To report a case of double Descemet's membrane in a patient who had penetrating keratoplasty after rupture of Descemet's membrane during deep anterior lamellar keratoplasty (DALK).

A 24-year-old female had keratoconus in her right eye and underwent DALK for treatment. Descemet's membrane was ruptured while separating the corneal stroma from Descemet's membrane with the big bubble technique. The operation method was changed from DALK to penetrating keratoplasty. Detached Descemet's membrane was observed in the anterior chamber after suturing. Sterile air was injected into the anterior chamber to attach the Descemet's membrane. Five days after the surgery, Descemet's membrane was detached and a second air injection was performed. Corneal edema was improved but Descemet's membrane was re-detached. Double Descemet's membrane was observed by anterior segment optical coherence tomography (OCT). The detached Descemet's membrane originated from the recipient's cornea and not from the donor's cornea. Detached Descemet's membrane was removed successfully. Patient's cornea was clear and best corrected visual acuity was 20/25.

When penetrating keratoplasty is performed instead of DALK, the surgeon should completely remove the remnant corneal stroma and Descemet's membrane. Remnant Descemet's membrane can be disregarded as it comes from the donor cornea. Unnecessary anterior chamber air injection causes endothelial damage. Anterior segment OCT is a useful tool to identify anatomical structures of transplanted cornea.