The coating was designed to solve a specific weakness of silicone hydrogels. Their siloxane-rich networks transport oxygen unusually well, but hydrophobic domains segregate toward the surface in water, creating chemically uneven interfaces associated with poor wettability, protein adsorption, unstable tear films, and friction. The researchers sought a hydrophilic outer layer without obstructing the oxygen-carrying channels inside the lens. Poly(HEMA) was grafted to Acuvue Oasys, Clariti 1 Day, and Ultra One Day lenses by free-radical polymerization at 80 degrees Celsius, using formulations containing 2.5%, 10%, or 20% HEMA. Linear poly(HEMA) chains became entangled with the existing crosslinked lens matrix, creating a semi-interpenetrating polymer network rather than a sharply separated film.

Surface analysis showed that the modification masked the underlying silicone chemistry. The proportion of surface oxygen increased in every lens type after treatment, while signals associated with silicon and nitrogen declined as the HEMA layer thickened. A new ester signal characteristic of poly(HEMA) appeared in high-resolution XPS spectra. Calculated surface coverage ranged from 34.90% ± 4.70% for 10% HEMA-treated Clariti to 88.92% ± 2.27% for 20% HEMA-treated Acuvue. Acuvue’s comparatively low swelling ratio, 47.2% ± 1.0%, was associated with greater coverage than in Clariti and Ultra, whose swelling ratios exceeded 98%. These relationships describe the tested materials and preparation conditions; they do not establish that swelling alone determines performance across all silicone hydrogels.

Depth profiling revealed that the interface was graded rather than a simple veneer. During incremental argon-cluster sputtering, the poly(HEMA) ester signal declined gradually with depth, indicating chemical intermingling with the substrate. ToF-SIMS provided a complementary three-dimensional view. In Acuvue-20HEMA, a fragment attributed to poly(HEMA) dominated the outermost region, while HEMA and siloxane signals coexisted in the subsurface, directly visualizing penetration and anchoring of the grafted chains. The same general chemical transition appeared in modified Clariti and Ultra lenses. This evidence supports formation of the intended semi-interpenetrating network across the three commercial substrates examined.

The investigators then used a custom AFM algorithm based on Hertz-model fits and force-distance curves to distinguish three mechanical regimes: the soft, hydrated outer poly(HEMA) coating, an intermediate semi-IPN region, and the stiffer base lens. Unlike XPS and ToF-SIMS, the aqueous AFM measurements characterized the interface in a hydrated environment. The method identified the surface contact point and the coating-to-semi-IPN transition, then estimated the thickness of each region. Coating thickness increased with HEMA concentration, ranging from 19.23 ± 1.10 nm to 46.28 ± 0.61 nm for Acuvue, from 36.83 ± 5.31 nm to 71.68 ± 6.74 nm for Clariti, and from 39.60 ± 6.47 nm to 54.31 ± 2.00 nm for Ultra. The 20% formulations generally produced the thickest modifications.

The architecture corresponded with measurable improvements in surface behavior. All HEMA-treated lenses had lower static water contact angles than their untreated counterparts. Acuvue-20HEMA had a contact angle of 55.64° ± 0.85°, compared with 90.31° ± 0.67° for pristine Acuvue. Its advancing angle fell from 38.57° ± 0.39° to 29.28° ± 3.35°, while contact-angle hysteresis decreased from 17.09° ± 0.82° to 7.12° ± 3.40°, indicating reduced surface heterogeneity. Solvent Black 3 stained exposed hydrophobic regions on pristine lenses but produced little visible staining after modification, particularly on Acuvue-20HEMA. Atomic force microscopy topography likewise showed that root-mean-square roughness fell by 42% for Acuvue-20HEMA, 20% for Clariti-20HEMA, and 23% for Ultra-20HEMA.

The antifouling tests linked these structural changes to protein and cell behavior. Poly(HEMA) reduced adsorption of bovine serum albumin and lysozyme relative to untreated lenses, with the 20% formulations generally performing better than the 10% formulations. Acuvue-20HEMA also reduced L929 fibroblast adhesion more effectively than Acuvue-10HEMA despite their similar surface coverage. The investigators attributed this difference to the greater physical thickness of the coating and semi-IPN. Cell viability for L929 and V79 fibroblasts remained above the 70% threshold specified in ISO 10993-5 for all pristine and modified lenses, indicating that washing removed enough residual reagents to satisfy that laboratory cytotoxicity criterion. The assays did not assess safety or effectiveness during human lens wear.

