Katelaris 2002.

Methods	Parallel‐group RCT
Participants	188 participants with seasonal allergic conjunctivitis
Interventions	Two treatment arms: olopatadine hydrochloride 0.1%; cromolyn sodium 2% (nedocromil sodium). Duration of treatment 6 weeks
Outcomes	Investigator's assessment of ocular signs and symptoms: mean ocular symptom scores of itching and redness and physicians' impression scale scores, per protocol data (5‐point scale; 0 = none, 4 = very frequent) Participants' assessment of itching and redness using diary (10‐point scale; 0 = none, 9 = severe) Time points: at days 1 to 14, and 30 to 42 after treatment
Country	6 European countries and Australia
Number randomised, gender (male:female)	188 participants randomised, 185 participants analysed. M:F 103:82
Age mean (SD), median, range	Mean (SD): olopatadine 33.0 years (19.3); cromolyn sodium 36.8 years (20.9)
Notes	Not reported when study was conducted. 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)	Low risk	Computer‐generated (p.1563 ‐ study procedures): "A computer‐generated randomization schedule was used to assign sequencial patients to the study treatments in an equal ratio."
Allocation concealment (selection bias)	Unclear risk	The method used to conceal the allocation sequence was not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Analysis per‐protocol participants not intention‐to‐treat analysis. Less than 10% lost to follow‐up, and reasons were given
Selective reporting (reporting bias)	Low risk	Evidence was available of adequate 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	Double‐masking (p.1563 ‐ study procedures): "Double‐masking was ensured through the use of identical opaque bottles and similar‐appearing contents and labeling."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double masking (p.1563 ‐ study procedures): "Double‐masking was ensured through the use of identical opaque bottles and similar‐appearing contents and labeling."