Treatment improved the vision of many of the 507 older children with amblyopia studied at 49 eye centers. Previously, eye care professionals often thought that treating amblyopia in older children would be of little benefit. The study results, funded by the National Eye Institute (NEI), part of the National Institutes of Health (NIH), appear in the April issue of Archives of Ophthalmology.
"Doctors can now feel confident that traditional treatments for amblyopia will work for many older children," said Paul A. Sieving, M.D., Ph.D., director of the NEI. "This is important because it is estimated that as many as three percent of children in the United States have some degree of vision impairment due to amblyopia. Many of these children do not receive treatment while they are young," he said.
Amblyopia is a leading cause of vision impairment in children and usually begins in infancy or childhood. It is a condition resulting in poor vision in an otherwise healthy eye due to unequal or abnormal visual input while the brain is developing in infancy and childhood. The most common causes of amblyopia are crossed or wandering eye (strabismus) or significant differences between the eyes in refractive error, such as, astigmatism, farsightedness, or nearsightedness.
Children in the study were divided randomly into two groups. One group was fitted with new prescription glasses only. The other group was fitted with glasses as well as an eye patch, or the eye patch along with special eye drops, to limit use of the unaffected eye. These children were also asked to perform near vision activities. The patching, near activities, and eye drops force a child to use the eye with amblyopia. Patching was prescribed for periods of two to six hours daily, while the eye drops were administered daily for the children seven though 12 years of age.
The study investigators defined successful vision improvement as the ability to read (with the eye with amblyopia) at least two more lines on a standard eye chart. The study investigators found that 53 percent of children age seven through 12 years who received both glasses and treatment with patches and near activity met this standard, while only 25 percent of those children in this age group who received glasses alone met the standard. For children age 13 through 17 years who were treated with both glasses and patches (these children did not get drops), 25 percent met the standard while 23 percent of children of these ages who received only glasses met the standard.
The study also revealed that among children age 13 through 17 years who had not been previously treated for amblyopia, 47 percent of those who were treated with glasses, patching and near activities improved two lines or more compared with only 20 percent of those treated with glasses alone. Despite the benefits of the treatment, most children, including those who responded to treatment, were left with some visual impairment. They did not obtain "20/20" vision.
"This study shows how important it is to screen children of all ages for amblyopia." said study co-chairman Richard W. Hertle, M.D., Children's Hospital of Pittsburgh.
Commented co-chairman Mitchell M. Scheiman, O.D., Pennsylvania College of Optometry, "This study shows that age alone should not be used as a factor to decide whether or not to treat a child for amblyopia. The opportunity to treat amblyopia does not end with the pre-school years."
It is not known, say the authors of the current study, whether vision improvement will be sustained in these children once treatment is discontinued. The NEI is supporting a one-year, follow-up study to determine the percentage of amblyopia that recurs among the children who responded well to treatment, as well as many other clinical studies of amblyopia at eye centers nationwide.
Dr. Sieving also commented that the current study results are "a wonderful example of the adaptability of the human visual system and brain. The NIH is exploring ways to take advantage of this adaptability in order to better understand and treat vision problems and other neurological conditions."
The study described in this release was conducted by the NEI-funded Pediatric Eye Disease Investigator Group. The Group focuses on studies of childhood eye disorders that can be implemented by both university-based and community-based practitioners as part of their routine practice. The study was coordinated by the Jaeb Center for Health Research in Tampa, Florida. A list of study centers is attached.
The National Eye Institute is part of the National Institutes of Health (NIH) and is the Federal government's lead agency for vision research that leads to sight-saving treatments and plays a key role in reducing visual impairment and blindness. The NIH is an agency of the U.S. Department of Health and Human Services.
B-roll package available by calling 301-496-5248 or by satellite (see dates and coordinates below). Photos and other materials available in downloadable, camera-ready format on the NEI Website at http://www.nei.nih.gov/ats3.
Background
Amblyopia is a condition that occurs when a child's visual system does not develop properly, resulting in abnormal sight in one or both eyes. The condition is sometimes called "lazy eye." The condition affects as many as three percent of children in the United States. It is the most common cause of monocular visual impairment in both children and young and middle-aged adults.
The disorder is caused by any condition that sends the brain abnormal or unequal visual input during infancy or childhood. These conditions can include an imbalance in the positioning of the eyes, such as strabismus, in which the eyes are crossed inward (esotropia) or turned outward (exotropia). Amblyopia also can result from a major difference in refractive error between the two eyes, such as nearsightedness, farsightedness, or astigmatism. Less common causes of amblyopia are cornea and lens diseases and injury to the eye of a young child. The results reported in this study do not include amblyopia from these less common causes.
It has been commonly thought that the best time to try to correct amblyopia was during infancy or early childhood before the eyes and the entire visual system, including the brain, have fully matured. Although most eye care professionals agreed that amblyopia could be treated effectively in young children, many have thought that treatment beyond a certain age is ineffective. Some clinicians thought that a treatment response was unlikely after the age of six or seven years, while others considered age nine or ten years to be the upper age limit for successful treatment.