Critically, the sub-100-nanometer interface did not compromise the principal bulk functions tested. Optical transmission across visible, UVA, and UVB wavelengths was virtually unchanged, and each lens retained its original UV class. Oxygen permeability remained statistically unchanged because oxygen continued to diffuse through continuous siloxane channels in the bulk material. Fully hydrated tensile strength, macroscopic Young’s modulus, and equilibrium water content were also preserved, apart from an approximately 5% reduction in equilibrium water content for three modified formulations, which the authors associated with reduced surface roughness and effective surface area. Wettability persisted after 14 days in aqueous media, physiological saline, and simulated tear fluid at physiological temperature. Clariti-20HEMA and Ultra-20HEMA remained consistent through five hydration-dehydration cycles, while Acuvue-20HEMA showed a slight contact-angle increase from the fourth cycle but remained more hydrophilic than the untreated control. Poly(HEMA) also survived three steam-sterilization cycles without loss of its characteristic infrared signals.

The platform additionally accommodated a light-responsive prodrug containing a polymerizable methacrylate, a photocleavable o-nitrobenzyl linker, and dexamethasone. Copolymerizing the prodrug with HEMA anchored it to the Acuvue surface, where exposure to 405-nanometer light triggered release that largely stopped in darkness. The HEMA-containing system showed a small sustained release during dark intervals, attributed to hydrogen bonding and physical retention of cleaved drug within the hydrated polymer mesh. HPLC and mass spectrometry showed that the prodrug retained its structure during steam sterilization at 121 degrees Celsius. At 0.1% prodrug and 0.1% HEMA, the lenses remained optically transparent; raising the prodrug concentration to 0.5% caused phase separation and reduced optical transmission to 38.59% ± 3.52%, demonstrating that loading must remain within a tightly controlled window.

Taken together, the experiments present a quantitative method for linking buried coating chemistry, nanoscale architecture, interfacial mechanics, and biological performance on soft, curved biomedical substrates. The strongest performance occurred where the coating combined high surface coverage with sufficient thickness, while the failure at excessive prodrug loading showed that functionalization can disrupt optical properties. The work is an engineering and proof-of-concept study involving three commercial contact-lens materials, two fibroblast cell lines, and model protein assays; it did not evaluate long-term wear, clinical outcomes, or performance across the wider range of implants and therapeutic devices envisioned by the authors. Its broader contribution is a characterization strategy that can test how a buried interface is built, rather than relying only on fabrication chemistry and surface-level performance measurements.

Subject of Research: Nanoscale poly(HEMA) interface engineering and characterization in silicone hydrogel contact lenses

Article Title: Nanoscale Buried Interface Control in Silicone Hydrogels Enables a Biointerface Engineering Platform

Article References: Chen, P.-H., Wang, J.-H., Chen, C., Fu, S.-H., Chakravarthy, R. D., & Lin, H.-C. (2026). Nanoscale Buried Interface Control in Silicone Hydrogels Enables a Biointerface Engineering Platform. Advanced Science, Article e78148. https://doi.org/10.1002/advs.78148

Image Credits: AI Generated

DOI: 10.1002/advs.78148

Keywords: silicone hydrogels, contact lenses, nanocoatings, poly(HEMA), biointerfaces, atomic force microscopy, ToF-SIMS, X-ray photoelectron spectroscopy, antifouling, drug delivery, Nanoscale, Buried

The review, led by Graziana M. Ragonese of the PolitoBIOMed Lab at the Politecnico di Torino together with colleagues in Trieste and Calabria, takes an explicitly biomechanical view of a disease that affects an estimated 0.24 percent of the global population. A recent meta-analysis cited in the paper puts prevalence at roughly 289 cases per 100,000 people, with markedly higher rates in Africa and South Asia. The disease typically announces itself in the teenage years with mild thinning and small refractive errors, then can progress relentlessly for two decades or more. In its wake come photophobia, monocular double vision, and progressive blurring that contact lenses may eventually fail to tame. Between 15 and 20 percent of patients ultimately need a corneal transplant, and the authors are blunt about why that endpoint is problematic: only one donor cornea is available worldwide for every seventy needed, and roughly a tenth of transplants face long-term immune rejection or other serious complications.

