Cell biological mechanisms underlying posterior capsule opacification: search for a therapy

The present paper overviews our recent studies for PCO prevention using an in vitro human capsular bag model and application of hyperthermia and photodynamic therapy with Bacteriochlorin A as the sensitizer as described in previous papers. These studies clearly showed that both treatments are successful in vitro and almost completely reduce the proliferation of lens epithelial cells on the posterior capsule and thus are potential candidates to eliminate the occurrence of PCO in vivo. Hyperthermia has a threshold temperature between 55 degrees C and 60 degrees C which makes this approach not very useful for in vivo application. Threshold conditions for PDT/BCA are much more moderate. Recent preliminary in vivo studies in the rabbit showed that using the in vitro threshold conditions, the formation of a ring of Soemmering and outgrowth of lens epithelial cells on the posterior capsule is significantly reduced. However, these conditions have an adverse affect on the corneal stroma and endothelium. Studies of PDT conditions which further reduce LEC outgrowth without affecting the corneal integrity are in progress.