Impact of Residual Stromal Thickness on the Outcomes of Manual Deep Anterior Lamellar Keratoplasty

Purpose: – To analyze how postoperative outcomes of manual deep anterior lamellar keratoplasty (mDALK) in eyes affected by keratoconus are influenced by the residual stromal thickness (RST) of the recipient. Methods: – Retrospective interventional case series. Patients underwent DALK between 2011 and 2025 at “Magna Graecia” University of Catanzaro, Italy. Big-bubble DALK was the favorite stromal dissection technique, whereas mDALK was reserved as backup strategy. Best spectacle-corrected visual acuity (BSCVA) and tomographic parameters were evaluated preoperatively (T0) and postoperatively after complete suture removal (1 year, T2). RST was assessed 1 month postoperatively (T1) using the CASIA SS-1000 anterior-segment optical coherence tomography (Tomey, Nagoya, Japan). Measurements were performed at the center of the cornea and at 12 paracentral points along 6 different meridians equally spaced at 30 degrees. Results: – In total, 288 eyes underwent DALK. Of these, 234 (81.3%) underwent successful pneumatic or viscoelastic dissection, whereas 54 (18.7%) required mDALK. In this subgroup, a significant correlation was found between postoperative BSCVA and central RST [56.17 ± 15.43 μm (95% confidence interval: 52.06–60.29); ρ = 0.397, P = 0.003], but not with paracentral RST [66.75 ± 22.54 μm (95% confidence interval: 60.74–72.76); ρ = 0.24, P = 0.07]. Conclusions: – Central RST presented a low-moderate yet significant correlation with postoperative BSCVA at 1 year. Corneal surgeons should aim to minimize RST compatibly with a safe stromal dissection.