That shortfall is the engine driving the search for alternatives. The review’s central insight is a careful separation of four outcomes that clinicians and patients often conflate: stiffening the cornea, flattening its shape, improving vision, and stabilizing the disease. A treatment that improves one does not necessarily deliver the others. Contact lenses, the workhorse of early-stage care, illustrate the point perfectly. Rigid gas permeable lenses, made from silicone-acrylate materials with a Young’s modulus of 1 to 1.9 megapascals, sit over the irregular cornea and form a tear lens that neutralizes irregular astigmatism. They work optically, but they add no intrinsic strength to the stroma, and their rigidity itself can generate excessive contact pressure, epithelial damage, and tear film disruption. Softer hydrogel lenses, at 0.4 to 0.6 megapascals, drape over the cone and often undercorrect. Hybrid, piggyback, and scleral designs vault the cornea to sidestep these problems, yet the review’s verdict is unsparing: lenses manage symptoms, not the disease.

The one established therapy that genuinely changes the cornea’s mechanical properties is corneal collagen crosslinking, or CXL, which the authors describe as the reference treatment for progressive keratoconus. The logic is molecular. The cornea’s shape is maintained by an exquisitely ordered lattice of collagen fibrils, and in keratoconus this organization is disrupted, in part through reduced natural crosslinking. CXL reverses the trend artificially: riboflavin droplets are activated with 370-nanometer ultraviolet-A light, generating reactive oxygen species that forge new covalent bonds between fibrils. In the standard epithelium-off Dresden protocol, 30 minutes of irradiation at 3 milliwatts per square centimeter delivers a total fluence of 5.4 joules per square centimeter. Ex vivo stress-strain testing shows the payoff dramatically, with corneal rigidity increasing roughly 4.5-fold, from a Young’s modulus of 1.3 megapascals to 5.9 megapascals. Long-term studies report sustained stabilization for up to ten years.

Yet even the gold standard has soft spots, and the review dissects them with unusual technical candor. Faster accelerated protocols trade irradiance for time, and pulsed delivery schemes aim to boost oxygen availability during treatment, but direct comparisons between protocols are muddied by differing experimental models and follow-up durations. Transepithelial CXL, which spares the corneal surface to reduce pain and infection risk, pays a steep biomechanical price: tight epithelial junctions limit riboflavin diffusion. In rabbit corneas, epi-on treatment raised the Young’s modulus by about 21 percent, versus roughly 102 percent for the standard approach, which helps explain its weaker record against ectasia progression. Iontophoresis-assisted CXL, using a low-intensity electric current to drive riboflavin through intact tissue, stiffens the cornea less than the standard technique, with a two-year mean keratometry reduction of 2.1 percent compared with 4.3 percent. For very thin corneas, where endothelial safety limits conventional dosing, modified options such as hypo-osmolar riboflavin, contact lens-assisted irradiation, and individualized fluence protocols are expanding the eligible population, though long-term equivalence remains an open question.

The most striking data in the review concern the gap between what we can measure and what we cannot. Intracorneal ring segments, crescent-shaped polymethyl methacrylate implants threaded into stromal tunnels, act as spacers between collagen lamellae, and finite element models show their flattening effect is proportional to segment thickness and inversely proportional to corneal diameter. The implants also stretch strain-stiffening collagen lamellae at the corneal periphery, raising effective structural stiffness. But the measurable result is geometric remodeling, not intrinsic tissue stiffening, and the nomograms that guide segment selection are, the authors note, largely empirical and often based on unpublished clinical data. Reported outcomes vary widely with cone morphology, tunnel depth, and design: Intacs delivered a maximum keratometry reduction of about 3.8 diopters at three years, KeraRing segments showed early migration in around 6 percent of eyes, and Ferrara segments were associated with extrusion in 4.8 percent and disease progression in 26 percent of one cohort.

