Background: In absolute aqueous-deficient dry eye, severe signs and symptoms may persist despite punctal occlusion and frequent application of artificial tear substitutes. In this group of patients the three major salivary glands, the parotid, the submandibular and the sublingual gland, have been used to lubricate the ocular surface.
Material and methods: A PubMed search was performed using the keywords 'dry eye, major salivary glands, parotid gland, parotid duct, sublingual gland, submandibular gland (SMG), transposition, transplantation' to identify the current literature on major salivary gland transplantation. The surgical procedures are described, their principle advantages and disadvantages and the published results are analyzed.
Results: To use the parotid gland as a source of substitute lubrication its secretory duct is transposed to the lower conjunctival fornix. The procedure results in a purely serous secretion and severe gustatory reflex epiphora. Parts of the sublingual gland, which produces a mucoserous secretion, have been transplanted into the subconjunctival space. Since the graft is left without a direct vascularisation, it frequently becomes non-functional. The SMG finally produces a more tear-like, seromucinous secretion. It is transferred as a free, denervated graft to the temporal fossa, where a microvascular anastomosis with the temporal artery and vein is established. Graft survival in the long term is 72%. Graft viability is associated with a significant improvement of Schirmer's test, break-up time, rose bengal staining and symptoms. In 38% of eyes with a viable graft, salivary epiphora results, which is independent of gustatory stimuli. Since the salivary tear film is substantially hypoosmolar, microcystic epithelial oedema can result and subsequent corneal transplantation remains unsuccessful.
Conclusion: Of the three major salivary glands, the parotid and the SMG have been used successfully to provide substitute lubrication in severely dry eyes. The surgical technique varies significantly in terms of complexity and reversibility. While the procedures are capable of improving comfort, due to the salivary character of the new tear film subsequent ocular surface reconstruction remains unsuccessful.