Hyperguides

Ophthalmology / Refractive surgery

Management of Corneal Flap Striae Following LASIK

Charles A. Barsam, MD Peter J. McDonnell, MD
Article


Introduction

LASIK's success as a surgical means of correction of refractive error is due in part to the low complication rate associated with this procedure. Many of the complications associated with the procedure are associated with the creation and manipulation of the corneal lamellar flap. Corneal flap striae and folds are some of the most commonly encountered post-LASIK complications, and their presence can result in the loss of best-corrected visual acuity (BCVA).

Incidence

In the literature, the incidence of flap striae and folds ranges from 1.1% to 3.5% in numerous series.1-3 Striae have an increased incidence in patients with unusually thick or thin flaps and in the presence of either a free corneal cap or an epithelial defect. Intraoperatively, flaps can become desiccated, secondarily wrinkled, excessively manipulated, or misaligned, and each of these instances may result in flap irregularities.4 Flap misalignment can also occur postoperatively, as a properly positioned flap can become malpositioned after removal of the lid speculum and surgical drapes, or if the patient inadvertently rubs the eye after surgery.5

Postoperative examination of the patient at the slit lamp prior to discharge and on the first postoperative day is useful in the detection of flap striae. Detection of flap striae through the operating microscope can be challenging. However, the use of the slit beam held off the pupillary axis and retroillumination through a dilated pupil are effective means of discovering flap irregularities. Horizontal striae are more frequently seen with nasally hinged flaps and vertical striae are more characteristic of flaps created with a vertical hinge.4

Avoiding Flap Striae

Meticulous surgical technique can result in a lowered incidence of flap-related complications. Prior to cutting the corneal flap, alignment marks can be placed on the cornea to provide landmarks for proper postablation flap repositioning. As the flap is reflected during the procedure, care must be taken to assure proper flap hydration; excessive hydration or dehydration can result in poor interface adherence and tented regions of misalignment.5 Some surgeons advocate using specialized instruments to depress the flap at the end of the procedure. It is theorized that compression of the flap removes excess fluid from the flap interface and reduces the incidence of striae. Tests can be performed at the completion of the procedure to demonstrate acceptable flap positioning. At the completion of the procedure, the peripheral cornea can be depressed with a forceps or spatula to assess the presence of striae. If they radiate into the flap, this suggests proper flap adherence. The patient should be examined while blinking after removal of the surgical drapes and lid speculum. Proper flap placement is suggested if no movement or displacement of the flap is observed during blinking.5

Management

If striae exist post-LASIK, it is imperative to assess whether their presence has affected visual acuity or the quality of vision. If striae are located peripherally or do not impact vision, then they will likely not require intervention. Striae that negatively impact vision should be dealt with promptly; the longer they are present, the more difficult they become to remove.4,5 Striae are usually identified immediately postoperatively or on the first postoperative day. If striae are found in this time frame, careful flap dissection and lifting should be carried out by hyperhydration with a hypotonic solution. After refloating, the flap is repositioned with a compression maneuver aimed at dehydrating and smoothing each side of the flap.4 After this procedure, it may take up to 48 hours to visualize before folds are resolved.

There is no consensus for treatment if striae have been present for more than 24 hours. While some believe that the management of these striae is no different than that of those noted in the early postoperative period, others believe that chronic striae represent a different pathological process than flap misalignment or torsion. Dr. Steinert and colleagues theorize that these striae are progressively fibrosing folds in Bowman's layer.4,6 These authors recommend an epithelial debridement combined with either hydration and tension on the striae or phototherapeutic keratectomy (PTK) of Bowman's layer. These procedures are aimed at eliminating the striae by breaking the tension that retains the folds in Bowman's layer in apposition.4,6

Although relatively uncommon, striae can result in loss of BCVA and patient dissatisfaction. Therefore, early recognition and treatment are beneficial in the resolution of this post-LASIK flap-related complication.

References

  1. Gimbel HV, Penno EE, van Westernbrugge JA, Ferensowicz M, Furlong MT. Incidence and management of intraoperative and early postoperative complications in 1000 consecutive laser in situ keratomileusis cases. Ophthalmology. 1998;105(10):1839-1848.

  2. Lin RT, Maloney RK. Flap complications associated with lamellar refractive surgery. Am J Ophthalmol. 1999;127(2):129-136.

  3. Pannu JS. Incidence and treatment of wrinkled corneal flap following LASIK. J Cataract Refract Surg. 1997;23(5):695-696.

  4. von Kulajta P, Stark WJ, O'Brien TP. Management of flap striae. Int Ophthalmol Clin. 2000;40(3):87-92.

  5. Hernandez-Matamoros J, Iradier MT, Moreno E. Treating folds and striae after laser in situ keratomileusis. J Cataract Refract Surg. 2001;27(3):350-352.

  6. Steinert RF. LASIK: Intraoperative and postoperative flap striae. In: Buratto L, Brint S, eds. LASIK: Surgical Technique and Complications. 2000:563.