Outcomes of therapeutic penetrating keratoplasty and deep anterior lamellar keratoplasty in acanthamoeba keratitis: A systematic review and meta-analysis.

While acanthamoeba keratitis (AK) is a sight-threatening corneal infection, a thorough comparison of the outcomes of therapeutic penetrating keratoplasty (PK) and therapeutic deep anterior lamellar keratoplasty (DALK) is lacking. We aimed to compare clinical outcomes of PK and DALK in AK. The study was preregistered in the PROSPERO database (CRD420251233705). A comprehensive search of Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials (CENTRAL) was conducted through 11 November 2025. Eligible studies reported outcomes after PK or DALK in patients with AK, specifically graft survival, best spectacle-corrected visual acuity (BSCVA) and postoperative complications. Of the 1257 studies screened, 28 studies comprising 478 eyes with AK were included in the meta-analysis. Individual participant data (IPD) were available from 11 studies. The pooled graft survival rate was significantly higher after DALK (0.90, 95% CI 0.48-0.99) than after PK (0.63, 95% CI 0.54-0.71) (p = 0.025). No significant difference was observed in either BSCVA improvement between PK (-1.00, 95% CI -1.36 to -0.64) and DALK (-1.29, 95% CI -2.30 to -0.28) (p = 0.314), or in postoperative BSCVA between PK (0.97, 95% CI 0.68 to 1.25) and DALK (0.86, 95% CI -0.02 to 1.74) (p = 0.739). Postoperative complications did not differ significantly between the two procedures (all p ≥ 0.91). DALK may provide superior graft survival compared with PK in AK, while visual and postoperative outcomes appear comparable between the two procedures. Within the observed follow-up periods, treatment delay alone was not clearly associated with visual outcomes after PK.