title: Effect of lens base curve on subjective comfort and assessment of fit with silicone hydrogel continuous wear contact lenses.
abstract: OBJECTIVE
  To study the effect of base curve on subjective comfort of silicone hydrogel extended wear lenses.
  
  
  METHODS
  Ninety-five subjects were first trial fitted with 8.6-mm base curve lotrafilcon A (Focus Night & Day) lenses and then with 8.4-mm lenses only if poor subjective comfort or poor fit was present. Comfort and fit were assessed after 15 min. Subjects with discomfort or signs of poor fit were then trial fitted with 8.4-mm lenses.
  
  
  RESULTS
  Of 190 eyes, 74.2% were fitted with 8.6-mm lenses, and 23.7% required 8.4-mm lenses. Two (2.1 %) subjects could not be fitted with either base curve. Mean steep keratometry (K) reading for eyes dispensed with 8.6-mm lenses was 43.88 D and 45.56 D for eyes dispensed in the 8.4-mm lenses (p < 0.001).
  
  
  CONCLUSIONS
  A clinically useful criterion showing the need for 8.4-mm lenses was steep K of > or = 45.50 D; 77% of these eyes required the steeper lens for good comfort and fit. Subjective discomfort with 8.6-mm lenses was also a useful signal for the need of a steeper lens; mean comfort scores for those subjects rose from 6.33 with 8.6-mm lenses to 9.44 with the 8.4-mm lenses for eyes requiring the steeper lens (p < 0.001).
authors.affiliation: Centre for Contact Lens Research, University of Waterloo, Ontario, Canada.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Dumbleton
authors.forename: Robin L
authors.initials: RL
authors.lastname: Chalmers
authors.forename: John
authors.initials: J
authors.lastname: McNally
authors.forename: Simone
authors.initials: S
authors.lastname: Bayer
authors.forename: Desmond
authors.initials: D
authors.lastname: Fonn
mesh_terms: D000328:Adult; D003262:Contact Lenses, Extended-Wear; D004867:Equipment Design; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D017755:Prosthesis Fitting
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate