This study compares the efficacy of Hylo-Dual (Hyaluronic acid 0.05% & Ectoine 2.0%) and Olopatadine (Olopatadine hydrochloride ophthalmic solution 0.1%) in the control of seasonal allergic conjunctivitis in the pediatric population. Half of participants will receive Hylo-Dual, while the other half will receive Olopatadine treatment for 2 months.

Seasonal allergic conjunctivitis (SAC) is an inflammatory response of the conjunctiva triggered by exposure to seasonal allergens. SAC is the most common form of ocular allergy, with an estimated prevalence of approximately 15 to 20%. The distressing signs (redness, chemosis, eyelid swelling) and symptoms (itching, tearing, redness) of SAC may cause extreme discomfort, with a burden due to the frequency and duration of the disease more than to its seriousness.

Olopatadine hydrochloride ophthalmic solution 0.1% is a topical antiallergic agent that is both an antihistamine with high affinity and selectivity for the histamine H1 receptor and a mast cell stabilizer that inhibits the release of histamine and other proinflammatory mediators from human conjunctival mast cells. The efficacy and tolerability of olopatadine has been demonstrated by several comparative studies in adults and children with seasonal allergic conjunctivitis.

Hylo-Dual eye drops is an approved treatment in Canada for children 6 years and older, containing 0.5mg/ml Sodium Hyaluronate, 20mg/ml Ectoine, a borate buffer and water. Ectoine is a natural substance formed by microorganisms to protect themselves from extreme environments (e.g.: salt lakes or hot geysers). They adapt to these conditions by so-called extremolytes, like ectoine, which are osmoprotective substances stabilizing biological membranes. Ectoine has a strong water-binding capacity, forming a physiologic barrier protecting cell membranes from contact with allergenic substances and against inflammatory responses to environmental stress (such as dehydration, e.g. by hyperosmolar tears, UV radiation or airborne allergens). Additionally, ectoine has a stabilizing effect on the lipid phase of the tear film by increasing its elasticity, which causes it to spread evenly over the eye surface and protects against the excessive evaporation of tears.

To the knowledge of the investigators, no systematic interventional prospective study exists comparing the efficacy of Olopatadine and Hylo-Dual for the treatment of seasonal allergic conjunctivitis in the pediatric population. The research question is to determine if both treatment options are equally effective in this population, therefore providing further clinical pharmacologic data relevant to children.

Inclusion Criteria:

• Children of either sex and any race aged 6 to 18 years
• History of seasonal allergic conjunctivitis lasting at least 1 allergy season (including patients with rhinoconjunctivitis and atopic dermatitis)
• Current complaint of itching and conjunctival redness in both eyes
• Positive skin reaction to at least one common local grass pollen, including Gramineae, at screening or in the 12 months before the study

Exclusion Criteria:

• Another previous or ongoing ocular disorder
• Presence of significant corneal involvement
• Sensitivity to any component of the study medications
• Use of medication between 1 week before the study and study completion that could confound the interpretation of results (i.e. antihistamines, corticosteroids, nonsteroidal anti-inflammatory drugs, mast cell stabilizers, topical ocular vasoconstrictors)
• Participation in other pharmacologic studies during the month before the study
• Poor baseline visual acuity (not correctable to ≥ 0.6 logMAR in both eyes)
• Autoimmune disease associated with dry eye syndrome (eg, rheumatoid arthritis)
• Inability to discontinue wearing contact lenses during the study
• Inability to discontinue the use of concomitant medication: immunosuppressive drugs, sulfa- or neomycin-containing antibiotics, antibiotics causing allergic reaction