This pilot study will test the preliminary efficacy and feasibility of an intervention protocol for one method of electric current stimulation, repetitive transorbital alternating current stimulation (rtACS), to treat visual impairment in people with glaucoma. We will evaluate a study protocol to use in future clinical trials to test the effectiveness of rtACS to ameliorate the progressive effects of vision loss both structurally and functionally in the eye, the visual pathway, and in regard to people's independence (i.e., functional ability). In this prospective, randomized controlled, double-masked pilot study, we will: 1) determine an effect of rtACS on ophthalmic structure and function (from retina to visual brain), 2) assess the methodology of procedures for assessment of people's functional ability and quality of life (QoL) to determine an effect of rtACS, and 3) assess the feasibility and implementation of the pilot study protocol for a larger multi-site, randomized controlled trial.
Participants will engage in baseline, intervention, post-intervention, and follow-up visits over the span of approximately 8 weeks. The expected outcomes for this project are that (1) rtACS activates viable but poorly or non-functional retinal ganglion cells to improve their structural and functional capabilities, (2) measures of retinal, optic nerve, and visual brain structures and function will correspond with improvement in visual function, and (3) changes in visual function following rtACS will be associated with improvements in participants' functional ability and QoL. rtACS has successfully been used in the rehabilitation of visual impairments in people with optic neuropathies; however, we do not know the clinical value of rtACS specifically for people with glaucoma, including the effect of rtACS on people's functional ability and QoL.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
18
Electric current stimulation; rtACS is a non-invasive application of electric current to stimulate the retina to induce synaptic efficacy, in particular those cells that have some measure of dysfunction but are not dead, and oscillations of nearby neuronal ensembles.
A computer-controlled sham stimulation function for masking interventionist to study group. The device will be used to deliver a weak electric current stimulation protocol to participants via electrodes placed transorbitally, with one reference electrode positioned elsewhere.
New York University School of Medicine
New York, New York, United States
Change in Peripapillary RNFL Thickness
Peripapillary retinal nerve fiber layer (RNFL) thickness (μm) measured using optical coherence tomography (OCT).
Time frame: Baseline, Week 4
Change in Macular Ganglion Cell-Inner Plexiform Layer Thickness
Macular ganglion cell-inner plexiform layer thickness (μm) measured using OCT.
Time frame: Baseline, Week 4
Percentage Change in ON Head Cup-to-Disc Ratio
Percentage change in optic nerve (ON) head cup-to-disc ratio measured using OCT.
Time frame: Baseline, Week 4
Change in Humphrey Visual Field Analyzer Score
The Humphrey Visual Field Analyzer assesses the mean deviation (dB), a measure of visual field sensitivity through threshold testing. dBs tested by the Humphrey analyzer range between 0 and 50 dB (0 is the brightest and 50 is the dimmest). A value of 0 means the patient could not see the brightest target, and a 50 means the dimmest target was seen. Most values are around 30 dB, and any numbers below this range imply a possible visual field defect.
Time frame: Baseline, Week 4
Change in Score on Assessment of Life Habits (LIFE-H), Short Form 3.1
The LIFE-H short form 3.1 is a 77-item questionnaire developed to measure: (1) how a respondent accomplishes regular activities and social roles and (2) respondent's satisfaction with how regular activities and social roles are accomplished. The LIFE-H total score is obtained by summing the scores on each item and then dividing by the number of items. The LIFE-H score ranges from 0 to 9, where a score of 0 indicates total handicap or total disruption in participation and a score of 9 means an optimal level of participation.
Time frame: Baseline, Week 4
Change in Minnesota Low Vision Reading Test (MNRead): Reading Acuity Score
An estimate of reading acuity is given by the smallest print size at which the patient can read the entire sentence without making significant errors. This method measures acuity to the nearest 0.1 logMAR. Each sentence in the MNRead Reading Acuity chart has 60 characters, which corresponds to 10 standard length words, assuming a standard word length of 6 characters (including a space). Reading acuity is calculated as follows: Reading acuity = size of smallest sentence read + 0.01 x number of errors.
Time frame: Baseline, Week 4
Change in Score on National Eye Institute Visual Functioning Questionnaire (VFQ-39)
National Eye Institute VFQ-39 measures health-related quality of life in 12 domains: general vision, ocular pain, near activities, distance activities, vision-specific social functioning, vision-specific mental health, vision-specific role difficulties, vision-specific dependency, driving, color vision, peripheral vision, and composite score. For each domain: the lowest and highest possible scores are 0 and 100 points, respectively. Higher score means higher functioning. The total score is the average of the domain scores.
