Transcutaneous Auricular Vagus Nerve Stimulation in Dry Eye

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.

The Schirmer test is objectively used to measure tear secretion without anesthetized. A healthy eye should wet more than 10 mm of the standard filter strip in 5 minutes. The travel rate along the test strip is proportional to the tear production rate.

Corneal Fluorescein Staining (CFS) was measured using the National Eye Institute (NEI) scale, which ranges from 0 (no staining) to 3 (heavy staining) for each of the 5 areas of the cornea (inferior, superior, central, nasal, and temporal).

The total score ranging from 0 to 15 is the sum of the 5 regions, with higher scores indicating greater symptom severity.

The 5-Item Dry Eye Questionnaire (DEQ-5) contains five questions regarding the frequency and intensity of eye discomfort, eye dryness and watery eyes in the past month. The score ranges from 0 to 22, a score > 6 suggests dry eye, with higher scores indicating greater symptom severity.

Depression was assessed with the 9-item Patient Health Questionnaire (PHQ). Patients were classified as having no depression (PHQ score: 0-4), mild (PHQ, score: 5-9), and moderate to severe depression (PHQ score: 10-27). Scores range from 0 to 27, with higher scores indicating greater symptom severity.

36-Item Short Form Health Survey (SF36) measures quality of life on the basis of eight dimensions or concepts

that are frequently used in health studies. These eight dimensions are estimated from eight subscales that examine

physical functioning (SF36-PF), role functioning-physical (SF36-RP), bodily pain (SF36-BP), general health (SF36-

GH), vitality (SF36-VT), social functioning (SF36-SF), role functioning-emotional (SF36-RE), mental health (SF36-MH)

and reported health transition (SF36-HT). Item responses were ranging from 0 (best) to 100 (worst), with higher scores are equivalent to greater severity of better quality of life.