Glaucoma: The Fight to Prevent Blindness – Medical Frontiers
It’s often said that around 80% of information we take in each day comes through our eyes. But glaucoma, known as the silent thief of sight, can gradually and irreversibly steal away part of our vision before we even notice. The eye takes in light and sends that information to the [music] brain where it’s interpreted, allowing us to see. The information is [music] transmitted by the optic nerve located deep behind the eyeball. Glaucom [music] is a disease that damages the optic nerve. If it worsens, it can lead to blindness. The American Academy of Opthalmology says about 70 million people worldwide have glaucoma. It predicts that this number will exceed [music] 100 million by 2040. Now efforts are underway in Japan to develop [music] surgical techniques to stop glaucoma from progressing as well as drugs to protect and regenerate the optic nerve. Doctors and researchers are racing [music] against time to find new ways to protect and preserve the precious eyesight that [music] remains. When we look at something, light is [music] refracted by the cornea and the lens forming an image on the retina inside the eye. If glaucoma progresses and the optic nerve is damaged, that image is no longer accurately transmitted to the brain. [music] Glaucom symptoms are divided into three stages. In the early stage, there are usually no noticeable symptoms. Part of your visual field may begin to disappear, but because most of your vision remains intact, you’re unlikely to feel any inconvenience. In the moderate stage, the missing areas grow larger. Your vision may become blurry or your eyesight might worsen. Many people start to notice symptoms at this point. But if only one eye is affected, the other eye often compensates, making changes harder to detect. A survey in Japan found that one in 20 people in their 40s had glaucoma. Yet around 90% of them had no noticeable symptoms and were not receiving treatment. In the advanced stage, vision loss extends to the center of the visual field. Eyeight becomes significantly impaired and without treatment, blindness may occur. Modern medicine has [music] yet to fully uncover the cause of glaucoma. As a [music] result, there is currently no fundamental treatment that can restore lost vision or repair the visual field. The only option is to manage the condition and prevent it from getting worse. [music] We spoke with Professor Shoji Noyuki, president of the Japan Glaucom Society. >> Professor Shoji, thank you so much for your time today. >> So, it’s often said that the exact causes of glaucoma aren’t fully understood. my eyesight problems in general. Maybe somebody’s thinking, you know, I’m nearsided or I’m farsighted. Will I potentially develop glaucoma? For example, my dad had glaucoma. Is there a chance then that I might develop glaucoma? The inside of the eyeball is filled with a clear jellyike substance. Eye pressure helps maintain the shape of the eyeball and allows it to function properly. This pressure is regulated by a fluid called aqueous humor [music] located between the cornea and the lens. When the amount of aquous humor increases, eye pressure rises. When it decreases, eye pressure goes down. If the balance between the production and drainage of this fluid is disrupted, pressure builds up damaging the optic [music] nerve. This is considered one of the causes of glaucoma. The international standard for normal eye pressure ranges from 10 [music] to 21 mm of mercury. When the pressure exceeds 21 mm, [music] there’s a risk of damage to the optic nerve. But is there any way to tell if your own eye pressure is actually elevated or high? Yoshida Hiroshi was around 50 when he was diagnosed with glaucoma after a routine health check. The disease caused significant vision loss in his left eye both in acuity and field. Although his right eye remained in good condition, After being diagnosed with glaucoma, Yoshida was prescribed eye drops. Eye drops target [music] aqueous humor, the fluid that can raise eye pressure. They either reduce its production or help it drain [music] more efficiently, leading to lower eye pressure. [music] It’s said that for every 1 millm of mercury [music] that eye pressure drops, the risk of glaucoma decreases by 10%. A clinical trial in Japan involving patients with elevated eye pressure found that eye drops reduce the pressure by 6.6 [music] mm in 1 month. The effect was shown to last for a long period of time. Yoshida continued using eye drops for 20 years, [music] successfully slowing the progression of his condition. And if eye drops don’t lower the pressure in the eye, what other treatments then are available? For 20 years, Yoshida kept his glaucoma under control [music] with eye drops. But eventually he lost more of his visual [music] field. Vision in his left [music] eye declined sharply and his doctor recommended surgery. Most glaucoma surgeries aim to improve drainage of the aqueous humor which raises eye pressure. The fluid exits through an opening between [music] the cornea and iris covered by a structure called the tbecular meshwork. Doctors