* Basal rate of tear production is 2.2 ul/minute in standard conditions of humidity and temperature.
* Lacrimal system's drainage capability is 100 ul/minute in health.
* Shedding tears is a common reaction to undesirable or unexpected events.
* Epiphora is not included in this question.
The ability of lacrimal drainage system may vary with race therefore approximate rate of lacrimation sufficient enough to cause spillage of tears over the cheeks seems to be 50 times more than the basal secretion.
Secretory tests check for any evidence of dry eye to rule out any reflex cause of watering and many tests should be performed to assess the quantity and the breakup time of tear film. Schirmers test, tear film breakup time, and Rose Bengal staining are the commonly performed secretory tests. These tests provide information about the quantity of tear production and quality of precorneal tear film and are part of the diag- nostic workup for patients with suspected dry eye disease as the cause of watering. Schirmers tests are commonly performed office test for dry eye evaluation. In Schrimers I test, a Whatmann filter paper of 35×5 mm dimension is folded 5 mm from the tip and placed at the inferior conjunctival fornix laterally and the amount of wetting of the filter paper strip is noted. This checks for both basal and reflex secretion from the main and accessory lacrimal glands. The same test performed after anesthetizing the conjunctiva measures only the basal secretion from the accessory lacrimal glands. Schirmers II test measures only reflex secretion and is performed by placing the filter paper strip in the anesthetized conjunctiva and stimulating secretion from the main lacrimal gland by placing a cotton applicator on nasal mucosa which stimulates the trigeminal nerve. Tear film breakup time is a function of the mucin layer of tear film. Normal breakup time is 10–15 s and values less than 10 s indicate a mucin deficiency dry eye disease.
http://www.ncbi.nlm.nih.gov/pubmed/24979582
http://www.ncbi.nlm.nih.gov/pubmed/24354575
Article Powered Endoscopic Dacryocystorhinostomy: A Decade of Experience
Conference Paper "Primary endoscopic dacryocystorhinostomy with and without s...
- Badges
- Science method