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 mu L/min) and SS (0.21 mu L/min) was significantly lesser than normal lobes (1.05 mu L/min, and EDE (0.99 mu L/min 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.