Watson 2005.

Methods	Within-subject study with random assignment of the first device used
Participants	2 groups of 15 veteran participants with age-related or juvenile macular degeneration or diabetic retinopathy, visual acuity 20/50 or less in the better eye
Interventions	Hybrid-diffractive spectacle magnifier compared with a refractive spectacle magnifier and an aplanatic spectacle magnifier (2 separate experiments)
Outcomes	MNREAD reading speed, reading acuity and critical print size. Pepper Visual skills for Reading Test. Morgan Low Vision reading Comprehensioon Assessment. Self-report of satisfaction with reading using a visual analogue scale
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random presentation of first device, but sequence generation method not described; even so, selection bias should be low since all participants used all devices (cross-over study design)
Allocation concealment (selection bias)	Low risk	Unclear if order of randomisation could be foreseen since no detail given; despite this, selection bias should be low since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

AMD - age-related macular degeneration

CCTV - closed circuit television

EOMD - early onset macular disease

ETDRS - Early Treatment of Diabetic Retinopathy Study

LVA - low-vision aid

SD - standard deviation VRD - virtual retinal display