Inadvertent inversion of corneal flap following microkeratome-assisted laser-assisted in situ keratomileusis.

Abstract

A 21-year-old male with stable myopic astigmatism in OD (-1.50DS/-0.75 DCX900) and OS (-1.50DS/-0.75DCX900) underwent microkeratome-assisted laser-assisted in situ keratomileusis (LASIK). According to the referring surgeon, preoperative topography and pachymetry were normal. On postoperative day 1, UCVA in OD was 6/18 and 6/9 in OS. Slit-lamp biomicroscopy revealed the inferior epithelial defect. The patient was put on moxifloxacin 0.5%, prednisolone acetate 1% suspension, and sodium-hyaluronate eye drop 3 times a day. Epithelial defect healed after 24 h but UCVA remained 6/18 in OD. The patient was then referred for further management. On presentation, the patient had BCVA 6/6 (+2.00DS/-4.75DC × 980) in OD and UCVA 6/6 in OS. Slit-lamp biomicroscopy revealed a hvorizontal line in OD [Fig. 1a and b]. Tomography on Pentacam (OCULUS Optikgeräte GmbH Postfach, 35549 Wetzlar, GERMANY) showed corneal astigmatism and inferior steepening [Fig. 1c and d]. Clinical diagnosis of inadvertent inversion (inferior folding on itself) of the LASIK flap was considered. Lifting and repositioning of the LASIK flap were planned. The corneal epithelium between the horizontal line and peripheral cornea was removed. LASIK flap was lifted and repositioned with LASIK spatula. Interface irrigation was done. The margin of the flap was dried and uniformity of gutter width was ensured. A bandage contact lens (BCL) was placed. The lid speculum was removed carefully. The topical medication was continued as before surgery. On day 1, the LASIK flap was well apposed. On day 7, the patient achieved BCVA of 6/9 in OD (+0.75DS/-0.50DC × 930). After 4 weeks of flap repositioning, the patient achieved UCVA of 6/6 (-2). The horizontal line had disappeared, corneal astigmatism decreased considerably, and the area of steepening disappeared [Fig. 2a-d].Figure 1: Slit-lamp biomicroscopy and Scheimpflug corneal tomography of the right cornea with LASIK flap inversion. Diffuse illumination photograph shows an inferior horizontal line and irregularity of LASIK flap (a), these findings on retro-illumination suggestive of inadvertent inversion (b). The axial curvature map on Scheimpflug corneal tomography shows against the rule corneal astigmatism (c) and the area of inferior corneal steepening corresponding to inverted flap on anterior elevation map (d)Figure 2: Slit-lamp biomicroscopy and Scheimpflug corneal tomography of the right eye 4 weeks after flap lifting and reposition. The disappearance of the horizontal line and absence of inferior corneal irregularity on diffuse illumination (a) and retro-illumination suggestive of well-apposed LASIK flap (b). The axial curvature map on Scheimpflug corneal tomography shows a decrease in corneal astigmatism (c) and the absence of inferior corneal steepening on the anterior elevation map confirms proper apposition of LASIK flap (d)Discussion Inadvertent flap inversion occurs rarely. Inspection of the flap integrity and ensuring uniformity of gutter may prevent this complication. Prednisolone acetate 1% suspension being white has been advocated to enhance the visibility of gutter width.[1] Inadvertent flap inversion may occur if the patient squeezes the eyelids while removing the drapes and speculum.[2] Mechanical trauma due to forceful blinking, eyelid squeezing, and eye rubbing has been implicated to cause flap shift within 24 h of surgery.[3] In our case, most probably, this complication happened either due to squeezing during speculum removal or due to eyelids impinging on the flap margin, postoperatively in a flap that was not well adhered. Inadvertent flap inversion should be considered an emergency. Early repositioning of the flap should be done to prevent the development of fixed folds and epithelial ingrowth. Eyelid speculum and drapes should be removed carefully to prevent dislodgment of the flap. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.