Clinical Efficacy of Electrical Auricular Transcutaneous Stimulation for Dry Eye: A Sham-Controlled, Randomized Trial

Abstract

Purpose: This study aimed to evaluate the clinical efficacy of low-frequency ear transcutaneous stimulation (TS) for improving ocular symptoms and signs in patients with dry eye disease (DED). The primary outcome was the Ocular Surface Disease Index (OSDI) score difference between TS and sham groups, while secondary outcomes included tear breakup time (TBUT), Schirmer test (strip meniscometry tube, SMTube), and corneal staining (National Eye Institute [NEI] score).

Methods: Patients with a TBUT <5 seconds and tear volume by Schirmer test <5 mm, along with ocular symptoms, were randomized into a TS treatment group (n = 25) and a sham group (n = 24). The TS treatment device was applied bilaterally twice daily for 8 weeks, with each session lasting 30 minutes. The OSDI questionnaire score, corneal and conjunctival stain score (NEI score), TBUT, and tear secretion volume (SMTube) were analyzed at baseline and 4 and 8 weeks after treatment.

Results: The sham group showed no significant changes in any parameters at 4 and 8 weeks. The TS group demonstrated significant improvements in NEI score, TBUT, and SM tube values at both 4 and 8 weeks compared to the sham group (p = 0.002, p = 0.001, and p = 0.017, respectively, at 4 weeks; p = 0.001, p = 0.001, and p = 0.001, respectively, at 8 weeks). No significant difference in OSDI was found between groups at 4 weeks (p = 0.061), but at 8 weeks, the TS group showed a significantly greater improvement (p = 0.018).

Conclusions: The low-frequency ear TS device significantly improved DED symptoms and objective measures compared to the sham group. These findings support the potential of TS as a novel treatment option for DED.

Keywords: Dry eye syndromes; Electrical transcutaneous stimulation; Ocular Surface Disease Index.

Fig. 1

Flowchart for the randomized controlled study. TS = transcutaneous stimulation; OSDI = Ocular Surface Disease Index; NEI = National Eye Institute.

Fig. 2

Images of ear treatment points and device. (A) Schematic diagram of auricular transcutaneous electrical treatment points. (B) Transcutaneous electrical stimulation device.

Fig. 3

Changes in the Ocular Surface Disease Index (OSDI) score from the baseline to 8 weeks after treatment. There is a difference between groups in OSDI scores between the transcutaneous stimulation (TS) treatment and sham groups at 8 weeks of treatment (p = 0.018). Compared between the 4 and 8 weeks of treatment results, only the TS group showed a statistically significant decrease in OSDI score (p = 0.028).

Fig. 4

Changes in the National Eye Institute (NEI) score from the baseline to 8 weeks after treatment. Statistically significant improvements from baseline are observed in all groups after treatment. At 4 and 8 weeks, the NEI score of the transcutaneous stimulation (TS) treatment group is lesser than that of the sham group (p = 0.002 and p = 0.001, respectively). In addition, only the TS group showed a statistically significant decrease in the NEI score (p = 0.018).

Fig. 5

Changes in the tear breakup time (TBUT) from the baseline to 8 weeks after treatment. Statistically significant improvements from baseline are observed in the transcutaneous stimulation (TS) treatment group at 4 and 8 weeks. After treatment, the TBUT of the TS group was statistically longer than that of the sham group (p = 0.001 and p < 0.001, respectively). In addition, the TS group showed a statistically significant increase in TBUT (p = 0.003).

Fig. 6

Changes in the tear secretion volume from the baseline to 8 weeks after treatment. Statistically significant improvements from baseline are observed in the transcutaneous stimulation (TS) group at 4 and 8 weeks. After treatment, the tear secretion values of the TS group were statistically more improved than that of the sham group (p = 0.017 and p < 0.001, respectively). In addition, there was a statistically significant difference between the tear secretion volume between 4 and 8 weeks in the TS group (p = 0.005).