High myopia, defined as vision worse than -5.0 D, affects a substantial portion of the global population, with projections indicating that it will impact half the world's population by 2050. A significant subset of these cases involves progressive high myopia, which current treatments like glasses, orthokeratology, LASIK, ICL, IOL, and corneal refractive surgery often fail to effectively manage. These traditional treatments primarily address refractive errors, not the underlying axial elongation and scleral weakening that characterize progressive high myopia. This lack of effective management leads many patients to develop pathological symptoms, including severe ocular deformation, retinal, choroid, and scleral alterations, and visual field defects. Such pathological myopia significantly increases the risk of blindness. Two primary methods are currently used to treat progressive high myopia: posterior scleral cross-linking (PSCL) and posterior scleral reinforcement (PSR). PSCL uses drugs and light to strengthen the sclera, while PSR uses implanted materials for scleral support. However, both methods present challenges. PSCL struggles with full posterior pole sclera exposure, while PSR requires extensive surgical exposure, which increases complexity and duration. The effectiveness of PSR is also dependent on surgeon skill. This study aims to overcome these limitations by developing a multifunctional therapeutic patch that combines the benefits of both PSCL and PSR in a compact, easily implantable, and battery-free design.

The existing literature highlights the significant global burden of high myopia and its associated pathological complications. Current treatment options, while effective in correcting refractive errors, often fail to halt the progression of axial elongation and scleral thinning, leading to long-term visual impairment and increased risk of blindness. Studies on posterior scleral cross-linking (PSCL) demonstrate its potential in strengthening the sclera and controlling eye axis growth, but the challenges of achieving complete posterior pole exposure limit its efficacy. Similarly, while posterior scleral reinforcement (PSR) has proven effective in relieving conditions like myopic macular splitting and preventing further axial growth, it remains a complex surgical procedure with outcome variability depending on surgical skill and the lack of precise intraoperative measurements. The need for a minimally invasive, precisely controllable, and effective treatment for progressive high myopia is clearly established by the current literature.

This study developed a multifunctional wireless, battery-free eye modulation patch. The patch consists of piezoelectric transducers (PZTs), an electrochemical micro-actuator, a drug microneedle array, µ-LEDs, a flexible circuit, and biocompatible encapsulation. The PZTs convert external ultrasound energy into electrical energy, powering and controlling the device. The electrochemical micro-actuator, driven by the ultrasound-generated electricity, precisely shortens the axial length by driving the posterior sclera inward. The microneedle array delivers riboflavin into the posterior sclera. The µ-LEDs emit blue light to induce collagen cross-linking (SCXL), strengthening the sclera. The patch's design and fabrication involved microfabrication techniques, including photolithography, electroplating, and PDMS molding. The functionality of each component was tested in vitro. The wireless power transfer efficiency was evaluated using pork tissue to mimic the in vivo environment. The in vivo experiments were performed on New Zealand white rabbits. Surgical procedures involved implanting the patch onto the rabbit sclera, activating the micro-actuator for axial length modulation, and subsequently performing SCXL using the blue µ-LEDs. Axial length changes were measured using optical coherence tomography (OCT) and ocular ultrasonography (A-scan). Scleral biomechanical properties (Young's modulus) were assessed before and after SCXL. Histological and immunohistochemical analyses were performed to evaluate tissue integrity and potential inflammatory responses. The study also employed COMSOL simulations to optimize the µ-LED array configuration for effective SCXL.

In vivo experiments demonstrated the efficacy of the eye modulation patch in rabbits. The micro-actuator successfully reduced the axial length by an average of ~1217 µm within 6 minutes. The combination of riboflavin delivery and blue light-induced SCXL resulted in a significant 387% increase in scleral strength at 22 days post-treatment. Histological analysis showed a compact arrangement of collagen fibers and reduced porosity in the SCXL group compared to the control group. Immunohistochemical staining revealed no activation of microglia or astrocytes, indicating no neurodegenerative effects. Furthermore, intraocular pressure remained within the normal range post-surgery, suggesting the patch does not induce glaucoma. The study confirms the biocompatibility and safety of the patch, without causing retinal detachment, choroidal hemorrhage, or other complications.

The results demonstrate that the wireless, battery-free eye modulation patch provides a novel approach for treating high myopia by addressing both axial elongation and scleral weakening. The significant reduction in axial length and the substantial increase in scleral strength achieved in the rabbit model suggest its translational potential for human application. The minimally invasive nature of the procedure, the precise control offered by wireless ultrasound, and the absence of batteries all contribute to enhanced patient safety and comfort. The successful integration of drug delivery and light-induced SCXL within a single device represents a significant advancement in myopia management. The observed absence of significant inflammation or adverse effects further supports the patch's biocompatibility.

This study presents a novel wireless, battery-free eye modulation patch that effectively reduces axial length and enhances scleral strength in a rabbit model. The promising results suggest its potential as a safe and effective treatment for high myopia. Further research, including larger-scale animal studies and clinical trials, is needed to validate the long-term efficacy and safety of this innovative approach.

The study's limitations include the relatively small sample size and the short-term follow-up period (22 days). The findings in rabbits may not fully translate to human outcomes. Long-term studies are needed to assess the durability of the axial length reduction and the long-term biocompatibility and safety of the patch. Further optimization of the patch design and parameters may be necessary for optimal performance in humans.