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Bionic eye, handheld autorefractor measurements acceptance, mechanism for AMD, contact lenses with gold nanoparticles
After studying a bionic eye using a sheep model, researchers are confident it is safe for human trials. A paper found that eyeglasses made from QuickSee handheld autorefractor measurements were accepted equally to those made from subjective refraction measurements. A team from the University of Maryland School of Medicine has identified a new potential mechanism for age-related macular degeneration. Researchers reported infusing contact lenses with gold nanoparticles to create a safer way to see colors.
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Study identifies new mechanism that may cause blindness in older adults
Using laboratory-grown roundworms, as well as human and mouse eye tissue, University of Maryland School of Medicine (UMSOM) researchers have identified a new potential mechanism for age-related macular degeneration – the leading cause of blindness among older adults. The UMSOM researchers say that the findings suggest a new and distinct cause that is different from the previous model of a problematic immune system, showing that the structural organization of the eye’s light-detecting cells may be affected by the disease. The discovery offers the potential to identify new molecular targets to treat the disease. It was published in the Proceedings of the National Academy of Sciences (PNAS). Several years ago, researchers had identified genetic mutations in the protein complement factor H as a contributor in a large number of macular degeneration cases. Complement factor H marks cells in the body as self and protects them from attack by the immune system, whose job it is to eliminate invading pathogens and cells that do not belong. As a result, due to complement factor H’s role in this process, it was thought that macular degeneration was likely due to the immune system attacking its own body’s cells that were not marked properly as “self.”
According to Dr. Vogel, since identifying effective new therapies for the disease has been slow, he wanted to see if his team could find new insights from studying the disease components in his laboratory model of the roundworm, C. elegans.
Dr. Vogel’s team found a worm version of complement factor H protein located in the sensory neurons that help the worms detect chemicals, food, touch, and temperature. The protein appeared specifically in the middle region of the sensory neuron’s little antennas, known as cilia (that do the work of sensing the environment), just next to another known important antenna protein called inversin. However, in worms bred to lack complement factor H, they found the inversin spread throughout the antennas rather than remaining in the middle of the antennas. Next, the researchers confirmed their results in the lightdetecting cells in tissue from human retinas. Complement factor H and inversin had the same positioning next to each other in the antenna of light-detecting cells from healthy
Glowing sensory cells in the worm that make complement factor H protein. Photo: PNAS
samples. Yet in people with complement factor H mutations (i.e. people genetically predisposed to macular degeneration), they found the inversin spread around, no longer restricted to its neat banding pattern on the antenna. “Our findings suggest that complement factor H plays a role in maintaining the organization of photoreceptor cilia, and this process may be defective in age-related macular degeneration,” says Vogel. “We plan to continue this work to determine how this structural disruption affects vision and to determine whether we can reverse the disruption and restore photoreceptor function.”
A bionic eye being developed by a team of biomedical researchers at the University of Sydney and UNSW has shown to be safe and stable for long-term implantation in a threemonth study, paving the way towards human trials. The Phoenix99 Bionic Eye is an implantable system, designed to restore a form of vision to patients living with severe vision impairment and blindness caused by degenerative diseases, such
The ocular and subcutaneous implant components of the Phoenix99. Photo: University of Sydney as retinitis pigmentosa. The device has two main components which need to be implanted: a stimulator attached to the eye and a communication module positioned under the skin behind the ear. Published in Biomaterials, the researchers used a sheep model to observe how the body responds and heals when implanted with the device, with the results allowing for further refinement of the surgical procedure. The biomedical research team is now confident the device could be trialled in human patients. The team will now apply for ethics approval to perform clinical trials in human patients, as they continue to develop and test advanced stimulation techniques. The Phoenix99 Bionic Eye works by stimulating the retina – a thin stack of neurones lining the back of the eye. In healthy eyes, the cells in one of the layers turn incoming light into electrical messages which are sent to the brain. In some retinal diseases, the cells responsible for this crucial conversion degenerate, causing vision impairment. The system bypasses these malfunctioning cells by stimulating the remaining cells directly, effectively tricking the brain into believing that light was sensed. “Importantly, we found the device has a very low impact on the neurons required to ‘trick’ the brain. There were no unexpected reactions from the tissue around the device and we expect it could safely remain in place for many years,” said Mr Samuel Eggenberger, a biomedical engineer who is completing his doctorate with Head of School of Biomedical Engineering, Professor Gregg Suaning.
