Comparison of trephination techniques in penetrating and lamellar keratoplasty for keratoconus: Results from a large university eye hospital

Penetrating keratoplasty (PK) – using various trephination techniques (mechanical, femtosecond laser with mushroom [FEMTO-MR] or top hat [FEMTO-TH] profile, excimer laser) – and deep anterior lamellar keratoplasty (DALK) are surgical treatments for advanced keratoconus. This retrospective study compares the long-term results of these techniques in a cohort of 605 first-time keratoplasty eyes treated for keratoconus at a tertiary corneal transplant centre in Germany. The 5-year graft survival rate exceeded 90% in all groups. Rejection was significantly more frequent in the FEMTO-MR group (50% at 2.5 years, compared to less than 30% in the other groups). Visual acuity below 0.5 (BSCVA < 6/12 Snellen) was observed in approximately 25% of patients after PK, 2.5 years after complete suture removal, but was not observed after DALK. A refractive cylinder greater than − 5 diopters of astigmatism at 5 years after complete suture removal was found most common after FEMTO-TH (~ 40% vs. ~25% after FEMTO-MR and mechanical trephination, ~ 20% after DALK, ~ 10% after excimer PK). In conclusion, all techniques achieved high graft survival, with less favorable results in femto-groups. Function after DALK and excimer PK tended to be slightly better in comparison to mechanical PK.