Two newer players are changing that calculus. The continuous 360-degree MyoRing, inserted into a corneal pocket rather than tunnels, acts as an artificial limbus, redistributing load around the entire periphery and producing more symmetric flattening; comparative studies found greater maximum keratometry reductions than the segmental KeraRing. Meanwhile, corneal allogenic intrastromal ring segments, or CAIRS, replace inert plastic with donor stromal tissue that can integrate biologically, be customized to individual anatomy, and suit thinner corneas, with one-year data showing maximum keratometry falling from 55.85 to 50.69 diopters. Combination strategies capture the complementary physics: implants reshape while crosslinking stiffens. A retrospective series of inferior-segment Intacs with and without CXL found the combined group achieved a mean keratometry reduction of 1.34 diopters versus 0.64 for implants alone, and a best-corrected visual acuity gain of 6.5 lines versus 0.93, though the authors caution that optimal timing and sequencing remain unstandardized.

Beyond the established toolkit, the review maps a regenerative frontier. Cell-based therapies aim to restore the keratocyte population, the principal stromal cells that maintain the extracellular matrix, using corneal stromal stem cells and adipose-derived stem cells; early clinical studies reported favorable safety but only moderate visual and thickness improvements, with little direct biomechanical assessment. Stromal lenticule implantation adds donor or refractive surgery byproducts to restore volume and redistribute stress, sometimes combined with CXL, though small cohorts, short follow-up, and persistent interface haze temper enthusiasm. Tissue-engineered scaffolds of polylactic acid, polyglycolic acid, or biologically derived collagen matrices aim to mimic the extracellular matrix itself, collagen constituting roughly 70 percent of it; early-phase studies of biosynthetic substitutes demonstrated integration, re-epithelialization, and preserved transparency, but challenges of optical clarity, strength, degradation, and long-term stability persist.

Perhaps the review’s most consequential argument is about measurement. If stiffening, flattening, and stabilization are distinct outcomes, then clinical endpoints such as corneal thickness, curvature, and visual acuity are insufficient on their own. The authors call for future trials to incorporate objective biomechanical metrics, including corneal hysteresis, Brillouin microscopy, optical coherence elastography, and patient-specific computational modeling, so that researchers can determine whether a therapy truly reinforces the ectatic cornea or merely improves its shape. The digital twin paradigm, in which a patient’s tomographic, biomechanical, and clinical data feed a personalized model that simulates disease progression and predicts treatment outcomes, is flagged as the likely framework for individualized planning.

The upshot is a field in transition. Keratoconus management has moved from masking a deforming cornea to arresting it with CXL, reshaping it with rings, and now contemplating its biological regeneration. What the Torino-led team makes clear is that none of these steps alone completes the task. The destination they describe is multimodal: stabilizing the tissue mechanically, rebuilding its structure, and regenerating its biology, all guided by predictive models that treat the cornea as what it ultimately is, an engineered structure that can be measured, modeled, and repaired.

Subject of Research: Biomechanical stabilization strategies for the keratoconic cornea, including crosslinking, intrastromal implants, and regenerative therapies

Article Title: Biomechanical stabilization of the keratoconic cornea: a review of current therapeutic strategies

Article References: Ragonese, G. M., Grosso, E., Carbonaro, D., Torta, E., Lepore, E., & Gallo, D. (2026). Biomechanical stabilization of the keratoconic cornea: a review of current therapeutic strategies. Frontiers in Medical Technology, 8, Article 1919880. https://doi.org/10.3389/fmedt.2026.1919880

Image Credits: AI Generated

DOI: 10.3389/fmedt.2026.1919880

Keywords: keratoconus, corneal biomechanics, collagen crosslinking, intracorneal ring segments, CAIRS, corneal stiffness, contact lenses, stromal regeneration, tissue-engineered scaffolds, digital twin, corneal transplant shortage, Brillouin microscopy

The appeal of graphene begins with an almost improbable list of properties packed into a sheet of carbon just one atom thick. The material transmits roughly 97.7 percent of visible light, conducts electricity with carrier mobility exceeding 200,000 square centimeters per volt-second at room temperature, and exhibits a Young’s modulus of approximately 1 terapascal with tensile strength above 130 gigapascals. For a contact lens, that combination is extraordinary. A graphene layer can be transparent enough not to disturb vision, conductive enough to carry sensor signals and antenna currents, and mechanically robust enough to survive the relentless deformation of blinking. Unlike brittle transparent conductors such as indium tin oxide, graphene bends and stretches with the soft hydrogel substrates that modern lenses are made from, making it a natural candidate for embedding electronics directly into the ocular environment.

