The functional effect of repetitive transorbital alternating current stimulation (rtACS) in a double-masked randomized clinical trial

Abstract

Purpose : Electrical stimulation therapy (EST) is reported to be effective in a range of clinical ophthalmic conditions to treat functional deficits. rtACS is a non-invasive EST procedure that is reported to improve contrast sensitivity, visual function, and quality of life. The purpose of this double-masked, randomized, sham-controlled clinical trial is to determine if there is a functional difference between the rtACS treated versus sham control subjects.

Methods : Subjects with moderate to advanced glaucoma (VF mean deviation (MD) ≤-6.00 dB) in at least one eye were randomized into sham (control) or rtACS intervention groups. Treatment (and sham) were delivered in 10 interventions (limited to 1 per day) within 2 consecutive weeks. All subjects had baseline, postintervention (PI; 1 week) and follow-up (FU; 4 weeks) visits with 24-2 VF testing (Humphrey Field Analyzer; Zeiss, Dublin, CA). The effect of treatment was assessed by comparing the average change from baseline to PI and FU respectively between the rtACS and sham groups for the following: 1) MD; 2) number of threshold sensitivity points which improved, worsened, or remained unchanged; 3) number of threshold sensitivity points which improved, worsened, or remained unchanged in vulnerable locations (edges of scotoma) that were defined at baseline. Baseline characteristics were also compared between eyes which showed improvement in MD and those which worsened.

Results : No significant difference was detected in age and disease severity between the 14 rtACS treated eyes and 18 sham group eyes (16 subjects; Table 1). A common finding across analysis methods 1-3 was a stable or slightly improved VF in the rtACS group between baseline to PI and baseline to FU, while in the same period, a deterioration was noted for the sham group (Table 2). Neither the trends for these changes nor the difference between the groups was statistically significant. No statistically significant difference was detected in baseline age or MD between improved and worsened eyes.

Conclusions : While none of the sham versus rtACS results reached statistical significance, there was a trend toward functional improvement in the rtACS group. Larger cohorts and longer follow-up are warranted to further evaluate the effects of rtACS in glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.