Abstract
Purpose: :
To investigate whether non-liquid (inspissated) material is the normal content of functional meibomian glands (MG).
Methods: :
10 subjects (mean age = 35.5 +/- 10.2 years) asymptomatic for dry eye and lid margin disease with healthy appearing eyelids were enrolled. Only right eyes were used for analysis. After undergoing a slitlamp examination, standardized diagnostic MG expression for functionality was performed along the lower lid margin. Next, the region of the lower lid with a minimum of 4 functional MGs was selected for cold manual expression. A Mastrota paddle, modified to measure the force used during the expression, was utilized for the expression. The force required to evacuate the first visible, non-liquid secretion was recorded. The appearance of the non-liquid secretion (color and morphology) was recorded. This force was maintained until no more secretion was evacuated from the expressed MGs. During the extended expression, any change in the appearance of the MG contents was noted (color and morphology).
Results: :
The mean number of MGs yielding liquid secretion, indicating functionality, in each section of the eyelid: temporal = 0.6+/-0.9, central = 3.8+/-1.0, nasal = 4.2+/-1.0. In all cases the nasal (67.3%) or the central section (36.7%) of the eyelid showed the highest MG function due to the largest number of MGs yielding liquid secretion and was therefore selected for manual expression. The mean force required to evacuate the first non-liquid secretion = 12.7+/-5.6 PSI. 80% of the non-liquid secretion was white, 20% was yellowish. The morphology of the non-liquid secretion was filamentary (33.3%), columnar (46.7%), globular (6.7%) or mixed (13.3%). With continued pressure over the glands, 93.3% of the glands showed no change in the color or morphology of secretion while 6.7% of the gland secretions turned yellow with maintained pressure but the secretion morphology remained the same.
Conclusions: :
Normal functional MGs contain non-liquid contents that can be evacuated with increased force, approximately 35X the force for evacuating liquid material. This non-liquid precursor material is typically whitish in color and has a semi-solid appearance (has been described as inspissated). With continued force the material typically does not change its appearance.
Keywords: cornea: tears/tear film/dry eye • eyelid