Flap Studies & Articles PDF Print E-mail

These quick-links will provide you faster access to the studies & articles provided: 

Accidental self-removal of a flap - a rare complication of LASIK surgery  - - To report a rare complication in which the patient accidentally removed the LASIK corneal flap.

LASIK Flap Only 2.4% as strong as Normal Cornea  - The human corneal 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 corneal stroma.

Traumatic corneal flap dislocation one to six years after LASIK in nine eyes with a favorable outcome - To report our experience treating eye trauma after LASIK refractive surgery.

Comparison of residual stromal bed and flap thickness in primary and repeat laser in situ keratomileusis in myopic patients - To compare the change in residual stromal thickness and flap thickness between primary laser in situ keratomileusis (LASIK) and repeat LASIK in myopic patients.

Central Flap Necrosis After LASIK With Microkeratome and Femtosecond Laser Created Flaps - To report nine cases of severe central flap inflammation and necrosis after LASIK.

Flap Displacement during Vitrectomy 24 months after LASER IN SITU KERATOMILEUSIS  - “The LASIK flap never heals… the LASIK flap can be easily dislodged from simple contact with the eye such as a finger poke.”

Traumatic flap displacement and DLK after LASIK  - Traumatic flap displacement and subsequent diffuse lamellar keratitis after laser in situ keratomileusis.

Late-onset flap folds and partial dehiscence of flap  - Late-onset repetitive traumatic flap folds and partial dehiscence of flap edge after laser in situ keratomileusis.

Late traumatic dislocation of LASIK flaps  (1)  - A case of traumatic flap displacement with a fingernail injury four years after LASIK is reported.

Late traumatic dislocation of LASIK flaps  (2)  - The second patient had a blunt trauma that caused a dislocation of the flap.

Flap tearing during lift-flap laser in situ keratomileusis retreatment  - This report suggests that flaps with margins near the limbus or a corneal pannus may be prone to an earlier and stronger healing process at the edge that may lead to a flap tear during LASIK retreatment.

Precision of flap measurements for laser in situ keratomileusis in 4428 eyes  - Flap thickness varies significantly depending on the microkeratome used. Factors that influence flap thickness are primarily corneal thickness, patient age, preoperative keratometry, preoperative refraction including astigmatism, and corneal diameter.

Predictability of corneal flap thickness in laser in situ keratomileusis using three different microkeratomes  - Corneal flap thickness tended to be considerably thinner than expected on both eyes using the ACS and Hansatome.

Inaccurate Flap Cut  - Here is a case report of a woman who developed ectasia following LASIK due to in accurate flap cut.

Late traumatic displacement of laser in situ keratomileusis flaps  - Laser in situ keratomileusis corneal flaps are vulnerable to traumatic dehiscence and dislocation, which can occur more than 2 years after the procedure.

Traumatic flap dislocation 4 years after LASIK  - The patient was examined 5 days after being struck in the face and found to have a flap dislocation.

Mismatch between flap and stromal areas after laser in situ keratomileusis as source of flap striae  - Excess flap area may cause striae because of wrinkling.

Uveitis-associated flap edema and lamellar interface fluid collection after LASIK - To report two cases of corneal pathology associated with anterior uveitis after LASIK.

Noninflammatory flap edema after lasik associated with asymmetrical preoperative corneal pachymetry - To report persistent unilateral flap edema following LASIK in patients with asymmetrical central corneal thickness.

Evaluation of corneal flap dimensions and cut quality using the SKBM automated microkeratome - To evaluate flap dimensions and cut quality with repeated blade use of the automated Summit Krumeich-Barraquer microkeratome (SKBM [LadarVision])

Flap-related complications present challenges for surgeons

Surgeons review some common flap-related problems and how to handle them.

By Amar Agarwal, MS, FRCS, FRCOphth; Jairo Hoyos, MD; Melania Cigales, M

Flap-related problems after LASIK are a concern for any refractive surgeon. Common causative factors are inadequate suction, microkeratome malfunction and corneal curvature anomalies. This article reviews some common complications and ways to avoid or manage them.




Quote:  Microstriae are very faint, small, disorganized, superficial wrinkles in the LASIK flap. Unlike macrostriae, which result from the flap’s slippage, microstriae are produced by the mechanical forces of a LASIK flap...

Traumatic late flap dehiscence and Enterobacter keratitis following LASIK - To report a case of traumatic flap dehiscence and Enterobacter keratitis 34 months after LASIK.

Flap interface particles are another finding whose clinical significance is undetermined.

A Finnish study found that particles of various sizes and reflectivity were clinically visible in 38.7% of eyes examined via slit lamp biomicroscopy, but apparent in 100% of eyes using confocal microscopy.

Some patients have reported large chunks of metal in their corneas after lasik.

Watch a video of a confocal exam of another LASIK patient with an extraordinary amount of metallic debris from the LASIK microkeratome blade.

LASIK Blade Leaves Metal Under Flap

LASIK flap disintegrates during lifting

(with unchanged convexity) overlying a newly contoured flap bed (with less convexity). The unchanged arc length of the flap must therefore fit into the shorter arc length of the flap’s bed. This disparity in shapes causes microstriae.

