Glaucoma is a group of eye diseases that can lead to vision loss. Pressure builds up in the eye, and if the fluid in the eye doesn’t drain fast enough, the pressure can damage the optic nerve. According to the Centers for Disease Control (CDC), approximately 3 million people in the U.S have glaucoma and it is the second leading cause of blindness worldwide. While there is no cure, there are treatments that can help preserve vision. As you can guess, research is taking place to develop better treatments and learn more about the disease.
Once a week, not once a day
A researcher at the Missouri University of Science and Technology was awarded a National Institutes of Health’s R01 grant for the development of weekly eye drops for those who have glaucoma. Currently, people with glaucoma are prescribed daily eye drops to reduce the pressure in the eye and lessen the impact and symptoms of the disease.
Wouldn’t it be better to have daily, as opposed to weekly, eye drops? The trouble with daily eye drops is that approximately 2 percent of the drug reaches the target location. Scientists in the lab of Dr. Hu Yang, the Doshi Endowed Department Chair of Chemical and Biochemical Engineering at the Missouri University of Science and Technology, developed the treatment that led to the R01 grant. This treatment uses a nanoparticle delivery system that brings more of the medication to the eye.
In addition, it will deliver more than one type of medication to the eye. So, the drops will both drain blockages in the eye and reduce the production of the aqueous humor, which is the fluid that causes eye pressure. In fact, Yang was able to develop multiple versions of the treatment, and it will be possible to begin clinical trials before his five-year grant runs out.
“This treatment should make a significant difference for patients with glaucoma, so we obviously would like to see them benefit from it as soon as possible,” said Yang. “We have worked on this for several years and are highly optimistic about its potential efficacy.”
Link between myopia and glaucoma
What do myopia and glaucoma have in common? They both affect vision, and myopia may lead to glaucoma. The link between them has been studied for almost 100 years, and many studies, such as the Blue Mountains Eye Study and the Beijing Eye Study, have discovered that the risk of getting glaucoma increases in people with high myopia (6D or more).
The problem is how do you distinguish between patients who have visual field defects related to myopia that happen to mimic glaucoma, but don’t show the progression characteristics of glaucoma and those who really have glaucoma. It starts with the optic nerve, since diagnosis is based on it. The optic nerve of persons with myopia will look different than the optic nerve of someone with glaucoma. The patient may even have visual field defects. Yet, the defects don’t progress or progress differently.
Research in this area seeks to determine whether or not persons who are diagnosed with myopia and glaucoma follow a path similar to the classic presentation of primary open-angle glaucoma. This kind of glaucoma presents with a visual field defect that is curved like a bow in one half in the sensory field, which is then followed by a similar loss in the other half and ultimately, loss of all vision.
Kuldev Singh, MD, MPH from Stanford University, stated in an article in the American Academy of Ophthalmology’s EyeNet Magazine that myopia might be associated with regional damage to the optic nerve, either the superior or inferior rim, and the other half of the nerve is spared. “Those with myopia may perhaps be less likely to follow the same progressive primary open-angle glaucoma pattern, where the other half of the nerve and corresponding visual field ultimately become damaged.” said Singh.
This was seen in one study where persons with myopia presented with steep-edged visual field defects and had normal intraocular pressure. This resulted in a diagnosis of primary open-angle glaucoma or glaucoma suspect. While these eyes may show defects, they less commonly show new defects in the opposite half years later. Singh stated that not all progression is to be considered equally significant. The greater concern in situations like this is when patients show new field defects in regions of the optic nerve that were previously healthy.
So how is an eye doctor to manage patients who have both high myopia and odd-looking optic nerves? In the same article, Simon K. Law, MD, of the Jules Stein Eye Institute at the University of California Los Angeles (UCLA), recommends taking pictures of the optic nerve over time. If changes present themselves, then the glaucoma is progressing. Also, he wants doctors to be aware that changes in the visual field aren’t always because of glaucoma. It can come from other types of optic nerve damage or even other defects, such as myopic retinal degeneration.
Of course, more research is needed to learn more about the connection between myopia and glaucoma. In the meantime, Singh notes that it is best to follow these patients over time and use medication when necessary.
Myopia and glaucoma, whether they are studied separately or together, remain subjects of ongoing investigation. Still, it is clear that understanding and managing these conditions requires both a nuanced approach for diagnosis and treatment, and a collaborative effort across disciplines. Through continued research, innovative technologies, and a commitment to personalized patient care, it is possible to navigate the complexities of these conditions with greater precision and efficacy.
Sources:
https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucoma/types-glaucoma
https://www.cdc.gov/visionhealth/resources/features/glaucoma-awareness.html
https://news.mst.edu/2023/07/eye-opening-research-nih-funds-glaucoma-treatment-research-at-st/
https://www.aao.org/eyenet/article/myopia-glaucoma-sorting-out-diagnosis