Abstract
Purpose:
To develop and validate a questionnaire to assess near and distance vision, symptoms and satisfaction after surgical correction of presbyopia.
Methods:
The AcuFocus Corneal Inlay Presbyopic Questionnaire (ACIPQ) was developed using FDA Patient-Reported Outcomes guidance, the U.S. Navy Refractive Questionnaire and applicable NEI RQL 42 questions. Content and construct validity and reliability were established through expert and subject review of a pilot survey. The 46-item ACIPQ was administered to 507 subjects in the US IDE study of the KAMRA corneal inlay preoperatively and at 3, 6, 12, 18, 24, 30 and 36 months postoperatively. Near items included ratings for how easy it is to see at near for 6 good lighting and 6 dim lighting tasks. Validation of 12 near vision items on the ACIPQ included Rasch modeling (6 month), repeatability at 6 and 12 months, and test of responsiveness to improvement in near vision (all visits).
Results:
The 7 point likert response scale for the near items demonstrated ordered thresholds on the category probability curve. The near items fit the Rasch model: reliability measures were acceptable, with person reliability = 0.96, item reliability = 1.00 and person separation of 5.0, and the 12 near vision items demonstrated unidimensionality. The questionnaire was well targeted (item-person separation 0.48 logits). Sum score for the near tasks improved by 26 points postoperatively from 21.7±12.1 at pre-op to 47.9±14.9 at 6 months (Rasch person scores rescaled to 0-100 scale, p<0.001) and reflected the significant improvement in unaided near vision (UCNVA) measured in the trial (25.9±3.8 to 40.3±7.3 letters, p<0.0001). There was a strong correlation between UCNVA and Rasch score for near tasks (R2 = 0.44), establishing responsiveness of the ACIPQ. The overall score for ease of near vision was stable across all postoperative visits (ANOVA, p>0.05). Assuming stability, the repeatability of the combined near vision score was assessed using 6 and 12 months data which showed good repeatability (Cronhbach’s Alpha 0.86).
Conclusions:
The ACIPQ questionnaire assessing presbyopic correction with the KAMRA corneal inlay appears to be a valid measure of subjective near vision and reflects the significant improvement in near visual acuity. The near task items conform to the Rasch model, are well targeted to the study population and show good discrimination.
Keywords: 669 quality of life •
678 refractive surgery •
653 presbyopia