Late-Onset Dehiscence of LASIK Flap. Poster Number: P-190 Authors: Hyunjin Jane Kim, Cary M. Silverman Category: Keratorefractive Authors have no financial interest or disclosures. Introduction
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Poster Number: P-190
Authors: Hyunjin Jane Kim, Cary M. Silverman
Authors have no financial interest or disclosures
Corneal flap displacement within 1 to 2 days following laser in situ keratomileusis (LASIK) is a well recognized complication.1-3 However, stability of the flap remains largely unknown as flap dehiscence has been reported as late as 7 years after LASIK.4 We report cases of flap dislocation 4 years and 9 years after laser LASIK, following trauma during routine domestic activities. We also review 33 known case reports of late flap dehiscence, most of which are single case reports. Largest case series described 4 patients with flap dislocadtion.5
A 30-year-old Black man had a LASIK procedure on July 8, 2004. Patient had an uncomplicated post operative course with uncorrected visual acuity (UCVA) of 20/20 in both eyes, and best spectacle corrected vision (BSCVA) was 20/15 with refractive error of -0.25-1.00 x 165 and plano -0.75 x 170, respectively. On June 23, 2008, 4 years post LASIK, patient’s right eye was struck with a piece of wood from a window trim. He presented two days after complaining of pain and slight decrease in vision in the right eye. Exam showed UCVA of 20/25 with a mild displacement of flap creating a fold and staining at the superior edge (Figure 1A).
Because the injury involved the periphery of the flap and vision was good, patient was treated medically with Vigamox (Alcon, Fort Worth,Texas) and Lotemax (Bausch&Lomb, Tampa, Florida) four times daily. Three days later, pain resolved and the UCVA was 20/30. By biomicroscopy, patient had persistent folds but the staining had improved. Drops were discontinued a week later. Five weeks after trauma, UCVA was 20/20-1 with no staining on slit lamp. Folds persisted as seen on Figure 1B.
Figure 1A.Color photos of right eye 2 days after being struck by a piece of wood from a window trim. Note a mild displacement of flap creating folds and staining at 12 o’clock position.
Figure 1B.Color photo of right eye after medical treatment of peripheral flap dehiscence. Flap folds persist just superior to the visual axis.
A 29 year-old man underwent bilateral LASIK on February 1, 1999. Two years postoperatively, UCVA was 20/30 and 20/40 and the BSCVA was 20/25 (plano -0.50 x 175) in the right eye and 20/20 (-0.50 -0.75 x165) in the left eye.
On March 18, 2008, after 9 years and 1.5 months since the uncomplicated LASIK, the patient presented to emergency room 3 days after getting struck with a dog’s paw in his left eye. Patient experienced a sharp pain and sudden decrease in vision. Patient was discharged from the emergency room on antibiotic drops as treatment for corneal abrasion, and was seen by an optometrist the next day, who then referred the patient to the author (CMS).
Upon first visit to our service, 5 days after initial trauma, the UCVA was count fingers and the slit lamp exam showed complete flap dislocation with mild flap edema without tears (Figure 2A). Stromal bed of the flap was epithelialized and interface did not have debris. Immediate removal of epithelium from stromal bed was completed under laser microscope. The flap interface was irrigated with balanced salt solution and the flap was repositioned using irrigating cannula, Weck-Cel sponges and a patent spatula. No alcohol glue or sutures were used.
The field was then irrigated with vancomycin fortified solution. A bandage contact lens secured the flap (Figure 2B) and patient was maintained on Vigamox and Omnipred (Alcon, Fort Worth,Texas), both at four times daily for 10 days. Patient was seen in follow up in 1 day, 1 week, and 1 month, and 3, months. Final UCVA was 20/25, with no evidence of epithelial ingrowth, folds or diffuse lamellar keratitis
Figure 2A.Color photo of left eye 3 days after being struck by dog’s paw. Flap is totally dislocated toward the nasal canthus, attached at the nasal hinge without a tear. Whitish debris represents epithelial ingrowth that is encompassing about 30% of stromal bed involving the visual axis.
