Learning Study: Improving Vision in Adults With Macular Degeneration

What this study is about

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.

Who can join (things the study team will check)

✅ You may be able to join if…

• 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)
• Central vision loss

🚫 You may not be able to join if…

• 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
• Severe hearing impairment.
• Contraindications for brain stimulation

Where this trial is running

• University of Waterloo, Waterloo, Ontario, Canada
• The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong

Who to contact

Ben Thompson, PhD · 15198884567 · ben.thompson@uwaterloo.ca

It's completely normal to call and ask questions before deciding anything. Mention the study ID: NCT04762368.