About this trial

The purpose of this study is to test whether a kind of brain stimulation called anodal transcranial direct current stimulation (a-tDCS) can be combined with perceptual learning to improve the ability of people with age-related macular degeneration (AMD) or juvenile macular degeneration (JMD) to read words presented to them on a computer screen better than if perceptual learning alone were used.

In addition, secondary measures of visual acuity will also be examined to determine whether brain stimulation can allow patients to resolve finer details of an image. The proposed treatment is the application of a-tDCS onto the participant's head, with brain stimulation aimed at Primary Visual Cortex toward the occipital pole, while patients undergo six separate sessions of training. The investigators will test the ability of participants to read words before the start of the training sessions (pre test) and after the completion of all training sessions (post test). This is a between-subjects design, and half of the participants will receive true stimulation, and the other half will receive sham stimulation. The difference between the pre and post tests when receiving active stimulation will be compared to the difference when receiving sham stimulation, because the sham stimulation is not expected to influence reading beyond a placebo. The aim of the study is to examine the potential of concurrent brain stimulation and perceptual learning as an effective treatment for macular degeneration that may be used in conjunction with more traditional eye-based interventions. The investigators hypothesize that the brain stimulation will enable higher performance in the reading task after and secondary measures after perceptual training due to an increase in the cortical excitability of the stimulated brain cells.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

Diagnosis of AMD (age 60+) or JMD (current age 18+).

Visual acuity (VA); between 6/9-6/96 in the better eye

Best-corrected near visual acuity of 4.0M at 40 cm or better in the better eye

Stable vision in previous 3 months (patient report)

Disqualifiers

Diagnosed dementia.

Not fluent in reading English (Waterloo) or Chinese characters (Hong Kong).

Any ocular surgery (including anti-vegF injections) within the duration of the study, except for: A. Chronic and continuous injections for at least 1 year. B. Injections stopped at least 2 months before participation. C. Injections in the untested eye

Ocular pathology other than JMD or AMD that can significantly reduce central vision. Example: mild cataract of grade 2 or below is acceptable

Trial design

Design model

Parallel

Treatments tested in this trial

Active anodal tDCS
Device
a weak electric current is applied to the head through electrodes to affect the cortical excitability of the targeted cells in the brain.
Sham anodal tDCS
Device
The tDCS machine will be used as in active stimulation, except the electrical current will not be applied.

Treatment groups

30 Participants

are divided into 2 treatment groups

Group A: Active + TrainingActive comparator 1 intervention

Group B: Sham + TrainingSham comparator 1 intervention

Trial outcomes

Primary outcomes

1

Change in Rapid Serial Visual Presentation (RSVP) Reading performance before and right after training.

Behavioral Measure - Participants will verbally read words presented on a computer. A variety of speeds and sizes will be presented, so that an accurate measure of the maximum reading speed, and the smallest text size readable at the maximum reading speed can be calculated. The maximum reading speed and smallest text size will be measured before and after training. The outcome measures are the change in these reading measurements from pre test to post test.

Time frame

The pre test and post test will take roughly 1 hour to complete, and they will be roughly 4-7 weeks apart.

2

Change in Rapid Serial Visual Presentation (RSVP) Reading performance 30 days after training

Behavioral Measure - Participants will verbally read words presented on a computer. A variety of speeds and sizes will be presented, so that an accurate measure of the maximum reading speed, and the smallest text size readable at the maximum reading speed can be calculated. The maximum reading speed and smallest text size will be measured before and after training. The outcome measures are the change in these reading measurements from pre test to the 30 day follow up.

Time frame

The test will take roughly 1 hour to complete, and they will be roughly 7-10 weeks apart.

Secondary outcomes

1

Change in Uncrowded Visual Acuity before and just after training

Visual acuity as measured by participants indicating the orientation of the gap present in a Landolt C stimulus using the freely available FrACT software https://michaelbach.de/fract/index.html . The outcome measure is the change in performance from pre test to the post test

Time frame

The pre test and post test will take roughly 5 minutes to complete, and they will be roughly 4-7 weeks apart.

2

Change in Uncrowded Visual Acuity before and 30 days after training

Visual acuity as measured by participants indicating the orientation of the gap present in a Landolt C stimulus using the freely available FrACT software https://michaelbach.de/fract/index.html . The outcome measure is the change in performance from pre test to the 30 day follow up.

Time frame

The pre test and post test will take roughly 5 minutes to complete, and they will be roughly 7 to 10 weeks apart.

3

Change in Crowded Visual Acuity before and just after training

Visual acuity as measured by participants indicating the orientation of the gap present in a Crowded (Ring) Landolt C stimulus using the freely available FrACT software https://michaelbach.de/fract/index.html . The outcome measure is the change in performance from pre test to post test.

Time frame

The tests will take roughly 5 minutes to complete, and they will be roughly 4 - 7 weeks apart.

4

Change in Crowded Visual Acuity before and 30 days after training

Visual acuity as measured by participants indicating the orientation of the gap present in a Crowded (Ring) Landolt C stimulus using the freely available FrACT software https://michaelbach.de/fract/index.html . The outcome measure is the change in performance from pre test to the 30 day follow up.

Time frame

The tests will take roughly 5 minutes to complete, and they will be roughly 7 - 10 weeks apart.

Learning Study: Improving Vision in Adults With Macular Degeneration

About this trial

Eligibility criteria

Qualifiers

Disqualifiers

Trial design

Treatments tested in this trial

Treatment groups

Trial outcomes

Primary outcomes

Secondary outcomes

Other outcomes

Sponsors and contacts