Answers are grounded in this paper and cite their sources.
It was found by the use of models approximating the in vivo state that there is a two-step response of a simulated tear film to blinking. The first is from the upper lid pulling the over the cornea by capillary action. The second is due to the relatively slow spreading superficial oily layer which drags along a second layer of tears to thicken and stabilize the precorneal tear film. A two-step phase after blinking was seen at the slit lamp biomicroscope in vivo, and a correlation with the tear film model was suggested. Spotwise drying of the tear film was also explained.
No takes yet. Share an insight, caveat, or question.
Stuart I. Brown (1969) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: