The flap never completely adheres to the cornea after LASIK. Peer-reviewed medical literature contains numerous reports of flap dislocations years after LASIK. Patients should be informed of this risk prior to having LASIK. The FDA website warns that patients who participate in contact sports are not good candidates for LASIK. FDA link.
Researchers found that the strength of the post-LASIK cornea at the flap interface is only 2% of original strength:
Dr. George O. Waring III: "This means you can lift the LASIK flap indefinitely after LASIK. My longest personal LASIK flap lift is 12 years, and it was done very easily. We have performed biomechanical studies now at Emory up to eight years post-operatively and find that the strength of the lamellar wound is about 2 percent of the normal cornea."
Source: Am J Ophthalmol. 2006 May;141(5):799-809. Peer Discussion: Corneal keratocyte deficits after photorefractive keratectomy and laser in situ keratomileusis.
Read medical literature on permanent weakness of the LASIK flap and late flap dislocations:
Laser Epithelial Keratomileusis for the Correction of Hyperopia Using a 7.0-mm Optical Zone With the Schwind ESIRIS Laser
Journal of Refractive Surgery Vol. 23 No. 4 April 2007
David P.S. O’Brart, MD, FRCS, FRCOphth; Faye Mellington, MBBS; Sophie Jones, MRCOphth; John Marshall, PhD
From the article: For LASIK, long-term published data are somewhat limited and the refractive and biomechanical stability remains uncertain. By its very nature LASIK must be regarded as more invasive in terms of corneal biomechanical stability than surface ablation procedures. The LASIK flap once cut may contribute little to the mechanical stability of the cornea and probably never completely adheres to the underlying stromal bed, with late traumatic flap displacement being reported as an infrequent complication.
Traumatic flap dislocation 4 years after LASIK due to air bag injury.
J Refract Surg. 2007 Sep;23(7):729-30.
Ramírez M, Quiroz-Mercado H, Hernandez-Quintela E, Naranjo-Tackman R.
Department of Cornea and Refractive Surgery, Asociación Para Evitar la Ceguera en México, Hospital Luis Súnchez Bulnes, Universidad Nacional Autónoma de México, Mexico City, Mexico. email@example.com
PURPOSE: To report a patient who developed corneal flap dislocation following air bag injury 48 months after LASIK.
METHODS: Evaluation by slit-lamp microscopy and fluorescein angiography.
RESULTS: A 29-year-old man was treated after air bag injury that occurred 48 months after LASIK. Examination revealed corneal flap dislocation, with severe folds and flap edema. Preoperative visual acuity was finger counting at 1 m. Visual acuity was 20/400 24 hours after repositioning the corneal flap. Retinal angiography revealed Berlin macular edema, which was injected with periocular steroids. Five days after injection, visual acuity remained 20/400, but improved to 20/40 1 month after injection.
CONCLUSIONS: Significant trauma can dislocate a corneal flap many months after surgery.
From the article:
"The corneal flap can be easily displaced following trauma many months after LASIK."
"The healing process at the corneal flap wound interface persists for several months after LASIK, which consists of disorganized collagen fibers that can be seen along the interface of the corneal flap creating a hypocellular primitive stromal scar.9,10 The risk of trauma, such as that associated with some occupations or participation in sports, should be discussed with the patient preoperatively and during follow-up to LASIK surgery."
Immunohistochemical Findings After LASIK Confirm In Vitro LASIK Model
Cornea, Volume 25(3), April 2006, pp 331-335
Priglinger SG, May CA, Alge CS, Wolf A, Neubauer AS, Haritoglou C, Kampik A, Welge-Lussen U.
"However, one aspect still in discussion is the wound-healing process in the created interface that leads to an easily removable flap even years after treatment."
"The lack of pronounced morphologic changes in the central area of the LASIK interface, which only showed little accumulation of fibronectin, supports the hypothesis of reduced wound-healing reactions after performing this surgical procedure. Only at the rim zone of the incision, scar tissue formation can appear and might form an incomplete fixation zone for the corneal flap. Due to this impaired healing process, even years after the LASIK procedure, a corneal flap displacement can occur.
In summary, our histologic findings confirm the well-known clinical phenomenon that wound-healing reactions are marginal after uncomplicated LASIK treatment."
Treatment of traumatic LASIK flap dislocation and epithelial ingrowth with fibrin glue.
Am J Ophthalmol. 2006 May;141(5):960-2.
Yeh DL, Bushley DM, Kim T.
Duke University Eye Center, Durham, North Carolina.
