What ODs Must Know about Drug-Eluting Contact Lenses

Drug-eluting contact lenses (DECLs) are specialized contact lenses designed to deliver medication directly to the eye over a sustained period.

They are embedded with pharmaceutical agents that gradually release the drug onto the ocular surface, improving bioavailability and potentially enhancing treatment effectiveness compared to traditional eye drops.

These lenses can be used to treat both acute and chronic ocular conditions.¹ Future advancements in smart lenses, biosensors, and nanotechnology are key to a future where lenses can provide both vision correction and sustained drug therapy.²

A timeline of contact lens developments through history

1508: Leonardo da Vinci is often credited with the idea of altering vision by placing a liquid-filled glass hemisphere over the eye for optical correction as early as 1508; however, this remains a controversial claim.³
1889: Others contribute the discovery of the first contact lenses to Adolf Fick and Eugène Kalt, who created the first glass scleral lenses without power.
- In 1889, Fick went on to describe the use of scleral lenses with optics for correct vision, and Kalt described contact lenses as an orthopedic appliance for the treatment of keratoconus.⁴
1940: This marks the development of small rigid-diameter lenses, and PMMA (polymethyl methacrylate) improved both lens comfort and oxygen permeability.^5,6
1950: Soft contact lenses followed, originating in Czechoslovakia in the 1950s, with their invention being attributed to Otto Wichterle.⁶ His research focused on the synthesis of cross-linked hydrophilic gels to find a material compatible with living tissues.
1961: By 1961, he had produced four hydrogel contact lenses.⁷
1987: The commercialization of disposable contact lenses began in 1987, making lenses more accessible and convenient to purchase.⁸
- Silicone hydrogel lenses were first available and prescribed by ECPs around 30 years ago.⁹

A look at drug-eluting lens history

An eye drop is the primary way to deliver medication to the ocular surface, but there are many limitations and opportunities for error when patients apply eye drops to their eyes. Most of the applied medication in a traditional eye drop is lost with blinking or tear drainage.¹ Recognizing these limitations, the concept of using a hydrogel contact lens as a drug-eluting device was introduced around 1960.¹⁰

Scientists began developing lenses that could deliver dexamethasone and latanoprost gradually over time, which could improve therapeutic outcomes for conditions like glaucoma, dry eye disease, and post-surgical healing.² Joseph Ciolino and Daniel Kohane published the first studies that demonstrated the possibility of embedding medications into contact lenses using molecular imprinting and nanoparticle technology.¹

Benefits and capabilities of drug-eluting contact lenses

Drug-eluting contact lenses have several capabilities that make them an innovative drug delivery system for ocular conditions, including:

Sustained drug release: DECLs enable a gradual and controlled release of medication over hours or days, which improves the drug’s retention time compared to traditional eye drops. This method reduces the need for frequent dosing, which improves patient compliance.²
- Different methods have been used for extending the release of drugs up to days or weeks; however, these may induce changes in both the optics and the physical properties of the lenses.¹¹
Increased bioavailability: Drug bioavailability, absorption, and effectiveness increase when the drug is delivered directly to the cornea. Furthermore, less of the medication is lost due to blinking, tear drainage, or systemic absorption.^2,12
- DECLs demonstrate prolonged drug residence time (10x higher than eye drops), improved drug bioavailability (50% bioavailability, which is 10x higher than eye drops),¹³ alongside a decrease in dosing frequency, drug concentration, and adverse effects. Furthermore, they can be removed when treatment is complete.²
Targeted ocular drug delivery: DECLs can be designed to release drugs specifically for conditions such as glaucoma, dry eye disease, corneal infections, allergies, or post-surgical healing.
- It is possible that contacts may deliver various classifications of drugs, including antibiotics, anti-inflammatories, antifungals, and glaucoma medications (e.g., latanoprost or timolol).
Dual function: DECLs are designed for vision correction and drug delivery in therapeutic and refractive treatments. Furthermore, they are made with biocompatible materials that maintain hydration and comfort. Because of the need for dual functionality, lens material choice is important.¹²
Smart feature integration: Current investigation includes the use of temperature- or pH-sensitive lenses that release the drug in response to specific eye conditions like glaucoma or diabetes. Future models may incorporate biosensors to monitor disease progression or drug effectivity.¹³
Improved patient compliance and convenience: DECLs improve patient compliance by reducing the burden of frequent daily eye drop applications. The lenses are ideal for chronic conditions like glaucoma, dry eye disease, or post-surgical recovery.¹¹
Reduced systemic side effects: By targeting the ocular surface, DECLs can minimize drug absorption into the bloodstream and lower the risk of systemic side effects like dry eye with allergy medications.¹²
Vision correction and treatment: The DECLs can correct vision and deliver medication, eliminating the need for separate treatments, which is helpful for contact lens wearers who require ophthalmic medication and desire to keep wearing their contact lenses.¹⁴
Customizable and versatile drug delivery: Again, DECLs can deliver various types of drugs for various ocular conditions. Future innovation may include nanotechnology and biosensors for more precise drug release in response to changes in ocular conditions (elevated intraocular pressure [IOP]).^2,13,16

Addressing DECL challenges and concerns

Despite the many benefits of drug-eluting contact lenses, many challenges and concerns still exist. There are challenges inherent in the lenses themselves, the patient experience, and gaining the approval of the governing regulatory boards.

