Refractive changes after corneal stromal filler injection for the correction of hyperopia

Purpose: To evaluate a new non-ablative and adjustable procedure for laser ablative refractive corneal surgery in hyperopia using the injection of a biocompatible liquid filler material into a stromal pocket. Methods: A total of 120 stromal pockets were created using a clinical femtosecond laser system in 96 rabbit corneoscleral discs and 24 whole globes. Pockets were cut at a depth of 120 or 250 ìm below the epithelial surface. Hyaluronic acid was injected manually into the pocket. To determine the refractive changes, three-dimensional optical coherence tomography images and a specifically developed picture recognition Matlab (The Mathworks) routine were used. Results: After injection, a steepening of the anterior and flattening of the posterior corneal surface was observed, which led to hyperopic correction. The two main factors determining the amount of correction were the pocket depth and the injected volume. After the pocket was homogeneously filled, an initial refractive increase was observed, followed by a linear relation between the injected volume and the refraction increase. Conclusions: This possible clinical protocol for controlled refraction correction of hyperopia suggests a potential readjustable clinical application.