The effect of photodynamic therapy with bacteriochlorin a on lens epithelial cells in a capsular bag model

Photodynamic therapy (PDT) with bacteriochlorin a(BCA) has proved to be a successful treatment for many cancers and to be cytocidal for different cell lines in culture. The present study aimed to investigate in vitro the potential of this treatment for killing lens epithelial cells (LECs) left in the human capsular bag after extracapsular cataract extraction (ECCE). Capsular bags were prepared from donor eyes using an ECCE procedure and incubated in various concentrations of bacteriochlorin a(1.6-50 microg ml(-1)) during various incubation periods (2-10 min). Subsequently, the capsules were illuminated during various exposure times (2-15 min) with a diode laser (wavelength 760 nm). After treatment, the capsular bags were cultured for 7 days in Eagle's minimal essential medium supplemented with 2% fetal calf serum. The specimens were fixed in glutaraldehyde/paraformaldehyde and examined with routine light microscopy, Hoechst staining for DNA and transmission electron microscopy. Proliferation of LECs on the posterior capsule was assessed in flat mounts. Capsular bags receiving BCA without illumination and capsular bags receiving illumination only served as controls.BCA alone or light alone have no effect on structure and proliferative activity of LECs. At a threshold protocol of incubation in BCA at 10 microg ml(-1)for 10 min and subsequent illumination for 15 min, proliferative activity of cells is largely arrested and nearly all LECs on the capsule exhibit severe signs of apoptosis. Photodynamic therapy with bacteriochlorin a induces cell death and suppression of proliferation inlens epithelial cells and could be a promising means of prevention of posterior capsule opacification.