Comparison performance of preserved versus unpreserved Levocabastin eyedrops in allergen challenge

INTERVENTION: 1. Preservative‐free Levocabastine 0.05% ophthalmic solution (formula LCM‐1218) 2. Preserved Levocabastine 0.05% ophthalmic suspension (Levophta, formula LCM‐1215) 3. Preservative‐free Levocabastine ophthalmic solution vehicle (formula LCM‐1228) 3/4 of patients will receive (1) in one eye and (2) in the second eye 1/4 of patients will receive (3) in one eye and (2) in the second eye One drop of the applicable medication/placebo will be administered by study personnel at 10 min (Visit 3) or 4 hours (Visit 4) prior to CPT. No further follow up. CONDITION: Allergic Conjunctivitis ; Eye Diseases ; Acute atopic conjunctivitis PRIMARY OUTCOME: Sum score for conjunctival hyperaemia (Grade 0‐3) and itching (Grade 0‐4) at 3, 5, and 10 minutes after CPT at Visits 3 and 4 SECONDARY OUTCOME: 1. Individual scores for the following, at 3, 5, and 10 minutes after CPT at Visit 3 and 4; 1.1. conjunctival hyperaemia; 1.2. itching; 1.3. eyelid swelling; 1.4. conjunctival chemosis; 1.5. tearing; 2. Proportion of eyes with a late phase reaction within 24 hours after CPT at Visit 3 and 4; 3. Safety Endpoints:; 4. Visual acuity (Monoyer scale); 5. Slit lamp; 6. IOP; 7. Subjective tolerance upon treatment administration; 8. Adverse events INCLUSION CRITERIA: 1. Healthy 2. Volunteers 3. Male or female 4. 18‐50 years old 5. History of allergic conjunctivitis 6. Normal screening ocular examination 7. Best corrected distance visual acuity (VA) must be 8/10 (Monoyer scale) or more 8. Intraocular pressure (IOP) must be <21 mm Hg 9. Positive screening conjunctival provocation test (CPT) including at least moderate itching and hyperaemia 10. Women of childbearing potential must have a negative pregnancy test 11. Contact lens wearers must agree to not wear contact lenses when CPTs are conducted