The Role of Tear Proteins in Tear Film Stability in the Dry Eye Patient and in the Rabbit

Surface Pressure Measurements of Human Tears and Individual Tear Film Components Indicate That Proteins Are Major Contributors to the Surface Pressure

“…7,8 Tear film instability and consequent dry eye have been associated with a deficiency of one or more of the tear film components. 9 Previous surface tension studies of tears and various tear film components [10][11][12][13] suggest that low surface tension is associated with a stable tear film. 14 Although meibomian lipids 15 have been shown to be the major contributors in lowering the surface tension of tears, the proteins lactoferrin, 15 lipocalin, 16,17 and mucin 13 have also been reported to further reduce the surface tension of lipids.…”

“…However, it is not clear whether other tear proteins also modulate the surface tension of tears, and there is some doubt about mucin contributing to the surface tension if levels similar to those found in tears are used. 6 In studies of the surface tension of whole tears or their components where contact angle measurement 10 or microcapillary tube measurements were used, 11,12 only a minimum surface tension (maximum surface pressure) was reported. By contrast, there have been a few reports on the dynamic surface tension profiles of whole tears or their components, and in these a Langmuir trough and Wilhelmy balance have been used.…”

Advances in Functional Restoration of the Lacrimal Glands

“…[70][71][72] Delivery of tear proteins and other contents of normal tears has been able to treat severe DED and diseased ocular surfaces, as demonstrated by clinical studies using tear substitutes such as autologous serum eye drops. 6,[73][74][75][76] We demonstrated that tears secreted from the bioengineered lacrimal glands contained tear proteins, including lactoferrin, which are produced in lacrimal gland acini. These results implied that the bioengineered lacrimal gland is much more physiologically relevant in vivo than previous attempts to restore lacrimal gland function.…”

Tears in health and disease

“…Holly et al 24 used a contact-angle method to measure tear surface tension; they found only a small decrease in surface activity in keratoconjunctivitis sicca and ocular pemphigoid, which they ascribed to reduction in mucus availability, and a rise in Stevens-Johnson syndrome which was ascribed to infiltration of other components with surfactant properties. Schoenwald et al, 25 using the horizontal-capillary method, showed that elevated surface tension in dry eye was at least partially corrected by boosting the output of tear proteins. It was shown that the improvement of surface activity was related to improved levels of one particular tear protein; although not named, this was identifiable as lipocalin.…”