Table 1.
Participant demographics.
Table 2.
Rasch analysis results of Catquest-9SF.
Table 3.
Statistically significant DIF in pooled pre- and post-operative scores.
Age groups were categorized as <65 years old and 65+ years old. DIF contrast <0.5 logits is considered small or absent, 0.50 to 1.0 logits is minimal, while >1.0 logits is notable.
Fig 1.
Person-item map for Catquest-9SF including A) pre-operative scores only and B) combined pre- and post-operative scores. The left side of the vertical line shows respondent data while the right side shows positioning of items. Respondents with higher visual function and items with higher difficulty are positioned at the bottom of the line. Each ‘#’ represents 2 respondents and each ‘.’ represents 1 respondent. M: mean, S:1 standard deviation, T: 2 standard deviations. The scale is in logits.
Fig 2.
Scatterplot of pre-operative versus post-operative Catquest-9SF scores, in logits.
Subjects who had improvement in visual function after cataract surgery fall under the diagonal line (a higher Catquest-9SF score represents poor visual function).
Table 4.
Extended analysis on subjects who had improvement or worsening of Catquest-9SF scores from pre- to post-operatively.
VA: Visual acuity. Those who had no change in score were grouped with those who had improvement in scores.
Table 5.
Rasch analysis on subsets of Catquest-9SF items.
Separate analyses presented for pre-operative scores only and combined pre- and post-operative scores (stacked data). *Presented as item: DIF contrast (p-value). PSI: person separation index, PR: person reliability.