Credit: National Eye Institute, National
Institutes of Health
Full size image available through contact |
Patching the unaffected eye of children with moderate amblyopia for two hours daily works as well as patching the eye for six hours. This research finding should lead to better compliance with treatment and improved quality of life for children with amblyopia, or "lazy eye," the most common cause of visual impairment in childhood. These results appear in the May issue of Archives of Ophthalmology.
"These results will change the way doctors treat moderate amblyopia and make an immediate difference in treatment compliance and the quality of life for children with this eye disorder," said Paul A. Sieving, M.D., Ph.D., director of the National Eye Institute, one of the Federal government's National Institutes of Health and the agency that sponsored the study. "This is very important, because it is estimated that as many as three percent of children in the U.S. have some degree of vision impairment due to amblyopia."
After four months of treatment, children with moderate amblyopia who wore an adhesive patch daily for two hours over their unaffected eye showed the same improvement in vision as those who wore a patch for six hours. Placing an opaque adhesive patch, or eye bandage, over the unaffected eye for six hours daily is considered one of the standard treatments for moderate amblyopia. Both groups of children in the study performed one hour a day of "near" work, such as coloring, tracing, reading, and crafts, while their eye was patched.
Amblyopia, which usually begins in infancy or childhood, is a condition of poor vision in an otherwise healthy eye because the brain has learned to favor the other eye. Although the eye with amblyopia often looks normal, there is interference with normal visual processing that limits the development of a portion of the brain responsible for vision. The most common causes of amblyopia are crossed or wandering eyes or significant differences in refractive error, such as farsightedness or nearsightedness, between the two eyes.
"Prior to these results, many children with amblyopia had to wear an eye patch during school hours," Dr. Sieving said. "For these children, the accompanying social and psychological stigma was very real. Many were stared at and teased by other children, which made them feel different. Now, children can look forward to attending school without the patch. This will make them feel better about themselves."
Dr. Sieving said it is crucial for young children to comply with the recommended treatment because visual impairment can persist into adulthood if amblyopia is not successfully treated in early childhood. Amblyopia is the most common cause of monocular (one eye) visual impairment among children and young and middle-aged adults.
"Because the daily burden to administer treatment for amblyopia falls on the parent, the findings from this study will immediately affect families that have young children with this eye disorder," said study chairman Michael Repka, M.D., professor of ophthalmology and pediatrics at the Wilmer Eye Institute of Johns Hopkins University School of Medicine in Baltimore. "The findings make it much easier for parents to monitor their children and encourage children to successfully comply with treatment. Timely and successful treatment for amblyopia in childhood can prevent lifelong visual impairment."
Patching the unaffected eye has been the mainstay of amblyopia treatment for decades. In March 2002, the same researchers reported the effectiveness of a second treatment, which involved using atropine eye drops that dilated the unaffected eye, temporarily blurring vision. Both treatments force the child to use the eye with amblyopia, stimulating vision improvement in that eye by helping the part of the brain that manages vision to develop more completely. However, with patching, opinions varied widely on the number of daily hours it should be prescribed. No prior study had provided conclusive evidence of the optimal number of patching hours.
In this study, 189 children less than seven years old with moderate amblyopia were randomly assigned to receive either two hours or six hours of daily patching. The average age of the children was 5.2 years. Both groups showed significant improvement in the vision of the eye with amblyopia. "After four months, we found that 79 percent of children in the two-hour group and 76 percent of the patients in the six-hour group could read at least two more lines on the standard eye chart," Dr. Repka said. "The study also found that parents of children who wore the patch for six hours were more concerned about social stigma than the parents of children who wore the patch for two hours."
Dr. Repka said having the child perform one hour of "near," or close-up, work per day while patched was an important part of the prescribed treatment. He said it remains unclear if the same amount of visual improvement would occur with patching alone. "We are planning a clinical trial to address the importance of near work in the treatment of amblyopia," he said.
