Abstract
Abstract: :
Purpose: Severe complications, including posterior capsule opacification (PCO), are often associated with intraocular lens (IOL) implantation in pediatric patients. We report the initial findings of the mechanism(s) underlying these age-dependent host responses and potential solution for such complications. Methods: One-piece poly(methyl methacrylate) (PMMA) IOLs (from Rafi System, Inc, Diamond Bar, CA) were used for this study. Some IOL were coated with albumin-affinity cibacron blue dye as described earlier (J Lab Clin Med, 124:537-45, 1994.). Because implants are coated with a layer of host proteins prior to interact with cells, it is believe that the species and state of adsorbed proteins determine the extent of host responses to implants. To test this hypothesis, we first investigated the role of adsorbed proteins in affecting PCO formation in both young (4 wk old) and adult (20 wk old) New Zealand White rabbits. Both cibacron blue-coated and un-coated IOLs were implanted into rabbit eyes for different periods of time (24 hr and 8 wk). Aqueous humors and IOL implants were then recovered for protein determination and PCO/cell accumulation analyses, respectively. Results: Similar to human, young rabbits triggered much greater extent of PCO formation to 8 wk-implants than did adult rabbits. Interesting, we find that, 24 hr following IOL implantation, young rabbits prompted more protein influx (≷3 folds) in aqueous humor than did adult ones. We have further uncovered that, in addition to albumin, fibrin(ogen) (Fg) is the major component of proteins in aqueous humor and has much higher concentration in younger rabbits than adult ones (110 ± 25 vs. 32 ± 11 µg/ml). Based on the foregoing results, we have then assumed that the massive influx and accumulation of Fg is responsible to the higher PCO rate in young rabbits. To test this hypothesis, we use cibacron blue-coated IOLs which can specifically, selectively and reversibly adsorbed albumin. Our preliminary studies have revealed that, by increasing the concentration of surface-bound albumin, cibacron blue coating significantly reduced (≷90%) the amounts of asorbed Fg. Most importantly, cibacron blue-IOLs trigger significant lesser PCO formation (100 vs. 12%) and cell accumulation in young rabbits. Conclusions: These results provide a potential link between Fg deposition and PCO formation in young rabbits. It is our hope that a more precise understanding of host:implant interactions may permit the future rational design of IOL implants with markedly improved safety and tissue compatibility in pediatric patients.
Keywords: 522 posterior capsular opacification (PCO) • 338 cataract • 631 wound healing