Direct visualization of aqueous tear secretion from lacrimal gland

To introduce a new method for direct observation of tear secretion from the palpebral lobes of the main lacrimal glands and Wolfring glands using fluorescein dye.

Twenty-six patients with dry eye and 26 healthy subjects were included in the study. Fluorescein was applied to the conjunctiva overlaying the palpebral lobe of the main lacrimal glands. Under cobalt blue light, we captured tear secretion from the glands in movies. We compared the number of excretory openings, the location and tear flow rate between the dry eye and healthy-subject groups. To observe tear secretion from the Wolfring glands, we everted the upper lids and applied fluorescein dye to the upper margin of the tarsus.

Mean number of excretory openings on the palpebral lobe was 2.5 in the dry eye group and 3.4 in the healthy-subject group (p = 0.031). Most of the openings were observed at the ridge, the most protruding portion of the palpebral lobe. Mean flow rate from the palpebral lobe was 0.45 μl/min in the dry eye group and 0.91 μl/min in the healthy-subject group (p = 0.046). Mean flow rate from the Wolfring glands was 0.007 μl/min in the dry eye group and 0.009 μl/min in the healthy-subject group (p = 0.615).

This visualization method allowed us to directly observe tear secretion from the palpebral lobe of the main lacrimal glands and Wolfring glands, and to quantitatively measure the tear flow rate from the lacrimal glands.