PURPOSE: To describe a case of a traumatic late dislocation of a laser-assisted in situ keratomileusis (LASIK) flap complicated by epithelial ingrowth.
DESIGN: Interventional case report.
METHODS: A 50-year-old woman presented 21 months after uncomplicated LASIK with painful vision loss in the right eye after minor trauma.
RESULTS: A dislocation of the LASIK flap was noted at examination and was repositioned. One week later, epithelial ingrowth was detected in the flap interface. The ingrowth was treated with flap lifting, debridement, and sealing of the flap with fibrin glue. Visual acuity returned to baseline, and there was no recurrence after 20 months of follow-up.
CONCLUSIONS: Traumatic dislocations of LASIK flaps may occur many months after uncomplicated surgery and may be associated with epithelial ingrowth after successful repositioning. The additional use of fibrin glue in conjunction with thorough debridement may be helpful in preventing the recurrence of epithelial ingrowth.
Traumatic corneal flap dislocation one to six years after LASIK in nine eyes with a favorable outcome.
J Refract Surg. 2006 Nov;22(9):884-9.
Landau D, Levy J, Solomon A, Lifshitz T, Orucov F, Strassman E, Frucht-Pery J.
Cornea and Refractive Surgery Unit, Dept of Ophthalmology, Hadassah University Hospital, P.O.B. 12000, Jerusalem 91120, Israel. firstname.lastname@example.org
PURPOSE: To report our experience treating eye trauma after LASIK refractive surgery.
METHODS: Nine eyes of eight patients (one woman and seven men) were treated for ocular trauma: blunt trauma (n=5), sharp instrument trauma (n=2,) and trauma from inflation of automobile air bags during a traffic accident (n=2). The time from LASIK varied between 3 months and 6 years. All patients were hospitalized as a result of severe decrease in visual acuity and pain.
RESULTS: Seven of nine LASIK flaps had some degree of dislocation and were lifted, irrigated, and repositioned. Two flaps were edematous without dislocation. Intensive topical steroids and antibiotics were used in all patients up to 3 weeks after trauma. Three months after trauma, five eyes regained their pre-trauma visual acuity (between 20/20 and 20/40), and three eyes lost one line of best spectacle-corrected visual acuity.
CONCLUSIONS: Trauma occurring several months or years after LASIK may cause flap injury. Adequate and prompt treatment usually is successful.
From the article: "Our report, as well as the related literature, indicates that the healing of the flap is incomplete even 6 years after LASIK surgery. The exact mechanism of long-term adhesion remains unclear."
Laceration and Partial Dislocation of LASIK Flaps 7 and 4 Years Postoperatively With 20/20 Visual Acuity After Repair
Journal of Refractive Surgery Vol. 22 No. 9 November 2006
George J.C. Jin, MD, PhD; Kevin H. Merkley, MD, MBA
From the article: "Although ocular trauma with corneal laceration can occur, we report that the lamellar flap is still susceptible to ocular trauma 7 years after LASIK. Informed consent should include discussion of long-term flap complications and patients should be advised to protect their eyes after LASIK, especially during high risk activities."
Late Traumatic Flap Dislocations After LASIK
J Refract Surg Vol 22, May 2006
Cheng AC, Rao SK, Leung GY, Young AL, Lam DS.
Excerpts from the full text:
"A number of cases of late onset traumatic LASIK flap dislocations have been reported, raising questions about the strength of the adhesion between the flap and the stromal bed.
In this series, we report three cases of late onset traumatic LASIK flap displacement and their management. One patient presented 7 years after the initial surgery, which, to our knowledge, is the longest duration reported.
A 23-year-old man with bilateral uncomplicated LASIK 7 years prior presented 2 days after sustaining a left eye injury by another person’s fingernail in a fight.
A 33-year-old woman underwent LASIK and presented after sustaining a broomstick injury 1 year postoperatively.
A 38-year-old woman with a history of uncomplicated bilateral LASIK 2 years before sustained a right eye
injury when a folder fell from a shelf.
The creation of a lamellar flap results in a potential plane of weakness in the cornea in which shearing forces can produce flap displacement. Recent histological and confocal studies have shown a central hypocellular primitive scar in the interface, allowing easy lifting of the flap in trauma. The fact that this potential plane can be disrupted many years after LASIK (7 years after the initial surgery in patient 1) indicates that corneal integrity is compromised by the surgical procedure and takes a long time, if ever, to restore."
Cohesive tensile strength of human LASIK wounds with histologic, ultrastructural, and clinical correlations.
J Refract Surg. 2005 Sep-Oct;21(5):433-45.