Technological challenges

One of the biggest challenges for DECLs is limited drug loading capacity. Contact lenses have limited space for drug incorporation, which limits the dose of drug they can deliver. Some ocular drugs require higher concentrations for treatment, which may be impossible to achieve with contact lens delivery.^2,15

Also, currently, the release of a precise, consistent amount of the drug over a prolonged period is difficult to achieve, leading to controlled and sustained release issues. Some drugs may leach out of the lens too quickly or unevenly, which may reduce the effect of the treatment.^2,15

In addition, there are challenges in achieving material compatibility and stability, which could lead to potential drug loss during use. The lens material (hydrogel vs. silicone hydrogel) may affect the drug release profiles. When the drug is embedded in the lens, some drugs may lose efficacy.^2,14

It’s unknown whether the drugs may leak out or break down during lens storage, handling, or insertion. Tearing, blinking, and lens movement may also impact its retention and efficacy.^2,12

Patient considerations for drug-eluting lenses

As with all contact lenses, a major determinant in success is patient comfort and wearability. Some drug-eluting lenses may alter the lens hydration or oxygen permeability, which may affect the patient’s comfort or create ocular surface problems. Extended wear contact lenses have the potential to increase the risk of dryness, irritation, or even corneal hypoxia in some patients.²

Lack of customization with a DECL may also lead to dissatisfaction. Patients all have different contact lens prescription needs, ocular conditions, and drug requirements, which makes personalized customization a challenge; future technology should address these issues.

For patients, cost and accessibility also play an integral role. Because of the commercialization process, the cost of producing drug-eluting lenses when compared to a standard contact lens or an eye drop is likely to be significantly more,¹⁵ which could limit affordability. Furthermore, it's unknown whether insurance companies will cover the lenses, which is a major barrier to their use by eyecare providers.

On the more serious side, there is also the risk of contamination, infection, and potential damage. We know that extended wear or prolonged lens use can increase the risk of a bacterial or fungal infection, a corneal ulcer, or an inflammatory condition like keratitis. Patients must be educated on proper hygiene and disinfection to minimize their risk.¹⁷

Currently, there is a lack of long-term safety and biocompatibility data. The effect of continuous drug exposure on the cornea and surrounding eye tissues remains a concern due to the lack of long-term study data. It’s possible the drugs or preservatives may cause corneal toxicity, irritation, or adverse effects with prolonged use.²

Regulatory roadblocks for DECLs

New technologies always bring regulatory and approval challenges. DECLs are a medical device combined with a pharmaceutical, which requires approval from the FDA.

The first drug-eluting contact lens, the ACUVUE Theravision with Ketotifen lens was approved in the US in 2022 to treat ocular allergies.² Clinical trials must demonstrate both safety and efficacy, which can delay commercialization.¹⁵

The future of drug-eluting contact lenses

In the future, DECLs could replace daily eye drop use for chronic conditions like glaucoma and dry eye disease, improving the patient’s adherence to treatment. DECLs could be used to deliver steroids or antibiotics for improved recovery after LASIK or cataract surgery.

While lenses are currently approved to treat allergic conjunctivitis, DECLs may be used to treat corneal issues like keratitis or an ulcer in the future.² Though the future of drug-eluting contact lenses is promising, advancements must be made in delivery, integration with smart technology, and in contact lens materials for commercialization.¹⁵

However, looking forward, we can expect advancements in drug delivery. Nanoparticles and micelles can be embedded in lenses to enhance drug stability and control release rates. Molecular imprinting can improve specific drug binding and sustained release.

Smart and stimuli-responsive lenses are key to the release of drugs in response to environmental changes, such as pH, temperature, or tear composition, and needed for use in certain disease conditions.^2,16 There will also be an integration with smart technologies. Contact lenses may include biosensors to monitor glucose levels (for diabetics) or intraocular pressure (for glaucoma patients).

Companies like Google (Verily) and Johnson & Johnson have explored such smart lenses. Furthermore, it would be extremely beneficial if the lenses could transmit real-time health data to mobile apps or healthcare providers, enabling personalized treatment adjustments.¹³

Also, to reach their full potential, more improvement is needed in contact lens materials and biocompatibility to allow for extended wear. Next generation contact lens materials may provide better oxygen permeability, and drug retention while maintaining clear vision and comfort.² Antimicrobial coatings added to the lens may reduce infection risks associated with long-term wear.¹⁸

Key takeaways about DECLs

Enhanced drug delivery and bioavailability: DECLs provide sustained and controlled drug release with improved absorption compared to traditional eye drops, with less drug loss due to blinking and tear drainage.
Improved patient compliance and convenience: DECLs eliminate the need for frequent dosing, which improves patient compliance and adherence to treatment.
Challenges exist in drug release and safety: Controlling the drug release rates while maintaining lens biocompatibility is a major challenge. The potential risk to patients, including infection and inflammation of an extended wear lens on the eye, must be considered.
Emerging technologies and smart features: As innovation and technology advances, future developments in DECLs are likely to include nanotechnology-based drug loading, biosensors, and smart lenses that release the drug in response to tear composition or intraocular pressure.
Regulatory and commercial potential: It is difficult to earn the FDA’s approval as a drug-device combination, but pharmaceutical and biotech companies must invest in the commercialization of drug-eluting lenses for various eye diseases.

Final thoughts

Drug-eluting contact lenses are a potentially transformative advancement in optometry and in drug delivery by offering a sustained, controlled medication release directly to the eye.

DECLs can improve patient compliance and therapeutic outcomes for conditions like glaucoma, dry eye disease, and healing in post-surgical eyes by improving drug bioavailability and reducing the frequency of drug administration.

While many challenges still exist to the commercialization of DECLs like drug load, patient safety, and regulatory approval, ongoing research in nanotechnology and lens materials will continue to improve their use.

Drug-eluting lenses have the potential to revolutionize eyecare for our patients by providing vision correction and targeted medical treatment.