Investigating Nasal and Ocular Immune Response to Conjunctival Allergen Exposure

The goal of this pilot study is to develop an eye allergen challenge model, called a conjunctival allergen challenge (CAC), using timothy grass as the allergen. This model will allow for a more consistent approach to studying allergic rhinoconjunctivitis (allergy of the eye and nose) and help us better understand the connections between the eye and the nose. The two main questions asked in this study are: 1. How can allergic symptoms be safely and accurately produced in a research setting? 2. What are the underlying connections between the eye and the nose, and how do they drive allergic rhinoconjunctivitis? This study will recruit both timothy grass-allergic participants with a history of eye and nose symptoms and non-allergic participants. Allergic participants will: * Be challenged with timothy grass extract diluted in sterile saline using the CAC model, which involves administering the allergen directly to the eye in a manner similar to applying eye drops. * Have nasal fluid and tear samples collected at various timepoints up to 6 hours after CAC exposure. * Complete ocular and nasal symptom questionnaires and assessments by a eye care professional. * Visit the study site 3 separate times: 1. Screening visit (Visit 1): to determine eligibility for the study. 2. CAC visit (Visit 2): to receive allergen exposure, complete symptom questionnaires, and provide study samples. 3. Follow-up (Visit 3): to complete a final symptom questionnaire (24 hours after allergen exposure). Non-allergic participants will: * Be challenged with timothy grass extract diluted in sterile saline using the CAC model, administered directly to the eye similarly to eye drops. * Have nasal fluid and tear samples collected at various timepoints up to 6 hours after CAC exposure. * Complete ocular and nasal symptom questionnaires and assessments by a eye care professional. * Visit the study site 3 separate times: 1. Screening visit (Visit 1): to determine eligibility for the study. 2. CAC visit (Visit 2): to receive allergen exposure, complete symptom questionnaires, and provide study samples. 3. Follow-up (Visit 3): to complete a final symptom questionnaire (24 hours after allergen exposure) and receive another CAC and nasal sponge sample for allergen-tracking purposes. This study will compare the nasal and ocular symptoms and allergic markers collected from tear and nasal fluid samples between allergic and non-allergic participants at baseline and at several timepoints after CAC exposure. It will also measure the concentration of allergen in the nasal sponge samples of non-allergic participants at the follow-up visit to assess how the allergen moves from the eye to the nose.