Evaluation of the Efficacy and Safety of DM934 Versus Théalose on Eye Dryness

Inclusion Criteria: * Subject with a moderate to severe dry eye syndrome needing artificial tears in the 3 months preceding the inclusion. * Subject having used only artificial tears without preservative (NaCl 0.9%, Larmabak®) during 1 to 2 weeks before inclusion (up to 6 times a day) (given during wash-out period). * Subject with a score ≥ 18 for the OSDI (Ocular Surface Disease Index). * Subject with at least one eye with: * Global ocular staining (cornea and conjunctiva) ≥4 and ≤9 on the Oxford scale (0 to 15) AND one of the following criteria: * Schirmer test ≥ 3 mm/5 min and ≤ 9 mm/5 min OR * Sum of 3 measurements of Tear film Break-Up Time (TBUT) ≤ 30s. * Subject, having given freely and expressly his/her informed consent. * Subject who is able to comply with the study requirements, as defined in the present CIP, at the Investigator's appreciation. * For applicable countries: subject being affiliated to a health social security system. * Female subjects of childbearing potential should use a medically accepted contraceptive regimen since at least 12 weeks before the beginning of the study, during all the study and at least 1 month after the study end. Exclusion Criteria: * Far best corrected visual acuity \< 1/10 (according to Snellen Chart) * Subject with severe ocular dryness with one of these conditions: * Eyelid or blinking malfunction * Corneal disorders not related to dry eye syndrome * Ocular metaplasia * Filamentous keratitis * Corneal neovascularization * Subject with severe meibomian gland dysfunction (MGD). * History of ocular trauma, infection or inflammation, not related to dry eye syndrome within the last 3 months prior to the inclusion. * History of ocular allergy or ocular herpes within the last 12 months. * Any troubles of the ocular surface not related to dry eye syndrome . * Subjects who underwent ocular surgery, including laser surgery, in either eye within the last 6 months. * Use of the following ocular treatments: isotretinoïd, cyclosporine, tacrolimus, sirolimus, pimecrolimus, punctual plugs during the month preceding the inclusion. * Subjects who have received ocular therapy (either eye) with any ophthalmic medication, except tear substitutes, within 2 weeks prior to study start or expected to receive ocular therapy during the study. * Any not stabilised systemic treatment, which can have an effect on performance or safety criteria, at the investigator appreciation. * Pregnant or nursing woman or planning a pregnancy during the study. * Subject deprived of freedom by administrative or legal decision. * Subject in a social or health institution. * Subject who is under guardianship or who is not able to express his/her consent. * Subject being in an exclusion period for a previous study. * Subject suspected to be non-compliant according to the Investigator's judgment. * Subject wearing contact lenses during the study.