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. 2010 Jan 20;2010(1):CD003974. doi: 10.1002/14651858.CD003974.pub3

Blades 2001.

Methods Design: three group, three period cross‐over trial 
 Purpose: study the effect of oral antioxidant therapy on marginal dry eye
Participants Patients: out‐patients with marginal dry eyes
Interventions Placebo: capsules without antioxidants 
 Untreated: no capsules 
 Experimental: capsules with antioxidants 
 (Co‐intervention: NS )
Outcomes Glasgow Caledonian University threads phenol read thread test (G‐CUT) 
 Tear thinning time 
 McMonnies dry eye questionnaire 
 Squamous cell metaplasia 
 Goblet cell density
Notes The outcome data from this cross‐over trial was not available from the first period only, and was calculated as deriving from a parallel group trial.
Risk of bias
Bias Authors' judgement Support for judgement
Adequate sequence generation? Unclear risk 'Latin squares'
Allocation concealment? Unclear risk No stated
Blinding? 
 Treatment provider Low risk 'This trial was double‐masked...'
Blinding? 
 Outcome assessor Unclear risk NS
Incomplete outcome data addressed? 
 All outcomes High risk Drop‐out > 15% or NS
Free of selective reporting? Unclear risk No protocol available
Free of other bias? Unclear risk The outcome data from this cross‐over trial was not available from the first period only, and was calculated as deriving from a parallel group trial.
No signs of variance inequality or skewness? Unclear risk Not relevant (not naturally positive continuous outcomes e.g. change)
Trial size > 49? Low risk N = 80
Clearly concealed allocation + trial size > 49 + drop‐out max 15% High risk Drop‐out > 15% or NS