Salivary gland transplantation for dry eye disease: Indications, techniques, and outcomes.

The transplantation of salivary glands to the eye serves as a substitute for restoring tear volume in patients with severe dry eye disease. The lacrimal gland and salivary glands share similar acinar-ductal organization with some differences in the nature of secretions. This review summarizes the comparative anatomy of salivary and lacrimal glands, various salivary gland transplantation techniques, their indications, outcomes and complications along with future perspectives. Autologous microvascular submandibular gland transplantation (SMGT) into the temporal fossa with duct placement into the conjunctival fornix improves tear volume considerably but provides a hyposmolar tear film, which can induce corneal edema (in 3.5-40% of eyes). The transplanted submandibular graft improves tear volume and stability but visual acuity and conjunctival inflammation remain unchanged. The transplanted submandibular gland maintains stable function in the long-term and can have hypersecretion in 24-60% secondary to persistent autonomic innervation. Partial SMGT, gland reduction surgery, topical atropine gel or Botulinum Toxin A injection are options for treatment of postoperative epiphora. Minor salivary gland transplantation (MSGT) into the upper and/or lower conjunctival fornix results in an average improvement of 2-4 mm in Schirmer values compared to 16 to > 30 mm observed in eyes after SMGT. Reflex epiphora is rarely a problem in MSGT. Both MSGT or SMGT can improve the ocular surface and quality of life of patients with severe, debilitating dry eye disease. However, postoperative visual acuity and outcomes of corneal transplantation are still inconsistent. More studies and additional technical improvements are needed to further improve the results of these procedures.