Figure 2. Focal Stromal Inflammation at the Flap Edge. Haze Is Primarily Seen at the Flap Edge (arrow), Likely Due to the Higher Laser Energy Settings Needed for the Side Cut.

Transient light sensitivity syndrome is a clinical condition characterized by unusual photosensitivity with normal visual acuity several weeks after otherwise uneventful LASIK with the femtosecond laser that typically responds to topical treatment with topical steroids or cyclosporine. Stonecipher et al14 reported a 1.1% rate of this complication in femtosecond LASIK (5667 total cases). These patients were treated with prednisolone acetate drops and one surgeon also used cyclosporine 0.05% ophthalmic solution. Patients noted improvement of symptoms within 1 week of treatment. Muñoz et al15 also reported transient light sensitivity syndrome after femtosecond laser–assisted LASIK. They reported a 1.3% incidence of transient light sensitivity, which decreased with aggressive use of postoperative topical steroids. Our study reports 12 (0.25%) eyes with transient light sensitivity syndrome (which occurred in 10 eyes with the 15-kHz laser and 2 eyes with the 30-kHz laser). It is theorized that higher energies used with previous femtosecond laser platforms (10 and 15 kHz) produce activated keratocytes and cause delayed return to their normal state, which may cause transient light sensitivity syndrome. Indeed, Stonecipher et al14 noted that when the raster and side-cut energy settings were lowered (by an average of 24% and 33%, respectively), a significant reduction in the incidence of transient light sensitivity syndrome was achieved. With the newer 60- and 150-kHz platforms, lower energy is delivered per pulse, which may result in a lower rate of transient light sensitivity syndrome in the future.

Direct Complications

Suction loss may occur during laser flap creation, which can lead to an incomplete flap. Retreatment to complete the flap may be problematic because the original plane of cutting may not be found and a second interface may be created. Also, a thin, buttonholed, or irregular flap may be created. Improper technique in applying the suction ring to the eye can cause loss of suction. A study examining risk factors for loss of suction in microkeratome-assisted LASIK found other risk factors for inadequate fixation, including narrow palpebral fissures, flat corneas, and young age.19 Narrower palpebral fissures leave limited room to effectively apply the suction apparatus to the eye. Younger patients may have stiffer lids that do not open as easily with a lid speculum. Conjunctival chemosis at the limbus may also interfere with the suction ring, not allowing adequate suction to build. Conjunctival massage can be used to push fluid away from the limbus in the case of conjunctival edema from repeated suction attempts. In addition, a conjunctival incision can be used to drain fluid and lessen edema. Sometimes delaying the procedure for a few hours to a few days may be needed to allow the edema to resolve.20 Binder reported suction loss in 6 eyes of 1000 cases.7 In our study, the rate of suction loss was 0.06%. A second pass successfully managed incomplete flaps, which resulted in intact flaps as planned. All procedures were completed, and the eyes that were followed for at least 6 months had excellent visual and refractive results.

Epithelial breakthrough (Fig 3) during femtosecond laser flap creation has been reported and studied only recently and only a few cases are reported in the literature. Srinivasan and Herzig21 reported the first case of subepithelial gas breakthrough during femtosecond laser flap creation for LASIK. They proposed that thin flaps or a focal break in Bowman’s layer may contribute to vertical gas breakthrough. In our study, we report 8/4772 (0.17%) eyes with this type of complication. In a previous study,10 we proposed that for gas breakthrough, a focal area of altered epithelium and thinned stroma in the area of scarring creates a low-resistance pathway that allows the gas bubbles to escape toward the surface instead of through the typical lamellar plane. Regarding epithelial breaks during flap lifting (after the femtosecond laser–assisted flap was created), it may be that stromal scarring may trap gas bubbles and not allow advancement through the flap interface to allow completion of the flap. In addition, during flap lifting itself, stromal fibrosis may anchor the flap to the underlying bed and induce breakthrough and flap tears. For these reasons, femtosecond laser flap creation should be done with caution in patients with corneal scars. If possible, increasing flap thickness may allow the creation of a flap interface more posterior to the scars. Also, another option may be to increase the energy of the raster pass and/or decrease the spot and line separation. If scars are widespread and visualization of anterior chamber structures is difficult, femtosecond laser flap creation should be avoided.

Epithelial Breakthrough (arrows). A Low Resistance Pathway Through Altered Epithelium and Thinned Stroma in the Area of a Corneal Scar May Result in This Complication.

