Residual Bed Thickness in Deep Anterior Lamellar Keratoplasty: A Comparative Study of Peeling-Off and Manual Technique

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PURPOSE: To compare residual stromal bed thickness (RST) and regularity after manual layer-by-layer deep anterior lamellar keratoplasty (M-DALK) and peeling-off deep anterior lamellar keratoplasty (PO-DALK), after failed pneumatic dissection. METHODS: This retrospective case series included patients who underwent M-DALK or PO-DALK. Best-corrected visual acuity (BCVA) was assessed preoperatively and 1 month postoperatively. Anterior segment optical coherence tomography used to measure central and peripheral RST and Fourier analysis to assess asymmetry (ASY) were evaluated 1 month after surgery. RESULTS: BCVA varied significantly from baseline to 1 month after surgery in both groups (both P < 0.001). Mean central RST was 55.91 μm [95% confidence interval (CI) 51.87-59.95] in the PO-DALK group versus 56.32 μm (95% CI 51.08-61.56) in the M-DALK group (P = 1.0). Mean peripheral RST was 59.40 μm (95% CI 54.27-64.52) in PO-DALK versus 65.73 μm (95% CI 58.27-73.18) in M-DALK (P = 0.62). In both groups, the difference between mean central and peripheral RST was significant (P = 0.0001 in PO-DALK, P < 0.0001 in M-DALK). However, the mean difference between peripheral and central RST was 5.32 μm (95% CI 3.95-6.69) in PO-DALK versus 11.18 μm (95% CI 7.8-14.56) in M-DALK (P = 0.002) and difference among peripheral RSTs was 4.15 μm (95% CI 3.32-4.97) in PO-DALK versus 13.57 μm (95% CI 8.68-18.46) in M-DALK (P < 0.0004). ASY analysis of the 3-mm and 6-mm zones did not reveal significant differences among the 2 groups (P > 0.05). CONCLUSIONS: PO-DALK provides a significantly more regular and homogeneous residual stromal bed than M-DALK. It is a simple and effective technique, offering a reliable alternative when pneumatic dissection fails.