An observational study in Allergic Rhinoconjunctivitis, sponsored by Dr. Anne Ellis. Recruiting at 1 site in Canada. Open to participants aged 18 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-01.
Sponsored by Dr. Anne Ellis · Observational
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:
This study will recruit both timothy grass-allergic participants with a history of eye and nose symptoms and non-allergic participants.
Allergic participants will:
Visit the study site 3 separate times:
Non-allergic participants will:
Visit the study site 3 separate times:
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.
The purpose of this pilot, single-centre, prospective, cohort study is to evaluate an updated CAC protocol using timothy grass allergen in participants with allergic rhinoconjunctivitis. The previously standardized CAC protocol from 1990 has not undergone any major public revisions, highlighting a clear need for an updated, evidence-based protocol to support modern ocular allergy studies. Therefore, we propose to develop and pilot a revised CAC model.
This study will enroll non-pregnant and non-lactating female and/or male participants. The pilot sample size will include 6 allergic and 6 non-allergic participants aged 18-70 years. Participants will be recruited from the Kingston, Frontenac, Lennox, and Addington region in Ontario, Canada. All 12 participants will attend three study visits: Visit 1 (Screening), Visit 2 (CAC exposure), and Visit 3 (Follow-up and additional CAC for non-allergic participants).
Visit 2 will occur a minimum of 21 days after Visit 1 and Visit 3 will occur 24 hours after allergen exposure during Visit 2. At Visit 2, symptom scores, tear samples, and nasal fluid (sponge) samples will be collected from all participants. At Visit 3, non-allergic participants will undergo an additional CAC and nasal sponge sampling to assess allergen movement from the eye to the nose.
The investigators hypothesize that CAC with timothy grass allergen in sensitized allergic individuals will induce a measurable allergic response in the eye receiving allergen instillation, compared to pre-exposure levels. This allergic response will be measured using symptom scores (Total Ocular Symptom Score (TOSS), Total Nasal Symptom Score (TNSS), and Total Rhinoconjunctivitis Symptom Score (TRSS)) and allergic biomarkers (IL-1rA, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-13, IL-25, IL-31, IL-33, EGF, VEGF-A, MCP-1, and TSLP) for the eye and the nose. The investigators also hypothesize that CAC will result in measurable allergen transport (Phl p 5) to the nasal cavity via the nasolacrimal duct, which is associated with activation of nasal mucosal immune responses in the absence of direct nasal allergen exposure.
717 studies on the registry are indexed under Rhinitis, Allergic; 94 are open to participants now.
This study's planned enrollment of 12 is below the median of 120 across 143 observational studies indexed under Rhinitis, Allergic.
Browse Rhinitis, Allergic studies →Dr. Anne Ellis is the lead sponsor of 3 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
Adults between 18 to 70 years old from the Kingston, Frontenac, Lennox, and Addington regions. Participants on file from previous enrolment in Kingston Allergy Research studies may be eligible for the study, if inclusion/exclusion criteria is met. We aim to recruit 6 timothy grass allergic participants and 6 non-allergic controls.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
All participants must be:
To be enrolled as an allergic participant, participants must:
To be enrolled as a non-allergic participant, participants must:
Exclusion Criteria:
Participants presenting with any of the following will not be included in the study:
Participant is currently receiving treatment for acne (e.g., isotretinoin) or has concluded less than 1 month prior to Visit 1.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allergic Participant Timothy Grass Challenge
Drug: Standardized Allergen Extract, Timothy Grass (Phleum pratense)
Non-Allergic Participant Timothy Grass Challenge
Drug: Standardized Allergen Extract, Timothy Grass (Phleum pratense)
Timothy grass-allergic participants will be exposed to diluted Timothy grass allergen using the CAC model.
Non-allergic participants will be exposed to diluted Timothy grass allergen using the CAC model.
Total Ocular Symptom Score (TOSS)
To evaluate how CAC exposure to timothy grass allergen affects TOSS, which is the total ocular symptom score calculated as the sum of scores for itchy, gritty or burning eyes, watery or tearing eyes, and eye redness. The score ranges from 0, indicating no eye allergy symptoms, to 9, indicating the maximum severity of symptoms. Post-exposure scores will be compared to baseline measurements in allergic participants.
