The aim of this study was to evaluate the incidence of surface scratches of heparin surface-modified PMMA IOL and the possible influence of these alterations on the biocompatibility of this material. Two groups of patients having HSM PMMA IOL after phacoemulsification were examined 7, 30, 90, and 180 days after surgery using specular microscopy. Subjects without any other pathologies were enrolled in group 1 and diabetic patients in group 2. The incidence of altrations of anterior IOL surface was assessed. The inflammatory cell reaction was first detected and then graded using a semiquantitative scale and the site of inflammatory cells in relation to surface scratches was evaluated. Scratches and other surface defects were evidenced on 89.1% of cases. The density of inflammatory cells was higher in diabetic patients. In these patients inflammatory cells were more often located inside surface scratches than spread on the IOL surface. This 'in vivo' cytologic study evidences the effectiveness of heparin surface modification in improving the biocompatibility of PMMA reducing the adesion of inflammatory cells. In addition the behaviour of inflammatory cells in diabetics suggests the use of this material in subjects with predisposing conditions to an increased postoperative breakdown of blood-aqueous barrier.