Microstriae can be a frustrating outcome in patients who undergo an otherwise perfect LASIK surgery. This effect is more common in high myopes, probably because more tissue is removed and there is an exaggerated disparity between the flap and its bed in regard to fit. Also, and unfortunately in some cases, the microstriae can have an unwelcome and detrimental effect on vision.  

Read the rest here:


Dr. Terry Kim of Duke University claims infections that may require flap amputation are on the rise


Two cases of air bag deployment injuries

Air bag-induced corneal flap folds after LASIK:

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. lasik@ibm.net

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 LASIK 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.

What a dilemma for LASIK patients -- accept the risk of dislodging your flaps or disconnect your air bag to protect your corneas and put your life in danger.

Close-up microkeratome blades reveal variation

May 28, 2002

Eurotimes May 2002  

A close-up look at a number of different disposable microkeratome blades using electron microscopy revealed considerable variation in size and cutting edge between both different manufacturers and among blades made by the same manufacturer. Researchers examined ten different microkeratome blade types, comparing five blades of each type. They studied scanning electron microscopic images up to a magnification of 700x the original size and measured blade length, width, and cutting edge. The researchers also examined the blades for any irregularities. The researchers looked at blades manufactured by Bausch & Lomb, Nidek, Moria, Allergan, Oasis, Schwind, Beaver, Alcon, and Asclepion-Meditec. They found variations between the ten different blade groups and among the five blades within each microkeratome blade group. The differences noted included length, width and cutting edge. They expressed concern about the diversity of size and cutting edge seen in blades created by different manufacturers for the same microkeratome, which could potentially compromise the procedure's precision. The blades studied also revealed different degrees of impurities and surface smoothness. These were readily visible at a magnification of 175x. Some blades were coated with impurities or showed deposits. The cutting edge of a particular blade was left relatively unsharpened by some manufacturers. Other blades revealed an additional cutting edge, while the same blade made by another manufacturer lacked it. They noted that some blades were fine, revealing no irregularities along the length of the cutting edge, no impurities or deposits on the blade surface and no variations in size. Such smoothness and consistentency were particularly evident with Amadeus (Allergan) microkeratome blades. 

This was published in 2002, and they were doing lasik for years before that. Why would they subject patients to this. Wouldn't they at least look at the blades before rolling lasik out to millions of people? This doesn't make sense.

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 2006George J.C. Jin, MD, PhD; Kevin H. Merkley, MD, MBA


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.

Flap-related complications present challenges for surgeons

Flap-related problems after LASIK are a concern for any refractive surgeon. Common causative factors are inadequate suction, microkeratome malfunction and corneal curvature anomalies. This article reviews some common complications and ways to avoid or manage them.

Buttonholing of the flap

Buttonholing is one of the more dreaded complications of LASIK (Figure 1), as it is often in the visual axis and may heal with scarring (Figure 2) and loss of best corrected visual acuity. Poor quality blades, inadequate IOP, keratome malfunction and steep corneas are predisposing factors. The procedure should be aborted and the flap should be realigned. The patient may require a deeper re-cut with customized ablation or PRK or PTK with mitomycin-C using a transepithelial approach.

Free caps

Free caps are also disastrous complications. The cap should be carefully placed epithelial side down in a drop of balanced salt solution to avoid stromal hydration. Alignment marks on the flap help in identifying the side as well as in realignment. Sufficient time should be given for good flap adhesion  One may secure it either with sutures or a bandage contact lens.

Incomplete or partial flap

An incomplete or partial flap can occur due to a loss of suction midway, any mechanical obstruction to the microkeratome or premature discontinuation of the pass (Figure 4). The surgeon generally has to abort the procedure and make a new flap with a deeper cut 3 to 6 months later. Never attempt to manually dissect as it can lead to loss of BCVA and topographical abnormalities and necessitate procedures such as PTK.

Visually significant striae

If identified, early striae can be treated with flap relifting, hydration (with hypotonic saline) and aggressive stretching for 5 to 8 minutes. In recalcitrant cases, suture placement at the flap edge may be required.

Post-LASIK ectasia

Post-LASIK ectasia may occur in patients with thin corneas, deep ablations or large optic zones. Here, the flap has to be made proportionately thinner. Not maintaining an adequate residual bed thickness causes a long-term increase in the surface parallel stress on the cornea and may lead to post-LASIK ectasia. Progressive ectasia may then need to be treated by deep anterior lamellar keratoplasty, penetrating keratoplasty, intrastromal corneal ring segments or collagen crosslinking with riboflavin treatment.

Epithelial defects

Epithelial defects can occur as a result of poor quality instruments or excessive preoperative anesthetics or in eyes with epithelial basement membrane dystrophy. They are a predisposing factor for infectious keratitis, diffuse lamellar keratitis and epithelial ingrowth.

Epithelial ingrowths

Epithelial ingrowths are seen as a faint white or gray opacity beneath the flap. They are more common after a displaced or torn flap, epithelial defects, or hyperopic or LASIK re-treatment. Treatment by lifting the flap with mechanical removal and irrigation of the surface is indicated if the ingrowth is progressive or extending centrally to the visual axis, associated with stromal melting, distorted flap edge, decreased BCVA or topographical abnormalities.

full article: http://www.osnsupersite.com/view.asp?rID=20897