Figure 3. Epithelial Breakthrough (arrows). A Low Resistance Pathway Through Altered Epithelium and Thinned Stroma in the Area of a Corneal Scar May Result in This Complication.

An irregular or decentered flap (Fig 4) may also occur during femtosecond laser flap creation. Irregular flaps can result from loss of suction. Patients with deep-set eyes, small corneas, or eyes with conjunctival edema can result in inadequate contact with the suction apparatus. Avoidance of cutting the flap when intraocular pressure is low (low suction) is an important precaution. Care should be taken in performing femtosecond LASIK in pseudophakic eyes that may be more susceptible to suction loss. Buttonhole flap formation, seen in steep corneas cut with microkeratomes, was not noted in our series. Buttonholes may occur in microkeratome cases due to buckling of the cornea at the applanation head, as well as proposed increased corneal resistance with upward movement of the cutting blade.20 With these types of complications (whether with microkeratome or femtosecond laser), the safest management may be to reposition the flap and abort the procedure. A deeper flap can typically be recut approximately 3 months later. In our study, this complication was found in three eyes. One eye had a LASIK procedure aborted due to irregular flap creation, and declined retreatment later. Despite this, the patient did not lose BSCVA.

Decentered Flap. The Shorter Arrow Points to the Flap Bed; the Longer Arrow Points to the Edge of the Excimer Laser Reticle, Which Is Centered over the Pupil.

Figure 4. Decentered Flap. The Shorter Arrow Points to the Flap Bed; the Longer Arrow Points to the Edge of the Excimer Laser Reticle, Which Is Centered over the Pupil.

Although the application of femtosecond technology in refractive surgery does not completely eliminate LASIK complications, it reduces the risk of flap-associated complications in comparison with microkeratomes. Microkeratomes have an incidence of overall complications that range from 0.24% to 14%.9,22–24 Microkeratomes have been unpredictable in the past with regard to epithelial defects and loose epithelium, but newer mechanical microkeratome designs have improved in this area, although they still have up to a 2.6% rate of epithelial complications.3 In addition, with growing concerns of corneal ectasia induced by refractive surgery, the thickness of the flap and its predictability have become of paramount importance. Microkeratomes can be variably predictable in their ability to produce consistent flap thicknesses,25,26 which is problematic if an unexpectedly thick flap is created. The femtosecond laser has demonstrated more predictable flap thickness than microkeratomes.3,4,27 Intraoperative pachymetry performed prior to flap lift can help the femtosecond laser operator detect an unusually thick or thin flap.28 In addition, the femtosecond laser creates a flap of more uniform thickness than microkeratomes, which helps treat and prevent higher order aberrations.29,30 The femtosecond laser has also shown better refractive and visual acuity outcomes when compared with traditional microkeratomes.3

Further improvements in femtosecond laser technology could further enhance LASIK outcomes. For example, the 60-kHz femtosecond laser platform allows for lower energy to be used for the lamellar flap creation. This lower energy may decrease the incidence of some of the indirect femtosecond–related complications reported here, such as DLK and transient light sensitivity syndrome.

Due to limitations in postoperative follow-up for our patients, we are unable to comment on the incidence of ectasia after LASIK in these cases with the femtosecond laser, although no patients developed ectasia to the best of our knowledge. There is also a lack of long-term studies in the literature quantifying the incidence of this complication in relation to femtosecond laser use. One can hypothesize that with more predictable flap thickness with the femtosecond laser, the incidence of ectasia after LASIK may be reduced.

Although femtosecond laser technology is not completely free of complications, it provides an attractive alternative to traditional microkeratomes. As with any new technology, there is heightened interest in performing studies to further determine the mechanisms that explain the complications. More studies are needed to help elucidate these mechanisms, as well as other potential advantages and disadvantages of the technology.

