[Chemical microanalysis of mineral deposits on explanted hydrophilic acrylic intraocular lenses].
OBJECTIVE
to perform chemical microanalysis of mineral deposits on the surface of explanted hydrophilic acrylic intraocular lenses (IOL).


METHODS
Two soft IOLs made of hydrophilic acryl (one, however, hydrophobic surface coated) and explanted 3 and 6 years after implantation were examined by scanning electron microscopy (EVO LS10, "Karl Zeiss", Germany). Chemical composition of the lens surface was studied using an energy-dispersive spectrometer (EDS X-Max50, Oxford, Great Britain).


RESULTS
Chemical microanalysis allowed identification of the deposits, which turned out to be non-stoichiometric hydroxylapatite (also, hydroxyapatite (HA)) crystals with zinc impurity (up to 1.4%weight).


CONCLUSIONS
The two samples represent two stages of a single process. The early stage is associated with newly formed HA crystals that are unable to cause any significant changes to the lens surface. However, as spherocrystals grow, they exert a crystallization effort that moves their growth centers apart with subsequent lens rupture and deformation. Crystal morphology undergoes dynamic changes: while primary (newly formed) crystals are sheaf-like, mature are spheres. A growing HA is non-stoichiometric. Zinc abundance accounts for appearance of its separate mineral phase. Hydrophilic properties of acrylic polymer determine its high affinity for HA crystals. Hydrophobic coating (sample no.1) does not completely prevent lens opacification due to mineral deposits on its surface.
Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021.
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Avetisov
Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021.
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Gamidov
Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021.
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Novikov
Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021.
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Fedorov
Research Institute of Eye Diseases, 11 A, B, Rossolimo St., Moscow, Russian Federation, 119021.
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Kas'yanov
D001672:Biocompatible Materials / Q000009:adverse effects / Q000737:chemistry; D002114:Calcinosis / Q000175:diagnosis / Q000209:etiology; D020878:Device Removal; D004577:Electron Probe Microanalysis / Q000379:methods; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000009:adverse effects / Q000737:chemistry; D019654:Lens Implantation, Intraocular / Q000009:adverse effects*; D007910:Lenses, Intraocular; D008855:Microscopy, Electron, Scanning / Q000379:methods; D011475:Prosthesis Failure / Q000209:etiology*; D012086:Reoperation / Q000379:methods; D013499:Surface Properties; D014792:Visual Acuity
D001672:Biocompatible Materials; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate