Comparison of meibomian gland loss and expressed meibum grade between the upper and lower eyelids in patients with obstructive meibomian gland dysfunction.

PURPOSE: The aim of this study was to compare meibomian gland loss (MGL) and expressed meibum grade between upper and lower eyelids in patients with obstructive meibomian gland dysfunction (MGD) and to evaluate the correlation between these 2 parameters and other clinical measurements.
METHODS: Twenty-six eyes of 26 patients with obstructive MGD were enrolled. Upper and lower MGLs were evaluated using noncontact meibography. Expressed meibum quality was assessed in 8 glands of the central third area of the upper and lower eyelids on a scale of 0 to 3 for each gland (total score range, 0-24). Tear film stability was evaluated based on tear break-up time (TBUT), and corneal staining was graded according to the National Eye Institute scale (range, 0-15).
RESULTS: The mean MGL in the lower eyelids (24.1% ± 10.8%) was significantly greater than that of the upper eyelids (11.2% ± 5.2%) (P < 0.001). The mean expressed meibum grade in the lower eyelids (16.5 ± 5.1) was also significantly larger than that of the upper eyelids (11.2 ± 5.2) (P < 0.001). MGL was significantly correlated with expressed meibum grade in both eyelids (r = 0.451, P = 0.021 in the upper eyelids; r = 0.626, P = 0.001 in the lower eyelids). The meibum grades of both the upper and lower eyelids were negatively correlated with TBUT and positively correlated with corneal staining score. However, the MGL in both the eyelids was not correlated with TBUT or with corneal staining score.
CONCLUSIONS: In patients with obstructive MGD, MGL and meibum grade in the lower eyelids were significantly greater than those of the upper eyelids. Although MGL and meibum quality showed a positive correlation with each other, TBUT and corneal staining score were significantly correlated with only meibum grade, and not with MGL.