Long-term outcomes of deep anterior lamellar versus penetrating keratoplasty for keratoconus

AimsTo compare the long-term outcomes of deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in keratoconus.MethodsRetrospective comparative case series (228 DALKs and 274 PKs). A biphasic linear model was used to describe the postoperative outcome of the endothelial cell density (ECD). Visual acuity, specular microscopy, corneal topography and optical coherence tomography findings were recorded.ResultsGraft survival of the 502 keratoconus eyes was 96.7 at 10 years and 95.6% at 20 years. Visual acuity improved from 20/378 +/- 5.1 lines preoperatively to 20/32 +/- 2.1 lines at 30 months. The corneal ECD decreased from 2494 +/- 382 cells/mm2 to 1521 +/- 659 cells/mm2 at 10 years. The mean simulated keratometry increased from 44.88 +/- 2.54 D at 1 year to 46.60 +/- 3.0 D at 3 years. The mean follow-up was 103.4 months for DALKs and 106.1 months for PKs. The cumulated incidence of postoperative ocular hypertension requiring treatment was significantly higher in PKs than in DALKs. The early- and late-phase rates of ECD loss were significantly lower in DALKs than in PKs. These figures in DALKs were 50% of those observed in PKs. The simulated mean keratometry was significantly higher in DALKs than in PKs in the mid but not in the long term. No significant differences in visual acuity were observed between both groups. Manual dissection-DALK featured slower visual recovery than PK and big bubble-DALK, whereas big bubble-DALK and PK featured similar visual recovery.ConclusionsDALK featuring higher endothelial survival and lower risk of postoperative ocular hypertension may be superior to PK when indicated for keratoconus.