P 237 A novel silicone intraocular lens concept

Purpose: To determine the level of proteolytic activity in lens epithelium samples from cataract surgery and to investigate a possible relation to the type of cataract. We wanted to estimate G-independent as well as Ca-dependent activity. Another purpose was to me.asure the activity of calpastatin, an endogenous inhibitor of calpain, which is a Ca-activated protease. Methods: Cataracts were typed and graded previous to surgery by slit lanm biomicroscouv. Caosulorhexis were immediatelv Dut in a hvootonic buffer containing i&h4 I?DTA and then frozen at-80%. After th'a~ing, the samples were incubated for one hour at room temperature, which lead to detachment of the epithelial cells from the capsule and rupture of the cell membranes, as confirmed by light microscopy. The solution of epithelial cell cytoplasma was then incubated with a synthetic fluorogenic substrate; N-succinyl-Leu-Tyr-7-amido4methylcoumain, in the absence and in the presence of calcium (5mM EDTA and 2mM Ca respectively). Caipastatin is a heat stable protein and its activity was measured as the inhibitory effect of the boiled sample solution on puritied rabbit lung calpain. Acavities were related to the level of LDH (lactat dehydrogenas) activity. i?esuuS: The means for the activities measured in the absence and presence of calcium appeared to be the same. However, there was .a big variation in the ratio of EDTA-/Ca-activity, although in most cases activity measured in the absence of Ca was slightly higher. Calpastatin activity was detectable in most samples. Conclusions: Net activity of C&dependent proteases seems to be inferior to total proteolytic activity. However, some samples do show a high Ca-dependent activity, but further analyses must be performed to be able to connect this to special diagnostic groups. P 236 .F'resenti+ion-of .a circular compressible intra-oculer lens (IOL) withn intermediary ring-on nearly-3609 The interposxmn of B ring, half+vay-between IOL periphery aad dptic. allows to eliminate, or at least tu strongly reduce cellular aecondmy migrations to the center of ~~~~~~~~~~~~~ This preservation of postericr capsule transparency mxt stay the essentiai aim. Nevertheless, immediate visual rehabilitation, object of the main progresses of these-last years, remains perfectly accessible with this kind of IOL. Because the circular design and the general :ohesion guarantee a correct centering inside the capsular bag, without secondary retiactions. then allow a reduced diameter of the optic, for a xnall incision (4,5mm only, instead of 5,5mm, for an optic diameter of imm). Beginning of the study : end of 1992. Purpose. Most of the soft lenses …