may apply a laser or make an incision there to promote drainage. But these treatments have challenges. Over time, the drainage pathway can clog again, possibly [music] requiring another surgery. And in excision surgery, if the new opening is too large, excessive fluid may be lost. This can lower eye pressure more than intended and cause reduced [music] eyesight or other complications. In 2023, a new surgical method was introduced in Japan with approval from the health ministry. It’s called micro shunt surgery. The procedure uses a tiny tube called a micro shunt. It’s just 8.5 [music] mm long, slightly longer than an eyelash, and has an extremely narrow inner diameter of 0.07 mm. The surgeon makes a small incision in the scara, the part of the eye next to the cornea. [music] The micro shunt is then inserted through the incision. It creates a new pathway for aquous humor, allowing [music] the fluid to drain more easily from the eye. [music] The micro shunt is soft and flexible and made [music] from a material designed to minimize rejection. Therefore, [music] it’s believed it can support stable long-term drainage of aquous humor. >> A clinical trial compared micro shunt surgery with a standard excision procedure. [music] It found that micro shunt surgery was slightly less effective at lowering eye pressure. [music] However, the operation was quicker and caused less bleeding, [music] reducing the burden on patients. Inserting a thin tube also lowers the chance of the wound closing up over time, [music] which helps reduce the risk of needing additional surgeries. In 2023, researchers reported the changes observed in about [music] 400 patients who underwent microshunt surgery in the US and Europe. This graph shows the shift in their average eye pressure over 2 years following the procedure. [music] Before surgery, pressure was 21 mm of mercury. 1 month later, it had dropped to a normal level of 13 mm. And even two years after surgery, it remained within a normal range. About 2 hours [music] after the surgery, the patients eye pressure was checked. >> [music] >> A drop in Yoshida’s eye pressure [music] was confirmed. >> [snorts] >> All right, let’s go. >> Glaucom is often caused by elevated eye pressure damaging [music] the optic nerve. But in some cases, symptoms can occur even when eye pressure is within the normal range. This condition is called normal tension glaucoma. A large-scale [music] survey by the Japan Glaucom Society found that more than 70% of glaucoma cases in Japan fall into [music] this category. >> Ozawa Kazutotomo is one such patient. He was diagnosed in his 40s even though he didn’t notice anything unusual. His eye pressure was a normal 15 mm of mercury, but a visual field test showed narrowing. Even now, his eye pressure remains in the normal range at 12 mm. Researchers [music] suspect that people with normal tension glaucoma have a weaker optic nerve that gets damaged [music] even at normal eye pressure. But the exact cause remains unknown. Is there a difference between ethnicities? For example, Caucasians versus Asians versus Is there differences at all? Glaucoma patients with normal eye pressure are also treated with eye drops or surgery. Currently, [music] the only treatment options are those that promote the drainage of aquous humor to reduce the [music] burden on the optic nerve. Once the optic nerve is damaged, it cannot be restored. However, in 2023, a Japanese research [music] team reported the potential for a new drug that can protect and even regenerate [music] the optic nerve in glaucoma patients. The discovery was made by Harada Takayuki at the Tokyo Metropolitan Institute of Medical [music] Science. Harada is a practicing opthalmologist. He has seen many patients lose [music] their vision to glaucoma. [music] [music] >> [music] >> Harada focused on [music] a protein found in the eye. It’s called BDNF or brain derived neurotrophic factor. BDNF [music] is produced in the brain’s hippocampus and cerebral cortex. It plays a [music] key role in supporting memory and learning and helps protect nerve cells. BDNF [music] is secreted from the brain into the eyes and it’s believed to help protect the optic nerve. Experts have found [music] that glaucoma patients have less BDNF in their eyes than people without the disease. [music] Harada has continued his research aiming to protect [music] and regenerate the optic nerve by increasing BDNF in glaucoma patients. That led him to explore gene therapy. [music] [music] Gene therapy aims to treat disease by altering the characteristics of genes that cause it. The optic nerve located [music] deep in the eye is made up of nerve fibers from individual nerve cells. Harada thought of altering the genetic [music] properties of these cells to strengthen the optic nerve. To do this, he used a virus. First, the virus is inactivated [music] to make it harmless. Then, a part of a protein called track B is added to the virus. This protein helps deliver BDNF related information into [music] cells. The modified virus is then injected into the eye. Once inside, it infects cells of the optic nerve and releases the protein. [music] The protein becomes embedded in the cells. Haraba injected this trackp loaded virus into the eyes of mice with glaucoma. He found that even in mice with low levels of BDNF, the nerve cells were protected. These images [music] show retinal ganglen cells in mice. These cells are [music] closely linked to optic nerve damage and they’re shown here in green. The image on the left is from a normal mouse. [music] The one on the right is from a mouse with glaucoma. 