The Efficacy of Transcorneal Electrical Stimulation for the Treatment of Primary Open-angle Glaucoma: A Pilot Study

The aim of this study was to evaluate the effects of transcorneal electrical stimulation in subjects with primary open-angle glaucoma. Five eyes of four male subjects with primary open-angle glaucoma (average age: 52.25 ± 14.68 years) were enrolled. The subjects underwent transcorneal electrical stimulation every 3 months according to the following procedure. A Dawson-Trick-Litzkow electrode was placed on the cornea, and biphasic electric current pulses (10 ms, 20 Hz) were delivered using a stimulator (BPG-1,BAK Electronics) and a stimulus isolation unit (BSI-2). A current that evoked a phosphene that the subject perceived in the whole visual area was delivered continuously for 30 min. Humphrey visual field testing was performed after every third transcorneal electrical stimulation treatment. Changes in mean deviation (MD) values were evaluated with a linear regression model. Transcorneal electrical stimulation was performed 18.2 ± 9.4 times over a period of 49.8 ± 23.0 months. The average pretranscorneal electrical stimulation intraocular pressure, best corrected visual acuity, and MD values were 11.8 ± 1.79 mmHg, 0.14 ± 0.19 (logMAR) and -17.28 ± 6.24 dB, respectively. No significant differences were observed in intraocular pressure before and after transcorneal electrical stimulation. However, there was a significant positive linear relationship between changes in MD values and the number of transcorneal electrical stimulation treatments (R² = 0.176, P = 0.005, Spearman correlation R =0.294, P = 0.008). Transcorneal electrical stimulation treatment may improve glaucomatous visual field defects in subjects with primary open-angle glaucoma. Large-scale studies are necessary to confirm these preliminary findings.