Stelmack 1991.

Methods	Method of allocation: The VA Cooperative Studies Center generated the randomization sequence and the code envelopes for randomising the order of device presentation. The set of envelopes was handed to the investigators at the beginning of the study. The research assistant opened an envelope at the time needed to assign the treatment order. Methods for the randomisation sequence: the 6 different possible orders of presentation of the devices were numbered in advance. A list of random numbers was computergenerated. The 7, 8, 9 and 0 were deleted and the remaining numbers used to identify the group (information provided by investigators). Masking: Participant - masking issues are not described, but the study should be unmasked given the use of recognisable devices; Provider: same as above; Outcome - same as above. Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: USA Number randomised: 37 participants admitted to the Central Blind Rehabilitation Center. Age: 50 or more. Sex: not reported. Inclusion criteria: 50 or older, diagnosis of post-disciform stage AMD or ocular histoplasmosis. Exclusion criteria: eye pathologies which would affect study results by compromisingvisual function
Interventions	Before allocation all participants were trained by a visual skills instructor to use his or her best retinal viewing area. Modifications of standard techniques were used, including stand with the bar, the clock method of distance training, the fixation and reading techniques. Participant progress in eccentric viewing training was monitored with the Pepper Visual Skills for Reading Test. Treatments: 3 types of commonly-used magnifiers: CCTV Illuminated Stand magnifier in conjunction with a bifocal or reading prescription to compensate for accommodative demand; Spectacle reading lenses: either prism half eyes or microscopes. The magnification used for each device was the lowest that enabled the participant to consistently read excerpts from the Readers Digest using the preferred level of illumination and a reading stand. Prior to testing each participant had a 1-hour training/practice session under the supervision of a visual skills instructor from the Central Blind Rehabilitation Center teaching staff
Outcomes	Silent reading speed recorded in words per minute; reading comprehension tested at the end of the article using 5 general questions graded from 0 - 5. Testing was considered invalid if the score was less than 4; reading duration measured in minutes and defined as the time the participant could read without visual discomfort
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quasi-randomised study: the order of presentation of the devices was rotated (counterbalanced) for consecutive participants; even so, selection bias should be avoided since all participants used all devices (crossover nature of the study design)
Allocation concealment (selection bias)	Low risk	Order of randomisation can be foreseen because rotation was used; 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	Low risk	Participants with disciform neovascular maculopathy were included who are expected to have stable vision during the study period
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified