Ex vivo evaluation of corneal filler injection for enhancement after small incision lenticule extraction

To investigate the feasibility of transparent corneal filler injection for enhancement after myopic Small Incision Lenticule Extraction (SMILE) overcorrection in an ex vivo eye model. Myopic SMILE procedure with an anticipated correction of -5.6 dpt was performed in 46 whole porcine eyes ex vivo. A hyaluronic acid filler was injected into the SMILE interface through the incision, which was subsequently sealed with fibrin glue. Three-dimensional optical coherence tomography (OCT) was acquired pre- and postoperatively, assessing the central filler thickness and refractive power changes. Based on the central pocket thickness and radius, the refractive power change after filler injection was calculated using the well-known Munnerlyn formula. The filler volume (0.4 to 1.7 µl) correlated linearly with the central pocket thickness (Pearson's r = 0.90, p < 0.0001; R² = 0.96). Based on the filler volume and central pocket thickness, a filler radius was calculated as 2.77 mm. According to the Munnerlyn formula, a central pocket thickness change from 30 μm to 148 μm corresponded to a calculated increase in refractive power from 2.9 to 14.5 dpt. The injection of a corneal filler via the primary SMILE-incision into the interface following myopic SMILE is a feasible method to partially reverse the refractive change ex vivo. Further development for clinical use is warranted.