Biophysical behaviour of the infant Meibomian lipid layer.

Infants have been known occasionally to stare without blinking for almost a minute. This puts great demands on the stability of their tear-film. To verify the stability of infant tears, we performed biophysical experiments on Meibomian gland secretion, which forms the outermost layer of the tear-film. The secretion was taken from infants belonging to one of three age-groups (1.5 years, 4-5 years, 7-10 years). Under in vitro conditions we determined the surface pressure and the surface potential of the film by spreading the secretion over a water surface and subsequently compressing and decompressing it. Sufficient amounts of Meibomian gland secretion were expressed in all age-groups. The surface pressure and the surface potential of the tears in infants corresponded to those in healthy adults. It was also found that the younger the patient was, the better was the consistency of the surface potential under repeated periods of compression and expansion. In comparison with the secretion of healthy adults, the infant Meibomian gland secretion showed better biophysical characteristics and a correspondingly higher stability in the tear-film.