Direct Visualization of Continuous Meibum Secretion From the Orifices of Meibomian Glands to the Tear Film.

Purpose: To present a new method to directly visualize meibum secretion on the tear film from meibomian gland orifices and show that meibum is continuously secreted between blinking. Methods: Eighteen patients with dry eye syndrome and 17 healthy subjects were included in the study. We used the Lipiscanner to evaluate the tear film lipid layer. The lipid layer was classified into thick, normal, and thin lipid layer. The lipid layer on the lower tear meniscus of the right eye was observed after a drop of saline solution was applied to the eye. We recorded continuous meibum secretion onto the tear meniscus surface. We calculated the rate of continuous meibum secretion by analyzing videos. Noncontact meibography was performed for meibomian glands in the lower eyelid. The quality of meibum from the 5 orifices at the same area was then scored. Results: The mean continuous meibum secretion rate was 2.7 pL/s in the healthy group and 8.0 pL/s in the dry eye group. The rates were 1.3, 6.7, and 9.4 pL/s in the thin, normal, and thick tear film lipid layer group, respectively. They were 3.4, 3.4, 10.7, and 18.1 pL/s in grade 0, 1, 2, and 3 meibomian gland dropout groups, respectively. The rates were 0.00, 4.7, 10.1, 2.0, and 0.7 pL/s in the normal meibum, yellow without increased viscosity, yellow with increased viscosity, toothpaste, and no meibum groups, respectively. Conclusions: We showed how to visualize meibum being secreted into the tear film from the meibomian gland orifices, and we were able to observe the continuous secretion of meibum between blinks.