Schmack I, Dawson DG, McCarey BE, Waring GO 3rd, Grossniklaus HE, Edelhauser HF.
Emory Eye Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
PURPOSE: To measure the cohesive tensile strength of human LASIK corneal wounds.
METHODS: Twenty-five human eye bank corneas from 13 donors that had LASIK were cut into 4-mm corneoscleral strips and dissected to expose the interface wound. Using a motorized pulling device, the force required to separate the wound was recorded. Intact and separated specimens were processed for light and electron microscopy. Five normal human eye bank corneas from 5 donors served as controls. A retrospective clinical study was done on 144 eyes that had LASIK flap-lift retreatments, providing clinical correlation.
RESULTS: The mean tensile strength of the central and paracentral LASIK wounds showed minimal change in strength over time after surgery, averaging 2.4% (0.72 +/- 0.33 g/mm) of controls (30.06 +/- 2.93 g/mm). In contrast, the mean peak tensile strength of the flap wound margin gradually increased over time after surgery, reaching maximum values by 3.5 years when the average was 28.1% (8.46 +/- 4.56 g/mm) of controls. Histologic and ultrastructural correlative studies found that the plane of separation always occurred in the lamellar wound, which consisted of a hypocellular primitive stromal scar centrally and paracentrally and a hypercellular fibrotic stromal scar at the flap wound margin. The pathologic correlations demonstrated that the strongest wound margin scars had no epithelial cell ingrowth-the strongest typically being wider or more peripherally located. In contrast, the weakest wound margin scars had epithelial cell ingrowth. The clinical series demonstrated the ability to lift LASIK flaps without complications during retreatments up to 8.4 years after initial surgery, correlating well with the laboratory results.
CONCLUSIONS: The human comeal stroma typically heals after LASIK in a limited and incomplete fashion; this results in a weak, central and paracentral hypocellular primitive stromal scar that averages 2.4% as strong as normal comeal stroma. Conversely, the LASIK flap wound margin heals by producing a 10-fold stronger, peripheral hypercellular fibrotic stromal scar that averages 28.1% as strong as normal comeal stromal, but displays marked variability.
"The clinical knowledge gained from the LASIK flap lift retreatment cases correlated well with the laboratory
results. The tip of the Sinskey hook typically fell into the LASIK wound margin with minimal effort correlating with the gap in Bowman’s layer seen histopathologically. Most of the resistance when lifting the flap occurred at the flap margin, particularly the cases >1 year after surgery and those with the wound in the corneal limbus, correlating with the area of hypercellular fibrotic stromal scarring and its greater measured tensile strength. Conversely, the resistance to lifting the flap in the central and paracentral regions of the interface wound was always minimal, correlating with the area of the hypocellular primitive stromal scarring and its lesser tensile strength. In some eyes, after the flap was lifted, the surface of the residual stromal bed in the central interface wound showed visible circular zones from previous broad area excimer laser ablation, further attesting to the minimal healing described pathologically in the central and paracentral LASIK bed. This study shows that the primary structural reason for the high cohesive tensile strength of normal corneal stroma is the collagen fibrils from interweaving corneal lamellae and the groups of bridging collagen filaments where stromal lamellae cross one another. Corneal stromal LASIK wounds were found to heal weaker than normal because these structures were not regenerated during the healing response. Moreover, the central and paracentral stromal LASIK wounds were found to heal by producing a hypocellular primitive stromal scar that is very weak in tensile strength, averaging 2.4% of normal, and displays no evidence of remodeling over time in specimens out to 6.5 years after surgery. In contrast, the more superficial, flap margin stromal LASIK wound, which is adjacent to the surface epithelium, was found to heal by producing a 10-fold stronger, hypercellular fibrotic stromal scar that reaches maximum tensile strength by approximately 3.5 years after surgery, averaging 28.1% of normal."
Pathologic findings in postmortem corneas after successful laser in situ keratomileusis.
Cornea. 2005 Jan;24(1):92-102.
Kramer TR, Chuckpaiwong V, Dawson DG, L'Hernault N, Grossniklaus HE, Edelhauser HF.
Emory Eye Center, Emory University, Atlanta, GA 30322, USA. Theresa_Kramer@emoryhealthcare.org
PURPOSE: To examine the histologic and ultrastructural features of human corneas after successful laser in situ keratomileusis (LASIK).
METHODS: Corneas from 48 eyes of 25 postmortem patients were processed for histology and transmission electron microscopy (TEM). The 25 patients had LASIK between 3 months and 7 years prior to death. Evaluation of all 5 layers of the cornea and the LASIK flap interface region was done using routine histology, periodic acid-Schiff (PAS)-stained specimens, toluidine blue-stained thick sections, and TEM.
