[Ocular surface temperature of meibomia gland dysfunction patients and the melting point of meibomian gland secretions].

Since meibomian gland dysfunction (MGD) is thought to be caused by raising of the melting point and degeneration of lipid secretions, the melting point of secretions and the temperature of the ocular surface were investigated.Twenty-three patients with MGD [mean age 69.3 +/- 7.2 (mean standard deviation) years) were examined. Seven subjects without MGD (mean age 32.5 +/- 5.8 years) were also observed as controls.Solid secretions obtained from MGD patients were heated and the melting point was measured. The weight ratio of lipids and cell components was also determined.Corneal temperature was 32.3 +/- 0.5 (mean +/- standard deviation) degrees C and eyelid temperature was 33.1 +/- 0.5 degrees C in the control subjects. Corneal temperature was 31.1 +/- 0.8 degrees C and eyelid temperature was 32.7 +/- 0.6 degrees C in MGD patients. However, the melting point of the secretions was 34.0 +/- 1.3 degrees C, which was higher than the temperature of the ocular surface and eyelid in both patients and controls. The cell components constituted about 60% of the secretions and the lipid composition, about 40%.The cause of MGD is thought to be solid ification of lipids because of elevation of the melting point and the increase in the cell components of the secretions.