June 2002

Research Capsules
Edited by Harrison Wein, Ph.D.

Drops for Lazy Eye as Effective as Patch
Autoimmunity May Be Caused by Infections
Discouraging Teen Drinking

Drops for Lazy Eye as Effective as Patch

Scientists have found that atropine eye drops given once a day to treat moderate amblyopia, or lazy eye, work as well as the standard treatment of patching one eye. The finding could lead to more success in correcting amblyopia by helping children avoid the social stigma of wearing an eye patch and making it easier for parents to help their kids stick to the treatment.

Amblyopia is the most common vision problem in children, affecting two or three of every 100 children. It can be caused by any condition that causes the brain to favor one eye such as crossed eyes, different focusing ability between the two eyes or childhood cataracts (clouding of the eye lens). The preferred eye becomes dominant and the weaker, "amblyopic" eye becomes ignored by the brain. The visual system in the brain for the amblyopic eye often fails to develop properly, and at some time between the ages of five and ten the condition can become permanent.

Patching the unaffected eye has been the standard treatment for amblyopia, but many kids don't like the teasing or the skin irritation that comes with wearing an eye patch. An alternative treatment – an eye drop called atropine – has been known for almost a century. This drug dilates the pupil and blurs the image seen by the dominant eye, forcing the brain to use the weaker eye. This method is often used when patching doesn't work, but few doctors try it at the beginning. NIH's National Eye Institute (NEI), therefore, funded a study to see whether atropine was as effective as patching for treating amblyopia in children under seven years of age. The study was conducted by a network of eye care professionals at universities in North America and in local community offices.

Two hundred and fifteen children received patching, and 204 received atropine eye drops once a day. The researchers found that 79 percent of those receiving the eye patch were treated successfully, while 74 percent receiving the atropine were treated successfully – a difference that isn't clinically significant. Vision in the amblyopic eye improved faster in the patching group, but the difference in the two groups at six months was not significant. Side effects were minimal for both groups.

Study chairman Dr. Michael Repka, professor of ophthalmology and pediatrics at the Wilmer Eye Institute of Johns Hopkins University School of Medicine in Baltimore, says, "This study shows that one drop a day of atropine works as well as patching the eye for some children with amblyopia. Since both patching and atropine work equally well, the choice of treatment can be made by the eye care professional in consultation with the parent."

Every child should have a complete eye examination at least once between the ages of three and five to avoid the risk of letting undetected amblyopia go beyond the age when it can be treated successfully. Early recognition and treatment can help prevent permanent vision problems. Your child may have amblyopia if you notice eyes that turn in or out, eyes that don't appear to track together or lack of depth perception.

– a report from The NIH Word on Health, June 2002
Archives of Ophthalmology 120:268-278

For more information on amblyopia and the Amblyopia Treatment Study from NIH's National Eye Institute, visit http://www.nei.nih.gov/amblyopia/index.htm.

Autoimmunity May Be Caused by Infections

Autoimmune diseases arise when the immune system, which normally defends the body against bacteria, viruses, and other invading microbes, mistakenly attacks the cells, tissues and organs of a person's own body. Why some people get autoimmune diseases has been a mystery, but a new study involving a virus called HTLV-1 reinforces the emerging idea that these conditions – which include multiple sclerosis, rheumatoid arthritis and inflammatory bowel disease – are triggered by infections, some of which may not even cause any symptoms on their own.

HTLV-1 usually causes no symptoms when it infects someone, but about five percent of the people who get it develop leukemia and up to three percent develop a neurological disorder called HAM/TSP (for HTLV-1-associated myelopathy/tropical spastic paraparesis) that resembles multiple sclerosis. Symptoms of HAM/TSP include muscle weakness and loss of control, mild sensory problems, hand tremors, and urinary and bowel problems.

In the new study, which was partly funded by two NIH components – the National Center for Research Resources (NCRR) and the National Institute of Neurological Disorders and Stroke (NINDS), scientists pinpointed a protein in nerve cells called hnRNP-A1 that all 13 of the people they studied with HAM/TSP made antibodies against. None of the 12 people they studied without an HTLV-1 infection made antibodies against it, and of ten people who had an HTLV-1 infection but no symptoms, only one made antibodies to this protein. So there was a strong relationship between people who made antibodies to hnRNP-A1 and those who had HAM/TSP.