Figure 2B.Color photo of left eye with bandage contact lens after surgical repair of the flap dislocation and epithelial ingrowth. There was no residual epithelial ingrowth and cornea was clear (note photographic artifact on inferonasal cornea).
Absence of scar formation in the lamellar interface explains rapid restoration and persistence of post-LASIK visual acuity.6, 7 Consequently, early displacement of LASIK is a well known phenomenon documented in large studies. Gimbel and associates reported 12 eyes of 1000 (1.2%) that had slipped flap within a day postoperatively.1 Similarly, Lin and Maloney reported 20 eyes out of 1019 (2.0%) that had displaced flap within 24 hours of LASIK.2 Stulting and associates repositioned 13 eyes out of 1062 (1.2%) within 2 days of surgery for dislocated flaps.3 Smaller case reports and series have been published on late (postoperative week one or more) presentation of flap dislocation. Our case is the first report in the English literature of flap displacement after over 9 years following LASIK, and a second report of late flap dehiscence treated medically without surgical repair.
33 cases have been reported on late onset unilateral flap displacement.4-26 Mean age was 35 years and there were 19 men and 15 women. Mechanisms of flap displacement ranged from spontaneous8, iatrogenic9, to traumatic displacement due to domestic tools4, 10-13, finger injury4, 5, 14, 15, airbag12, 16, 17, ball5, 18, 19, and animals5, 20, 21. The onset of flap slippage ranged from 10 days to 7 years. Most common presentation was immediate visual loss associated with pain. Slit lamp biomicroscopy revealed partial dehiscence of the flap in all but one case in which there was a total loss of flap.15 Sixteen cases (48%) presented with flap folds, and 10 cases had epithelial ingrowth, which was associated with delayed presentation after injury.
Only 2 cases of epithelial ingrowth were seen within 24 hours of injury and the rest presented 2 to 26 days after the injury. Twenty-two cases (67%) achieved final uncorrected or best spectacle corrected visual acuity of 20/20. Seven eyes (21%) went down in vision with the worst visual loss of 3 lines corresponding to the total loss of LASIK flap.15 All but 4 eyes underwent surgical repair at the first presentation following trauma. Two of the 4 cases underwent surgery later21, 22, one case was treated medically only22, and the last case had total flap loss.15 After initial treatment, 11 eyes developed diffuse lamellar keratitis, and 14 eyes epithelial ingrowth. Eleven of the 14 cases required additional surgery to remove epithelium ingrowth.
Lack of stability of the flap can be attributed to the same reasons that give rise to the optical clarity of flap. Animals as well as human studies have shown that adhesion between the flap-stromal bed interface is limited to the edge of the wound.6-7 We postulate that if enough force is applied tangential to the flap undermining tissue adhesions at the edge of the flap, the rest of the flap is then at risk of partial or total dislocation. This phenomenon is observed when the author (CMS) lifts the flaps more than 10 years following the original LASIK to perform enhancement surgeries.
Discussion continuedWe herein report the latest presentation of traumatic flap dislocation, emphasizing the fact that flap interface is vulnerable to traumatic dehiscence for up to 9 years following LASIK. The cases reported are comparable to 33 cases in literature. Case 2 presented 3 days after being struck with dog’s paw, and had extensive epithelial ingrowth. Despite delayed presentation and the extent of the injury, he was successfully treated and enjoyed good visual outcome. On rare occasions, peripheral flap dehiscence may be treated medically without surgical intervention as shown in Case 1 and in a case reported by Heickell and associates.22 In both cases, patient achieved final BSCVA of 20/20 after treatment with topical medications.All patients undergoing LASIK should be educated about this possible complication associated with lamellar corneal wound and instruct patients to seek ophthalmologic attention immediately to avoid other complications associated with flap dehiscence. The surgeon may also urge patients to use protective eye wear or even consider an alternative refractive procedure for patients with increased occupational hazard to blunt eye trauma, such as those who work in the military or law enforcement, or contact sport. Prompt surgical invention, however, is effective in restoring visual acuity in case of flap displacement.
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