Azevedo 1991.

Methods	Parallel‐group RCT
Participants	63 participants recruited with moderate or severe allergic conjunctivitis
Interventions	Three treatment arms: levocabastine 0.5 mg/ml eye drops; sodium cromoglycate 20 mg/ml eye drops; placebo eye drops. Duration of treatment 28 days
Outcomes	Participant assessment (ocular irritation, redness, photophobia, tearing, swollen eyelids, conjunctival oedema using a 4‐point scale; 0 = none, 3 = severe) Investigator assessment (ocular irritation, redness, photophobia, tearing, swollen eyelids, conjunctival oedema, using a 4‐point scale; 0 = none, 3 = severe) Time points: at baseline and day 14 and 28 of treatment
Country	Portugal
Number randomised, gender (male:female)	63 participants randomised, 60 participants analysed. M:F 24:36
Age mean (SD), median, range	Median (range): levocabastine 27 years (13‐55); sodium cromoglycate 26 years (9‐46); placebo 34 years (12‐51)
Notes	Not reported when study was conducted. Source of funding not reported. 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 list (p.691 ‐ treatment and methods): "Patients were randomly allocated (on the basis of a computer‐generated list) to three groups..."
Allocation concealment (selection bias)	Unclear risk	Method used to conceal the allocation sequence was not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data were nearly fully reported, with less than 10% lost to follow‐up, and the reasons were given
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	Double‐masked (p.691 ‐ treatment and methods): "The trial featured a doubled‐blind, parallel groups design"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐masked (p.691 ‐treatment and methods): "The trial featured a doubled‐blind, parallel groups design"