Excimer Laser-Assisted Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty for Patients With Keratoconus: A Retrospective Analysis From the Homburg Keratoconus Center

Purpose: To evaluate the outcome of excimer laser-assisted deep anterior lamellar keratoplasty (Exc-DALK) and penetrating keratoplasty (Exc-PKP) for keratoconus (KC). Methods: We included 123 eyes and compared the outcome of 30 eyes undergoing big-bubble Exc-DALK after stromal debulking (G1) against a matched group of 83 eyes undergoing Exc-PKP ( G2 ) in our department. G2 was created after performing a pseudorandom stratified bootstrapping of our PKP database starting with 2802 surgeries with removal of any bias. Main outcomes included best corrected visual acuity (BCVA), spherical equivalent (SE), tomographic changes, and endothelial cell density (ECD). Data were compared preoperatively, postoperatively with 2 double-running cross-stitch sutures according to Hoffmann [2 and 10 months postoperatively ( T1 and T2 )], after first suture removal [15 months postoperatively ( T3 )], and after final suture removal [26 months postoperatively ( T4 )]. Results: Preoperatively, all parameters were comparable without significant differences. At T1, G1 showed significantly better BCVA ( P = 0.01), lower SE ( P = 0.04), lower anterior and posterior topographic astigmatism (ATA and PTA, P < 0.01), lower maximal keratometry ( P = 0.02), and lower central corneal thickness ( P < 0.01). At T2, G1 showed significantly better BCVA ( P = 0.04), lower PTA ( P < 0.01), and higher ECD ( P < 0.01). At T3, G1 showed significantly lower ATA ( P = 0.01) and PTA ( P < 0.01) and higher ECD ( P = 0.02). At T4, G1 showed significantly lower PTA and higher ECD ( P < 0.01) but no significant difference in BCVA ( P = 0.07). Conclusions: Exc-DALK provided faster visual rehabilitation and represented an endothelial cell-sparing method compared with Exc-PKP. After final suture removal, Exc-DALK showed noninferior outcomes compared with Exc-PKP if the graft was placed on naked Descemet membrane.