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Sunday, July 14, 2024

The First Drug-Releasing Contact Lens Is Here

Allergy season is upon us, and for the 40 percent of contact lens wearers who suffer from itchy eyes, there’s a new option for how to treat them: the first lens that can deliver a drug directly to the eye. Made by Johnson & Johnson, they contain the antihistamine ketotifen and were approved by the US Food and Drug Administration earlier this month.

This may be just the start of using the contact lens as a platform for dosing medication. “The once futuristic concept of drug-delivery contact lenses is now a reality,” says Melissa Barnett, a principal optometrist at the UC Davis Eye Center who wasn’t involved in the development of Johnson & Johnson’s lenses. “Forthcoming drug-delivery contact lenses will have multiple therapeutic applications for various ocular diseases to improve overall health and quality of life.”

For decades, scientists have been attempting to put drugs into contact lenses to treat all sorts of conditions, such as cataracts and glaucoma, both of which are leading global causes of blindness. Eye drops are frequently used as treatments, but doctors say many patients forget to use them—a problem with what they refer to as “compliance.” And drops aren’t the best way to get medicine to the eye. About 95 percent of the active substance is lost due to tear drainage or drips down the cheek before it has a chance to be absorbed. Some retinal diseases, such as diabetic retinopathy and wet age-related macular degeneration, are treated with injections. Those aren’t ideal for patients who are squeamish about needles, and they can cause bleeding and infection.

Drug-eluting contact lenses could not only be more comfortable but also deliver more medication into the eye than drops do. However, it’s been a challenge to marry a drug with a specific contact lens. Soft contacts are made of a flexible, water-absorbing plastic called hydrogel that allows oxygen to pass through. But their properties vary from brand to brand. The architecture of the lens may also need to be slightly different depending on whether it is made to release antihistamines, antibiotics, anti-inflammatory medications, or other types of drugs.

“There needs to be a compatibility between the drug and the contact lens,” says Brian Pall, director of clinical science at Johnson & Johnson Vision. Some lenses don’t retain certain drugs well and release them too quickly. On the other hand, he says, “if the drug and the lens are too compatible, they can bind together in a way that, once it's put on the eye, the drug doesn't release.”

Controlling the duration of release has presented a conundrum. Early attempts at therapeutic contacts involved simply soaking commercially available lenses in drug solutions. But this approach tended to result in the medication being released all at once instead of slowly over time. This wasn’t very practical, since it might relieve symptoms for only a few hours. Contacts that release a drug gradually throughout the time the lens is worn would provide a longer therapeutic benefit. To get there, researchers are using technologies such as nanoparticles and molecular imprinting, which create cavities in a polymer structure that match the size and shape of a specific drug.J&J’s contacts are daily disposables, meaning they’re worn for a day and thrown out. In Phase 3 clinical studies, the contacts reduced itchiness from allergies as quickly as three minutes after putting the lenses in, and the effect lasted up to 12 hours. (The results were published in 2019 in the journal Cornea.) “When the lens is put on the eye, you get a very rapid release of medication to the eye, and then as the medication continues to elude out over the next several hours, it's a much slower release,” says Pall. “The quick release provides enough of the medication to allow for a very fast onset of action.” 

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Pall says the company is working to make the lens available as soon as possible to contact lens wearers in the US. It’s already available in Canada and Japan.

The company is interested in using the technology to treat other eye diseases, such as glaucoma. For it and other chronic eye conditions, Pall says, a longer-lasting, reusable contact that slowly releases medication over several days or more might be preferable to a daily disposable lens that provides quick relief for allergies. Wearers would take them out before sleeping to prevent eye infection.

Researchers at Massachusetts Eye and Ear and Boston Children’s Hospital are developing a contact lens that slowly releases the steroid dexamethasone—commonly used to treat inflammatory eye diseases—over the course of a week. In a 2019 study in the journal Biomaterials, the researchers tested the lenses in rabbits with uveitis and macular edema, two forms of eye inflammation. They found that the lenses provided 200 times more medication to the eye than drops and were as effective as injections in preventing damage to the retina—the light-sensing tissue at the back of the eye.

Drug-releasing capability is the latest innovation in contacts, which have come a long way since the first glass ones were made in the 1880s. (Unsurprisingly, those weren’t practical, because they were too uncomfortable to wear and blocked oxygen flow to the eye.) In 2019, the FDA approved the first soft contact lens that slows the progression of myopia, or nearsightedness, in children. It does this by changing the way the light bends inside the eye, preventing the eye from elongating. This elongation makes distant objects appear blurred. Though nearsightedness isn’t typically thought of as a serious health problem, high myopia can lead to damage in the central retinal area, causing retinal detachment, glaucoma, and cataracts. With rates of myopia in the United States increasing from 25 percent in the early 1970s to nearly 42 percent three decades later, more children may soon be wearing such contacts.

Companies like Mojo Vision are developing smart contact lenses that would use an embedded display to show notifications to wearers and even help people with low vision move around. J&J’s contacts are not exactly the bionic contact lenses from The Batman or The Matrix, nor are they going to prevent vision loss, but the recent regulatory approval opens the door to more applications for drug-releasing contacts. “I'd be more excited if this was going to help prevent loss of vision from glaucoma and macular degeneration and other age-related diseases that people go blind from, but it's a step in the right direction,” says Natasha Herz, clinical spokesperson for the American Academy of Ophthalmology and the chief of ophthalmology at Adventist Health Care in Rockville, Maryland.

Still, contact lenses may not be the perfect solution for every patient with an eye disease. Many people have trouble putting contacts in, and as they age, it gets harder to do so. “One challenge with eye drops—and this would be the same challenge with contact lenses—is that people don't have as good of dexterity as they get older,” Herz says. “But for those people who could put them in, I could see this really helping with compliance.”

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