RESULTS: In patients for whom visual acuity was known, the first postoperative day uncorrected visual acuity was 20/15 to 20/30. In patients for whom clinical records were available, the postoperative corneal topography was normal and clinical examination showed a semicircular ring of haze at the wound margin of the LASIK flap. Histologically, the LASIK flap measured, on average, 142.7 microm (range, 100-200). A spectrum of abnormal histopathologic and ultrastructural findings was present in all corneas. Findings at the flap surface included elongated basal epithelial cells, epithelial hyperplasia, thickening and undulations of the epithelial basement membrane (EBM), and undulations of Bowman's layer. Findings in or adjacent to the wound included collagen lamellar disarray; activated keratocytes; quiescent keratocytes with small vacuoles; epithelial ingrowth; eosinophilic deposits; PAS-positive, electron-dense granular material interspersed with randomly ordered collagen fibrils; increased spacing between collagen fibrils; and widely spaced banded collagen. There was no observable correlation between postoperative intervals and the severity or type of pathologic change except for the accumulation the electron-dense granular material.
CONCLUSIONS: Permanent pathologic changes were present in all post-LASIK corneas. These changes were most prevalent in the lamellar interface wound. These changes along with other pathologic alterations in post-LASIK corneas may change the functionality of the cornea after LASIK.
From the full text: "Other notable findings in or adjacent to the wound included evidence of spatial separation of the LASIK flap from the stromal bed, interface debris, collagen fibril disorganization, and changes in the interfibrillar spacing."
Late traumatic displacement of laser in situ keratomileusis flaps.
Cornea. 2003 Jan;22(1):66-9.
Tumbocon JA, Paul R, Slomovic A, Rootman DS.
Department of Ophthalmology, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada.
PURPOSE: To report the occurrence, management, and outcome of late-onset traumatic dehiscence and dislocation of laser in situ keratomileusis (LASIK) flaps.
METHODS: Two interventional case reports of patients with late-onset LASIK corneal flap dislocation after ocular trauma occurring at 7 and 26 months after surgery, respectively.
RESULTS: The flaps were lifted, stretched, and repositioned after irrigation and scraping of the stromal bed and the underside of the flap. A bandage contact lens was placed, and topical antibiotic and corticosteroids were given postoperatively. The dislocated corneal flaps were successfully repositioned in both cases. The patient whose dislocated flap was repositioned 4 hours after the trauma recovered his uncorrected visual acuity (UCVA) of 20/20 1 week after the procedure and had a well-positioned flap with a clear interface. The patient who was managed 48 hours after the injury required repeat flap repositioning at 10 and 24 days after the initial procedure for treatment of persistent folds and striae in the visual axis. His uncorrected visual acuity 2 weeks after the third flap repositioning was 20/40 + 2. Diffuse lamellar keratitis developed in both patients that resolved with the use of topical corticosteroids.
CONCLUSION: Laser in situ keratomileusis corneal flaps are vulnerable to traumatic dehiscence and dislocation, which can occur more than 2 years after the procedure.
Late-onset traumatic flap dislocation and diffuse lamellar inflammation after laser in situ keratomileusis.
Cornea. 2002 Aug;21(6):604-7.
Aldave AJ, Hollander DA, Abbott RL.
Department of Ophthalmology, The University of California-San Francisco, San Francisco, California, U.S.A. email@example.com
PURPOSE: To report a case of traumatic flap partial dislocation and subsequent diffuse lamellar inflammation 14 months after laser in situ keratomileusis (LASIK) retreatment.
METHODS: Case report of a late flap dislocation that occurred during routine recreational activity (struck with a finger in the right eye while playing basketball).
RESULTS: The partially dislocated LASIK flap was reflected nasally, and the stromal surfaces of the flap and bed were thoroughly scraped to remove debris and epithelial cells. The flap was repositioned, and a bandage contact lens was placed. Diffuse lamellar inflammation, which developed on post-trauma day number two, was successfully treated with frequent topical steroids. Three weeks after the injury, the patient had regained 20/20 uncorrected visual acuity.
CONCLUSIONS: Patients should be appropriately warned of the possibility of late flap dislocation with traumatic forces encountered during routine recreational activities. Full visual recovery is possible if the dislocation is promptly diagnosed and appropriately managed.
Late-onset traumatic laser in situ keratomileusis (LASIK) flap dehiscence.
Am J Ophthalmol. 2001 Apr;131(4):505-6.
