taVNS device (Elmmedicare, EC100, Shenzhen, China) was used to apply stimulation for patients.

Stimulation parameters comprised an electrical current of 1 mA at a frequency of 20 Hz, with a waveform width of 1 ms. Repurposed off-the-shelf devices were utilized for this purpose, with the stimulator generating single square-wave pulses lasting 1 ms each. Enhancing conductivity was achieved by wiping the ear with tap water. The electrodes were placed on the cymba conchae and concha around the affected ear, which is the region of rich vagus nerve branch distribution.

taVNS device (Elmmedicare, EC100, Shenzhen, China) was used to apply stimulation for patients.

Stimulation parameters comprised an electrical current of 1 mA at a frequency of 20 Hz, with a waveform width of 1 ms. Repurposed off-the-shelf devices were utilized for this purpose, with the stimulator generating single square-wave pulses lasting 1 ms each. Enhancing conductivity was achieved by wiping the ear with tap water. The electrodes were placed on the cymba conchae and concha around the affected ear, which is the region of rich vagus nerve branch distribution. Patients in control group were applied using the same stimulator, stimulation parameters and same sessions. However, the electrodes were placed on the antihelix around the affected ear, which is the region of few vagus nerve branch distribution.

taVNS device (Elmmedicare, EC100, Shenzhen, China) was used to apply stimulation for patients.

Stimulation parameters comprised an electrical current of 1 mA at a frequency of 20 Hz, with a waveform width of 1 ms. Repurposed off-the-shelf devices were utilized for this purpose, with the stimulator generating single square-wave pulses lasting 1 ms each. Enhancing conductivity was achieved by wiping the ear with tap water. The electrodes were placed on the cymba conchae and concha around the affected ear, which is the region of rich vagus nerve branch distribution.

The Ocular Surface Disease Index (OSDI) includes 12 questions grouped by poor symptoms and visual disturbance (light sensitivity, eyes feel gritty, painful or sore eyes, blurred vision or poor vision); visual function/tasks (problems when reading, driving at night, working on a computer or watching TV); and environmental questions (problems in windy conditions, places/areas with low humidity or areas that are air conditioned). The scores range from 0 to 100. On the basis of the score, the patient's symptoms can be categorized as normal (0-12), mild dry eye (13-22), moderate dry eye (23-32), or severe dry eye (33-100).

Tear breakup time (TBUT) is a clinical test used to assess for evaporative dry eye disease. To measure TBUT,

fluorescein is instilled into the patient's tear film and the patient is asked not to blink while the tear film is observed

under a broad beam of cobalt blue illumination. The TBUT is recorded as the number of seconds that elapse between

the last blink and the appearance of the first dry spot in the tear film, as seen in this progression of these slit lamps' photos over time. A TBUT under 10 seconds is considered abnormal.