The Effects of 3% Trehalose Ophthalmic Solution on Corneal Epithelial Barrier Function

Inclusion Criteria: * Adult subjects, \> age 18 years, with moderate-to-severe dry eye, defined as fitting criteria for dry eye stages 3 or 4 of the MGD Workshop Management and Treatment subcommittee report. * Subjects must have normal eyelid position and closure. * For enrollment as aqueous tear deficiency, subjects must have a Schirmer I result of \< 5.0 mm wetting in 5 minutes without anesthesia. Exclusion Criteria: * History or evidence of ocular or intraocular surgery in either eye within the past twelve months. LASIK and other kerato-refractive procedure patients can qualify if the most recent surgery or enhancement was 12 or more months prior. * History or evidence of serious ocular trauma in either eye within the past six months. * History of hypersensitivity to any component of the study medications. * History or evidence of epithelial herpes simplex keratitis (dendritic keratitis); vaccinia, active or recent varicella, viral disease of the cornea and/or conjunctiva; chronic bacterial disease of the cornea and/or conjunctiva; mycobacterial infection of the eye; and/or fungal disease of the eye. * History or evidence of active ocular allergy. * Females who are pregnant, nursing, or planning a pregnancy during the study. * Evidence of greater than mild eyelid deformity (e.g., ectropion, entropion, ptosis). * Use of concomitant topical ocular medications during the study duration. * Individuals using systemic steroids, immunosuppressive agents and/or anti-cholinergic (e.g. cold and allergy medications, tricyclic antidepressants) for treatment of autoimmune connective tissue disease may not be enrolled in the study if they have not been on a stable dosing regimen for a minimum of 30 days prior to the visit. * Individuals with uncontrolled diabetes or history or evidence of peripheral neuropathy. * Active intraocular inflammatory conditions such as iritis. * Individuals wearing rigid gas permeable or scleral contact lenses within the previous six months of enrollment. Subjects can have worn soft lenses, but not within one month prior to enrollment. * Individuals using punctual plugs inserted within 30 days of study start.