title: Visually significant calcification of hydrogel intraocular lenses necessitating explantation.
abstract: OBJECTIVE
  To report two cases of HydroviewR (Storz H60M) hydrogel intraocular lens (IOL) opacification necessitating explantation. To analyse the explanted lenses and compare them with a new lens in order to determine the cause of opacification.
  
  
  METHODS
  Two cases are presented. Both patients complained of subjective decreases in vision approximately 1 year following uneventful cataract extraction and implantation of hydrogel lenses by the same experienced surgeon in the same institution. The reduced contrast sensitivity was thought to be due to failure of the hydrogel lenses which appeared opacified at the slit-lamp. They were then exchanged for acrylic lenses. Pre- and postoperative contrast sensitivity testing was performed using the VectorvisionR CSV-1000E instrument. A detailed comparative analysis of the opacified explanted lenses and a new lens was undertaken. This included surface microscopy, infrared spectral analysis, X-ray elemental analysis, scanning electron microscopy, and electron microscopy of lens slices.
  
  
  RESULTS
  Lens exchange resulted in an improvement in subjective visual acuity (VA) and in objective contrast sensitivity testing. Analysis revealed deposits of calcium phosphate (hydroxyapatite) on the explanted lens' surfaces.
  
  
  CONCLUSIONS
  The surface of the HydroviewR H60M intraocular lens is subject to opacification as a result of calcium phosphate (hydroxyapatite) deposition, thereby limiting the patient's visual outcome, and in some cases necessitating explantation. The reason for surface calcification requires further study.
authors.affiliation: Dudley Specialist Medical Centre, Orange, NSW, Australia.
authors.forename: G T
authors.initials: GT
authors.lastname: Fernando
authors.forename: B B
authors.initials: BB
authors.lastname: Crayford
mesh_terms: D002114:Calcinosis / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D015350:Contrast Sensitivity; D020878:Device Removal; D017886:Durapatite / Q000032:analysis; D004577:Electron Probe Microanalysis; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D011475:Prosthesis Failure; D013055:Spectrophotometry, Infrared; D014786:Vision Disorders / Q000209:etiology* / Q000378:metabolism / Q000473:pathology
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D017886:Durapatite