title: Phakic intraocular lenses.
abstract: OBJECTIVE
  Laser in-situ keratomileusis has been tremendously successful in treating patients with mild and moderate ametropias. For patients with high degrees of refractive error, however, phakic intraocular lenses provide superior quality of vision without the risk of corneal ectasia. Early international results, as well as United States Food and Drug Administration clinical trials, have demonstrated the early safety and efficacy of phakic intraocular lenses. Nevertheless, long-term corneal endothelium cell density and crystalline lens clarity remain a concern.
  
  
  RESULTS
  Several new studies demonstrate the superior visual outcomes of phakic intraocular lenses over laser in-situ keratomileusis in patients with moderate and high myopia, particularly in the areas of visual quality and contrast sensitivity. New anterior segment imaging and measurement technologies have provided valuable information about in-vivo structure and function, with and without phakic lens implants. More is being learned about long-term endothelial cell stability and cataract formation, particularly in relation to implant positioning. New applications of phakic intraocular lenses in presbyopia and in other conditions are being explored.
  
  
  CONCLUSIONS
  Once plagued by complications and marginal outcomes, improved designs of phakic intraocular lenses are providing increasing safety and efficacy for the correction of severe ametropias. Long-term concerns with endothelial cell loss remain, but recent data suggest stabilization with time. Proper sizing and positioning are important and increasingly achievable with new imaging modalities. With continued research and experience, phakic intraocular lenses are becoming an invaluable addition to the mainstream refractive surgery armamentarium.
authors.affiliation: Minnesota Eye Consultants, Minneapolis, USA.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Chang
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Davis
mesh_terms: D006801:Humans; D020731:Keratomileusis, Laser In Situ; D019654:Lens Implantation, Intraocular / Q000379:methods*; D007908:Lens, Crystalline / Q000502:physiology*; D007910:Lenses, Intraocular; D054140:Refractive Surgical Procedures; D014792:Visual Acuity