title: Progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses.
abstract: OBJECTIVE
  To investigate the rate of progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses (pancorneal RGP-CL) compared to non-pancorneal RGP-CL. We also evaluated alterations in anterior chamber parameters with the progression of keratoconus and investigated the location of the cone in eyes with keratoconus.
  
  
  METHODS
  The current study was a retrospective study including patients with clinically evident keratoconus from the outpatient clinic from the Department of Ophthalmology of the Erasmus Medical Center, Rotterdam, the Netherlands. Medical history and contact lens characteristics were documented. All participants underwent ophthalmic examination including corneal topography. Corneal topography was repeated at one of the consecutive visits of the patient. Patients were divided into two groups: those wearing pancorneal RGP-CL and those wearing other contact lens types. As a measure of progression of keratoconus differences in corneal topography parameters between both groups were compared.
  
  
  RESULTS
  A total of 82 patients were included of which 42 had follow-up (mean 17.8 months) data. We found a significant difference in progression between eyes fitted with and without pancorneal RGP-CL (K-flat: p=0.09, K-steep: p=0.02, K-mean: p=0.02, and K-minimum: p=0.04). Compared with eyes fitted without pancorneal RGP-CL no significant difference in K-values was found for eyes fitted with pancorneal RGP-CL during follow-up. Furthermore, a significant decrease in anterior chamber volume (p<0.001) and corneal volume (p=0.008) was found during follow-up. In 86.6% the location of the cone was located infero-temporal.
  
  
  CONCLUSIONS
  Pancorneal RGP-CL have a better effect on stabilizing progression of keratoconus than non-pancorneal RGP-CL. The finding of an infero-temporal location of the cone in keratoconic corneas may improve results of contact lens fitting and surgical management.
authors.affiliation: Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands. Electronic address: w.ramdas@erasmusmc.nl.
authors.forename: Wishal D
authors.initials: WD
authors.lastname: Ramdas
authors.affiliation: Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Charles J W C
authors.initials: CJ
authors.lastname: Vervaet
mesh_terms: D000328:Adult; D003262:Contact Lenses, Extended-Wear; D019781:Corneal Topography; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D008137:Longitudinal Studies; D008297:Male; D017755:Prosthesis Fitting / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014786:Vision Disorders / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*
keywords: Contact lens; Keratoconus progression; Pancorneal; Rigid gas-permeable