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Effect of Transcranial Magnetic Stimulation on Visual Functions of Adult Amblyopia: a Preliminary Study

Primary Purpose

Amblyopia

Status
Recruiting
Phase
Not Applicable
Locations
Taiwan
Study Type
Interventional
Intervention
Theta burst transcranial magnetic stimulation (TBS) procedure
Sponsored by
National Taiwan University Hospital
About
Eligibility
Locations
Arms
Outcomes
Full info

About this trial

This is an interventional health services research trial for Amblyopia focused on measuring Transcranial magnetic stimulation, Amblyopia, Neuroplasticity

Eligibility Criteria

20 Years - 50 Years (Adult)All SexesDoes not accept healthy volunteers

Inclusion Criteria:

  1. Adult amblyopia participants, aged 20-50 years old.
  2. Based on inclusion criteria, there was a minimum of 2 lines difference in BCVA between the 2 eyes.
  3. An amblyogenic factor and history of amblyopia treatment was recorded

Exclusion Criteria:

  1. Unstable vital sign
  2. History of brain injury and/or head trauma
  3. Neurological and psychiatric disease
  4. Seizures or family history of seizure
  5. Pregnancy
  6. Uncontrolled migraine or the presence of metallic implants or shunt in the head or torso
  7. Wide region of ischemic cicatrix, multiple sclerosis, taking tricycle antidepressants,
  8. Analgesics or any drugs may decrease the threshold for inducing seizure
  9. Experienced sleep disorders during the rTMS treatment
  10. Severe alcoholism or taking seizure drugs
  11. Severe heart diseases or uncontrollable migraine caused by high intracranial pressure

Sites / Locations

  • National Taiwan University HospitalRecruiting

Arms of the Study

Arm 1

Arm 2

Arm 3

Arm Type

Experimental

Experimental

Sham Comparator

Arm Label

Intermittent theta burst

Continuous theta burst

Sham theta burst

Arm Description

The total TBS time is about 1 to 3 minutes and the subjects have to look at at a visual stimulus on a computer monitor while receiving TBS and continue the visual training until 20 minutes after the treatment. In iTBS group, the subjects look at the visual stimulus with amblyopic eye while in cTBS group, subjects look at visual stimulus with non-amblyopic eye. The subjects will receive three times of stimulations in one week. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.

The total TBS time is about 1 to 3 minutes and the subjects have to look at at a visual stimulus on a computer monitor while receiving TBS and continue the visual training until 20 minutes after the treatment. In iTBS group, the subjects look at the visual stimulus with amblyopic eye while in cTBS group, subjects look at visual stimulus with non-amblyopic eye. The subjects will receive three times of stimulations in one week. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.

The stimulus intensity in sham group is about half of that in iTBS/cTBS groups, and the subjects receive a placebo stimulation with the coil orientation tilted to 90°. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.

Outcomes

Primary Outcome Measures

Objective
Change from baseline best corrected visual acuity: distance visual acuity measured for each eye at a distance of 6 m. Visual acuity scored letter-by-letter instead and lonarithm of the minimum angle of resolution (logMAR) scores were recored.

Secondary Outcome Measures

Full Information

First Posted
May 2, 2022
Last Updated
March 6, 2023
Sponsor
National Taiwan University Hospital
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1. Study Identification

Unique Protocol Identification Number
NCT05393739
Brief Title
Effect of Transcranial Magnetic Stimulation on Visual Functions of Adult Amblyopia: a Preliminary Study
Official Title
Effect of Transcranial Magnetic Stimulation on Visual Functions of Adult Amblyopia: a Preliminary Study
Study Type
Interventional

2. Study Status

Record Verification Date
January 2023
Overall Recruitment Status
Recruiting
Study Start Date
January 5, 2023 (Actual)
Primary Completion Date
December 31, 2023 (Anticipated)
Study Completion Date
December 31, 2024 (Anticipated)

3. Sponsor/Collaborators

Responsible Party, by Official Title
Sponsor
Name of the Sponsor
National Taiwan University Hospital

4. Oversight

Studies a U.S. FDA-regulated Drug Product
No
Studies a U.S. FDA-regulated Device Product
No

5. Study Description

Brief Summary
Amblyopia, with a prevalence rates of 3% in adult population, is a common cause of vision impairment. It is characterized by impaired vision in one or both eyes because of disruption of normal visual stimuli and underdevelopment of the visual cortex, leads to lifelong visual deficits affecting both monocular and binocular visual function. Common causes of amblyopia include refraction error, anisometropia, strabismus and visual deprivation arising from ptosis or congenital cataract. Our previous studies had shed light on the relationship between abnormal early visual experience, and development of later amblyopia and possible neural developmental disorders. Functional recovery is difficult when neuroplasticity slows down at the end of the critical period. To date, there is no established effective treatment for adult amblyopia. Repetitive transcranial magnetic stimulation (rTMS) is one of the non-invasive stimulations had been used widely as a research tool to understand the brain functions and an established treatment modality in neuropsychiatric diseases. Theta burst stimulation (TBS) is a newer form of rTMS protocol which have a major advantage over traditional rTMS in their reduced administration duration and allowing stimulation at significantly lower intensities to attain comparable effects. TBS had been demonstrated to able to improve functions in participants with visual disorders. However, studies of its use on adult amblyopia are scarce. Due to lack of efficient treatment at present, it is of scientific significance to conduct placebo-controlled experiments on this topic. Investigators will evaluate the effect of three regimens of TBS (intermittent, continuous and sham), after one session and accumulative sessions, on visual functions of amblyopia adults shortly after treatment and 2 weeks later (lasting effect), in order to evaluate its potential role in amblyopia and find out the best paradigm for amblyopia treatment.