Beyond mechanics and conductivity, graphene brings a biointerface chemistry that the review’s authors highlight as central to its ocular promise. Its ultra-smooth surface topology minimizes protein adsorption and bacterial adhesion, two processes that plague conventional lenses by causing biofouling, discomfort, and infection risk. The material’s inherent antimicrobial activity operates through multiple mechanisms, including direct contact killing, oxidative stress induction, and disruption of bacterial membranes, offering a built-in defense against the microbial colonization that can lead to corneal ulceration and vision loss. Graphene’s aromatic structure and strong covalent bonding also confer resistance to chemical degradation and enzymatic breakdown under physiological conditions, while its naturally hydrophobic surface can be tuned through functionalization to optimize wettability and tear film stability. In principle, these features combine to reduce inflammation, extend safe wearing times, and create surfaces onto which drugs and recognition molecules can be grafted.

The review is careful to sort the literature by technological maturity, distinguishing conceptual device architectures from laboratory proof-of-concept studies and from experimentally demonstrated prototypes, and the differences are striking. At the most speculative end sit the so-called night-vision lenses. Graphene photodetectors on flexible transparent substrates have indeed demonstrated the ability to detect infrared light, converting infrared photons into electrical signals that could in principle be rendered as visible overlays in the wearer’s field of view. The review’s own schematic of such a device is explicitly labeled conceptual, and no integrated wearable lens system with this capability has been clinically validated. Still, the underlying photodetection physics, demonstrated in broadband graphene devices at room temperature, keeps the idea alive for security, defense, and augmented reality applications far beyond medicine.

More grounded are the proof-of-concept demonstrations of electromagnetic shielding and moisture retention. Laboratory studies of lenses coated with an approximately 5-nanometer graphene film reported an 80 percent reduction in microwave-induced protein denaturation, measured through controlled egg-white exposure experiments, alongside a 30 percent reduction in tear evaporation compared with conventional lenses. The dual function addresses two modern anxieties at once: growing exposure to wireless radiation in digital environments and the persistent problem of dry eye among lens wearers. The authors caution that these results represent demonstrations of material functionality rather than established smart lens products, but they illustrate how a single graphene layer can deliver protective properties that conventional hydrogel materials simply cannot match.

At the prototype level, two applications stand out. The first is transparent electroretinography. An experimentally demonstrated graphene-on-lens electrode system covers the full cornea while remaining highly transparent, enabling comprehensive retinal recordings without visual obstruction. In the reported configuration, the graphene electrodes achieved roughly a threefold improvement in signal-to-noise ratio compared with conventional DTL fiber electrodes, a gain the review attributes to the conformal, intimate contact between the atomically thin electrode and the corneal surface, which reduces movement artifacts and permits extended recording sessions without irritation. The second flagship prototype is a wireless intraocular pressure sensor for glaucoma management. Built around graphene nanowall strain gauges with a reported sensitivity of approximately 42,250 parts per million per millimeter of mercury, the lens detects the tiny corneal curvature changes caused by pressure fluctuations and transmits the data wirelessly via a near-field communication antenna. Validation in rabbit eyes demonstrated accurate pressure measurement with minimal tissue response, placing the technology firmly in the preclinical category but marking it as one of the field’s most translationally advanced achievements.

