title: Impact of keratoconus in the better eye and the worse eye on vision-related quality of life.
abstract: OBJECTIVE
  We assessed the impact of keratoconus disease indicators in the better eye and worse eye on quality of life (QoL) using the Vision and Quality of Life Index (VisQoL) multi-attribute utility instrument (MAUI).
  
  
  METHODS
  ?tlsb -.01w?>Patients with keratoconus completed the six-item VisQoL utility measure. Visual acuity was assessed using a logMAR chart, and corneal thickness and the keratometric values were measured by using Scheimpflug imaging (Pentacam). Four indicators of keratoconus disease status were considered in this study, namely best corrected visual acuity (BCVA), average front corneal curvature (Front Km), thinnest corneal location (TCL), and spherical equivalent refractive error (SE). As keratoconus is an asymmetric condition, we considered the disease parameters separately for the better eye and the worse eye. The association between the four keratoconus indicators and VisQoL utilities was assessed using multivariate linear regression.
  
  
  RESULTS
  A total of 170 patients with keratoconus completed the VisQoL. Patients' median age was 33 (IQR = 18) years (range, 14-75 years) and 58% (n = 99) were males. The median VisQoL utility value was 0.60 (IQR, 0.46; range, 0.02-0.99). The VisQoL utilities reduced with increasing age (ρ = -0.18, P = 0.02) and were higher for males (median = 0.65, IQR = 0.49) than females (median = 0.51, IQR = 0.40). In univariate analyses, BCVA in the better and worse eye, and Front Km and TCL in the worse eye were associated with lower VisQol utilities. However, after adjusting for relevant covariates, only BCVA in the better eye remained associated significantly with reduced VisQoL utilities (β = -0.20, P = 0.018).
  
  
  CONCLUSIONS
  Using a vision-specific MAUI, our study demonstrated substantial disutility relating to keratoconus. Worse vision in the better eye (but not the worse eye) was associated independently with a reduction in VisQoL utilities, suggesting that considering VisQoL utilities based on vision in the better eye is an important estimate of the impact of keratoconus from the patients' perspective. Treatment and rehabilitation interventions to retard the progression of vision impairment in the better eye resulting from keratoconus would be most efficacious at an early stage to improve QoL outcomes for patients with this disease.
authors.affiliation: Centre for Eye Research Australia, Melbourne, Australia.
authors.forename: Srujana
authors.initials: S
authors.lastname: Sahebjada
authors.forename: Eva K
authors.initials: EK
authors.lastname: Fenwick
authors.forename: Jing
authors.initials: J
authors.lastname: Xie
authors.forename: Grant R
authors.initials: GR
authors.lastname: Snibson
authors.forename: Mark D
authors.initials: MD
authors.lastname: Daniell
authors.forename: Paul N
authors.initials: PN
authors.lastname: Baird
mesh_terms: D000293:Adolescent; D000328:Adult; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000175:diagnosis / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D014786:Vision Disorders / Q000209:etiology / Q000523:psychology* / Q000534:rehabilitation; D014792:Visual Acuity; D055815:Young Adult
keywords: cross-linking; keratoconus; quality of life