Schirmer's test is done to assess the function of which of the following cranial nerve ?

The Schirmer's tear test is used to assess lacrimation function of facial nerve. Schirmer's test determines whether the eye produces enough tears to keep it moist. This test is used when a person experiences very dry eyes or excessive watering of the eyes. It poses no risk to the subject. A negative (more than 10 mm of moisture on the filter paper in 5 minutes) test result is normal. Both eyes normally secrete the same amount of tears. It is performed with the help of a 5 x 35 mm strip of Whatman-41 filter paper which is foldei 5 mm from one end and kept in the lower fornix at the junction of lateral one-third and medial two-thirds. The patient is asked to look up and not to blink or close the eyes. A young person normally moistens 15 mm of each paper strip. Because hypolacrimation occur with aging, 33% of normal elderly persons may wet only 10 mm in 5 minutes. Persons with Sjogren's syndrome moisten less than 5 mm in 5 minutes. How to read results of the Schirmer's test: *Normal which is >15 mm wetting of the paper after 5 minutes. *Mild which is 14-9 mm wetting of the paper after 5 minutes. *Moderate which is 8-4 mm wetting of the paper after 5 minutes. *Severe which is <4 mm wetting of the paper after 5 minutes.