Authors: Guillaume A. Mullie, Alejandro Juarez, Antoine Etcheverry, Nassima Taleb, Tanguy Boutin, Johanna Choremis, Michèle Mabon, Ellen Freeman, Charles-Édouard Giguère, Julia C. Talajic, Isabelle Brunette.

Disclosure Block: G.A. Mullie: None. A. Juarez: None. A. Etcheverry: None. N. Taleb: None. T. Boutin: None. J. Choremis: None. M. Mabon: None. E. Freeman: None. C. Giguère: None. J.C. Talajic: None. I. Brunette: None.

Abstract Title: Validation of a French translation of the Visual Function and Corneal Health Status (V-FUCHS) questionnaire and correlation with glare in Fuchs endothelial corneal dystrophy

Abstract Body:

Purpose: 1) To develop a French translation of the Visual Function and Corneal Health Status (V-FUCHS) questionnaire and to validate its use among French-speaking patients with Fuchs endothelial corneal dystrophy (FECD), before and after Descemet's membrane endothelial keratoplasty (DMEK). 2) To correlate patient-reported glare symptoms with objective straylight measurements.

Study Design: Cross-sectional study with re-administration of questionnaire at 4 weeks.

Methods: Study participants were recruited prospectively from July 2019 to October 2020 among French-speaking patients in Montreal, Canada. Participants were classified into six groups: 1) mild, 2) moderate, and 3) severe FECD; 4) unilateral or 5) bilateral DMEK; and 6) healthy controls. The original V-FUCHS instrument, with 15 items separated into two dimensions (visual acuity [VA] and glare), was translated to French and administered at the initial visit and 4-6 weeks later. Best corrected visual acuity (BCVA), modified Krachmer grade, objective glare measurements using the C-Quant straylight meter (Oculus GmbH, Wetzlar, Germany), central corneal thickness, and eye dominance were assessed at the initial visit. Construct validity was assessed using a Rasch model for polytomous items (partial credit model). Internal consistency was evaluated using Cronbach’s alpha for the VA and glare factors. Test-retest reliability was assessed using intra-class correlations (ICCs) to measure the agreement between the two series of responses. Predictive validity was examined by comparing mean scores (raw and latent) for the VA and glare factors between the five FECD groups using an analysis of variance (ANOVA). Questionnaire scores were correlated with clinical measurements.

Results: A total of123 participants were recruited, with a mean (SD) age of 66.7 (11.3) years. These included 36 healthy controls, 52 patients with unoperated FECD, and 35 patients post-DMEK. The mean time between administration of the questionnaires was 33 days. Appropriate construct validity was confirmed by infit and outfit statistics which were within the expected range (0.5-1.5). Internal consistency analysis using Cronbach’s alpha demonstrated good reliability (α > 0.8) for both the visual acuity (α=0.92; 95% CI 0.9-0.94) and glare factors (α=0.9; 95% CI 0.87-0.94). ICCs demonstrated good test-retest reliability for both the VA factor (raw score 0.725 [0.634-0.797], latent score 0.705 [0.622-0.772]) and glare factors (raw score 0.820 [0.764-0.863], latent score 0.816 [0.759-0.860]). A significant correlation was found between both VA and glare scores and the modified Krachmer grade (P<0.001), as well as between both scores and BCVA (P<0.001). No significant correlation was found between glare factor scores and C-Quant measurements.

Conclusions: The proposed French translation of the V-FUCHS instrument provides a valid and reliable tool for assessment of patient-reported visual disability in Francophone patients with FECD. Patient-reported outcome measures provided by this instrument should be used to optimize the timing of surgical intervention and to assess post-operative improvement in symptoms of FECD after DMEK.