This story is part of a series on the current progression in Regenerative Medicine. This piece is part of a series dedicated to the eye and improvements in restoring vision.
In 1999, I defined regenerative medicine as the collection of interventions that restore tissues and organs damaged by disease, injured by trauma, or worn by time to normal function. I include a full spectrum of chemical, gene, and protein-based medicines, cell-based therapies, and biomechanical interventions that achieve that goal.
Myopia, commonly known as nearsightedness, is a common eye condition characterized by the inability to see distant objects clearly. The prevalence of myopia is rapidly increasing globally, and by 2050, almost half the world's population is projected to suffer from this condition, and it is becoming increasingly prevalent among children.
Childhood myopia can significantly increase the risk of developing severe visual impairments later in life, such as myopic macular degeneration and retinal detachment. Unfortunately, there is currently no approved pharmacological therapy to treat the progression of childhood myopia. However, recent research on low-dose atropine as a potential treatment option has shown promising results, generating considerable interest.
What is Myopia?
Myopia, commonly known as nearsightedness, is an eye condition that affects a significant portion of the population. It occurs due to various factors, including genetic and environmental factors. The condition is characterized by longer axial length and flatter corneas in myopic eyes compared to non-myopic eyes.
Light plays a crucial role in vision, and in a healthy eye, it enters the eye and is refracted onto the retina, resulting in clear vision. However, in a myopic eye, the refracted light falls in front of the retina, leading to blurred vision. This occurs because the axial length of the eye increases while the refractive power of the cornea and lens remains the same.
Axial length is the distance between the cornea and the retina, which is longer in myopic eyes. The cornea, the transparent front part of the eye, helps refract the light entering the eye, and its flatter structure in myopic eyes contributes to the condition. The lens behind the iris also contributes to refracting the light, but its role remains unchanged in myopic eyes.
All About Atropine
Atropine, a medication derived from plants like belladonna, has been widely used for over a century with various medical applications. Once absorbed in the gut, it is distributed throughout the body, metabolized in the liver, and excreted in urine.
Atropine works by blocking specific receptors in the body that respond to acetylcholine. It is a competitive antagonist that competes with acetylcholine to bind to the receptors. This medication acts at the nerve endings without blocking the transmission of impulses along the nerve fibers. It has multiple effects on the body, including inhibition of secretions, reduction of muscle tone, relaxation of smooth muscles, increased heart rate, and elevated respiratory rate.
When applied to the eyes, atropine reduces the contraction of the ciliary muscle and causes the pupil to dilate. This action reduces the eye's ability to focus on nearby objects, making it primarily useful for diagnosing or treating eye conditions. For diagnostic purposes, atropine is helpful in cases where the doctor needs to examine the retina or the optic nerve. It can effectively dilate the pupil, allowing for a better view of the inside of the eye.
In addition to its diagnostic uses, atropine can be used therapeutically to treat conditions like uveitis, where eye inflammation can cause pain and discomfort. Atropine can also treat amblyopia, commonly known as lazy eye, by blurring the vision in the good eye, which ultimately helps to improve vision.
But can atropine be used to treat myopia or induce myopia in children and teenagers?
Clinical Trials Show Mixed Results
There have been clinical trials conducted on the use of low-dose atropine as a potential treatment for myopia. The most commonly studied concentration of atropine is 0.01%. It is important to note that the effectiveness of low-dose atropine in myopia treatment has produced diverse outcomes in the studies conducted.
A study recently published in JAMA Ophthalmology investigated the effectiveness of 0.01% atropine in slowing down myopia progression or axial elongation. The results of the survey revealed that low-dose atropine did not significantly slow the progression of myopia or axial elongation when compared to the placebo group.
However, another study, also published in JAMA Opthalmology, found that low-dose atropine (0.01%) significantly reduced myopia progression and axial elongation after three years. A similar result was seen in a review of clinical trials conducted in 2022.
It is suggested that the effectiveness of atropine in slowing down the progression of myopia can vary in different populations. So, while low doses of atropine may not significantly help some groups, they could be beneficial in reducing myopia progression in others. Still, it is essential to remember that atropine simply slows myopia progression. It does not entirely stop it or reverse it.
Additional studies are necessary to establish the efficacy of atropine as a remedy for myopia in diverse populations. Until this research is completed thoroughly, atropine will not be granted FDA approval for treating myopia. Therefore, it must be employed off-label for the time being.
A Future with Clear Vision
Research on the effectiveness of atropine in slowing myopia progression has generated mixed results. While some studies have suggested that low-dose atropine may provide a viable treatment option for myopia, others, particularly in the US population, have not found a significant benefit. However, some experts, like Michael F. Chiang, MD, director of the National Eye Institute, suggest continuing research to determine the most effective concentration of atropine for specific populations.
Future research may also explore the efficacy of optical and environmental approaches in reducing myopia progression. Nonetheless, the search for effective treatments for myopia continues, and the use of low-dose atropine remains a promising area of research.
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