Table 8 Items and scoring rule of SSQ

General discomfort

1

1

Fatigue

1

Headache

1

Eye fatigue

1

Difficulty focusing

1

1

Increased salivation

1

Sweating

1

Nausea

1

1

Difficulty concentrating

1

1

Fullness of head

1

Blurred vision

1

1

Dizzy (eyes open)

1

Dizzy (eyes closed)

1

Vertigo

1

Stomach awareness

1

Burping

1

Total

[1]

[2]

[3]