Geggel HS, Coday MP.
Virginia Mason Medical Center, Section of Ophthalmology, Seattle, Washington 98101, USA. firstname.lastname@example.org
PURPOSE: To report a case of laser in situ keratomileusis (LASIK) flap dehiscence following focal trauma six months after uneventful refractive surgery.
METHODS: Case report. A 37 year old man was seen one day after a tree branch snapped tangentially against his left cornea causing a dehiscence of his LASIK flap.
RESULTS: The flap was repositioned after treating the exposed flap stroma with a 50:50 mixture of distilled water and balanced salt solution. The patient regained 20/20 uncorrected visual acuity.
CONCLUSIONS: Patients should be informed about the potential for traumatic flap dehiscence following LASIK surgery and advised to wear eye protection when appropriate. Due to minimal wound healing except at the edges of the flap, corneal flap dehiscence may occur months or years after uneventful LASIK.
Traumatic flap displacement and subsequent diffuse lamellar keratitis after laser in situ keratomileusis.
J Cataract Refract Surg. 2001 May;27(5):781-3.
Schwartz GS, Park DH, Schloff S, Lane SS.
Associated Eye Care, Lake Elmo, Minnesota 55042, USA. email@example.com
A 45-year-old man was struck in the left eye by the edge of a paper shopping bag 3 weeks after having laser in situ keratomileusis (LASIK). The injury resulted in partial displacement of the LASIK flap. The patient developed diffuse lamellar keratitis (DLK) the day after the flap was repositioned. By day 4, visual acuity diminished to 20/60. By day 9, the clinical evidence of the DLK had resolved, and by day 15, uncorrected visual acuity was 20/20. Eye trauma 3 weeks after LASIK can result in displacement of the LASIK flap, and DLK can develop following flap replacement. Long-term anatomic and visual results are usually good.
Air bag-induced corneal flap folds after laser in situ keratomileusis.
Am J Ophthalmol. 2000 Aug;130(2):234-5.
Norden RA, Perry HD, Donnenfeld ED, Montoya C.
Department of Ophthalmology, University of Medicine and Dentistry, New Jersey, Newark, New Jersey, USA. firstname.lastname@example.org
PURPOSE: We describe a case of air bag-induced ocular trauma resulting in folds in the corneal flap 3 weeks after laser in situ keratomileusis.
METHODS: Case report. Three weeks after laser in situ keratomileusis, a 20-year-old man was involved in a motor vehicle accident and sustained blunt trauma to the right eye, which caused corneal flap folds, corneal edema, anterior chamber cellular reaction, and Berlin retinal edema.
RESULTS: Six weeks after laser in situ keratomileusis, persistent flap folds necessitated re-operation with lifting of the flap and repositioning. One week after the procedure, the visual acuity improved to 20/20-2, and the folds had cleared.
CONCLUSION: Trauma after laser in situ keratomileusis may produce folds in the corneal flap. With persistence of these folds, management by lifting and repositioning the corneal flap may be necessary to permit recovery of visual acuity.
Partial dislocation of laser in situ keratomileusis flap by air bag injury.
J Refract Surg. 2000 May-Jun;16(3):373-4.
Lemley HL, Chodosh J, Wolf TC, Bogie CP, Hawkins TC.
Department of Ophthalmology, Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, USA.
PURPOSE: A patient developed significant corneal complications from air bag deployment, 17 months after laser in situ keratomileusis (LASIK).
METHODS: Case report, slit-lamp microscopy, and review of the medical literature.
RESULTS: A 37-year-old woman underwent bilateral LASIK with resultant 20/20 uncorrected visual acuity. Seventeen months later, she sustained facial and ocular injuries from air bag deployment during a motor vehicle accident. Examination revealed bilateral corneal abrasions, partial dislocation of the right corneal LASIK flap, and a hyphema in the right eye. The LASIK flap was realigned, but recovery was complicated by a slowly healing epithelial defect and flap edema. One month following the injury, epithelial ingrowth beneath the LASIK flap was noted. Surgical elevation of the flap and removal of the epithelial ingrowth was performed. Eight months later, epithelial ingrowth was absent and the visual acuity was 20/40. Residual irregular astigmatism necessitated rigid gas permeable contact lens fitting to achieve 20/20 visual acuity.
CONCLUSIONS: Air bags may cause significant ocular trauma. The wound healing response of LASIK allows corneal flap separation from its stromal bed for an indeterminate time after surgery. Discussion of the possible risk of corneal trauma as part of informed consent prior to LASIK may be appropriate.