Plow 2010.

Study characteristics
Methods	Restitutive intervention versus restitutive intervention Design: "Randomised controlled, double‐blind pilot trial" Stratification: no Randomisation sequence: "Participants were randomly assigned using a predetermined enrollment sequence to 1 of 2 arms". Method of randomisation not stated. Correspondence with the author provided the information that "as subjects were admitted, they were randomly assigned to one of two groups based on an a priori generated randomization strategy." Comparisons: 2 groups: vision restoration therapy with active transcranial direct current stimulation (VRT + tDCS) and vision restoration therapy with sham transcranial direct current stimulation (VRT + sham) Allocation concealment: yes: "Participants and investigators analyzing visual field outcomes were blinded to the tDCS mode (active versus sham)." Blinding: yes: "Participants and investigators analyzing visual field outcomes were blinded to the tDCS mode (active versus sham)." Power calculation: not stated Intention‐to‐treat analysis: no Other recruitment details: "A total of 150 potential participants were screened. Following comprehensive neurological and ophthalmological screening, 12 patients ... were enrolled". Patient and public involvement: not stated
Participants	Total study population: 12 Withdrawals: 4 Method of diagnosing VFD: high‐resolution perimetry Characteristics of population: participant details are listed in Table 6. Type and severity of visual problems: participant details are listed in Table 7. Inclusion criteria: "Patients with unilateral postchiasmal visual field loss following stroke or brain damage, who were in the chronic phase of recovery (> 3 months post‐lesion)". Participants were "aged over 18, with deep hemianopic field loss as defined and confirmed by monocular perimetry along with established structural damage of the post‐charismatic visual system as documented by standard neuroimaging techniques (CT or MRI), medical reports, or a combination of these. Participants also had cognitive, language and motor function sufficient to understand the experiments and follow instructions, had given informed written consent to participate in the study and had motivation to participate in the VRT program." Exclusion criteria: "Any ocular visual pathology or contraindication to noninvasive brain stimulation and tDCS. Specific criteria drawn from safety guidelines pertaining to the use of noninvasive cortical stimulation include 1) the presence of any metallic, mechanical, or magnetic implant in the head or implantable device (e.g. cardiac pacemaker); 2) prior history of seizure or familial history of seizure disorder in a first degree relative, and 3) chronic use of neuroactive medication (e.g. neurostimulants, anticonvulsants, or antidepressants)." Baseline comparison of treatment groups: not stated. Baseline data were provided, but no statistical comparison. Time since stroke did not appear to be comparable, with the VRT + tDCS group mean, 20.8 months (SD 26.6, range 3 to 72 months), and VRT + sham group mean, 58.7 months (SD 72.9, range 10 to 192 months). This study appeared to include participants with visual field defects only (no visual neglect), although the method of ensuring no visual neglect was unclear Method of diagnosing visual field defect: "monocular perimetry", no further details of method Method of diagnosing visual perceptual problems: not stated
Interventions	Group 1: visual restoration therapy + transcranial Direct Current Stimulation (VRT + tDCS) (n = 6; data available for n = 4) Intervention: computer‐based stimulation of the visual field with active transcranial direct current stimulation, 30‐minute sessions twice per day, 3 times per week for 3 months of vision restoration therapy and concurrent transcranial direct current stimulation of 2 mA/minute Intervention type: restorative. Materials: computer‐based restitution therapy: "Vision Restoration Therapy (VRT; Novavision Inc, Boca Raton, Florida)", transcranial Direct Current Stimulation: "tDCS was applied using two 5 × 7 cm2 saline‐soaked sponge electrodes connected to a 9‐V battery‐driven stimulator (IOMED Inc. Salt Lake City, Utah)". Procedures: vision restoration therapy: "Briefly, participants were seated in front of a computer screen at a constant viewing distance and instructed to detect (signaled by a key press) the presence of a flashed light stimulus while maintaining fixation on a central target. Built‐in fixation monitoring required patients to respond to a color change of the central fixation target occurring at random intervals. Target stimuli were presented primarily in the region of the transition zone (identified by a prior visual field test; see details on high‐resolution perimetry), and the spatial parameters of customized therapy were determined based on weekly progress and results