Five-year Outcomes of Converted Mushroom Keratoplasty from Intended Deep Anterior Lamellar Keratoplasty (DALK) Mandate 9-mm Diameter DALK as the Optimal Approach to Keratoconus

Purpose: To compare the 5-year outcomes of 9-mm-deep anterior lamellar keratoplasty (DALK) for keratoconus with those of conversions to mushroom keratoplasty (MK). Design: Retrospective cohort study. Methods: The setting was the Ospedali Privati Villa Igea, Department of Ophthalmology, Forlì, Italy. The study population consisted of the medical records of all attempted DALK procedures (416 eyes) for the indication of keratoconus performed between January 2012 and January 2018; 68 eyes (16.4%) were converted to MK and analyzed as a separate cohort. The mean follow-up time was 33.8 ± 15.1 months. Procedure(s) consisted of 9-mm DALK and MK (9-mm anterior lamella with 6-mm posterior lamella). Outcome measurements were best-corrected visual acuity (BCVA), refractive astigmatism, and endothelial cell loss (ECL) at 5 years. Results: Average BCVA at 5 years was 0.06 ± 0.07 in the DALK group and 0.09 ± 0.15 in the MK group (P = .88). Refractive astigmatism following suture removal (all visits later than 12 months) was slightly less in the DALK cohort (5-year DALK = 2.16 ± 1.40 diopter [D]; MK = 3.02 ± 0.89 D; P = .04; mean difference = 0.86 D [95% confidence interval [CI]: 0.71-1.01]). ECL was significantly higher in the MK group than in the DALK group at all follow-up intervals (5-year DALK = 19.36 ± 21.47%; MK = 56.61 ± 15.82%; P < .001). The total all-cause graft failure rate at 5 years was 0.58% for DALK (2 of 348) cases and 5.88% for MK (4 of 68) cases. Conclusions: Excellent 5-year visual and clinical outcomes associated with a 2-piece MK in cases converted from intended DALK mandate large-diameter DALK (9 mm) as the optimal surgical approach to keratoconus.