title: Late postoperative opacification of hydrogel intraocular lenses: analysis of 13 explanted lenses.
abstract: OBJECTIVE
  We report the clinical, morphological, and ultrastructural findings of 13 consecutively explanted opacified Hydroview(R) (hydrogel) intraocular lenses (IOLs). Our purpose was to provide a comprehensive account on the possible factors involved in late postoperative opacification of these IOLs.
  
  
  METHODS
  Thirteen consecutive opacified hydrogel IOLs (Hydroview H 60 M, Bausch & Lomb) were explanted due to the significant visual impairment they caused. The IOLs underwent macroscopical examination, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrophoresis for protein detection. Three unused control Hydroview IOLs served for comparison.
  
  
  RESULTS
  Macroscopical examination showed a diffuse or localized grey-whitish opacification within the IOL optic. TEM confirmed the presence of lesions inside the optic in all the explanted IOLs and revealed 3 patterns of deep deposits: a) diffuse, thick, granular, electron-dense ones; b) small, thin, lattice-like ones, with prominent electron-lucent areas; and c) elongated electron-dense formations surrounded by electron-lucent halos. SEM showed surface deposits on four IOLs. EDS revealed oxygen and carbon in all IOLs and documented calcium, phosphorus, silicon and/or iron in the deposits. Two of the patients with iron in their IOLs had eye surgery prior to their phacoemulsification. Iron correlated well with the second TEM pattern of deep lesions, whereas calcium with the third TEM pattern. No protein bands were detected on electrophoresis. Control lenses did not show any ultrastructural or chemical abnormality.
  
  
  CONCLUSIONS
  The present study supports the presence of chemical alterations inside the polymer of the optic in late postoperative opacification of Hydroview IOLs. This opacification does not follow a unique pathway but may present under different ultrastructular patterns depending on the responsible factors. Mechanical stress during surgery may initiate a sequence of events where ions such as calcium, phosphorus, silicon, and/or iron, participate in a biochemical cascade that leads to gradual alteration of the polymer network. Intraocular inflammation due to previous operation may be a factor inducing opacification through increase of iron-binding capacity in the aqueous humour. Calcification accounts only partially for the opacification noted in this type of IOL.
authors.affiliation: Department of Ophthalmology, General Hospital of Patras Agios Andreas, Patras, Greece. jkatsimpris@yahoo.com
authors.forename: J M
authors.initials: JM
authors.lastname: Katsimpris
authors.forename: P E
authors.initials: PE
authors.lastname: Theoulakis
authors.forename: K
authors.initials: K
authors.lastname: Kouzi-Koliakos
authors.forename: E
authors.initials: E
authors.lastname: Pavlidou
authors.forename: I K
authors.initials: IK
authors.lastname: Petropoulos
authors.forename: G
authors.initials: G
authors.lastname: Koliakos
authors.forename: N
authors.initials: N
authors.lastname: Vouroutzis
authors.forename: A G
authors.initials: AG
authors.lastname: Konstas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003318:Corneal Opacity / Q000175:diagnosis* / Q000209:etiology*; D020878:Device Removal; D005260:Female; D006801:Humans; D020100:Hydrogels / Q000009:adverse effects*; D007910:Lenses, Intraocular / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D020100:Hydrogels