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Purpose To evaluate a novel, hands-free technique for shallowing the anterior chamber (AC) during Descemet membrane endothelial keratoplasty (DMEK) using sub-Tenon injection of balanced salt solution (BSS), compared with established intraoperative methods.Methods A comparative case series of 10 DMEK procedures in cases where it was difficult to shallow was conducted, in which AC shallowing during graft unfolding was achieved using sub-Tenon injection of BSS. This technique, which has not been previously described in the literature, was compared with conventional approaches previously used by the same surgical team, including fluidic control, controlled wound leakage, external equatorial globe pressure, and air-assisted manoeuvres. Intraoperative AC stability, graft unfolding time, ease of bimanual manipulation, requirement for additional manoeuvres, and technique-related adverse events were assessed.Results Established methods for AC shallowing rely on repeated intraoperative adjustments that may interrupt graft handling during unscrolling. Sub-Tenon injection produced a sustained and predictable posterior counterpressure, resulting in stable AC shallowing without the need for ongoing manual intervention. This enabled uninterrupted bimanual graft manipulation with both hands free throughout the critical unfolding phase. Graft unfolding time was reduced compared with procedures performed using established techniques, reflecting improved chamber stability and surgical ergonomics. Chamber depth remained stable during manipulation, and no intraoperative complications or technique-related side effects were observed.Conclusions Sub-Tenon injection of BSS represents a novel approach for hands-free AC shallowing during DMEK. By improving chamber stability and reducing graft unfolding time, this technique may enhance surgical efficiency. Larger studies are required to confirm its safety, reproducibility, and comparative benefit.