The antibodies that recognized hnRNP-A1 also recognized a protein from HTLV-1, which explains how an HTLV-1 infection might lead to HAM/TSP. The virus protein essentially "mimics" a protein found in nerve cells; in other words, to the immune system, the two proteins look the same. Once the immune system recognizes the viral protein as part of an invader, it thinks the nerve cell protein is an enemy too and proceeds to attack it, causing the neurological problems seen in HAM/TSP. Showing that this immune system confusion is the likely cause of HAM/TSP symptoms, the scientists found that antibodies from people with HAM/TSP interfered with nerve cell function in rat brains.

Put together, these experiments may explain how the virus causes symptoms in some people – by causing their immune system to attack the person's own nerves – but they still don't answer the question of why some people infected with HTLV-1 get HAM/TSP while others don't. The scientists speculate that it may have to do with how much the virus reproduces in the body, the genetic makeup of the infecting virus and the genetics of the infected person.

HTLV-1 is not transmitted through casual contact. It is spread by having unprotected sex with an infected partner, sharing needles or breast feeding.

– a report from The NIH Word on Health, June 2002
Nature Medicine 8,5:509-513

NINDS maintains a Tropical Spastic Paraparesis Information Page at http://www.ninds.nih.gov/health_and_medical/disorders/tropical_spastic_paraparesis.htm.

For more information about autoimmune diseases, see the National Institute of Allergy and Infectious Diseases (NIAID) booklet Understanding Autoimmune Diseases at http://www.niaid.nih.gov/publications/autoimmune/default.htm.

Discouraging Teen Drinking

The earlier you start drinking alcohol, the more likely you are to abuse or become dependent on it when you're older. That's why it's important for parents to help delay their children's initiation into the world of alcohol as long as they can. A new study shows that brief family intervention programs are a cost-effective way to delay teen drinking.

In the study, funded by NIH's National Institute on Drug Abuse (NIDA) and National Institute of Mental Health (NIMH), researchers at Iowa State University assigned families of sixth graders from 33 rural schools to one of two intervention programs or a control group. The programs were the Iowa Strengthening Families Program (ISFP), a seven-session intervention with parents and students, and Preparing for the Drug Free Years (PDFY), a five-session intervention primarily with parents. These programs emphasize healthy family and peer relationships and teach kids skills to resist social pressure to use alcohol. The participants reported their alcohol use themselves, and results were based on 478 families after four years of study.

The researchers found that, between the critical ages of 13 and 16, fewer teens in the two treatment groups started to use alcohol than in the control group. Those in the intervention groups, therefore, are predicted to have fewer problems with alcohol use as adults. The researchers conservatively estimated that preventing a single case of adult alcohol abuse produces an average savings of $119,633 in avoided costs to society. They calculated that the ISFP intervention could save $9.60 in future costs for each dollar invested in the program, and that the PDFY could save $5.85 for each dollar.

Alcohol problems have a great societal cost. According to statistics recently reported in a National Institute on Alcohol Abuse and Alcoholism (NIAAA) study, the annual economic costs of alcohol abuse in 1998 were about $185 billion. The Iowa State University researchers based their cost-benefit analysis on a more conservative estimate of $148 billion, which limited costs to those associated with factors like lost wages and decreased productivity. Less conservative estimates include the dollar value of less tangible costs – such as pain and suffering – that are also produced by alcohol disorders. If these costs had been factored in, the cost benefit of these interventions would have been even more dramatic. The scientists conclude that family interventions for the general public have the potential to bring considerable social and economic benefits to society.

– a report from The NIH Word on Health, June 2002
Journal of Studies on Alcohol 63, 2:219-228

For more information about teens and alcohol use, see Make A Difference - Talk to your child about Alcohol from NIH's National Institute on Alcohol Abuse and Alcoholism at http://www.niaaa.nih.gov/publications/makediff.htm.

For information about college students and drinking, visit http://www.collegedrinkingprevention.gov/.