References

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  14. Stonecipher KG, Dishler JG, Ignacio TS, Binder PS. Transient light sensitivity after femtosecond laser flap creation: clinical findings and management. J Cataract Refract Surg. 2006;32:91–94. doi:10.1016/j.jcrs.2005.11.015 [CrossRef]
  15. Muñoz G, Albarrán-Diego C, Sakla HF, Javaloy J, Alió JL. Transient light-sensitivity syndrome after laser in situ keratomileusis with the femtosecond laser. Incidence and prevention. J Cataract Refract Surg. 2006;32:2075–2079. doi:10.1016/j.jcrs.2006.07.024 [CrossRef]
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  18. Gil-Cazorla R, Teus MA, de Benito-Llopis L, Fuentes I. Incidence of diffuse lamellar keratitis after laser in situ keratomileusis associated with the IntraLase 15 kHz femtosecond laser and Moria M2 microkeratome. J Cataract Refract Surg. 2008;34:28–31. doi:10.1016/j.jcrs.2007.08.025 [CrossRef]
  19. Asano-Kato N, Toda I, Hori-Komai Y, Takano Y, Tsubota K. Risk factors for insufficient fixation of microkeratome during laser in situ keratomileusis. J Refract Surg. 2002;18:47–50.
  20. Melki SA, Azar DT. LASIK complications: etiology, management, and prevention. Surv Ophthalmol. 2001;46:95–116. doi:10.1016/S0039-6257(01)00254-5 [CrossRef]
  21. Srinivasan S, Herzig S. Sub-epithelial gas breakthrough during femtosecond laser flap creation for LASIK. Br J Ophthalmol. 2007;91:1373. doi:10.1136/bjo.2007.129213 [CrossRef]
  22. Pallikaris IG, Katsanevaki VJ, Panagopoulou SI. Laser in situ keratomileusis intraoperative complications using one type of microkeratome. Ophthalmology. 2002;109:57–63. doi:10.1016/S0161-6420(01)00862-4 [CrossRef]
  23. Nakano K, Nakano E, Oliveira M, Portellinha W, Alvarenga L. Intraoperative microkeratome complications in 47,094 laser in situ keratomieusis surgeries. J Refract Surg. 2004;20:S723–S726.
  24. Carrillo C, Chayet AS, Dougherty PJ, Montes M, Magallanes R, Najman J, Fleitman J, Morales A. Incidence of complications during flap creation in LASIK using the NIDEK MK-2000 microkeratome in 26,600 cases. J Refract Surg. 2005;21:S655–S657.
  25. Chayet AS. Clinical experience with the Nidek MK-2000 keratome system [abstract]. J Refract Surg. 2005;21:S659.
  26. Pietilä J, Mäkinen P, Suominen S, Huhtala A, Uusitalo H. Corneal flap measurements in laser in situ keratomileusis using the Moria M2 automated microkeratome. J Refract Surg. 2005;21:377–385.
  27. Stahl JE, Durrie DS, Schwendeman FJ, Boghossian AJ. Anterior segment OCT analysis of thin IntraLase femtosecond flaps. J Refract Surg. 2007;23:555–558.
  28. Eisner RA, Binder PS. Technique for measuring laser in situ keratomileusis flap thickness using the IntraLase laser. J Cataract Refract Surg. 2006;32:556–558. doi:10.1016/j.jcrs.2006.01.003 [CrossRef]
  29. Durrie DS, Kezirian GM. Femtosecond laser versus mechanical keratome flaps in wavefront-guided laser in situ keratomileusis: Prospective contralateral eye study. J Cataract Refract Surg. 2005;31:120–126. doi:10.1016/j.jcrs.2004.09.046 [CrossRef]
  30. Tanzer DJ, Schallhorn S, Brown MC. Comparison of femtosecond vs mechanical microkeratome in wavefront-guided LASIK. Paper presented at: American Society of Cataract and Refractive Surgery Symposium. ; April 15–20, 2005. ; Washington, DC. .

Complications in 4772 Eyes that Underwent LASIK with Femtosecond Laser Flap Creation

ComplicationsNo. Eyes (%)
Total44 (0.92)
Direct (flap)12 (0.25)
  Epithelial gas breakthrough8 (0.17)
  Incomplete flap/suction loss3 (0.06)
  Irregular flap due to corneal scar1 (0.02)
Indirect
  Diffuse lamellar keratitis20 (0.42)
  Transient light sensitivity12 (0.25)
Authors

From Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Fla (Haft, Yoo, Kymionis, Ide, O’Brien, Culbertson); and Vardinoyannion Eye Institute of Crete, University of Crete, Medical School (Kymionis).

Dr Yoo is a speaker for AMO/IntraLase and receives direct funding, indirect donation, or provision of equipment. Dr Culbertson is a consultant for AMO/IntraLase and receives direct funding, indirect donation, or provision of equipment. Dr O’Brien is a consultant for AMO/VISX. Drs Haft, Ide, and Kymionis have no proprietary interest in the materials presented herein.

Correspondence: Sonia H. Yoo, MD, Bascom Palmer Eye Institute, 900 NW 17th St, Miami, FL33136. Tel: 305.326.6322; Fax: 305.326.6337; E-mail: syoo@med.miami.edu

10.3928/1081597X-20091016-02

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