Biosensing extends the vision further into personalized medicine. A proof-of-concept graphene field-effect transistor functionalized with anti-cortisol antibodies has detected tear cortisol at a limit of detection of approximately 10 picograms per milliliter, with smartphone-compatible NFC readout envisioned for routine self-monitoring of stress hormones. Tear-based glucose sensing follows a similar logic, exploiting graphene’s vast surface area and tunable chemistry to immobilize glucose-specific enzymes for non-invasive diabetes surveillance. Drug delivery rounds out the application landscape: graphene oxide laden lenses have been investigated for the controlled release of timolol, cyclosporine, bimatoprost, antibiotics, anti-inflammatory agents, and growth factors, with release profiles that can respond to stimuli such as pH, temperature, or enzymatic activity. By delivering therapeutics directly to ocular tissues, such systems could improve efficacy while minimizing systemic side effects, and graphene’s photodynamic potential, generating reactive oxygen species under light exposure, adds yet another therapeutic modality for treating infections and neovascularization.

Turning these concepts into manufacturable devices is where the field confronts its hardest engineering trade-offs. Chemical vapor deposition produces the highest-quality monolayer graphene, grown on copper foil at around 1000 degrees Celsius in a methane and hydrogen atmosphere, but transferring that fragile film onto a curved, soft lens requires polymer-assisted wet transfer, careful etching, and meticulous rinsing, with costs estimated at roughly five dollars per lens. Solution-phase processing using graphene oxide is cheaper and compatible with existing lens manufacturing, but sacrifices film quality and electrical performance. Patterning strategies, including layer-by-layer assembly, electrochemical deposition, inkjet printing of graphene inks, and direct laser interference patterning at 355 nanometers, allow researchers to write sensors, antennas, and circuits onto curved surfaces, while hydrogel incorporation and microcontact printing embed graphene into the lens bulk. Even the assembly sequence matters: a representative workflow positions a graphene monolayer on a poly(methyl methacrylate) intermediate that serves as both transfer scaffold and dielectric buffer before final cast-molding into pHEMA hydrogel at 70 degrees Celsius.

Safety and regulatory hurdles may prove even more formidable than the engineering. Graphene’s impermeability, so useful for moisture retention, threatens to choke off the oxygen transmission that corneal health demands, prompting proposed solutions such as focused ion beam or laser drilling of 50-nanometer pores to restore permeability above 30 barrer. Heat dissipation is another concern, with temperature rises of 2 to 3 degrees Celsius observed under 2.4 gigahertz exposure, motivating micro-heat-spreader grids beneath the graphene layer. Delamination after roughly 30 days of wear, driven by weak graphene-hydrogel adhesion under the mechanical stress of blinking, may be addressed by silanizing the lens surface with 3-aminopropyl-triethoxysilane to create covalent bonds. More fundamentally, the toxicology remains unsettled: pristine graphene generally shows low short-term cytotoxicity toward corneal cells, but graphene oxide can induce oxidative stress and membrane damage, some studies report DNA strand breaks and mitochondrial damage in human corneal epithelial cell lines under prolonged exposure, and tear film enzymes such as peroxidases and lysozymes may partially degrade functionalized graphene into bioactive products whose in vivo toxicity is largely uncharacterized. No longitudinal human trials of embedded graphene lenses exist, and no graphene-enhanced contact lens has yet received regulatory approval, although the FDA and EMA have issued draft guidelines for nanomaterials in medical devices.

The review’s authors close with a sober but optimistic outlook for 2025 to 2030. Future platforms may combine graphene with other two-dimensional materials such as molybdenum disulfide or hexagonal boron nitride to build heterostructures capable of multimodal biosensing of glucose, lactate, cytokines, and cortisol, while micro-scale graphene supercapacitors and energy-harvesting modules could free lenses from external power, and artificial intelligence could interpret sensor signals in real time on the lens itself. Modular designs with interchangeable sensing and therapeutic units, harmonized ISO testing protocols for nanoparticle shedding and chronic exposure, and roll-to-roll manufacturing on copper-nickel foils to slash costs all feature in the proposed roadmap. For now, the authors conclude, graphene-based contact lenses remain a promising but technically and translationally immature technology, one whose success will be decided not only in the materials laboratory but in standardized toxicology, scalable manufacturing, and the slow, exacting work of proving that a sheet of carbon one atom thick can live safely on the human eye for years at a time.