12 [music] weeks after the experiment, many of its nerve cells have disappeared, leaving large [music] dark gaps. But in a glaucoma mouse treated with a [music] track B modified virus, the loss of nerve cells was reduced and many of the cells remained intact. Harada also injected the track B loaded virus [music] into mice with damage to the optic nerve, the connection between the eye and the brain. This image shows a damaged optic [music] nerve in a mouse. The white area is the only part that remains. When a virus [music] without track B is injected, there is little to no regeneration. But 2 weeks after [music] injecting the track B modified virus, the white area has grown, showing that the optic [music] nerve has begun to regenerate. After [music] 4 weeks, the optic nerve has regenerated even more and has [music] grown longer. Harada’s results have drawn attention from [music] Stanford University professor Jeffrey L. Goldberg who also studies nerve regeneration in glaucoma patients. So that really stood out as a very creative approach to uh building on prior work in a really positive creative way. I think that’s really attractive in our field not just in glaucoma for ner degenerative diseases but frankly for ner degenerative diseases throughout the brain and spinal cord and even peripheral nervous system. These involve preparing lots of the gene therapy of the of the gene therapy itself that are prepared in facilities that make them safe for human use. You have to take some of those materials and retest them in animals just to make sure that they’re really non-toxic and do appropriate studies of that sort. And I would love to see this translate into patient use one. Harada is continuing his research, hoping to make this gene therapy available for glaucoma patients as soon as possible. Glaucom often has no noticeable symptoms in the early stages. Many people don’t realize they have it until it has already progressed. We asked Shoji what we can do to [music] catch it early. >> So even if you’re not feeling it, are there any, for example, specific signs or symptoms? For example, dry eyes or feeling pressure in the eyes. Is there anything that we could look out for? Let’s see if you’ve experienced any of [music] the following in daily life. You don’t notice a small side dish on the table and [music] leave it untouched. You have trouble pouring tea from a pot into a cup. Your glasses always seem dirty. Parking has become more difficult [music] than before, and you often scratch your car. You miss a step when using stairs or getting on and off public [music] transport. If these things happen repeatedly, [music] it could be a sign of glaucoma. >> Obviously, testing is the best thing to go and do to detect whether or diagnose whether you have glaucoma. Is there any sort of self test that you can do? >> Here’s a simple selfch check you can try. Look at something bright like [music] a white wall or the sky. Cover one eye and focus on a single point for a few moments. Then switch [music] and do the same with the other eye. Note whether the view seems dimmer in one eye than the other or if any area appears darker. If you notice anything like that, please get your eyes examined as soon as possible. That’s a great tip. >> Once you’re diagnosed with glaucoma, it’s important to use eye drops properly. To help the drop [music] land in your eye, aim as if you’re letting it fall onto your eyebrow. One drop is enough. [snorts] If you use too many and they overflow, the liquid [music] may irritate the skin around your eye, so be careful. That’s so interesting [music] cuz I think if if I did it, I noticed when you did it, you were really aiming from quite a distance. I’d be much closer when I did mine. [music] Yeah. >> So, when you’ve put [snorts] the eye drops in, should you put your head down straight away or keep it up? >> [music] >> After applying the eye [music] drops, try not to blink. Gently press the inner corner of your eye and keep it closed for about a [music] minute. >> It was really interesting. I think I would have gotten my eye drop everywhere if I’d done it. over the age of 40 and particularly if we have a family history just how important it is [music] to go and have it checked or perhaps for everyone at home to do the selfch check that was really interesting as well and something that anyone can do straight away. [music] So, professor thank you so much for your time today. Oh, there
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Glaucoma is extremely difficult to diagnose in its early stages but doctors continue to search for ways to prevent patients from losing their sight.