Smart contact lenses and contact lenses that deliver medication are specialized lenses that enhance treatment of certain eye diseases. Contact lenses are transforming the way we deliver medical care and are becoming more than just devices to improve your vision.
The idea of using contact lenses to deliver medication for eye diseases was introduced a few decades ago, but our available technology had to improve so it would enable this idea to become a clinical reality.
The early attempts to use contact lenses as drug delivery devices involved simply soaking commercially available lenses in a particular drug solution. This approach just delivered all the drug at once rather than slowly, in a timed release fashion, so more research and study trials were needed to achieve the ideal of delivering medication via contact lenses.
One of the challenges in developing this drug-delivery technology was finding the right compatibility between the drug and the contact lens. Researchers found that some lenses didn’t retain the drugs and that others released the drug too quickly, and in other cases the drug and lens were too compatible causing the lens and the drug to bind together and then the drug would not be released.
First use of contact lenses as drug delivery devices
The original pioneer in using contact lenses as drug-delivery devices was the Polish ophthalmologist Xavier Galezowski who in 1886 used contact lenses as ocular bandages by applying cocaine to gelatin discs and then applying those discs to the eyes after cataract surgery. [NOTE: The local anesthetic effect of cocaine was discovered in 1884 and after that its use became widespread in 19th century medicine, but its undesirable effects soon became apparent and the chemical search began for other anesthetic drugs to replace it.]
Eye drops were and still are the standard method for delivering eye medications. But eye drops are on the surface of the eye for only a very short time which means the bioavailability is extremely low and is in the range of only 5 to 10%, making eye drops a less-than-ideal way to administer medication to the eyes.. Bioavailability is the proportion of a medication or drug that is absorbed and is able to have an active effect in the body.
The first successful drug-delivery contact lens
The first modern-era therapeutic contact lens was developed by Johnson & Johnson Vision Care and cleared for use by the FDA in March 2022. They are for eye allergy relief. Each daily wear contact lens contains 19 mcg ketotifen—an antihistamine that is slowly released to provide 12 hours of relief from allergic eye itch.
The research continues
Currently researchers are studying contact lenses that are molecularly imprinted and nanoparticle-loaded with medications to treat diabetic retinopathy, glaucoma, age-related macular degeneration, and cataracts.
Molecular imprinting generates an impression within a solid or gel which corresponds to another molecule and this acts as a receptor that can bind to a target molecule. Nanoparticle-loaded contact lenses contain drug nanoparticles so small (1-100 nm) that they can cross the blood-retinal barrier which means the contact lenses that are nanoparticle loaded can contain drugs that could reach the retina.
The future of smart contact lenses
Contact lens sensors can be used to monitor many diseases and conditions. Physical biomarkers in the eye can be tracked such as intraocular pressure, along with proteins and ions, such as glucose and lactate that can be measured in tear film.
The tear film contains a complex mixture of proteins including enzymes, neuropeptides, protective proteins, and also other substance classes like lipids, carbohydrates, and salts and ocular and systemic diseases, like diabetes and cancer, can change the makeup of tear film and for that reason tracking the makeup of tear film by smart contacts can be a way of monitoring for disease.
The Mojo Lens is a smart contact lens that has a built-in computer display that enables instantaneous hand-free access. The Mojo Lens is in the prototype testing phase and is not available commercially.
We are not far from a time when smart contact lenses will magnify what we are looking at by using an eye blink, monitor our eye pressure and glucose levels, alert us to cancer and other diseases in their beginning stages, and offer us augmented reality that can overlay digital content in real-world environments. The future smart contact lenses will include integrated circuitry, LEDs and an antenna for wireless communication.