title: Corneal shape changes induced by first and second generation silicone hydrogel contact lenses in daily wear.
abstract: OBJECTIVE
  To compare the corneal topographical changes induced by two first and second generation silicone-hydrogel (SiH) contact lenses after 3 months of daily wear (DW).
  
  
  METHODS
  Prospective, consecutive case-series in which patients wore one of 3 different contact lenses (either the first generation SiH Focus Night & Day, the second generation SiH Acuvue Oasys or the monthly disposable Soflens 38 hydrogel lens as control group) on a DW basis for 3 months. Over-refraction, visual acuity, mean keratometry, corneal astigmatism, corneal eccentricity, superficial regularity and superficial asymmetry indices were monitored over the 3-month period.
  
  
  RESULTS
  Nineteen eyes of 10 patients completed the study. Seven Focus Night & Day, 7 Acuvue Oasys and 5 Soflens 38 contact lenses were fitted. There were no significant changes between any of the parameters measured at the 3-month visit in any of the SiH groups (non-parametric Wilcoxon test, p>0.05). However, the control group (Soflens 38) showed statistically significant changes regarding mean keratometry, corneal astigmatism and corneal eccentricity (p<0.05). Three patients wearing the first generation SiH showed adverse events of different degree related to their high modulus of elasticity.
  
  
  CONCLUSIONS
  After 3 months of DW, wearers of first and second generation SiH lenses showed greater corneal stability than hydrogel monthly disposable contact lenses users regarding commonly used topographic corneal shape indices. However, complications related to the mechanical properties of first generation SiH were seen in three patients in the follow-up time.
authors.affiliation: EUOOT, Escola Universitària d'Optica i Optometria de Terrassa, Terrassa (Barcelona), Spain. falbaoo@gmail.com
authors.forename: Francisco
authors.initials: F
authors.lastname: Alba-Bueno
authors.forename: Angel
authors.initials: A
authors.lastname: Beltran-Masgoret
authors.forename: Cristian
authors.initials: C
authors.lastname: Sanjuan
authors.forename: Marc
authors.initials: M
authors.lastname: Biarnés
authors.forename: Jesús
authors.initials: J
authors.lastname: Marín
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects* / Q000145:classification; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D018450:Disease Progression; D004209:Disposable Equipment; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008297:Male; D011446:Prospective Studies; D012828:Silicones; D013997:Time Factors; D055815:Young Adult
chemical_list: D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate