title: How should initial fit inform soft contact lens prescribing.
abstract: OBJECTIVE
  To investigate how initial HEMA and silicone-hydrogel (SiHy) contact lens fit on insertion, which informs prescribing decisions, reflect end of day fit.
  
  
  METHODS
  Thirty participants (aged 22.9±4.9 years) were fitted contralaterally with HEMA and SiHy contact lenses. Corneal topography and tear break-up time were assessed pre-lens wear. Centration, lag, post-blink movement during up-gaze and push-up recovery speed were recorded after 5,10,20min and 8h of contact lens wear by a digital slit-lamp biomicroscope camera, along with reported comfort. Lens fit metrics were analysed using bespoke software.
  
  
  RESULTS
  Comfort and centration were similar with the HEMA and SiHy lenses (p>0.05), but comfort decreased with time (p<0.01) whereas centration remained stable (F=0.036, p=0.991). Movement-on-blink and lag were greater with the HEMA than the SiHy lens (p<0.01), but movement-on-blink decreased with time after insertion (F=22.423, p<0.001) whereas lag remained stable (F=1.967, p=0.129). Push-up recovery speed was similar with the HEMA and the SiHy lens 5-20min after insertion (p>0.05), but was slower with SiHy after 8h wear (p=0.016). Lens movement on blink and push-up recovery speed was predictive of the movement after 8h of wear after 10-20min SiHy wear, but after 5 to 20min of HEMA lens wear.
  
  
  CONCLUSIONS
  A HEMA or SiHy contact lens with poor movement on blink/push-up after at least 10min after insertion should be rejected.
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Boychev
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Laughton
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.
authors.forename: Gulshan
authors.initials: G
authors.lastname: Bharwani
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.
authors.forename: Hafsa
authors.initials: H
authors.lastname: Ghuman
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom. Electronic address: j.s.w.wolffsohn@aston.ac.uk.
authors.forename: James S
authors.initials: JS
authors.lastname: Wolffsohn
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic; D004311:Double-Blind Method; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D055656:Prescriptions; D017755:Prosthesis Fitting / Q000379:methods*; D019919:Prosthesis Implantation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Contact lenses; HEMA; Prescribing; Settling time; Silicone hydrogel