Time frame: Pre-CAC up to 24 hours post-CAC.
Total Nasal Symptom Score (TNSS)
To evaluate how CAC exposure to timothy grass allergen affects TNSS, which is the total nasal symptom score calculated as the sum of scores for runny nose/post-nasal drip, nasal congestion/stuffiness, sneezing, and itchy nose. The score ranges from 0, indicating no nasal allergy symptoms, to 12, indicating the maximum severity of symptoms. Post-exposure scores will be compared to baseline measurements in allergic participants.
Time frame: Pre-CAC up to 24 hours post-CAC.
Ear/Palate/Throat symptom score
To evaluate how CAC exposure to timothy grass allergen affects the ear/palate/throat symptom score. The score ranges from 0, indicating no allergy symptoms, to 3, indicating the maximum severity of symptoms. Post-exposure scores will be compared to baseline measurements in allergic participants.
Time frame: Pre-CAC up to 24 hours post-CAC.
Total Rhinoconjunctivitis Symptom Score (TRSS)
To evaluate how CAC exposure to timothy grass allergen affects TRSS, which is the sum of TNSS and TOSS symptom scores plus ear/palate/throat itching symptoms. The score ranges from 0, indicating no allergy symptoms, to 24, indicating the maximum severity of symptoms. Post-exposure scores will be compared to baseline measurements in allergic participants.
Time frame: Pre-CAC up to 24 hours post-CAC.
Physician-assessed ocular signs
To evaluate how CAC exposure to timothy grass allergen affects ocular redness, chemosis, and perilimbal injection based on assessment of a physician. Post-exposure scores will be compared to baseline measurements in allergic participants.
Time frame: Pre-CAC up to 6 hours post CAC.
Concentrations of alarmins (IL-25, IL-33, TSLP) from nasal sponge samples
To evaluate how exposure to timothy grass allergen in a CAC affects nasal allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 1 hour, 3 hours, and 6 hours post-CAC.
Concentrations of alarmins (IL-25, IL-33, TSLP) from tear samples
To evaluate how exposure to timothy grass allergen in a CAC affects ocular allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 20 minutes, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of type 2 cytokines (IL-4, IL-5, IL-9, IL-13, IL-31) in nasal sponge samples
To evaluate how exposure to timothy grass allergen in a CAC affects nasal allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of type 2 cytokines (IL-4, IL-5, IL-9, IL-13, IL-31) in tear samples
To evaluate how exposure to timothy grass allergen in a CAC affects ocular allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 20 minutes, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of chemokines (IL-6, IL-8, and MCP-1) in nasal sponge samples
To evaluate how exposure to timothy grass allergen in a CAC affects nasal allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of chemokines (IL-6, IL-8, and MCP-1) in tear samples
To evaluate how exposure to timothy grass allergen in a CAC affects ocular allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 20 minutes, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of regulatory cytokines (IL-1rA and IL-10) in nasal sponge samples
To evaluate how exposure to timothy grass allergen in a CAC affects nasal allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of regulatory cytokines (IL-1rA and IL-10) in tear samples
To evaluate how exposure to timothy grass allergen in a CAC affects ocular allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 20 minutes, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of growth factors (ECF and VEGF-A) in nasal sponge samples
To evaluate how exposure to timothy grass allergen in a CAC affects nasal allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of growth factors (ECF and VEGF-A) in tear samples
To evaluate how exposure to timothy grass allergen in a CAC affects ocular allergic biomarkers, by comparing post-CAC levels to pre-CAC baseline levels.
Time frame: Baseline, 20 minutes, 1 hour, 3 hours, and 6 hours post-CAC.
Concentration of Phleum pratense (Phl p 5) in nasal sponge samples
To evaluate the movement of timothy grass allergen from the eye to the nose post-CAC.
Time frame: 5 min post-CAC.
Incidence and severity of adverse events
Assessed for their frequency, severity, (mild, moderate, severe) and relationship to the study intervention.
Time frame: Pre-CAC up to 6 hours post CAC.
Use of rescue medication or medical intervention
Any rescue medication or other medical intervention required to manage symptoms or adverse events following CAC will be recorded, including the type of medication or intervention and the reason it was required.
Time frame: Pre-CAC up to 6 hours post CAC.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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