blindness
Scientists have known for more than 200 years that vision begins with a series of chemical reactions when light strikes the retina, but the specific chemical processes have largely been a mystery.
Spitting cobras have an exceptional ability to spray venom into eyes of potential attackers. A new study reveals how these snakes maximize their chances of hitting the target.
Misdiagnosis of a severely paralyzing disease can now be averted due to a blood test developed by Mayo Clinic researchers and their Japanese collaborators. Often misdiagnosed as multiple sclerosis, neuromyelitis optica (NMO) also causes blindness in many sufferers. The finding will help doctors correctly treat NMO -- also known as Devic's syndrome -- sooner and more effectively. In some countries, misdiagnosis may be as high as 30 percent. Early diagnosis is important because NMO is best treated differently than multiple sclerosis.
Gene mutations that impair the ability of photoreceptor cells to properly dispose of waste -- and as a result cause the blinding eye disease retinitis pigmentosa -- have been identified by vision researchers at the University of Utah's Moran Eye Center. The discovery raises concerns that carbonic anhydrase inhibitors (medications often used to treat both heart and eye diseases) may adversely affect vision. Retinitis pigmentosa (RP) is one of the most common causes of blindness. It affects one in 3,500 people or approximately two million people worldwide. Patients with RP typically are diagnosed with night blindness and, as the disease progresses, they eventually lose all of their peripheral vision and a significant portion of their central vision.
A fundamental cellular event related to programmed cell death has been decoded by cell biologists. The work could provide insights on two devastating inherited diseases. In healthy cells, mitochondria (tiny energy substations that churn out each cell's power supply) continually fuse together and split in two. When mitochondrial fusion goes awry, cells are targeted for programmed cell death, or apoptosis. Apoptosis is a normal process in healthy individuals, but if mitochondrial fusion doesn't work, the wrong cells die, causing disease. This is what happens in two neurodegenerative diseases: dominant optic atrophy, the most common inherited cause of blindness, and Charcot-Marie-Tooth disease, which reduces sensation in the feet, lower legs and hands. Both diseases kill nerve cells.
Scientists have produced the first molecular-scale images of DNA binding to an adenovirus enzyme -- a step they believe is essential for the virus to cause infection. The images show how binding to DNA may stimulate the enzyme and are already being used to design new antiviral drugs to block this interaction. ''We were quite surprised to see that DNA actually stimulated the activity of the enzyme,'' said Brookhaven National Laboratorybiologist Walter Mangel. ''If we can block this interaction, we should be able to prevent the virus from replicating, and thereby thwart infection.'' Adenoviruses cause respiratory, gastrointestinal, and eye infections, including highly contagious viral pink eye. Some adenovirus eye infections lead to blindness.
Seeking a cure for an inherited disease that causes blindness in over one million people worldwide, Dartmouth Medical School researchers have discovered a critical role for zinc in retinitis pigmentosa. The amount of zinc, a trace metal naturally absorbed by the body, can determine whether a key protein for vision functions normally or misfolds, they found.
Temporary rapidly induced blindness has provided evidence that an older, primitive part of the brain plays a role in processing visual information unconsciously.
This finding by researchers at Houston's Rice University was published in the Proceedings of the National Academy of Sciences online this week (www.pnas.org).
For the study, six volunteers with normal vision underwent more than 600 trials in which they had to look at a target placed at varying locations on a computer screen. For half of the trials, the participants were asked to move their eyes to the location of the target, and their eye movements were measured electronically.
Researchers at the Stanford University School of Medicine have developed a prototype for a new kind of implantable chip they believe could be adapted to serve as both a prosthetic retina for people who suffer from a common form of age-related blindness and as a drug-delivery system that could treat conditions such as Parkinson's disease.
Eye drops that reduce elevated pressure inside the eye can delay or possibly prevent the onset of glaucoma in African Americans at higher risk for developing the disease, researchers have found. This makes it more important to identify African Americans at higher risk for developing glaucoma so they can receive prompt evaluation for possible medical treatment.
Scientists have discovered a protein in the cell wall of parasites that's crucial to the molecular mechanism allowing them to move between cells, survive and cause disease. The discovery was made in Toxoplasma gondii, an organism that can cause blindness and brain damage in people with an impaired immune system and can cause severe disease in first trimester fetuses. In addition, the organism is used as a model experimental system for studying the closely related mosquito-borne malaria parasite Plasmodium.
Cholesterol-busting statins, the largest-selling prescription drugs in the U.S., may protect older people from blindness, a new study shows. Aspirin also appears to provide significant protection, according to the research. Scientists at UCSF assessed the use of statins and aspirin among more than 300 elderly patients with age-related macular degeneration, or AMD, a common condition among people over 70. About one in eight cases of AMD deteriorates into what is called wet AMD, the leading cause of irreversible severe vision loss in older people.
High intake of dietary fats may increase the risk of progression of age-related macular degeneration, according to an article in the December issue of The Archives of Ophthalmology, one of the JAMA/Archives journals.
According to information in the article, age-related macular degeneration (AMD, a common, progressive eye disease in older people that causes blindness) is the leading cause of irreversible visual impairment and blindness in the United States and in other developed countries. Six percent to eight percent of people aged 75 and older have the advanced stages of AMD associated with blindness. It is estimated that more than eight million people have the intermediate stages of AMD, and of these about 1.3 million people will develop advanced AMD within the next five years.
Over 52 million people worldwide can avoid going blind if current and new resources are successfully implemented, according to a new study. Researchers for the Johns Hopkins Bloomberg School of Public Health and the London School of Hygiene and Tropical Medicine found that without extra intervention, the global number of blind individuals would increase from 44 million in 2000 to 76 million in 2020. "Vision 2020 - The Right to Sight"?an initiative cosponsored by the World Health Organization and the International Agency for the Prevention of Blindness and aimed at eliminating avoidable blindness from cataract, trachoma, onchocerciasis, vitamin A deficiency and refractive errors?would decrease the 2020 projection by 52 million individuals. The economic gain of this program would be approximately $102 billion. The study, "The Magnitude and Cost of Global Blindness: An Increasing Problem That Can Be Alleviated," will appear in the April 2003 issue of the American Journal of Ophthalmology.
Drugs commonly prescribed to osteoporosis and cancer patients may also cause serious ocular side effects in some cases. That's the conclusion of a study published today by scientists at the Oregon Health & Science University Casey Eye Institute. This research is expected to alert physicians to monitor patients for eye problems not previously associated with the drug. The announcement may also help physicians identify problems earlier, therefore preventing long-term sight damage. Finally, this finding may prompt drug companies to update their product labeling, forewarning physicians and users.
