• By Rahul T. Pandit, MD
    Refractive Mgmt/Intervention

    To analyze the clinical features and factors that increase the risk of flap buttonholes, the authors retrospectively reviewed records of all patients who developed a flap buttonhole during LASIK performed at their institute.

    Of a total of 944 eyes undergoing LASIK from 2006 to 2008, 0.42 percent (four eyes) developed a partial-thickness flap buttonhole. Of the 230 eyes undergoing thin-flap LASIK (flap thickness ≤90 μm), the incidence was 1.7 percent (four eyes).

    The Moria M2 microkeratome, with either a 130-μm or 90-μm plate, was used to create a superiorly hinged flap in each eye. All cases began with the right eye and proceeded to the left, using the same blade for both eyes.

    All four cases occurred in the second eye of patients who underwent thin-flap LASIK. There were no clinically significant differences between right and left eyes of patients who underwent thin-flap LASIK without complication versus those with partial-thickness buttonholes.

    This data is consistent with previous reports indicating that the second eye is more susceptible to complications when a microkeratome is re-used. It also suggests that attempted thin-flap formation increases this risk, due to either blade dulling or desiccation and further thinning of the cornea in the partially-closed second eye.

    The authors caution against re-using microkeratome blades for second eyes, and they recommend applying artificial tears in the second eye at the beginning of the procedure on the first eye. They also note that intraoperative subtraction pachymetry may be helpful in predicting buttonhole risk in the second eye.