NCT03569202.

Methods	Study design: randomized, parallel‐group, controlled group Number randomized (total and per group): 64 participants (planned)
Participants	Country: Finland Age (mean ± SD, range): 18 to 80 years (planned) Gender: both (planned) Inclusion criteria: ability and willingness to give informed written consent prior to any screening procedure after explanation of the nature and possible consequences of the study; age between 18 and 80 years; at least two the following conditions (A and B):A. Symptomatic dry eye with OSDI score ≥20. AND B1. Tear film break‐up time (TBUT) <10 seconds. OR B2. Positive ocular (corneal and conjunctival) staining pattern; body weight at least 45 kg; under stable topical and/or systemic therapy for at least 4 weeks before the study procedures and apparent ability and willingness to abstain from other therapies until completion of the study period; ability and willingness to self‐administer eye drops; ability and willingness to understand and fill in the OSDI questionnaire; ability and willingness to comply with the study protocol and other study‐related procedures. Exclusion criteria: history of ocular surgery, trauma, or refractive laser vision correction procedure less than 3 months earlier; evidence of acute or chronic infection in the cornea or conjunctiva; diagnosis of Sjögren's syndrome; unwillingness or apparent disability to discontinue contact lens use during study period and at least one week before the first dosing day; current ocular allergy symptoms; known allergy to any constituent of the trehalose emulsion eye drops or control eye drops; currently pregnant, nursing or planning to become pregnant before completion of the study period; any other condition that may, in the Investigator's opinion, jeopardize the safety or availability of the subject or adherence to the study protocol or may interfere with the interpretation of the results and would thus make the subject inappropriate for entry in the study.
Interventions	Intervention #1: topical application of preservative‐free multidose Piiloset trehalose emulsion eye drops 3 times daily Intervention #2 (control): topical application of preservative‐free multidose hyaluronic acid eye drops 3 times daily Length of follow‐up: 30 days Notes: none
Outcomes	Primary outcome(s): OSDI; tear osmolarity; TBUT Secondary outcome(s): blink rate; corneal staining; conjunctival staining Adverse events reported? (Y/N): Y Measurement time points (specify intervals at which outcomes were assessed): baseline, 10 and 30 days Other issues with outcome assessment (eg, quality control for outcomes, if any): none
Notes	Recruitment status: completed Actual completion date: November 8, 2018 Last update posted: November 20, 2018

OSDI: Ocular Surface Disease Index

TBUT: tear break‐up time