Varguez‐Rodriguez 2009.

Methods	Parallel‐group RCT
Participants	40 participants (naive‐treatment) with seasonal allergic conjunctivitis
Interventions	Two treatment arms: olopatadine 0.1%; ketotifen 0.025%. Duration of treatment 4 weeks
Outcomes	Assessment of ocular symptoms: itching, watering, burning (range 0‐3; 0 = none, 3 = severe) and signs: redness, chemosis (absent, present) Unclear if outcomes were measured by participants or clinicians, or both
Country	Mexico
Number randomised, gender (male:female)	40 participants randomised. M:F 23:17
Age mean (SD), median, range	Mean (SD): olopatadine 19.7 years (6.6); ketotifen 21.05 years (8.3)
Notes	Source of funding not stated. Declaration of interest by the authors was not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method used to generate the allocation sequence was not described
Allocation concealment (selection bias)	Unclear risk	The method used to conceal the allocation sequence was not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete outcome data reported, all the participants randomised were analysed
Selective reporting (reporting bias)	Low risk	Evidence was available of proper outcome reporting
Other bias	Low risk	No apparent evidence of other risk of bias
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Masking of participants (p.401 ‐ methods): "All the bottles had the same appearance and the patient did not know the treatment received."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Masking of investigators (p.401 ‐ methods): "All the bottles had the same appearance and the patient did not know the treatment received."