Is the wait over for this novel way of combating axial length elongation to revolutionize myopia management?
The myopia pandemic is one of the greatest challenges faced by optometry today. Despite having several options at our disposal to treat the disease, the number of cases continues to rise exponentially. Could contact lens-based drug delivery systems for myopia management be the answer?
The clock is ticking in optometry clinics across the world. The growing prevalence of myopia poses a significant challenge for the ocular healthcare community, particularly in East Asia, where it could easily be described as endemic. This has a stark effect on children born in the ‘screen age,’ who spend more time in front of a tablet than playing outside.
Fortunately, there are treatments available, particularly in developed countries.
Innovations in myopia management
In the United States, soft multifocal contact lenses, orthokeratology contact lenses and low-concentration atropine have all been shown to effectively slow myopia progression and eye growth.
“Many other countries, including Canada, also have access to spectacles that can slow myopia progression and eye growth, but they still need to go through the FDA approval process before they will be on the market in the United States,” said Dr. Jeffrey Walline, acting dean and associate dean for research at The Ohio State University College of Optometry (Columbus, Ohio).
A specialist in both myopia treatment and pediatric contact lens studies, Dr. Walline argues that the one silver lining of myopia’s progression is that research is increasing at the same pace. One of the most promising potential treatments is contact lens-based drug delivery systems designed specifically for myopia management.
“As myopia affects such a significant proportion of the world, and because it is related to sight-threatening complications, much more scientific evidence is being generated. The scope of myopia management is rapidly evolving, so doctors need to be aware of the latest advances in evidence-based myopia management,” Dr. Walline said.
“A contact lens-based drug delivery system would offer patients two concurrent treatments, as combination treatment has been shown to be more effective than monotherapy. However, to date, most of the contact lens-based drug delivery methods have not extended delivery time sufficiently to provide better treatment outcomes,” he added.
The advantage of using a contact lens-based drug delivery system is that the drugs they release have a prolonged contact time with the cornea, leading to improved bioavailability.
Over 50% of the drugs released from a contact lens delivery system can diffuse into the cornea, which is at least 35 times more efficient than eye drops. This increase in efficiency permits substantially reduced concentrations to be used, decreasing the potential for side effects as less drug is absorbed systemically.1
However, according to Dr. Walline, there’s a problem: We currently don’t have any contact lens-based drug delivery systems for myopia management.
Similar solutions have recently emerged to treat other conditions, but there’s still nothing for myopia, despite a large body of research on the matter that highlights its potential efficacy.
The problem lies primarily with sub optimal kinetics, as drug release has been primarily diffusion-controlled, and first-order kinetics are typically observed—meaning that the rate of drug release is not consistent over time. This results in most of the drug being released in the initial stages.1
Addressing the research gap
“The issue of kinetics means that contact lens-based drug delivery systems for myopia management would not be able to work at maximum efficiency. They would deliver the drugs required by the patient, but the results would be erratic due to the skewed treatment schedule. This should be a priority area for researchers working on myopia,” said Dr. Monica Chaudhry, director of the Monica Chaudhry Vision Institute (MCVI) in Gurugram, India.
Dr. Chaudhry has made myopia one of her top priorities. While rates are lower in India than the global average, they are also on the rise. She believes that a contact lens-based drug delivery system would be ideal for treating myopia, especially in cases where contact lenses are used for myopia control. However, at present, that belief remains theoretical due to limitations faced by researchers.
“A major limitation in this field is the scarcity of in vivo studies validating the effectiveness of a contact lens delivery platform,” explained Dr. Chaudhry.
“There have only been two published animal studies using contact lens drug delivery systems to treat ocular conditions—both indicated enhanced bioavailability and reduced systemic drug uptake compared to conventional eye drop treatment. Further research is urgently needed,” Dr. Chaudhry added.
The challenge is clear: Significant research is required before optometry is ready to begin using contact lens-based drug delivery systems for myopia management.
“These challenges should inspire researchers and doctors to examine ways to utilize contact lens-based drug delivery systems for myopia management. With increased and more detailed research, we could begin to deploy contact lens drug delivery systems for myopia treatment,” shared Dr. Chaudhry.
The rising tide of myopia
The urgency is acute; myopia will not stop growing exponentially. Studies consistently report exceptionally high rates of myopia among schoolchildren in East Asia, with a prevalence of 73%, while North America also experiences high rates at 42%. Risk factors for the disease, especially among children, include low outdoor time and near work, dim light exposure, the use of LED lamps for homework, inadequate sleep, maintaining a reading distance of less than 25 cm, and residing in urban environments. Yet myopia prevalence continues to increase around the world.2
It is estimated that 1.4 billion people were myopic in 2000, and it is predicted that by 2050, that number will reach 4.8 billion. Myopia is known to be associated with several ocular complications, such as retinal detachment, glaucoma, cataracts, optic disk changes, and maculopathy—making it an emerging crisis of great proportions.2
Perhaps someone reading this article will take up the rallying call. If that happens, optometry may soon benefit from contact lens-based drug delivery systems in the near future. While there may be initial challenges, further research should resolve them.
Will you be the one to make the breakthrough?
References
- Phan CM, Hui A, Subbaraman L, Jones L. Insights to Using Contact Lenses for Drug Delivery. Clin Exp Pharmacol 2014;3:145.
- Grzybowski A, Kanclerz P, Tsubota K, et al. A Review on the Epidemiology of Myopia in School Children Worldwide. BMC Ophthalmol. 2020;20(1):27.
Editor’s Note: This article was published in COOKIE Magazine Issue 15.