Improving Vision in Adults With Macular Degeneration
关键词
抽象
描述
This study will be carried out in Ontario, Canada (University of Waterloo) and Hong Kong (The Hong Kong Polytechnic University). There are two conditions: Active brain stimulation and sham/placebo brain stimulation. This study uses a within-subjects design, such that all participants will take part in both conditions on separate sessions.
Participants will be recruited from university-affiliated clinics and local clinical practices. Following full informed consent, participants will complete baseline testing and clinical testing to confirm that they meet eligibility criteria including: a diagnosis of macular degeneration without any additional eye disease, impaired vision but with enough visual acuity that the computer monitor can still present readable word, and no contraindications for brain stimulation interventions. Eligible participants will then be randomized to either receiving the active stimulation first or the placebo stimulation first.
The primary outcome measure is verbal reading accuracy for sentences presented on a computer screen following a Rapid Serial Visual Presentation (RSVP) task in which a single word is presented on the screen at a time. Participants will freely observe the words and will indicate the words on the screen verbally. The secondary outcome measures are crowded and uncrowded visual acuity as measured by Freiburg Visual Acuity & Contrast Test (FrACT) using the Landolt C stimulus. The "C"'s gap will be oriented randomly, and the participant will indicate the orientation of the stimulus. Crowded visual acuity will be assessed with Landolt C surrounded by a solid ring, while uncrowded visual acuity will be assessed with the Landolt C alone.
The study consists of 3 sessions:
Session 1: The first session will include the clinical evaluation. In addition, the first session will also collect the participant's individual RSVP performance threshold by presenting a variety of reading speeds and print sizes. The selected threshold will be the combination of print size and presentation speed required for a given participant to achieve roughly 55% performance accuracy.
Session 2 and 3: Brain stimulation sessions. At the start of each session, participants will perform baseline pre tests for the uncrowded and crowded visual acuity tasks as well as the RSVP task using their selected threshold from Session 1. They will then undergo a-tDCS to their primary visual cortex - this stimulation may be either active or placebo on any given day, but all participants will have been exposed to both sham and placebo by the end of Session 3. During the brain stimulation, participants will perform post tests for the primary outcome measure (RSVP) and the two secondary outcome measures (crowded and uncrowded visual acuity). Five minutes after the completion of the brain stimulation, participants will again perform all three post tests. A third set of post tests will be completed 30 minutes after the completion of the brain stimulation.
All outcome measures will be analyzed by comparing the baseline (pre test) scores to the post test scores, examining whether the active brain stimulation condition resulted in greater post test improvement relative to the placebo brain stimulation condition. The time course of the effect of brain stimulation will also be examined by comparing the effect of brain stimulation at each of the 3 post tests to one another.
日期
最后验证: | 06/30/2020 |
首次提交: | 09/22/2019 |
提交的预估入学人数: | 09/26/2019 |
首次发布: | 09/30/2019 |
上次提交的更新: | 07/22/2020 |
最近更新发布: | 07/26/2020 |
实际学习开始日期: | 11/30/2019 |
预计主要完成日期: | 02/28/2021 |
预计完成日期: | 02/28/2021 |
状况或疾病
干预/治疗
Device: anodal tDCS Active Stimulation
Device: anodal tDCS Sham/Placebo Stimulation
相
手臂组
臂 | 干预/治疗 |
---|---|
Experimental: Active then Sham Participants in this arm will be exposed to active stimulation during session 1 and sham/placebo stimulation during session 2 | |
Experimental: Sham then Active Participants in this arm will be exposed to sham/placebo stimulation during session 1 and active stimulation during session 2 |
资格标准
有资格学习的年龄 | 18 Years 至 18 Years |
有资格学习的性别 | All |
接受健康志愿者 | 是 |
标准 | Inclusion Criteria: 1. Diagnosis of AMD (age 60+) or JMD (current age 18+). 2. Central vision loss and use of a peripheral preferred retinal locus (PRL) to fixate on visual objects, as confirmed by a microperimeter. 3. Visual acuity (VA); between 0.5 and 1.0 logMAR inclusive (6/18-6/60) in the better eye. 4. Best-corrected near visual acuity of 4.0M at 40 cm or better in the better eye 5. Stable vision for the previous 3 months (by patient report). Exclusion Criteria: 1. Diagnosed dementia. 2. Not fluent in reading English (Waterloo) or Chinese characters (Hong Kong). 3. Any ocular surgery (including anti-vegF injections) within the duration of the study. 4. Ocular pathology other than JMD or AMD that can reduce central vision. 5. Severe hearing impairment. 6. Contraindications for brain stimulation |
结果
主要结果指标
1. Rapid Serial Visual Presentation (RSVP) Reading Pre-Test [This test is roughly 6 minutes in length, occurring before brain stimulation.]
2. Rapid Serial Visual Presentation (RSVP) Reading Post-Test 1 (during stimulation) [This test is roughly 6 minutes in length, occurring during the 20 minute brain stimulation period.]
3. Rapid Serial Visual Presentation (RSVP) Reading Post-Test 2 (5 min after stimulation) [This test is roughly 6 minutes in length, occurring 5 minutes after the completion of stimulation.]
4. Rapid Serial Visual Presentation (RSVP) Reading Post-Test 3 (30 min after stimulation) [This test is roughly 6 minutes in length, occurring 30 minutes after the completion of stimulation.]
次要成果指标
1. Uncrowded Visual Acuity Pre-Test [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Pre-Test" before brain stimulation.]
2. Uncrowded Visual Acuity Post-Test 1 (during stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 1" while brain stimulation is ongoing.]
3. Uncrowded Visual Acuity Post-Test 2 (5 min after Stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 2" 5 minutes after brain stimulation completion.]
4. Uncrowded Visual Acuity Post-Test 3 (30 min after Stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 3" 30 minutes after brain stimulation completion.]
5. Crowded Visual Acuity Pre-Test [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Pre-Test" before brain stimulation.]
6. Crowded Visual Acuity Post-Test 1 (during stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 1" while brain stimulation is ongoing.]
7. Crowded Visual Acuity Post-Test 2 (5 min after stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 2" 5 minutes after brain stimulation completion.]
8. Crowded Visual Acuity Post-Test 3 (30 min after stimulation) [Roughly 2 minutes in length, administered after the primary outcome measure "RSVP Reading Post-Test 3" 30 minutes after brain stimulation completion.]