Wouldn’t it be nice if there were fixes for vision diseases, such as macular degeneration and retinal vein occlusion, that could maintain vision, and in some cases improve vision—not just keep the disease from getting worse? Well, wouldn’t you know it, research done at Stanford University and Columbia University, showed that it is possible to do so by way of bionic or pharmaceutical means.
In 2019, researchers at Stanford University implanted a microchip that worked with specially designed glasses in patients with macular degeneration. This restored vision to the center of the patients’ visual field. A follow-up study was done two years later to find out two things: First, if patients would be able to integrate the prosthetic central vision with whatever natural peripheral vision that remained. Second, would the prosthetic vision last?
Tests were conducted using virtual reality glasses. Scientists wanted to know if patients could see projected lines and letters while their natural peripheral vision was blocked. Researchers presented the patients two lines. One was projected directly on the implant with invisible near-infrared light and the other was displayed on a screen that was farther away. Having an image on a screen that is farther away forced patients to use their natural peripheral vision.
Researchers were happy to learn that the prosthetic vision integrated well with the patients’ peripheral vision, which was not affected by macular degeneration. The patients had no problem seeing the both patterns at once. This is important news since previous retinal implants created distorted perception and it demonstrates that the brain can distinguish between the prosthetic and natural retinal codes. The visual acuity of the prosthetic is approximately 20/460, enabling patients to see large letters. Researchers are working on an implant that will provide visual acuity exceeding 20/100.
Now for the pharmaceutical part of this blog entry. Could eye drops replace injections as a treatment for retinal vein occlusion? A study at Columbia University Vagelos College of Physicians and Surgeons suggests yes.
Retinal vein occlusion happens when a vein in the retina becomes blocked. This leads to swelling in the eye, inflammation, damage to the retina, and vision loss. The standard treatment involves injecting anti-VEGF into the eye. While this treatment reduces swelling and can improve vision, those with damage to the retina caused by impaired blood flow, don’t achieve a good outcome with anti-VEGF.
This study found that an experimental eye drop treatment was two times as effective as the anti-VEGF treatment at reducing swelling and improving blood flow in the retina of mice with retinal vein occlusion. The drops contain an experimental drug that blocks caspase-9, an enzyme that causes cell death. The drops also prevented photoreceptors from failing and preserved visual function. The anti-VEGF shots had no effect on the photoreceptors or visual function.
Researchers think that the drops improve the health of the blood vessels in the retina, which reduces the toxic signaling that damages the neurons in the retina and leads to loss of vision. Future studies are being planned with the hopes of testing the drops in human clinical trials and finding other therapeutic targets.
The successful integration of prosthetic vision with natural peripheral vision and the promising results of experimental eye drops signifies a significant leap forward. As a result of ongoing research and clinical trials, scientists are on the cusp of revolutionizing how these debilitating conditions are treated. The future of sight-saving treatments appears brighter than ever and these breakthroughs serve as beacons of hope, whereby vision impairment is no longer a sentence to darkness, but a condition that can be effectively managed and mitigated.
Sources:
https://med.stanford.edu/news/all-news/2022/02/macular-degeneration-retinal-implants.html
https://www.cuimc.columbia.edu/news/could-drops-replace-eye-injections-retina-disease