Various types of optic opacification of intra ocular lenses (IOL) have been reported.1234 We report evaluation of an explanted single-piece hydrophilic acrylic lens (SC60B-OUV) following opacification. A 62-year-old nondiabetic female presented with complaints of gradual diminution of vision in the right eye for the last three months. She had undergone uneventful phacoemulsification and implantation of foldable hydrophilic acrylic IOL (SC60B-OUV) for senile cataract in the right eye five years back. On examination best corrected visual acuity (BCVA) in right eye was found to be 20/400. A grayish opalescence was seen involving the optic of the IOL [Fig. 1A]. Fundus examination and intraocular pressure were normal. The left eye was pseudophakic with polymethyl methacrylate intra ocular lens (PMMA IOL) and BCVA of 20/20.
After informed consent, the patient underwent uneventful IOL explantation and exchange with a PMMA IOL. The adhesion between IOL and ocular tissues was released by visco dissection. A 5.5 mm optic PMMA IOL (Cee on from AMO Allergan) was implanted through a 5.5 mm incision after explanting the opacified IOL. The postoperative period was uneventful with BCVA in right eye improving to 20/20 at six weeks [Fig. 1B].
A detailed examination of the explanted IOL revealed that the opacification was confined to the central portion of the optic of the IOL, with haptics and edges being clear [Fig. 1C and D]. Electron microscopy (LEO 435 VP) revealed no abnormal deposits on the IOL surface [Fig. 2A]. After sectioning the IOL into 1 x 2 mm blocks, the saggital surface evaluation [Fig. 2B] by scanning electron microscope showed electron dense deposits in the opacified portion only [Fig. 2C]. The central opacified disc was surrounded by a clear zone of 220 to 250 µm thickness [Fig. 2D].
Characteristic opacification involving the central part of the optic with clear edges of SC60B-OUV lens has been described by many researchers.1234 Opacification is attributed to the presence of granules in the optic which are supposed to be composed of calcium as suggested by staining with alizarin red and energy dispersive radiograph analysis.124 We analyzed and compared the clear and opacified areas of IOL explanted 56 months after implantation and found that the electron dense deposits of variable sizes were only limited to the central portion of the opacified areas. Despite being intraocular for five years, the peripheral areas of the lens remained clear which suggests that the opacification starts from the centre of IOL and the aqueous humor probably might have a protective role. Although the mobile ions in aqueous have been reported to be similar in diabetics and controls, the total opacification of a similar model reported in a diabetic patient2 may be the result of altered flow dynamics of aqueous humor and blood-ocular barrier breakdown in diabetics.5 Exact cause of opacification is yet unknown and the hypothesis suggested is based on clinicopathological observation. We recommend the analysis of aqueous in all patients with IOL opacification. The different patterns of calcium precipitation have also been attributed to the differences in the water content of the hydrophilic acrylic materials.4 This report is different from the earlier ones as this is the longest interval between surgery and IOL explantation without total opacification of IOL optic.
Authors would like to thank Mr. Rakesh Pathania [Faculty: Sophisticated Analytical Instrument Facility, AIIMS, New Delhi] who helped us in analyzing the lens surface under scanning electron microscope.
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