For nearly half a century, contact lenses have been proposed as a means of ocular drug delivery that may someday replace eye drops, but achieving controlled drug release has been a significant challenge. Researchers at Massachusetts Eye and Ear/Harvard Medical School Department of Ophthalmology, Boston Children’s Hospital, and the Massachusetts Institute of Technology are one step closer to an eye drop-free reality with the development of a drug-eluting contact lens designed for prolonged delivery of latanoprost, a common drug used for the treatment of glaucoma, the leading cause of irreversible blindness worldwide.
“In general, eye drops are an inefficient method of drug delivery that has notoriously poor patient adherence. This contact lens design can potentially be used as a treatment for glaucoma and as a platform for other ocular drug delivery applications,” said Joseph Ciolino, M.D, Mass. Eye and Ear cornea specialist and lead author of the paper.
The contacts were designed with materials that are FDA-approved for use on the eye. The latanoprost-eluting contact lenses were created by encapsulating latanoprost-polymer films in commonly used contact lens hydrogel. Their findings are described online and will be in the January 2014 printed issue of Biomaterials.
“The lens we have developed is capable of delivering large amounts of drug at substantially constant rates over weeks to months,” said Professor Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Boston Children’s Hospital.
In vivo, single contact lenses were able to achieve, for one month, latanoprost concentrations in the aqueous humor that were comparable to those achieved with daily topical latanoprost solution, the current first-line treatment for glaucoma.
The lenses appeared safe in cell culture and animal studies. This is the first contact lens that has been shown to release drugs for this long in animal models.
Latanoprost: Prostaglandin Treatment for Glaucoma
Age-related health complications often lead to significant deterioration in quality of life when not well managed. Whether you are approaching the latter part of your life, or caring for an aging family member, it is important to know what age-related complications can have long term impact and what costs and benefits are associated with treatment.
In managing an age-related vision complication, such as glaucoma, many senior adults are not only confused about treatment options but also avoid tend to be non-compliant in treatment programs. Glaucoma, as the second leading cause of blindness in adults, is a complication that must be well managed in order to ensure quality of life.
Because conditions such as hypertension, diabetes and even thyroid disorders can create a complication such as glaucoma, regular vision and eye screenings are crucial to the health of the senior adult. In many cases, glaucoma is asymptomatic, meaning the senior adult will not even be aware the complication is of concern.
Once diagnosed, the use of prostaglandins is quite common for glaucoma. Specifically, a drug known as Latanoprost promotes flow within the eye and reduced intraocular pressure. In fact, very few drugs are given the recognition as a first-line form of therapy for glaucoma; Latanoprost has gained this recognition.
To be effective, however, the senior adult must be persistent and compliant in the use of Latanoprost. Because the dosing regimen is as much as four times per day, many senior adults find they are not compliant in the dosing regimen. As a result, glaucoma is not well managed and the use of Latanoprost may not be cost effective.
The newly designed contact lens has a clear central aperture and contains a drug-polymer film in the periphery, which helps to control drug release. The lenses can be made with no refractive power or with the ability to correct the refractive error in near sided or far sided eyes.
“A non-invasive method of sustained ocular drug delivery could help patients adhere to the therapy necessary to maintain vision in diseases like glaucoma, saving millions from preventable blindness,” Dr. Ciolino said.
How does it work?
Xalatan eye drops contain the active ingredient latanoprost, which is a type of medicine called a prostaglandin analogue. (NB. Latanoprost eye drops are also available without a brand name, ie as the generic medicine.) Latanoprost is used to lower raised pressure within the eyeball.
The pressure within the eyeball is naturally maintained by a continuous flow of liquid called aqueous humour through the eyeball. Aqueous humour is produced by a part of the eye called the ciliary body. It drains out of the eyeball through channels called the trabecular meshwork. If the outflow of aqueous humour is blocked, the aqueous humour builds up inside the eye, increasing the pressure within the eyeball. This pressure needs to be reduced, as otherwise it can damage the optic nerve and impair vision as a result.
Latanoprost reduces the pressure in the eye by mimicking the action of a naturally-occuring prostaglandin. Prostaglandins are a group of natural body chemicals found in many places in the body. In the eye, they increase the drainage of the aqueous humour out of the eyeball. Latanoprost is a synthetic prostaglandin that acts on the same receptors in the eye as the natural prostaglandins. It therefore causes an increase in the drainage of aqueous humour out of the eyeball. This decreases the pressure within the eye. Latanoprost is used to lower raised pressure in the eye, for example in glaucoma.
Earlier versions of this lens were described in the popular press in the Boston Globe, Scientific America, The Economist, CNN.com, and other media outlets.
A full list of authors is available in the PDF. This study was supported by grants NEI IK08EY019686-01, Massachusetts Eye Lions Research Fund, New England Cornea Transplant Fund, NIGMS GM073626, Eleanor and Miles Shore Foundation and a Career Development Award from Research to Prevent Blindness.
About Massachusetts Eye and Ear
Mass. Eye and Ear clinicians and scientists are driven by a mission to find cures for blindness, deafness and diseases of the head and neck. After uniting with Schepens Eye Research Institute in 2011, Mass. Eye and Ear in Boston became the world’s largest vision and hearing research center, offering hope and healing to patients everywhere through discovery and innovation. Mass. Eye and Ear is a Harvard Medical School teaching hospital and trains future medical leaders in ophthalmology and otolaryngology, through residency as well as clinical and research fellowships. Internationally acclaimed since its founding in 1824, Mass. Eye and Ear employs full-time, board-certified physicians who offer high-quality and affordable specialty care that ranges from the routine to the very complex. U.S. News & World Report’s “Best Hospitals Survey” has consistently ranked the Mass. Eye and Ear Departments of Otolaryngology and Ophthalmology as among the top hospitals in the nation.
About Boston Children’s Hospital
Boston Children’s Hospital is home to the world’s largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 1,100 scientists, including seven members of the National Academy of Sciences, 13 members of the Institute of Medicine and 14 members of the Howard Hughes Medical Institute comprise Boston Children’s research community. Founded as a 20-bed hospital for children, Boston Children’s today is a 395 bed comprehensive center for pediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Boston Children’s also is the primary pediatric teaching affiliate of Harvard Medical School.
Massachusetts Eye and Ear Infirmary