‘Acute-angled bevel’ sign to assess donor lenticule orientation in ultra-thin descemet stripping automated endothelial keratoplasty

Abstract

A 6.5-year-old boy with congenital hereditary endothelial dystrophy underwent clear corneal ultra-thin descemet stripping automated endothelial keratoplasty (DSAEK). After graft insertion, it was difficult to assess graft orientation due to hazy cornea. Intraoperative optical coherence tomography (iOCT) showed a well-attached graft and the bevelled edge of donor lenticule made an acute angle with the overlying stroma. Postoperative anterior segment OCT confirmed the presence of acute-angled bevel sign. A wetlab experiment was performed with experimental corneoscleral tissues to confirm the findings. Donor lenticule was injected in the artificial chamber with stromal-side up as well as stromal side-down. ‘Acute-angled bevel sign’ was observed on iOCT in the experimental cases with stromal-side up. In inverse graft, the acute-angled bevel was not observed, instead the configuration was obtuse angled. Identifying the ‘acute-angled bevel sign’ on iOCT confirms correct graft orientation after unfolding and is extremely useful for hazy corneas and ultrathin DSAEK lenticules.