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
Amblyopia
Keywords
Transcranial magnetic stimulation, Amblyopia, Neuroplasticity

7. Study Design

Primary Purpose
Health Services Research
Study Phase
Not Applicable
Interventional Study Model
Crossover Assignment
Masking
Participant
Allocation
Randomized
Enrollment
30 (Anticipated)

8. Arms, Groups, and Interventions

Arm Title
Intermittent theta burst
Arm Type
Experimental
Arm Description
The total TBS time is about 1 to 3 minutes and the subjects have to look at at a visual stimulus on a computer monitor while receiving TBS and continue the visual training until 20 minutes after the treatment. In iTBS group, the subjects look at the visual stimulus with amblyopic eye while in cTBS group, subjects look at visual stimulus with non-amblyopic eye. The subjects will receive three times of stimulations in one week. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.
Arm Title
Continuous theta burst
Arm Type
Experimental
Arm Description
The total TBS time is about 1 to 3 minutes and the subjects have to look at at a visual stimulus on a computer monitor while receiving TBS and continue the visual training until 20 minutes after the treatment. In iTBS group, the subjects look at the visual stimulus with amblyopic eye while in cTBS group, subjects look at visual stimulus with non-amblyopic eye. The subjects will receive three times of stimulations in one week. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.
Arm Title
Sham theta burst
Arm Type
Sham Comparator
Arm Description
The stimulus intensity in sham group is about half of that in iTBS/cTBS groups, and the subjects receive a placebo stimulation with the coil orientation tilted to 90°. The visual function evaluation includes BCVA, contrast sensitivity and stereoacuity. Visual functions will be evaluated right after TBS session (t1). Participant will receive same type of treatment for another 2 times within one week followed by visual function tests (t2). To evaluate the long-term effect, participants will be followed for another visual function tests (t3) after 2 weeks.
Intervention Type
Device
Intervention Name(s)
Theta burst transcranial magnetic stimulation (TBS) procedure
Intervention Description
The procedure includes determining the specific occipital point at which place the stimulation coil; this corresponds to the area where magnetic stimulation is most capable of inducing phosphenes or transient visual phenomena. The phosphenes are directly induced by stimulation of the visual cortex and their presence indicates that the magnetic stimulation is in the correct location. The subjects would wear a personalized swimming cap with the determined area for stimulation marked on it. The major differences between iTBS and cTBS are the frequency and interval of stimulus.
Primary Outcome Measure Information:
Title
Objective
Description
Change from baseline best corrected visual acuity: distance visual acuity measured for each eye at a distance of 6 m. Visual acuity scored letter-by-letter instead and lonarithm of the minimum angle of resolution (logMAR) scores were recored.
Time Frame
1 month for each participant

10. Eligibility

Sex
All
Minimum Age & Unit of Time
20 Years
Maximum Age & Unit of Time
50 Years
Accepts Healthy Volunteers
No
Eligibility Criteria
Inclusion Criteria: Adult amblyopia participants, aged 20-50 years old. Based on inclusion criteria, there was a minimum of 2 lines difference in BCVA between the 2 eyes. An amblyogenic factor and history of amblyopia treatment was recorded Exclusion Criteria: Unstable vital sign History of brain injury and/or head trauma Neurological and psychiatric disease Seizures or family history of seizure Pregnancy Uncontrolled migraine or the presence of metallic implants or shunt in the head or torso Wide region of ischemic cicatrix, multiple sclerosis, taking tricycle antidepressants, Analgesics or any drugs may decrease the threshold for inducing seizure Experienced sleep disorders during the rTMS treatment Severe alcoholism or taking seizure drugs Severe heart diseases or uncontrollable migraine caused by high intracranial pressure
Central Contact Person:
First Name & Middle Initial & Last Name or Official Title & Degree
Tzu-Hsun Tsai, PhD
Phone
886223123456
Ext
65906
Email
lucia_tsai@yahoo.com.tw
Overall Study Officials:
First Name & Middle Initial & Last Name & Degree
Tzu-Hsun Tsai
Organizational Affiliation
National Taiwan University Hospital
Official's Role
Principal Investigator
Facility Information:
Facility Name
National Taiwan University Hospital
City
Taipei county
ZIP/Postal Code
100225
Country
Taiwan
Individual Site Status
Recruiting
Facility Contact:
First Name & Middle Initial & Last Name & Degree
Tzu-Hsun Tsai, PhD
Phone
886223123456
Ext
65906
Email
lucia_tsai@yahoo.com.tw

12. IPD Sharing Statement

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Effect of Transcranial Magnetic Stimulation on Visual Functions of Adult Amblyopia: a Preliminary Study

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