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. 2013 Jul 1;2013(7):CD003586. doi: 10.1002/14651858.CD003586.pub3

Rossi 1990.

Methods RCT
Setting: USA
Participants 39 stroke patients from an inpatient stroke rehabilitation unit with HHA or VN
 Experimental: n = 18, control n = 21
 Mean age: experimental 72.6 years, control 63.3 years
 Sex (male/female): experimental 10/8, control 9/12
 Mean weeks post‐stroke: experimental 4.4, control 4.7
 Side of stroke (right/left): experimental 16/2, control 13/8
 Lesion type (infarct/haemorrhage): experimental 15/3, control 18/3
 Inclusion: participants free of disabling cardiac pulmonary or rheumatological problems, HHA determined by inability to detect 1 cm red target on tangent screen examination, VN defined as inability to detect bilateral tachistoscopically presented targets using HFVS
 HHA/VN: experimental 12/6, Control 15/6
 Exclusion: people with best‐corrected visual acuity worse than 20/200; inability to comprehend and co‐operate with assessments
Interventions 15‐diopter plastic press‐on fresnel prisms (cut to a half circle, to fit on the inside of spectacle lenses, overlaying the affected hemi‐field with the base of the prism towards the affected field to produce an intended effect of shifting a peripheral image more towards the centre) worn for all daytime activities versus no prism treatment
 Both groups received routine rehabilitation programs including ADL training and table‐top visual perception retraining tasks
 For analysis of bottom‐up and top‐down rehabilitation approaches this review coded the experimental condition as bottom‐up
Outcomes The study collected eight types of outcomes:

  1. Modified MMSE

  2. MVPT

  3. line bisection

  4. line cancellation (number of errors)

  5. HFVS

  6. Tangent Screen Examination

  7. BI

  8. frequency of falls


Outcomes were assessed at baseline, 2 weeks and 4 weeks. This review used line bisection, BI and falls. The 4‐week outcome data were used. However, as prisms were still being used at that time this review analysed them as 'immediate' rather than 'persisting' effects
Notes Clarification of randomisation procedure sought but not obtained
 Control group younger but otherwise groups were similar on demographic and clinical background factors including BI
 Data for VN subgroup not reported separately to HHA subgroup therefore all outcome data in this review are for VN and HHA combined. The authors report that the HHA diagnosis precluded a diagnosis of neglect and that participants with either HHA or VN who were treated with prisms showed equal improvement
 The prism group wore their prisms during outcome assessments
 Cancellation data reported as errors rather than correct performance. Line bisection scores are errors in cms from the middle
 SEM data converted to SD for analysis
Risk of bias
Bias Authors' judgement Support for judgement
Allocation concealment (selection bias) Unclear risk No details of randomisation provided
Blinding of outcome assessment (detection bias) 
 All outcomes High risk Outcome assessor not blinded, apart from Tangent screen examinations which were judged by an observer who was unaware of group allocation
Incomplete outcome data (attrition bias) 
 All outcomes Low risk 2 treatment and 5 control not retested on tangent screen examination because of scheduling problems, but outcomes of interest seem to be complete
Free of systematic differences in baseline characteristics of groups compared? High risk Difference in age, control group younger
Did authors adjust for baseline differences in their analyses? High risk