skip navigation

S M L Text size
Home » Resources » Clinical Studies » A Randomized Trial Comparing Part-time Versus Full-time Patching for Severe Amblyopia

NEI Clinical Studies

Archived Page

The information on this page is archived and provided for reference purposes only. It was current when it was produced, but may now be out-of-date. Persons having difficulty accessing this information may contact for assistance. For reliable, current information on this and other topics, we recommend that you visit the National Eye Institute website index.

A Randomized Trial Comparing Part-time Versus Full-time Patching for Severe Amblyopia

Purpose | Background | Description | Patient Eligibility | Recruitment Status | Current Status | Results | Publications | Resource Centers | NEI Representative



Amblyopia is the most common cause of monocular visual impairment in both children and young and middle-aged adults. Patching has been the mainstay of amblyopia therapy. It is generally held that the response to treatment is best when it is instituted at an early age, particularly by age two or three, and is poor when attempted after eight years of age.

For severe amblyopia, it is generally accepted that occlusion with patching is the standard of care. Other modalities of treatment, such as atropine penalization and optical penalization, are widely considered insufficient as initial treatments for severe amblyopia. However, controversy exists with regard to how many hours per day of patching should be prescribed. Advocates of full-time patching purport that such a regimen is needed to restore visual acuity more rapidly and more effectively. Advocates of part-time patching believe it to be better tolerated by the child and family, therefore producing less stress on the parent-child relationship and producing better results through better compliance. Part-time patching may also promote the development of binocularity in patients who have "straight-eyes", reduce the chance of a straight-eyed patient developing manifest strabismus or losing stereopsis, and reduce the incidence of reverse- or occlusion-amblyopia.


The study is a randomized trial comparing daily patching regimes for children with severe amblyopia. It will consist of about 160 children. Patients in the severe (20/100 to 20/400) group will patch part-time (6 hours) or full-time (all or all but one waking hour) of each day for the 4 month study period. There are at least two follow up visits during the 4-month period. Visual acuity is the major study outcome. It is assessed at the 4-month exam.

Patient Eligibility

Patients must be less than 7 years of age with original cause of amblyopia due strabismus or anisometropia (a refractive error difference of more than one diopter between the two eyes.) Visual acuity in the amblyopic eye must be between 20/100 and 20/400, visual acuity in the sound eye of 20/40 or better and there must be at least 3 lines of acuity difference between the two eyes. Patients must have had no patching treatment (other than spectacles) within six months prior to enrollment and no other amblyopia treatment of any type used within one month prior to enrollment.

Patient Recruitment Status

Completed. Recruitment began in May 2001 and closed in April 2003 after 175 patients were enrolled.

Current Status of Study



For severe amblyopia, prescribing six hours of daily patching produces an improvement in visual acuity that is of similar magnitude to the improvement produced by prescribing full-time daily patching in children 3 to less than 7 years of age.


The Pediatric Eye Disease Investigator Group: A Randomized Trial of Patching Regimens for Treatment of Severe Amblyopia in Children. Ophthalmology 110, Number 11: 2075-2087, 2003.

Resource Centers

Co-Chairman's Office
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

Michael X. Repka, M.D.
Wilmer Eye Institute
233 N. Wolfe Street
Baltimore, MD 21287-9028
Telephone: (410) 955-8314
Fax: (410) 955-0809

Data Coordinating Center
Roy W. Beck, Ph.D.
Pamela S. Moke, M.S.P.H.
Raymond T. Kraker, M.S.P.H.
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

NEI Representative

Donald F. Everett, M.A.
National Eye Institute
National Institutes of Health
Suite 1300
5635 Fishers Lane MSC 9300
Bethesda, MD 20892-9300
Telephone: (301) 451-2020
Fax: (301) 402-0528

Last Updated: 3/15/2004

Department of Health and Human Services NIH, the National Institutes of Health