of monthly tests." Transcranial direct current stimulation: "tDCS was applied using two 5 × 7 cm2 saline‐soaked sponge electrodes connected to a 9‐V battery‐driven stimulator delivering a constant current of 2 mA for the entire duration of the training procedure. Following the 10‐20 International EEG co‐ordinate system, the anode was placed at the occipital pole and the cathode (reference) was positioned at the vertex. Electrodes were then secured using nonlatex rubber straps, and an identical montage was worn by all patients throughout training." Provided by: University eye clinic. Delivery: face‐to‐face, individual, location University eye clinic (Table 5). Regimen: "We used a contracted VRT regimen lasting 3 months (2 half‐hour sessions, separated by a 30‐minute rest interval, for 3 d/wk)." Tailoring: not stated. Modification: not stated. Adherence: not stated Group 2: visual restoration therapy + sham transcranial Direct Current Stimulation (VRT + sham) (n = 6; data available for n = 4) Intervention: computer‐based stimulation of the visual field with sham transcranial direct current stimulation, 30‐minute sessions twice per day, 3 times per week for 3 months of vision restoration therapy, transcranial direct current stimulation turned on for 30 seconds then ramped down to zero and turned off. Intervention type: restorative. Materials: see above. "Experimental blinding with respect to active or sham transcranial direct current stimulation was implemented according to standard protocol guidelines described previously". Procedures: see above. Provided by: see above. Delivery: see above (Table 5). Regimen: see above. Tailoring: not stated. Modification: not stated. Adherence: not stated
Outcomes	See Table 8 Visual field ‐ high‐resolution perimetry: position of visual field border and stimulus detection accuracy Visual field ‐ subjective topograhic measure of perceived visual field deficit Extended ADL ‐ Veterans Affairs Low Vision‐Visual Functional Questionnaire (LV‐VFQ) QoL ‐ Vision Impairment (IVI) profile Other ‐ independent measure of fixation performance during training and HRP testing Time points when outcomes were assessed: baseline and at completion of training (3 months)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	"Participants were randomly assigned using a predetermined enrollment sequence to 1 of 2 arms". Method of randomisation not stated. Correspondence with the author provided the information that "as subjects were admitted, they were randomly assigned to one of two groups based on an a priori generated randomization strategy."
Blinding (performance bias and detection bias) All outcomes	Low risk	Correspondence with the author stated "the investigators assessing the visual field results (primary outcome) were also blinded to patient group assignment. Once visual field assessment was complete, they were provided with an encrypted copy of the data without any identifying information". Correspondence with the author stated "Blinding to stimulation (i.e. sham) was maintained by exploiting the inherent properties of tDCS. All patients wore the electrode montage regardless of the group they were relegated to. When the tDCS unit is turned on, current is slowly ramped up until the target current level is reached. During this time, patients will typically report a tingling or itching sensation beneath the surface of the anode electrode (overlying the occipital cortex). This sensation subsides shortly after a couple of minutes of habituation. Thus, in the experimental group, the current remains on but in the sham control group, the current is turned off. In either case, the patient is not aware of this happening. This fact is exploited for the purposes of experimental blinding since patients in the VRT + tDCS group can not perceive sensation of stimulation and neither can those patients who are in the VRT + sham tDCS group."
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were 4 dropouts who were not included in data analysis. Reasons for dropouts were provided, and were even between the groups. The author supplied the following information: "Out of 12 patients who were enrolled into the study, 4 (i.e. 2 from each group), were excluded or could not complete the study. Here are the reasons: VRT + tDCS group: Patient 1 ‐ excluded soon after randomization as she had an unrelated adverse event that excluded her from participation; Patient 2 ‐ excluded from analysis due to technical issues that could not allow us to ascertain whether sufficient tDCS current was being delivered throughout the training period. VRT + sham tDCS group: Patient 1: did not receive allocated intervention due to onset of medication use that was contraindicated with tDCS; Patient 2 ‐ discontinued due to onset of a medical condition that precluded her from further participation."
Other bias	Low risk	No other concerns noted