title: Distribution of overnight corneal swelling across subjects with 4 different silicone hydrogel lenses.
abstract: OBJECTIVE
  To determine distribution of central corneal swelling (CCS) across subjects after 8 hr of sleep in eyes wearing silicone hydrogel lenses with various oxygen transmissibility (Dk/t) values and in eyes without lenses.
  
  
  METHODS
  Twenty-nine neophytes wore lotrafilcon A (Dk, 140), balafilcon A (Dk, 91), galyfilcon A (Dk, 60), and senofilcon A (Dk, 103) lenses in powers -3.00, -10.00, and +6.00 diopters on separate nights, in random order, and on 1 eye only. The contralateral eye (no lens) served as the control. Central corneal thickness was measured using a digital optical pachometer before lens insertion and immediately after lens removal on waking.
  
  
  RESULTS
  The average difference between the mean (7%) and the median (6.8%) CCS of all lenses was only 0.2%, suggesting a normal distribution. There was no correlation between the mean and the range of the CCS (r=0.058, P=0.766). Normal CCS distributions were also found with each lens-wearing eye and the control eye (P>0.20 for all). There was a significant correlation between lens-wearing eye and control eye (r=0.895, P<0.001) and between lotrafilcon A and each of the other 3 lenses for mean CCS across the study participants (P<0.001 for all).
  
  
  CONCLUSIONS
  Distribution of corneal swelling in both lens-wearing eye and control eye followed a normal curve. An individual's corneal swelling response seems to be independent of lens type.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. ammoezzi@sciborg.uwaterloo.ca
authors.forename: Amir M
authors.initials: AM
authors.lastname: Moezzi
authors.forename: Desmond
authors.initials: D
authors.lastname: Fonn
authors.forename: Jalaiah
authors.initials: J
authors.lastname: Varikooty
authors.forename: Doris
authors.initials: D
authors.lastname: Richter
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D015715:Corneal Edema / Q000175:diagnosis / Q000209:etiology*; D003936:Diagnosis, Computer-Assisted; D004311:Double-Blind Method; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D000860:Hypoxia / Q000150:complications / Q000209:etiology*; D008875:Middle Aged; D012828:Silicones; D055815:Young Adult; D005466:Fluorocarbons
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D012828:Silicones; C481129:lotrafilcon A; D005466:Fluorocarbons