Subject of Research: Graphene-integrated contact lenses for ocular biosensing, drug delivery, and antimicrobial protection

Article Title: Graphene-integrated contact lenses for ocular sensing, drug delivery, and antimicrobial protection

Article References: Shaker, L. M., Alamiery, A., & Hussien, N. A. (2026). Graphene-integrated contact lenses for ocular sensing, drug delivery, and antimicrobial protection. Discover Chemistry, 3(1), Article 481. https://doi.org/10.1007/s44371-026-00894-0

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00894-0

Keywords: graphene, contact lenses, smart lenses, biosensors, drug delivery, antimicrobial, intraocular pressure, glaucoma, electroretinography, biocompatibility, chemical vapor deposition, wearable electronics

The clinical motivation is stark. Myopia has become one of the fastest-growing public health problems in the world, particularly among children and adolescents, and it is far more than a simple refractive error that glasses can fix. Progressive myopia involves excessive elongation of the eyeball, driven by a cascade that begins in the retina and ends in structural weakening of the sclera, the tough outer coat of the eye. Genetic susceptibility combines with environmental pressures such as prolonged near work, insufficient outdoor light exposure and abnormal retinal defocus to alter retinal neurotransmission, including dopamine signalling. These changes disturb the release of growth modulators such as retinoic acid, TGF-β and insulin-like growth factor, which in turn destabilize the balance of collagen synthesis and degradation in the sclera, mediated by matrix metalloproteinases and activated fibroblasts. The result is a thinner, softer sclera that deforms under normal intraocular pressure, stretching the eye axially and predisposing patients to retinal detachment, myopic macular degeneration and optic neuropathy.

SENGs attack this problem from a fundamentally different angle than conventional optical correction. The review divides the technology into two complementary classes. Piezoelectric nanogenerators, or PENGs, exploit materials such as zinc oxide nanowires, barium titanate nanoparticles and piezoelectric polymers like PVDF and its copolymer P(VDF-TrFE), in which mechanical deformation shifts internal charge distributions and creates a piezoelectric potential that drives current through an external circuit. Triboelectric nanogenerators, or TENGs, instead harvest charge generated when two materials with different electron affinities make contact and separate, an effect amplified by electrostatic induction. PENGs deliver moderate voltages with relatively higher current and suit implantable stimulation scenarios, while TENGs produce high open-circuit voltages at very low currents and excel in flexible wearable formats such as contact lenses and eyeglass-mounted sensors. Both operate comfortably within the mechanical regime of the eye, where a normal blink imposes roughly 2 to 5 kilopascals of pressure and forceful blinking can exceed 10 kilopascals.

The most striking preclinical demonstrations come from device prototypes that translate these physics into therapy. One electro-driven drug delivery system integrates barium titanate nanoparticles coated with atropine into an orthokeratology lens. When the wearer closes their eyes, eyelid pressure triggers the piezoelectric effect, generating transient microvoltages that are proposed to perturb the interfacial electrostatic equilibrium of the nanoparticles and promote atropine desorption. Release rates reach approximately 80 percent within 12 hours, with more release accumulating the longer the eyes remain closed, effectively synchronizing drug delivery with natural physiology. In guinea pig myopia models, this system achieved superior reversal of refractive error compared with atropine eye drops alone or combined lens-plus-drop regimens, increased choroidal blood flow velocity, and raised ocular tissue drug concentrations more than twenty-fold above blood levels without detectable systemic toxicity or ocular surface irritation.

Electrical stimulation itself may also remodel the diseased sclera. Inspired by the electrocyte discharge of electric eels, researchers developed a biomimetic piezoelectric patch called BPP@PVDF, made by spin-coating a piezoelectric PVDF membrane onto a bovine pericardium scaffold. Under physiological ocular deformation, the patch generates self-powered microcurrents that were associated with increased scleral fibroblast proliferation and type I collagen synthesis. In rabbit models of lens-induced myopia, eyes receiving the patch showed over 40 percent less axial elongation than sham-operated controls, along with denser and more regularly organized collagen fibers, 20 to 30 percent greater scleral tensile strength and no abnormalities in intraocular pressure, retina or cornea. The authors are careful to stress, however, that the intracellular signaling pathways connecting generated electricity to fibroblast activation remain incompletely defined, and long-term risks such as pathological fibrosis have not been systematically excluded.

