The purpose of this study is to determine if Thealoz is effective in Dry Eye Syndrome exposed to controlled adverse environmental conditions.

Inclusion Criteria:

• Man/woman ≥ 18 years old, able to freely give consent to participate in the study
• Fluorescein corneal staining ≥ 1 and ≤ 3 in Oxford Scales
• At least 2 of the following tests altered:
• Ocular Surface Disease Index (OSDI) Test symptoms between 12 and 40
• BUT ≤10 seconds
• Lissamine green conjunctival staining ≥ 1
• Schirmer Test without anesthesia ≤ 5 mm
• Informed consent signed
• Data protection consent signed

Exclusion Criteria:

• Sensitivity or known intolerance to any of the product used in the study
• Story of ocular infections or severe ocular inflammation within the 6 previous months to study inclusion
• Any active ocular pathology other than Dry Eye Syndrome
• Any traumatize or ocular surgery that may affect corneal sensitivity and/or normal tear distribution (e.g. cataract surgery, refractive surgery) within the 6 previous months to study inclusion
• Use of contact lenses in the 3 previous months to study inclusion
• Use of any ocular topical medications other than the treatment for Dry Eye Syndrome
• Ocular treatment for Dry Eye Syndrome with corticosteroids 1 month before inclusion visit or Cyclosporin A 3 months before inclusion
• Diagnosis of Rosacea or Severe Blepharitis (associated to systemic or ocular pathologies) Any severe uncontrolled systemic disease that may affect the eye (except for primary or secondary Sjögren)
• Start, discontinuation or change within the study of the dosage of antihistaminics, cholinergic agents, beta blockers, anti depressants or any other systemic drugs with potential effects in the tear film
• No pregnant or breastfeeding women is allowed to participate in the study. Childbearing potential women must use contraceptive means during the whole study.
• Participation in another clinical trial in the last 30 days before study inclusion