Late Dislocation of a LASIK Flap Caused by a Fingernail

This report of a delayed traumatic dislocation of a laser in situ keratomileusis (LASIK) corneal cap highlights the long-term dangers of the procedure. Recommendations are made on how to approach repair of a dislocated LASIK cap.

A 28-year-old white woman came to our casualty service following uncomplicated, bilateral LASIK performed elsewhere. Preoperative refraction was −2.25 diopters (D)OD and −3.75 DOS. Postoperatively she achieved an unaided visual acuity of 20/20 OU. Ten months after surgery, her fingernail brushed the left eye while she was removing a sweater, resulting in painful displacement of the corneal cap.

The cap was repositioned using topical (0.5% tetracaine hydrochloride) and sub-Tenon (2% lignocaine hydrochloride) anesthesia. Operative manipulation suggested that the cap had everted, the lower edge of its nasal hinge had torn, it had twisted about the residual hinge, and one of its edges had folded over (Figure 1 A). The stromal bed and cap were debrided. Three 10-0 interrupted nylon sutures were used to secure the cap and the patient was discharged receiving preservative-free topical antibiotics and tear supplements.

Five days later, debris was noted in the interface between the cap and the corneal stroma, suggesting the presence of epithelial ingrowth. With the patient under general anesthesia, the nylon sutures were removed and the corneal cap was everted, revealing a sheet of gelatinous material (Figure 1 B) that was wiped with a sterile surgical sponge and sent for histologic assessment (Figure 2). The undersurface of the cap and the stromal bed were cleaned with 100% alcohol to destroy residual epithelium. The cap was allowed to dry and then was hydrated before repositioning. The surface of the cap was stroked with a cyclodialysis spatula to remove excess fluid in the interface. A soft bandage lens was applied after debriding the epithelium on the surface of the cap.

Forty-three days postoperatively, irregular astigmatism had reduced unaided visual acuity to 20/200. Retroillumination photography confirmed the recrudescence of epithelial ingrowth under the nasal part of the cap (Figure 3) with the presence of microcysts compatible with those seen histologically. One hundred three days after the second operation, an attempt was made to debride the epithelial ingrowth again. On this occasion it was impossible to easily define a cleavage plane for the cap. A small central area of corneal stroma was removed followed by scraping of the residual cap area. A bandage lens was applied and keratoplasty was scheduled given the poor predicted visual outcome. However, to our surprise, the unaided visual acuity had improved to 20/40. A −1.00-D sphere/ −0.00-D cylinder axis 135° correction improved the visual acuity to 20/20 OD. A corneal thickness of 429 µm in the left eye vs 528 µm in the right eye suggested that the cap had indeed been removed at the third operation. The patient is currently being managed conservatively.

In flap repositioning, both the stroma and cap should be thoroughly cleaned. Alcohol, though used in our case, is not considered essential. When the cap is replaced, optimal adhesion is achieved by eliminating excess interface fluid by stroking the flap with a cyclodialysis spatula. A sterile surgical sponge should be used to remove fluid from the edge of the cap. The eyelid speculum should be left in place for 5 minutes to allow the cornea to deturgess under the influence of the endothelial pump. Optimal cap-stromal adherence is confirmed by the absence of independent movement of the cap when depressing the adjacent cornea external to the cap.

Our case is the first that we know of in which dislocation of a LASIK cap has resulted from a trivial act of daily living performed in the late postoperative period. Recent reviews of LASIK state that cap dislocation occurs in 0.7% to 5.8% of cases with a mean of around 2%.^1-3 These tend to occur in the first few days following surgery and may be related to patients rubbing their eyes. In this case, the fingernail was inserted at the stromal keratectomy plane and dislocated the flap. Debridement of edematous corneal epithelium during vitrectomy has resulted in iatrogenic cap dislocation.⁴ When retreatment is performed for LASIK it is possible to define the original cleavage plane between cap and stroma using a surgical hook even after 1 year. These observations clearly illustrate that corneal integrity is never fully restored after creation of a LASIK flap. The basis for this inherent weakness has recently been reported in a rabbit model of LASIK in which irregular corneal stromal regeneration was observed at the wound margin.⁵ Flap dislocation as a potential late complication should be discussed as part of informed consent prior to surgery. Laser in situ keratomileusis should perhaps be contraindicated in patients who are at high risk of sustaining glancing corneal injuries (eg, rugby players).

As LASIK increases in popularity, the complication we have reported may become more common. It is therefore important for patients to be informed of the risk preoperatively and for general ophthalmologists to be familiar with the optimal way to perform primary repair in case care cannot be transferred to the original LASIK surgeon.

Corresponding author and reprints: C. K. Patel, BSc, FRCOphth, Department of Ophthalmology, Oxford Eye Hospital, Radcliffe Infirmary, Woodstock Road, Oxford OX3 0NJ, England (e-mail: ckpatel@ukgateway.net).