title: Optical quality and intraocular scattering assessed with a double-pass system in eyes with contact lens induced corneal swelling.
abstract: OBJECTIVE
  To evaluate the impact of contact lens (CL)-induced corneal swelling on the optical quality of the eye by means of the double-pass technique.
  
  
  METHODS
  Measurements of 6 healthy subjects were obtained in 5 visits over 1 week, at baseline and after sleeping with 4 different CLs of +0.50 D, +2.00 D, +5.00 D and +8.00 D (Acuvue2), randomly fitted on 4 different days. The control eye wore no CL. Corneal pachymetry and optical quality of the eye (OQAS, Visiometrics) were measured once at baseline and at three interval times in the follow-up visits: immediately after CL removal, and 1 and 2 h after CL removal. Optical quality was evaluated by means of the Strehl ratio and OQAS values at 100%, 20% and 9% contrasts. Intraocular scattering was evaluated with the objective scatter index (OSI).
  
  
  RESULTS
  Mean overnight swelling was 5.98 ± 4.29% in CL-eyes versus 0.30 ± 0.78% in control eyes (p < 0.01). Corneal swelling was maximal immediately after CL removal and decreased with time (p < 0.01). A significant worsening in all optical quality parameters and a significant increase of the OSI were found in eyes with corneal swelling (p < 0.05). Two hours after CL removal there were no statistically significant differences (p > 0.05) between CL-eyes and control eyes in any of the measured parameters.
  
  
  CONCLUSIONS
  Corneal swelling has a significant impact on the optical quality of the eye and on intraocular scattering as assessed with the double-pass technique.
authors.affiliation: IOBA-Eye Institute, University of Valladolid, Valladolid, Spain. Electronic address: victoria@ioba.med.uva.es.
authors.forename: Victoria
authors.initials: V
authors.lastname: de Juan
authors.affiliation: Center for Sensors, Instruments and Systems Development (CD6), Technical University of Catalonia, Terrassa, Barcelona, Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Aldaba
authors.affiliation: IOBA-Eye Institute, University of Valladolid, Valladolid, Spain; Department of Physics and Optics, School of Optometry, University of Valladolid, Valladolid, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Martin
authors.affiliation: Center for Sensors, Instruments and Systems Development (CD6), Technical University of Catalonia, Terrassa, Barcelona, Spain.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Vilaseca
authors.affiliation: IOBA-Eye Institute, University of Valladolid, Valladolid, Spain.
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Herreras
authors.affiliation: Center for Sensors, Instruments and Systems Development (CD6), Technical University of Catalonia, Terrassa, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Pujol
mesh_terms: D000328:Adult; D003261:Contact Lenses / Q000009:adverse effects*; D015715:Corneal Edema / Q000175:diagnosis* / Q000209:etiology*; D063171:Corneal Pachymetry / Q000379:methods; D006801:Humans; D008297:Male; D012016:Reference Values; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis* / Q000209:etiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult
keywords: Contact lens; Contact swelling; Optical quality; Overnight; Scattering