Footnotes

• Contributors The following are members of EVER (Eye and Vision Epidemiology Research) group: JC (project coordinator), JS (chief investigator), NM and GL (consultant ophthalmologists). JC carried out data collection for the trial, performed statistical analysis, cleaned and analysed the data, and drafted and revised the paper. She is the guarantor. NM initiated the collaborative project, provided conception of study design, analysed the data, and drafted and revised the paper. GL critically reviewed the data and manuscript, providing significant intellectual and critical comments. JS critically reviewed the manuscript and provided approval of the final manuscript for submission for publication.

• Funding This project was generously supported by an unconditional grant from The Eye Surgery Foundation, Perth, Western Australia.

• Competing interests None.

• Ethics approval Curtin University Human Research Ethics Committee.

• Provenance and peer review Not commissioned; internally peer reviewed.