Field work includes USP visits and USPs returning to the study optometrist to have the spectacles assessed. After the first couple days of field work and data collection, it is important for the entire study team including USPs to reflect on their experiences, identify and resolve any issues for smoother running of the project.

Study staff will need to develop a system of tracking dispensed spectacles, so that they can be linked to the USP and Optical Service ID. However, to ensure the privacy of the optical services, no business names or their addresses should be kept once the study is complete.

If USPs return to the study optometrists with multiple pairs of glasses, it is important to continue to complete focimetry after vision and comfort are checked. It might practically appear more efficient to check vision and comfort with all pairs of glasses followed by focimetry. However, we do not recommend consecutively checking vision and comfort with all pairs of glasses at the same visit as checking vision and comfort with multiple pairs of glasses in a row is unlikely to provide reliable outcomes.

Assessing data quality

A Q.REC study is only as good as the quality of data collected and recorded. It is important to be familiar with each data collection form and the type or expected data for each variable/field, and to regularly conduct data quality control. We recommend data quality should be assessed at the following points and who is needed to be followed up with:

Data quality assessment recommendations

Data collection tool	When to conduct data quality control	Who to follow up with
Form A: Baseline USP Data Record Form	As soon as baseline refractions are complete and entered into REDCap	Study optometrists
Form C: USP Optical Service Visit Checklist	During USP data collection to minimise USP recall bias.	USPs
Form D: Assessment of Glasses	During spectacle assessment when study optometrists record or enter and upload the data into REDCap.	Study optometrists

Things to look out for across all data collection forms:

Missing data

REDCap has been designed where some fields/variables are compulsory to enter, therefore minimising missing data. However, it is still important to review the forms to see if there are any missing data, and to follow up with the corresponding person who entered the data.

Letters or symbols (string data) where there should be numbers

Most data are easier to analyse when numbers are entered in. Some typing errors (such as including letters or symbols) can cause number data to become text when downloaded as spreadsheets or data files for data analysis software like SPSS or STATA. Examples to look out for during data quality control include optometrists entering in ‘plano’ for spherical component of a prescription, or ‘N/A’ or ‘-‘ for no cylinder power or a near addition. All should be entered as ‘0’ or ‘0.00’

Examples include:

• Additional ‘.’ in the number, i.e. “+5..00”
• A space before or after a number

Text comments

Some data collection forms will have variables/fields where the data recorder can include some text. This might be in spaces where they select ‘Other’ and a new box appears to add some sort of description or note, or an ‘Additional Notes’ section. It is important to review the text comments to see if it can be updated to an existing checkbox, whether the context of the description is clearly understood, and to observe for signs where the data recorder might need additional assistance.

Form A: Additional things to look out for:

• Inconsistency in the recorded USP age and/or gender across the (minimum) 3 Form A’s completed. You need to be certain that each study optometrist has entered the right information corresponding to the correct USP ID.
• Missing or incorrect positive or negative signs in front of spherical power or near addition
• Incorrect number data entry e.g. +12.5 entered rather than +1.25
• Both distance and near (binocular) pupillary distances should be entered in (i.e. there should be no missing data) , even if only one type of single vision lenses is recommended.
• Pupillary distances appear to be outside normal ranges of (47 – 75mm).
• Near viewing distances appear to be outside traditional ranges of (30 – 55cm).
• Optometrists should tick all the spectacle lens types, not just one, that they think the USP would be suitable for after they discuss with the USP their refractive error correction needs.

Form C: Additional things to look out for:

Any variables where ‘Unsure’ has been selected. Follow up with the USP to go through their experience and determine whether a ‘Yes’, ‘No’ or other checkbox can be selected.

Any procedures of the refractionist/optometrist that do not appear to make sense. Examples:

• If the USP selected ‘Yes’ that a distance subjective refraction was completed, but reported ‘No’ phoropter or trial frame were used, then how was subjective refraction completed?
• If the USP selected ‘Yes’ that a distance subjective refraction was completed, and ‘Yes’ a trial frame was used, but ‘No’ spherical or cylindrical component were completed, then what occurred during the distance subjective refraction completed?
• If the USP recorded they were ‘Unsure’ what type of glasses they were recommended yet recorded ‘Yes’ to clear communication about the which glasses (lenses or frames) they needed.

Consistency of clinician gender and qualification certificates amongst the USPs that attend the same store. This does depend on the size of the service. It is possible USPs see different clinicians on different days and/or are tested in different consultation rooms. However, it should be followed up with all USPs when all forms for the same store are entered and compared.

Form D: Additional things to look out for:

• Ensure the type of glasses lenses are selected correctly
• Missing or incorrect positive or negative signs in front of spherical power or near addition
• Incorrect number data entry e.g. +12.5 entered rather than +1.25
• Lens centration distances are outside normal ranges of 47 – 75mm.
• Near viewing distances appear to be outside traditional ranges of 30 – 55cm.
• Visual acuity and/or comfort levels for all spectacles dispensed are the same.
• Cylindrical axes from the written prescription are missing
• Written prescriptions have not been uploaded into REDCap