Dr. Repka noted that these results do not necessarily apply to all children with amblyopia. "Children with more severe amblyopia, or who have amblyopia from causes other than crossed eyes or refractive error, may need a different treatment regimen," he said. "The Pediatric Eye Disease Investigator Group (PEDIG), which conducted this study, is currently conducting a clinical trial on children with severe amblyopia and expects the results will be available in the Fall of 2003."
The study described in this release was conducted by the PEDIG at 35 clinical sites throughout North America. The PEDIG 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 funded by the National Eye Institute and 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. Background
A Randomized Trial Comparing Part-time to Minimal-time Patching for Moderate Amblyopia
The term "amblyopia" derives from the Greek word for "dullness of vision." It is estimated that amblyopia affects two or three of every 100 children in the United States.
The disorder is caused by conditions that affect normal visual development. 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 can also 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.
Despite the common occurrence of amblyopia, there has been little quality data on its natural history. For decades, patching the unaffected eye had been the standard treatment for amblyopia (In March 2002, researchers reported the effectiveness of drug therapy with a cycloplegic eye drop [atropine] that dilates the pupil and blurs the image seen by the unaffected eye). However, opinions varied widely on the number of hours of patching per day that should be prescribed. No prior study had provided conclusive evidence of the optimal number of prescribed patching hours. This information would be crucial, since reported rates of compliance for patching varied widely, from 49 to 87 percent. Compliance with the prescribed dosage of patching hours is an important factor in determining the level of success of amblyopia treatment.
A Randomized Trial Comparing Part-time to Minimal-time Patching
To address the clinical issue of the optimal number of patching hours for moderate amblyopia, researchers conducted a clinical trial called A Randomized Trial Comparing Part-time to Minimal-time Patching for Moderate Amblyopia. Its purpose was to compare two hours versus six hours of daily patching for children with moderate amblyopia (20/40 to 20/80) and less than seven years of age. The study was funded by the National Eye Institute and conducted by the Pediatric Eye Disease Investigator Group (PEDIG), a network of eye care professionals at universities and community offices in North America. The PEDIG professionals have a goal of determining the best treatment for various eye problems in children.
Between May 2001 and May 2002, 189 patients entered the trial, with 95 randomly assigned to the two-hour patching group and 94 assigned to the six-hour patching group. The number of patients enrolled per site at the 35 sites ranged from one to 21 (median three). The average age of the patients was 5.2 years; 44 percent were female, and 85 percent were white. To avoid including in the study those patients whose prior treatment was unsuccessful, enrollment was restricted to children who had not been previously treated for amblyopia; or had not received patching treatment within six months of enrollment and had not received other amblyopia treatment of any type (other than eyeglasses) within one month of enrollment.
Parents in both groups were advised that the daily hours of patching should be continuous when possible. In addition to patching, parents were instructed to have the child spend at least one of the hours of patching time each day doing "near" visual activities, such as reading, writing homework assignments, making crafts, coloring, tracing, cutting out objects, connecting dots, doing hidden pictures and word finds, playing computerized video games, or other activities requiring eye-hand coordination. Instructions of one hour of near activities were identical in both the two-hour and six-hour patching groups.
After four months, 97 percent of patients in the two-hour group and 95 percent in the six-hour group completed the primary outcome exam. Patients in both groups showed substantial improvement in the eye with amblyopia, averaging 2.40 lines from baseline in each group. At four months, 79 percent of patients in the two-hour group and 76 percent of patients in the six-hour group had improved by two or more lines on the eye chart.
Vision in the unaffected eye decreased by either one or two lines on the standard eye chart in about 21 percent of patients in the two-hour group, and about 24 percent of patients in the six-hour group. However, this is normal for patients with amblyopia, and vision in the unaffected eye is expected to return to normal when treatment is completed.