Drug delivery to the back of the eye is a second major frontier. Intravitreal injections carry infection and retinal detachment risks, while non-invasive routes typically achieve delivery efficiencies below 5 percent. A wearable electric switch system comprising an electrically driven drug delivery lens and a flexible square-wave generator addresses this bottleneck by using electrical stimulation to transiently open junctions between retinal pigment epithelial cells, reducing resistance along the sclerochoroidal-retinal pathway. The system delivered immunoglobulin G with 14 percent efficiency, approaching the 16 percent achieved by intravitreal injection, enhanced macromolecular penetration three- to five-fold in rabbit eyes and worked across monoclonal antibodies, DNA origami and extracellular vesicles, with adjustable waveform parameters providing a controllable safety window.

The same physics also supports closed-loop sensing. Triboelectric sensors mounted on skin or eyeglasses can distinguish voluntary from involuntary blinks, decode eye movements in eight directions with micrometer spatial resolution, and monitor intraocular pressure with sensitivities of about 1.28 megahertz per millimeter of mercury. A wireless therapeutic contact lens platform integrating sensing, wireless communication and iontophoretic drug delivery has maintained stable intraocular pressure readings for up to two months in rabbits while delivering anti-glaucoma medication on demand. Combined with machine learning, such self-powered sensors could feed adaptive algorithms that adjust stimulation and drug-release parameters in real time, forming the basis of an intelligent feedback loop between the eye, external computation and therapy. The review notes that tellurium nanowire retinal nanoprostheses and the clinically validated PRIMA photovoltaic implant, while not energy harvesters themselves, provide powerful engineering templates for wireless neural interfacing and long-term biointegration that future SENG platforms can borrow.

Formidable challenges separate the laboratory from the clinic. The eye is a hostile environment for electronics: tear fluid shields surface charges, millions of blinks per year accelerate mechanical fatigue and delamination, and materials such as zinc oxide can dissolve and release cytotoxic ions, while lead-based piezoceramics pose obvious toxicity concerns that push designers toward lead-free alternatives like barium titanate and biodegradable polymers such as PLGA. A fundamental ‘power gap’ also persists, since blink-driven generators produce transient bursts rather than the continuous, tightly regulated currents needed for reliable neuromodulation, and patients with dry eye or impaired ocular motility generate too little biomechanical energy for dependable therapy. Hybrid devices that pair nanogenerators with miniature supercapacitors or thin-film batteries could buffer this variability. Regulatory pathways add another layer of complexity, because multifunctional platforms combining stimulation, drug delivery, biosensing and artificial intelligence will likely be classified as combination products requiring coordinated review of electrical safety, pharmacology, software reliability and cybersecurity. Pediatric use, the population that most needs myopia control, raises additional ethical and developmental concerns that will demand adult safety data first.

Even so, the trajectory is clear. Ophthalmic biomaterials are evolving from passive structural supports into dynamic, intelligent systems that sense, respond and adapt. By harvesting the eye’s own motion to power stimulation, drug release and continuous monitoring, self-generated electricity nanogenerators sketch a future in which myopia is actively managed as the progressive neurovascular disease it truly is, rather than passively corrected with lenses. If materials scientists, neuroscientists and clinicians can close the remaining gaps in energy stability, chronic biocompatibility and validated dosing, the review concludes, blinking may one day do far more than keep the eye wet. It could power the therapy that saves a child’s sight.

Subject of Research: Self-powered bioelectronic nanogenerators for myopia treatment and vision restoration

Article Title: Bioelectronic interfaces for restoring vision pathways

Article References: Wang, T., Zhao, B., Du, Y., Wu, S., Jiang, Y., Li, J., Miao, Y.-B., & Shi, Y. (2026). Bioelectronic interfaces for restoring vision pathways. Materials Today Bio, 40, Article 103652. https://doi.org/10.1016/j.mtbio.2026.103652

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103652

Keywords: myopia, nanogenerators, triboelectric, piezoelectric, bioelectronics, drug delivery, retina, sclera, biomaterials, energy harvesting, contact lenses, neuromodulation