Sources: University of Sydney [2]
Color blindness-correcting contact lenses
Researchers reported infusing contact lenses with gold nanoparticles to create a safer way to see colors in ACS Nano. Some daily activities, such as determining if a banana is ripe, selecting matching clothes or stopping at a red light, can be difficult for those with color blindness. Most people with this genetic disorder have trouble discriminating red and green shades, and red-tinted glasses can make those colors more prominent and easier to see. However, these lenses are bulky and the lens material cannot be made to fix vision problems. Thus, researchers have shifted to the development of special tinted contact lenses. Although the prototype hot-pink dyed lenses improved red-green color perception in clinical trials, they leached dye, which led to concerns about their safety. Gold nanocomposites are nontoxic and have been used for centuries to produce "cranberry glass" because of the way they scatter light. So, Ahmed Salih, Haider Butt and colleagues wanted to see whether incorporating gold nanoparticles into contact lens material instead of dye could improve red-green contrast safely and effectively. To make the contact lenses, the researchers evenly mixed gold nanoparticles into a hydrogel polymer, producing rose-tinted gels that filtered light within 520-580 nm, the wavelengths where red and green overlap. The most effective contact lenses were those with 40 nm-wide gold nanoparticles, because in tests, these particles did not clump or filter more color than necessary. In addition, these lenses had water-retention properties similar to those of commercial ones and were not toxic to cells growing in petri dishes in the lab. Finally, the researchers directly compared their new material to two commercially available pairs of tinted glasses, and their previously developed hot-pink dyed contact lens. The gold nanocomposite lenses were more selective in the wavelengths they blocked than the glasses. The new lenses matched the wavelength range of the dyed contact lenses, suggesting the gold nanocomposite ones would be suitable for people with red-green color issues without the potential safety concerns. The researchers say that the next step is to conduct clinical trials with human patients to assess comfort. The paper is freely available as an ACS AuthorChoice article.
Autorefractor measurements accepted by patients
A paper published by researchers at the Aravind Eye Institute in India, Johns Hopkins University, and the Massachusetts Eye and Ear Institute found that eyeglasses made from QuickSee handheld autorefractor measurements were accepted equally to those made from subjective refraction measurements. The study authors suggest that QuickSee, due to its accuracy and portability, could be used to radically expand access to eyeglasses in remote and low resource settings which lack professionals and clinical equipment to provide accurate prescriptions. The paper in Ophthalmology, "Investigation of the accuracy of a low-cost, portable, autorefractor to provide well-tolerated eyeglass prescriptions: a randomized crossover trial," concluded that patients accepted eyeglasses made from QuickSee measurements equally to those made from subjective refraction. PlenOptika, the maker of the device, assisted in study design but its execution, analysis, and reporting was independent of the company. Shivang Dave, PhD, CEO of PlenOptika and one of QuickSee's inventors, and his colleagues Daryl Lim, PhD, Eduardo Lage, PhD, and Nicholas Durr, PhD, invented the technology while researchers at the Massachusetts Institute of Technology, in collaboration with the Regional Government of Madrid. The development was supported in part by grants from the National Eye Institute of the National Institutes of Health. In wealthy nations where patients have access to licensed health care QuickSee handheld autorefractor in use in India. Photo: PlenOptika providers, the technology has also helped eye doctors provide on-site care, such as in nursing homes, correctional facilities, and community health centers. Even large eye health centers are using the device to manage large patient volumes efficiently. To date, QuickSee has been used to measure over three million people in 45 countries, and was found in prior peer-reviewed studies to produce measurements that strongly agree with subjective refraction.
Sources: PlenOptika
Referenzen: [1] www.medschool.umaryland.edu [2] www.sydney.edu.au
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