Guillon Terre Plaine

This is a randomised, double-masked, placebo-controlled Phase 3 study of the safety and efficacy of STN1013800 in the treatment of acquired blepharoptosis. Subjects diagnosed with acquired blepharoptosis who meet eligibility criteria at Visit 1 (Screening) will return within 8 days for Visit 2 (Baseline, Day 1). At Visit 2 (Baseline, Day 1) they will be randomised to receive double-masked treatment for 6 weeks, with study visits completed at Week 2 (Day 14) and Week 6 (Day 42), and a post-treatment visit completed 2 weeks (± 3 days) after last study drug administration. Approximately 234 adult subjects with blepharoptosis who meet all the eligibility criteria will be randomised in a 1:1 ratio to receive: * STN1013800 BID * Placebo BID Note that: * On study visits Day 1 and Day 42, the AM dose is administered at 08:00 (at site) and the PM dose is administered at 16:00 (self-administered at home) * On study visit Day 14, the AM dose is administered at 06:00 (self-administered at home), the PM dose is administered at 14:00 (at site)