Researchers note that the amount of vision improvement after four months in the eye with amblyopia should not be considered to be the maximum amount of improvement that can occur with patching. Instead, four months represented the maximum length of time they believed the treatments could be maintained in the study before either increasing the prescribed number of hours of patching or switching to an alternate treatment for amblyopia might be necessary.
Part-Time vs. Minimal Time Patching for Amblyopia
Current Principal Investigators & Study Centers
Clinical Centers
Alabama
Wendy L. Marsh-Tootle, O.D.
Robert P. Rutstein, O.D.
University of Alabama at Birmingham
School of Optometry
1716 University Boulevard
Birmingham, AL 35294
Alaska
Robert W. Arnold, M.D.
Ophthalmic Associates
542 West Second Avenue
Anchorage, AK 99501-2242
Alberta (Canada)
William F. Astle, M.D.
Anna L. Ellis, M.D.
Alberta Children's Hospital
1820 Richmond Road, SW
Calgary, Alberta T2T 5C7 Canada
California
Carmen Barnhardt, O.D.
Susan A. Cotter, O.D.
Raymond H. Chu, O.D.
Susan M. Shin, O.D.
Southern California College of Optometry
2575 Yorba Linda Boulevard
Fullerton, CA 92831
James B. Ruben, M.D.
The Permanente Medical Group
1650 Response Road
Sacramento, CA 95815
Connecticut
Darron A. Bacal, M.D.
Eye Physicians & Surgeons, PC
202 Cherry Street
Milford, CT 06460
Andrew J. Levada, M.D.
The Eye Care Group, PC
1201 West Main Street, Suite 100
Waterbury, CT 06708
Florida
Susanna M. Tamkins. O.D.
NOVA Southeastern University
3200 S. University Drive
Ft. Lauderdale, FL 33328
Georgia
Scott R. Lambert, M.D.
The Emory Eye Center
Department of Ophthalmology
1365-B Clifton Road, N.E.
Atlanta, GA 30322
Illinois
Deborah R. Fishman, M.D.
Pediatric Eye Associates
3612 Lake Ave Unit 3
Wilmette, IL 60091-1000
Indiana
Daniel E. Neely, M.D.
David A. Plager, M.D.
Naval Sondhi, M.D.
Derek T. Sprunger, M.D.
Indiana University Medical Center
702 Rotary Circle
Indianapolis, IN 46202
Kansas
David A. Johnson, M.D.
Grene Vision Group
655 North Woodlawn
Wichita, KS 67208
Maryland
Stephen R. Glaser, M.D.
15235 Shady Grove Road, Suite 101
Rockville, MD 20850
Michael X. Repka, M.D.
Wilmer Eye Institute
233 Wilmer Institute
600 N. Wolfe Street
Baltimore, MD 21287-9028
Mexico City (Mexico)
Miguel Paciuc, M.D.
Paseo de las Palmas 735-1102
Lomas de Chapultepec
Mexico City 11000, Mexico
Michigan
Patrick J. Droste, M.D.
Robert J. Peters, O.D.
Pediatric Ophthalmology, P.C
5050 Cascade Road SE
Grand Rapids, MI 49546
Minnesota
Susan Schloff, M.D.
Associated Eye Care
280 N. Smith Ave
St. Paul, MN 55102
Jonathan M. Holmes, M.D.
Mayo Clinic
200 First Street, SW
Rochester, MN 55905
Stephen P. Christiansen, M.D.
C. Gail Summers, M.D.
University of Minnesota
Department of Ophthalmology
Box 493
420 Delaware Street, SE
Minneapolis, MN 55455
Missouri
Oscar A. Cruz, M.D.
Bradley V. Davitt, M.D.
Cardinal Glennon Children's Hospital
1465 South Grand Boulevard
St. Louis, MO 63104
North Carolina
David K. Wallace, M.D.
University of North Carolina
Department of Ophthalmology
617 Burnett-Womack, CB #7040
Chapel Hill, NC 27599-7040
Ohio
Constance E. West, M.D.
