title: Sympathetic swelling response of the control eye to soft lenses in the other eye.
abstract: OBJECTIVE
  To compare central corneal swelling and light scatter after 8 hours of sleep in eyes wearing high- and low-Dk hydrogel lenses and to the contralateral control eyes.
  
  
  METHODS
  Twenty neophyte subjects wore a Lotrafilcon A (Dk, 140; Ciba Vision, Duluth GA) silicone hydrogel lens and an Etafilcon A (Dk, 18; Acuvue; Vistakon, Jacksonville, FL) 58% water content hydrogel lens of similar center thickness in random order in the right eye only, for overnight 8-hour periods. The contralateral nonwearing left eyes served as controls. Central corneal thickness was measured using an optical pachometer and light scatter using a Van den Berg stray-light meter before lens insertion, after lens removal on waking, and every 20 minutes for the next 3 hours.
  
  
  RESULTS
  Central corneal swelling induced by the Etafilcon A lens on eye opening was significantly higher than with the Lotrafilcon A lens (8.66%+/-2.84% versus 2.71%+/-1.91%; P<0.00001). Light scatter induced by the Etafilcon A lens on eye opening was significantly higher than with the Lotrafilcon A lens (46.09+/-5.62 versus 42.78+/-6.07 Van den Berg units, P = 0.0078). The swelling of the control eyes paired with the Etafilcon A lens-wearing eyes was also slightly but significantly higher than that of the control eyes paired with the Lotrafilcon A lens-wearing eyes (2.34%+/-1.26% versus 1.44%+/-0.91%; P = 0.0002). Light-scatter measurements were not significantly different between control sets of eyes but showed the same trend.
  
  
  CONCLUSIONS
  In neophyte subjects, corneal swelling of the contralateral control eyes appears to be influenced by the swelling of the fellow lens-wearing eyes-that is, the swelling of the contralateral control eye was significantly lower when there was less swelling of the fellow eye wearing the high-Dk lens. Although there was no statistically significant difference in light-scatter measurements between the control sets of eyes, a trend similar to the corneal swelling results was observed, which could be used to support the suggestion that this may be a sympathetic physiological response rather than an unusual sampling coincidence.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Ontario, Canada. dfonn@sciborg.uwaterloo.ca
authors.forename: D
authors.initials: D
authors.lastname: Fonn
authors.forename: R
authors.initials: R
authors.lastname: du Toit
authors.forename: T L
authors.initials: TL
authors.lastname: Simpson
authors.forename: J A
authors.initials: JA
authors.lastname: Vega
authors.forename: P
authors.initials: P
authors.lastname: Situ
authors.forename: R L
authors.initials: RL
authors.lastname: Chalmers
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D003315:Cornea / Q000473:pathology*; D015715:Corneal Edema / Q000209:etiology* / Q000473:pathology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008027:Light; D008297:Male; D012542:Scattering, Radiation
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate