THE FUNCTION of any healthy organ varies widely both at rest and when stimulated. Therefore any amount of tear flow which allows the eye to function normally and without discomfort must be considered as normal, at least for that particular eye. What are tears? Strictly speaking, tears are the fluid secreted by the lacrimal gland without the admixture of the secretion of the other glands of the conjunctiva. There is probably only one method to collect this secretion, namely, at the fistula of the lacrimal gland. This was done by Ahlström in one case, as cited by Schirmer.1 He estimated the daily output of the lacrimal gland to be 4 gm. However, the fine tube pressed in the fistula itself must have acted as a stimulus to the lacrimal gland and caused increased secretion. Anyway, such a condition is very rare.
However, the watery fluid which accumulates in the
de ROETTH A. LACRIMATION IN NORMAL EYES. AMA Arch Ophthalmol. 1953;49(2):185–189. doi:10.1001/archopht.1953.00920020190008
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