Children's Hospital Medical Center
3333 Burnet Avenue
Cincinnati, OH 45229
Richard W. Hertle, M.D.
Pediatric Ophthalmology Associates, Inc.
555 South 18th Street, Suite 4C
Columbus, OH 43025
Marjean T. Kulp, O.D.
The Ohio State University College of Optometry
P. O. Box 182342
Columbus, OH 43218
Pennsylvania
Brian J. Forbes, Ph.D., M.D.
Monte D. Mills, M.D.
Children's Hospital of Philadelphia
Wood Building, 1st Floor
34th & Civic Center Building
Philadelphia, PA 19104
David I. Silbert, M.D.
Family Eye Group
2110 Harrisburg Pike, Suite 215
Lancaster, PA 17604
Nicholas A. Sala, D.O.
Pediatric Ophthalmology of Erie
2201 W. 38th Street
Erie, PA 16506
Mitchell M. Scheiman, O.D.
Pennsylvania College Of Optometry
1200 West Godfrey Avenue
Philadelphia, PA 19141
Rhode Island
Glenn E. Bulan, M.D.
D. Robbins Tien, M.D.
Pediatric Ophthalmology & Strabismus Assoc.
2 Dudley Street, Suite 505
Providence, RI 02905
John P. Donahue, M.D., Ph.D.
Rhode Island Eye Institute
150 East Manning Street
Providence, RI 02906
Texas
David R. Stager, Sr., M.D.
Pediatric Ophthalmology, P.A.
8201 Preston Road, Suite 140A
Dallas, TX 75225-6203
David K. Coats, M.D.
Evelyn A. Paysse, M.D.
Texas Children's Hospital
6621 Fannin, CCC-640.00
Houston, TX 77030
David R. Weakley, Jr., M.D.
University of Texas Southwestern Medical Ctr.
5323 Harry Hines Boulevard
Dallas, TX 75235-9057
Virginia
Earl R. Crouch, Jr., M.D.
Eastern Virginia Medical School
Department of Ophthalmology
880 Kempsville Road, Suite 2500
Norfolk, VA 23502-3931
Wisconsin
Jane D. Kivlin, M.D.
Mark S. Ruttum, M.D.
Medical College of Wisconsin
925 N. 87th Street
Milwaukee, WI 53226-4812
Resource Centers
Co-Chairman's Office
Michael X. Repka, M.D.
Wilmer Eye Institute
233 Wilmer Institute
600 N. Wolfe Street
Baltimore, MD 21287-9028
Telephone: (410) 955-8314
Fax: (410) 955-0809
E-mail: mrepka@jhmi.edu
Jonathan M. Holmes, M.D.
Mayo Clinic
Department of Ophthalmology W7
200 First Street Southwest
Rochester, MN 55905
Telephone: (507) 284-3760
Fax: (507) 284-8566
E-mail: holmes.jonathan@mayo.edu
Data Coordination Center
Roy W. Beck, Ph.D.
Pamela S. Moke, M.S.P.H.
.
Raymond T. Kraker, M.S.P.H.
Danielle L. Chandler, M.S.P.H.
R. Clifford Blair, Ph.D.
Heidi A. Gillespie
Alisha N. Lawson
Nicole M. Boyle
Julie A. Gillett
Shelly T. Mares
Brian B. Dale
Jaeb Center for Health Research
3010 E 138th Avenue, Suite 9
Tampa, FL 33613
Telephone: (813) 975-8690
Fax: (813) 975-8761
E-mail: pedig@jaeb.org
http://public.pedig.jaeb.org/
NEI Representative
Donald F. Everett, M.A.
National Eye Institute
6120 Executive Boulevard, MSC 7164
Executive Plaza South, Suite 350
Bethesda, MD 20892-7164
Telephone: 301-451-2020
Fax: 301-402-0528
Journal
Archives of Ophthalmology