contact lens

Last reviewed 01/2018

Contact lenses are used to correct errors of refraction such as

  • myopia
  • hyperopia (hypermetropia)
  • astigmatism
  • presbyopia

There are two types of lenses:

  • hard lenses
    • most commonly used are rigid gas-permeable (RGP)
      • made of plastics, silicone or fluoropolymers
      • used for astigmatism
      • used to combat allergies
        • when tendencies to form protein deposits in lenses
    • soft lenses -commonest in use
      • many types
        • daily wear lenses
        • extended wear
          • lenses removed at least weekly for cleaning and disinfection
          • greater risk of corneal infection
        • disposable wear
          • recommended for allergies
          • toric soft contact lenses - astigmatism

Cautions to contact lens use include:

  • frequent eye infections
  • severe allergies
  • dry eye that is resistant to treatment
  • working in a dusty environment


  • complications associated with contact lenses
    • change in corneal physiology, leading to
      • epithelial,
      • stromal, and
      • endothelial compromise
    • lens deposition
    • allergic conjunctivitis
    • giant papillary conjunctivitis
    • peripheral infiltrates
    • microbial keratitis
    • neovascularization


  1. Sucheck JK et al. Contact lens complications. Ophthalmol Clin North Am. 2003 Sep;16(3):471-84.