Tear secretion from the lacrimal gland: variations in normal versus dry eyes.

PURPOSE: To investigate the secretory status of the main lacrimal gland in healthy and dry eye disease (DED) via fluorescein-assisted direct assessment of tear secretion from the palpebral lobes. METHODS: Included were 25 healthy subjects (50 lobes) and 75 subjects with DED (cicatrising conjunctivitis (CC, n=27), evaporative dry eyes (EDE, n=25) and Sjogren's syndrome (SS, n=23)). Analysed parameters included number and location of ductular openings, tear flow rate per gland and per ductule, and the time lag for the initiation of secretion. RESULTS: Ductular openings could be observed in all patients with EDE and healthy subjects whereas only 33% (18/54) glands of CC patients and 67% glands (31/46) patients with SS revealed ductules. The median number of ductules per lobe was 4 in normal (range 3-5), 3 in EDE (3-6), 1 in SS (0-3) and 0 in CC group (0-3) (p<0.000001). The median tear flow rate per lobe in CC (0.00 [Formula: see text]) and SS (0.21 [Formula: see text]) was significantly lesser than normal lobes (1.05 [Formula: see text], and EDE (0.99 [Formula: see text] eyes. The tear flow rate differed significantly between SS and CC group (p<0.0001). The maximum time lag occurred in the CC group (median, 20 s), followed by the SS group (median, 1.5 s) whereas the EDE group had similar time lag (<1 s) as of normal glands (p<0.0001). CONCLUSION: Direct assessment of tear secretion from the palpebral lobe demonstrates significant differences between EDE, aqueous deficient dry eye and dry eye in CC.