Table 1.

Overview of psychometric analyses

Analysis		Description
Item properties	Quality of completion	Missing data at the item level at baseline and 1-year follow-up
	Item response distributions and floor/ceiling effects	Examined for each item at baseline and 1-year follow-up to identify any skewed distributions
Reliability	Internal consistency	Cronbach’s alpha was calculated at baseline and 1 year
	Test–retest reliability (TRT)	Evaluated by examining the stability of scores between days 30–90 and days 90–180 in stable patients
		An ICC coefficient of ≥ 0.70 was considered evidence of good TRT [19]
Construct validity	Convergent validity	Evaluated by examining correlations between mVFQ-25 scores and other measures at baseline and 1-year follow-up
		Items assessing related concepts were expected to correlate at ≥ 0.50 (MLMT; bilateral change score and assigned first eye, FST, and VF). Measures assessing unrelated concepts (VA) were expected to correlate at < 0.30 [19]
	Known-groups analysis	mVFQ-25 scores were compared between groups defined in terms of VF severity category (mild and moderate versus severe) and MLMT scores [19]
Ability to detect change	Responsiveness	mVFQ-25 scores were compared among groups defined as ‘improved’ or ‘stable/worsened’ on the basis of changes in MLMT scores [19]