Time frame: Baseline, Week 4
Change in Score on 36-Item Short Form Survey (SF-36)
The SF-36 is a 36-item patient-reported questionnaire that covers eight health domains: physical functioning (10 items), bodily pain (2 items), role limitations due to physical health problems (4 items), role limitations due to personal or emotional problems (4 items), emotional well-being (5 items), social functioning (2 items), energy/fatigue (4 items), and general health perceptions (5 items). Scores for each domain range from 0 to 100, with a higher score defining a more favorable health state. The total score is the average of the domain scores.
Time frame: Baseline, Week 4
VEP-Measured Amplitude (15% Contrast) at Baseline
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 15% contrast parameters.
Time frame: Baseline
VEP-Measured Latency (15% Contrast) at Baseline
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 15% contrast parameters.
Time frame: Baseline
VEP-Measured Amplitude (85% Contrast) at Baseline
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 85% contrast parameters.
Time frame: Baseline
VEP-Measured Latency (85% Contrast) at Baseline
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 85% contrast parameters.
Time frame: Baseline
VEP-Measured Amplitude (15% Contrast) at Week 4
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 15% contrast parameters.
Time frame: Week 4
VEP-Measured Latency (15% Contrast) at Week 4
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 15% contrast parameters.
Time frame: Week 4
VEP-Measured Amplitude (85% Contrast) at Week 4
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 85% contrast parameters.
Time frame: Week 4
VEP-Measured Latency (85% Contrast) at Week 4
Visual evoked potential (VEP) identifies decreased visual function and helps with discriminations of glaucomatous changes by measuring amplitude (micro volts) and latency (milliseconds (ms)) with 85% contrast parameters.
Time frame: Week 4
Pelli-Robson Contrast Sensitivity Chart Score at Baseline
The Pelli-Robson test measures contrast sensitivity using a single large letter size (20/60 optotype), with contrast varying across groups of letters. The chart uses letters (6 per line), arranged in groups whose contrast varies from high to low. Patients read the letters, starting with the highest contrast, until they are unable to read two or three letters in a single group. A score is assigned based on the contrast of the last group in which two or three letters were correctly read. The score, a single number, is a measure of the subject's log contrast sensitivity. A Pelli-Robson score of 2.0 indicates normal contrast sensitivity of 100 percent. Scores less than 2.0 signify poorer contrast sensitivity. Pelli-Robson contrast sensitivity score of less than 1.5 is consistent with visual impairment and a score of less than 1.0 represents in visual disability.
Time frame: Baseline
Pelli-Robson Contrast Sensitivity Chart Score at Week 4
The Pelli-Robson test measures contrast sensitivity using a single large letter size (20/60 optotype), with contrast varying across groups of letters. The chart uses letters (6 per line), arranged in groups whose contrast varies from high to low. Patients read the letters, starting with the highest contrast, until they are unable to read two or three letters in a single group. A score is assigned based on the contrast of the last group in which two or three letters were correctly read. The score, a single number, is a measure of the subject's log contrast sensitivity. A Pelli-Robson score of 2.0 indicates normal contrast sensitivity of 100 percent. Scores less than 2.0 signify poorer contrast sensitivity. Pelli-Robson contrast sensitivity score of less than 1.5 is consistent with visual impairment and a score of less than 1.0 represents in visual disability.
Time frame: Week 4
Early Treatment Diabetic Retinopathy Study (ETDRS) Visual Acuity Score (VAS) at Baseline
ETDRS charts have five Sloan letters on each line; the lines are of equal difficulty, and there is a geometric progression in letter size from line to line. Beginning with Chart 1, the right eye is tested with the left eye occluded. Following the completion of testing the right eye, the left eye is tested with Chart 2 while covering the right eye. Each letter is scored as right or wrong. Correct letters are circled on the scoresheet. Each letter read correctly is assigned a score and each line is totaled at the end of testing. VAS awards one point for every letter correctly guessed. The total scores range from 0 to 100, with higher scores indicating greater visual acuity.
Time frame: Baseline
Early Treatment Diabetic Retinopathy Study (ETDRS) Visual Acuity Score (VAS) at Week 4
ETDRS charts have five Sloan letters on each line; the lines are of equal difficulty, and there is a geometric progression in letter size from line to line. Beginning with Chart 1, the right eye is tested with the left eye occluded. Following the completion of testing the right eye, the left eye is tested with Chart 2 while covering the right eye. Each letter is scored as right or wrong. Correct letters are circled on the scoresheet. Each letter read correctly is assigned a score and each line is totaled at the end of testing. VAS awards one point for every letter correctly guessed. The total scores range from 0 to 100, with higher scores indicating greater visual acuity.
Time frame: Week 4
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