Refractive outcome of keratoconus treated by big-bubble deep anterior lamellar keratoplasty in pediatric patients: two-year follow-up comparison between mechanical trephine and femtosecond laser assisted techniques

Background: To evaluate refractive outcome 24 months after Deep Anterior Lamellar Keratoplasty (DALK) in pediatric patients by comparing results achieved using mechanical trephine and femtosecond laser.Methods: Twenty eyes of 20 patients affected by keratoconus were evaluated. To perform big-bubble DALK, 10 eyes (Group 1; mean age 11.2 +/- 22 years) were subjected to the Hessburg-Barron mechanical trephine and the remaining 10 eyes (Group 2; mean age 11.3 +/- 3.1 years) to a 150 kHz femtosecond laser that performed mushroom incisions. Preoperative thinnest point in the corneal thickness map and K readings were measured by the Sirius Scheimpflug camera. We also evaluated corrected distance visual acuity (CDVA) as logMAR value using spectacles, spherical equivalent and refractive astigmatism.Results: Mean preoperative thinnest point and pre- and post-operative K readings did not show significant difference (P> 0.05) between the two groups. CDVA, spherical equivalent and refractive astigmatism were respectively, 0.14 +/- 0.08 logMAR and 0.13 +/- 0.10 logMAR (P= 0.8), - 4.2 +/- 1.1 D and - 2.8 +/- 1.2 D (P= 0.03), 4.4 +/- 2.0 D and 3.6 +/- 1.2 D (P= 0.4) in Groups 1 and 2. All DALK procedures were uneventful.Conclusion: Our findings suggest that femtosecond laser compared to mechanical trephine could significantly reduce the spherical equivalent amount in pediatric big-bubble DALK.