Refractive Changes After Corneal Stromal Filler Injection for the Correction of Hyperopia

Abstract

Hyperopia affects approximately 25% of the general population. 1 Currently available surgical options for the correction of hyperopia have significant disadvantages. Laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) can only be used for low hyperopia and are accompanied by an increased risk of regression, repeated corrective surgery, and higher order aberrations, 2 mainly due to ABSTRACT 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 µm 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.

Low Energy Blue Pulsed Light‐Activated Injectable Materials for Restoring Thinning Corneas

“…Previous ex vivo studies showed that corneal thickness could be increased by injecting unmodified hyaluronic acid filler solution into an intrastro-mal pocket, however stability of the injected materials over time was not reported. [51][52][53] Cornea stromal cell structure was not adversely affected by the creation of the intrastromal pocket nor by the presence of the injected materials over the 48 h period based on Confoscan imaging (Figure S8, Supporting Information). DSC results confirmed the injected material did not significantly affect the cornea denaturation temperature (Figure S9, Supporting Information).…”

“…Further, compared to previously developed corneal stromal filler materials that use only unmodified hyaluronic acid, our functionalized materials have been shown to form stable gels post-crosslinking that can withstand the high intracameral pressure of the cornea. [51][52][53] In addition, hyaluronic acid materials alone are very hydrophilic and without including other components into the filler or crosslinking, the intrastromal material will swell causing corneal edema. In addition to cornea thickness tunability, cornea curvature may also be modified by photo-cross-linking the injected material using stiff lenses applied to the corneal surface to maintain the desired shape until the material is fully crosslinked.…”

Optical Vortex Beam for Gentle and Ultraprecise Intrastromal Corneal Dissection in Refractive Surgery

“…The increased precision and reduction in mechanical side effects in intrastromal cutting by the use of a vortex beam make this a promising approach for flap cutting in LASIK 4 and intrastromal pocket dissection for hyperopia correction 13,14 and offers even greater potential for improving SMILE. 10 In SMILE, a small lenticule is dissected and removed through a small side cut to achieve refractive correction in one step.…”

“…Recently, a novel approach for hyperopia correction based on dissection of an intrastromal pocket followed by the injection of a biocompatible filler material has been introduced. 13,14 Despite more than 20 years of experience with LASIK and SMILE, there is still room for improvement with regard to efficiency, precision, and safety. Significant improvements can be achieved by addressing the key step of the refractive laser procedure: intrastromal dissection.…”

“…Recently, a novel approach for hyperopia correction based on dissection of an intrastromal pocket followed by the injection of a biocompatible filler material has been introduced. 13 , 14 …”