Abstract
Purpose :
The study was designed to provide evidence for safety and reliability for at-home electrical stimulation therapy (EST). The study also provides preliminary effectiveness endpoint measurements. We hypothesized that individuals will adhere to an at-home therapy regimen that is safe and reliable to provide effective vision restoration therapy for retinitis pigmentosa (RP).
Methods :
11 adults with RP (age 35-69; median 61) were enrolled to receive at-home supervised EST with the tDCS mini-CT device (Soterix Medical) and RELO-Stick skin electrodes. EST was applied to the participant’s preferred viewing eye with parameters: 1) 10ms duration biphasic pulses; 2) 20Hz frequency; and 3) 0.5mA current. EST was applied for 20 minutes/day, 4 days/week for 8 weeks via transdermal stimulation at 2 different locations: 1) 5 participants had an electrode located just above the eyebrow and a second electrode behind the ear on the mastoid bone and 2) 6 participants had the same electrode location above the eyebrow and a second electrode located at the top of the cheekbone. Endpoints were evaluated at baseline, 1 month and after therapy ended.
Results :
Participants had ETDRS BCVA 20/22-20/174 (median 20/42), low luminance ETDRS BCVA 20/24-29/191 (median 20/50) and low luminance low contrast ETDRS BCVA 20/48-20/240 (median 20/100). Participants had central visual field areas 146-14,570 deg2 (median 2,168 deg2) with the Octopus 900 kinetic perimetry protocol. All safety endpoints (e.g., slit lamp, SD-OCT, electrical phosphene threshold) provided good safety evidence with no adverse events. The effectiveness endpoints provided: 1) 6 participants had a significant visual field area difference (>20%); 2) 5 participants had a significant response in blue full-field stimulus thresholds (>0.12 log cd/m2; Diagnosis FST); 4 participants had a significant response in 5 or more of the macular perimetry pattern locations; 3) 4 participants had a significant response in low luminance – low contrast BCVA (> 7 letters). The IVI questionnaire revealed the impact on self-reported abilities. All participants wished to continue doing therapy at the end of the study.
Conclusions :
This study provided results that EST was well tolerated, even preferred, as the at-home therapy allows individuals to do everyday activities during treatment. Currently individuals with RP have no approved vision restoration therapy option, in clinic or at home.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.