There had been limited data available to eye researchers on treatment of children older than seven. However, some clinicians reported that treatment did benefit older children. To prepare for a possible randomized clinical trial on treating amblyopia in older children, the National Eye Institute (NEI) funded a pilot study that was completed in 2003. The pilot study showed that after treatment, 27 percent of 66 children with amblyopia, ages ten through 17 years, improved their vision in the affected eye. They gained the ability to read two or more lines of a standard eye chart. The results justified the NEI-funded, Randomized Trial of Treatment of Amblyopia in Children 7 to <18 Years Old. The trial was coordinated by the Pediatric Eye Disease Investigator Group (PEDIG), a network of eye care professionals at universities and community offices in North America.
The purpose of this trial was to treat two age sets of "older" children, seven through 12 years old and 13 through 17 years old, with conventional amblyopia treatments, both patching and atropine eye drops. At 49 clinical sites nationwide, 507 children with amblyopic eye vision ranging from 20/40 to 20/400 were recruited into the trial from October 2002 to March 2004. Eye care professionals then prescribed new eye glasses for all the study children, to obtain the "optimal optical correction." Both sets of children were then randomly divided into either a "treatment group" or an "optical-correction-only group," children who received only glasses.
In the treatment group, seven- through 12-year-old children received two to six hours daily patching of the unaffected eye with near activities, plus daily atropine drops in that eye to temporarily blur their near vision. The 13 through 17-year-old children in the treatment group received the patching and near activities but not the eye drops. The near activities included hand-held computer games, homework, reading, computer work, and the use of workbooks designed for the study with mazes, and word finds. Vision improvement in the eye with amblyopia occurred over a period of six to 24 weeks.
The results confirm the pilot study results that conventional treatment of amblyopia can be effective in children even after age seven. As is the case with patients younger than seven, however, most of the older patients are also left with some remaining visual impairment despite treatment. The investigators are continuing to study the children for a year after stopping their treatment to determine whether the benefit reported in this paper will be sustained.
The study authors also reported that patients participating in the clinical trial may differ from patients in usual clinical practice. The children in the study, with the guidance of their parents, may have a different level of compliance than may be achieved in clinical practice.
For decades, patching the unaffected eye had been the standard treatment for amblyopia. In March 2002, NEI-supported researchers reported the effectiveness of drug therapy with an eye drop (atropine) that dilates the pupil and blurs the image seen by the unaffected eye during near viewing. In May 2003, results of another NEI-funded study, also conducted by the PEDIG at 35 clinical sites, indicated that patching the unaffected eye of children with moderate amblyopia for two hours daily works as well as patching the eye for six hours.
Older Children Can Benefit from Treatment for Childhood's Most Common Eye Disorder – Current Study Centers
Institution - City / State
- Alberta Children's Hospital Alberta, CANADA
- Ophthalmic Associates Anchorage, AK
- University of Alabama at Birmingham School of Optometry Birmingham, AL
- Southern California College of Optometry Fullerton, CA
- Eye Care Group, PC Waterbury, CT
- Eye Physicians & Surgeons, PC Milford, CT
- Vision Center of Delaware Newark, DE
- Bascom Palmer Eye Institute Miami, FL
- Palm Beach Eye Foundation/Visual Health and Surgical Center Lake Worth, FL
- The Emory Eye Center Atlanta, GA
- Wolfe Clinic West Des Moines, IA
- Katherine Ann Lee, M.D., PA. Boise, ID
- Pediatric Eye Associates Wilmette, IL
- Indianapolis Eye Care Center Indianapolis, IN
- Midwest Eye Institute Indianapolis, IN
- Grene Vision Group Wichita, KS
- New England College of Optometry Boston, MA
- Pediatric Ophthalmology Service Boston, MA
- Wilmer Institute Baltimore, MD
- Pediatric Ophthalmology, P.C. Grand Rapids, MI
- Associated Eye Care Saint Paul, MN
- Mayo Clinic Rochester, MN
- University of Minnesota Minneapolis, MN
- Cardinal Glennon Children's Hospital St. Louis, MO
- Michael F. Gallaway Marlton, NJ
- Goldblum Family Eye Care Center, P.C. Albuquerque, NM
- State University of New York, College of Optometry New York, NY
- SUNY Downstate Medical Center Brooklyn, NY
- Children's Hospital Medical Center Cincinnati, OH
- Eye Centers of Ohio Canton, OH
- Ophthalmology Consultants, Inc. Willoughby, OH
- Pediatric Ophthalmology Associates, Inc. Columbus, OH
- The Cleveland Clinic Foundation, Ophthalmology at Beachwood Beachwood, OH
- The Ohio State University Columbus, OH
- Dean A. McGee Eye Institute, University of Oklahoma Oklahoma City, OK
- Casey Eye Institute Portland, OR
- Family Eye Group Lancaster, PA
- Pediatric Ophthalmology of Erie Erie, PA
- Pennsylvania College of Optometry Philadelphia, PA
- Rhode Island Eye Institute Providence, RI
- Southern College of Optometry Memphis, TN
- Vanderbilt Eye Center Nashville, TN
- Pediatric Ophthalmology, P.A. Dallas, TX
- Texas Children's Hospital Houston, TX
- UT Southwestern Med Ctr Dallas, TX
- Eastern Virginia Medical School Norfolk, VA
- Medical College of Wisconsin Milwaukee, WI
- Children's Eye Care & Adult Strabismus Sugery South Charleston, WV
Journal
Archives of Ophthalmology