Laser in Situ Keratomileusis (LASIK) is increasingly performed to correct refractive errors. Traumatic flap displacement after LASIK, though rare, has been reported earlier. To the best of our knowledge, all previously reported cases occurred within 4 years of LASIK. We report herewith a case of traumatic flap displacement caused by a fingernail injury, four years after LASIK.
A 23-year-old lady presented in August 2002, with complaints of irritation, watering and defective vision in the right eye following an accidental fingernail trauma from her 6-month-old child.
Her records showed that she had undergone bilateral simultaneous myopic LASIK elsewhere 4 years earlier for a preoperative myopia of 6 DSph. Her postoperative course was apparently uneventful and she had recovered to best corrected visual acuity of 6/6. She was asymptomatic in both eyes following the procedure. As per her records the procedure had been performed with a Hansatome and a Bausch & Lomb 217c excimer laser. She was seen three hours following the injury with a visual acuity of 3/60 in the right eye and 6/6 P in the left eye. The conjunctiva in the right eye was congested and the corneal cap was displaced around 1.5 mm inward circumferentially from 6 o’ clock to 12 o’ clock hours with flap folds across the visual axis [Figure - 1]. The left eye was normal with a well-anchored, well centered corneal cap.
Flap replacement was performed an hour after presentation. The flap was refloated using balanced salt solution under peribulbar anaesthesia and anchored with four interrupted 10-0 nylon sutures. A large epithelial defect was seen from the 7 o’ clock to 12 o’ clock position. The patient was advised to use a combination of Tobramycin (0.3 mg %) and Dexamethasone (0.1mg %), four times a day for 10 days. She was reviewed after 10 days; the flap had healed well with the sutures in place. She was advised to taper her eye drops over the next 10 days and was reviewed 20 days after the repositioning. At this follow-up, two sutures which had become loose were removed. Small islands of epithelial ingrowth were seen at the 7 o’ clock and 8 o’ clock positions, extending about 4 mm inside the corneal cap, up to the temporal margin of the pupil [Figure - 2]. The visual acuity had improved to 6/6 P and the patient had no visual complaints. No active intervention was done since the patient was asymptomatic and she was reviewed periodically. The epithelial islands were non-progressive at the sixth month follow-up [Figure - 3].
Most complications associated with LASIK are flap related. They include intraoperative flap complications like shifted flap, buttonhole formation, free flap and wrinkled flap and postoperative complications like micro and macro striae and flap slippage and dislocation.
The mechanism postulated for early flap adherence includes endothelial pumping, capillarity, fiber interlacing, intracorneal suction, intracorneal molecular attraction and ionic bonding. Whatever the mechanism, the anecdotal ease at which a flap can be lifted months after surgery for retreatment indicates that the flap actually never heals fully.
Flap slippage and displacement most commonly occur in the early postoperative period and presumably as a result of mechanical disruption such as forceful blinking, lid squeezing and eye rubbing. Late displacement, through rare, has been reported.
Even though many reports have been published, no case has been described with such a complication four years after LASIK. It indicates that adhesion occurs only in the anterio-posterior plane and probably never happens in the tangential plane. Injuries due to shearing mechanisms such as a fingernail injury or a contact lens injury can more often cause flap displacement than seemingly heavier injury in the anterio-posterior direction such as boxing or blunt ocular trauma from occupational hazards. Patients should be warned of such sequelae. Likewise, foreign body removal with a spud or needle on a LASIK flap also carries a similar risk, acting like a shearing force.
Epithelial ingrowth is an often-reported complication especially following flap displacement. Conventional management includes aggressive scraping of the epithelial ingrowth after lifting the flap. In our case, the epithelial ingrowth was noticeable three weeks after the repositioning. Since the patient did not have visual complaints, we decided to observe her, and at the 6-month follow-up, the epithelial ingrowth was non-progressive. Aggressive scraping of the epithelial ingrowth may be unnecessary in most cases and can be considered if documented progression occurs.
In conclusion, the fragile adherence of the corneal flap even years after a LASIK procedure merits a discussion between the ophthalmologist and the patient. It should be a part of all informed consent procedures during LASIK surgery.
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Conflict of Interest:
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