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Visual Cortex Stimulation in Patients With Amblyopia

This study has been completed.
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:
First received: November 17, 2004
Last updated: June 23, 2006
Last verified: June 2006

This study will examine whether direct current (DC) polarization (electrical stimulation) of the visual cortex can cause a temporary improvement of vision in an amblyopic eye of an adult. Amblyopia (also called lazy eye) is reduced vision in an eye, caused by abnormal brain processing of visual information. In amblyopia, the visual cortex (the part of the brain that processes visual information) favors the other eye and suppresses the image from the amblyopic eye.

Amblyopia in children is treated by patching or blurring the good eye, which forces the child to use the amblyopic eye and overcome suppression by the brain. This treatment only works in children 8 years old and younger, however. Electrical stimulation of the brain can temporarily change the function of the visual cortex in adults with good vision, but its influence on the visual function of people with amblyopia is unknown. If DC polarization can improve vision in amblyopic eyes in adults, it would show that the visual cortex is still plastic, and it might help researchers develop a treatment for adults with amblyopia in the future.

Patients 18 years of age and older with amblyopia caused by crossing in or turning out of the eyes in childhood or by a difference in near- or farsightedness between the eyes may be eligible for this study. Candidates are screened with a medical history and complete eye examination, including a glaucoma screening and checks of vision, in- or out-turning of the eyes, depth perception, need for glasses, and the interior structures of the eyes.

Participants undergo two study sessions, scheduled at least 24 hours apart, involving the following procedures:

  • Examination: Before each session, the patients' distance vision, contrast sensitivity (ability to see fading letters), and ability to read small print are checked in both eyes.
  • DC polarization: Patients receive either 20 minutes of electrical stimulation or 20 minutes of sham stimulation (each patient will receive both electrical and sham stimulation on different days).
  • Repeat examination: Immediately after the stimulation and again 20 minutes later, patients undergo repeat visual function testing. Those who show any differences in visual function 20 minutes after the stimulation are examined again 1 hour after the stimulation. Patients in whom the effect continues after 1 hour are examined again after 1 week.

Condition Intervention Phase
Amblyopia Anisometropic Ambyopia Amblyopia, Suppression Procedure: Anodal stimulation Phase 1

Study Type: Interventional
Study Design: Primary Purpose: Treatment
Official Title: Investigation of Visual Plasticity by a Direct Current Stimulation of Occipital Cortex in Adult Amblyopia

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 10
Study Start Date: November 2004
Estimated Study Completion Date: June 2006
  Show Detailed Description


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Amblyopia as defined by at least 2 logMAR units difference in the visual acuity between the two eyes as measured by ETDRS chart

VA in the sound eye 20/40 or better

VA in amblyopic eye 20/40-20/400

Amblyopia due to anisometropia, strabismus or both

No ocular cause of reduced VA and no prior ocular surgery


Deprivation amblyopia

Structural ocular disease or prior ocular trauma/surgery

Current serious medical or psychiatric condition of any kind

History of any significant trauma or medical condition affecting the brain or skull

History of epileptic seizure

History of significant psychiatric illness, i.e., requiring medication or hospitalization

Current use of neuroactive medication or recreational drugs


Presence of metal in the head other than dental hardware

Broken skin in the area of the stimulating electrodes

Presence of implantable pacemaker or defibrillator

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00097162

United States, Maryland
National Eye Institute (NEI)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Eye Institute (NEI)
  More Information

Publications: Identifier: NCT00097162     History of Changes
Other Study ID Numbers: 050005
Study First Received: November 17, 2004
Last Updated: June 23, 2006

Keywords provided by National Institutes of Health Clinical Center (CC):
Cortical Suppression
Impaired Vision
Cortical Plasticity
Adult Amblyopia

Additional relevant MeSH terms:
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Vision Disorders
Sensation Disorders
Neurologic Manifestations
Eye Diseases
Signs and Symptoms processed this record on August 17, 2017