title: A hyper-Dk piggyback contact lens system for keratoconus.
abstract: OBJECTIVE
  To report the fitting of a hyper-Dk piggyback contact lens system in a case of keratoconus.
  
  
  METHODS
  Case report.
  
  
  RESULTS
  A patient with keratoconus, suboptimal visual acuity, corneal neovascularization, and marked conjunctival hyperemia, who was intolerant of rigid gas-permeable contact lenses, was fitted with a novel piggyback contact lens system that incorporated a hyper-oxygen transmissible hydrogel contact lens, on top of which was fitted a hyper-oxygen transmissible rigid gas-permeable lens. This novel contact lens system provided a significant improvement in visual acuity, comfort, and lens wear time. There was a marked reduction in corneal vascularization and ocular hyperemia.
  
  
  CONCLUSIONS
  This hyper-Dk piggyback contact lens system satisfied the ocular and visual requirements of this patient, for whom other nonsurgical options for vision correction had been unsuccessful. This system has potential application in the visual rehabilitation of other cases of corneal irregularity, including unsuccessful refractive surgery, ocular trauma, and keratoplasty. Piggyback contact lens systems require the same level of expertise to fit as basic forms of soft and rigid contact lenses. The hyper-oxygen transmissible lens materials available make these dual-lens systems a viable option for the compromised cornea.
authors.affiliation: Department of Optometry and Neuroscience, University of Manchester Institute of Science of Technology, Manchester, UK. clare.odonnell@umist.ac.uk
authors.forename: Clare
authors.initials: C
authors.lastname: O'Donnell
authors.forename: Carole
authors.initials: C
authors.lastname: Maldonado-Codina
mesh_terms: D001672:Biocompatible Materials; D003261:Contact Lenses; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000628:therapy*; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D010539:Permeability; D017755:Prosthesis Fitting; D012029:Refraction, Ocular / Q000502:physiology; D012826:Silicone Elastomers; D014792:Visual Acuity / Q000502:physiology
chemical_list: D001672:Biocompatible Materials; D012826:Silicone Elastomers; D010100:Oxygen