A preliminary study on the prevention of posterior capsule opacification by photodynamic therapy with bacteriochlorin A in rabbits.
OBJECTIVE
Photodynamic therapy (PDT) with bacteriochlorin a (BCA) has proven to be successful in the treatment of cancers and to be cytocidal for lens epithelial cells (LECs) in culture. The present study aimed to determine whether PDT with BCA is also effective in destroying LECs in the capsular bag in vivo and could therefore be a strategy for prevention of posterior capsule opacification (PCO).


METHODS
BCA was obtained by saponification and acid hydrolysis of bacteriochlorophyll a and was formulated in 30% polyethylene glycol, 20% ethanol and 50% water. Nine albino rabbits were anesthesized and both pupils dilated. Extracapsular lens extraction by phacoemulsification was performed on both eyes. One eye of each animal served as control. In the other eye, 1.5 ml BCA (10 or 50 microg/ml) was injected in the capsular bag and after 10 min, the eye was illuminated with a diode laser (wavelength 760 nm) for 10 or 15 min. Six weeks after surgery, the rabbits were sacrificed and the globes were enucleated, the capsular bags and the corneas removed, fixed and examined using stereomicroscopy and light microscopy.


RESULTS
In the control capsular bags, extensive proliferation of LECs and formation of a complete ring of Soemmering was found, while in the PDT-treated capsular bags, LEC proliferation was markedly diminished and an incomplete irregular and much thinner ring of Soemmering was formed. Using the presently described application, the corneas of the PDT-treated animals were opaque and swollen and had lost their endothelial lining.


CONCLUSIONS
PDT with BCA induces cell death in LECs and greatly reduces the formation of a ring of Soemmering. Therefore, it could be a promising novel means of prevention of PCO, provided the total length of the treatment can be substantially reduced and the negative effects on corneal transparency avoided.
van Tenten
Yasmine
Y
Department of Ophthalmology, University Hospital of Antwerp, Edegem, Belgium. yvantenten@hotmail.com
Schuitmaker
Hans J
HJ
De Groot
Veva
V
Willekens
Ben
B
Vrensen
Gijs F J M
GF
Tassignon
Marie-José
MJ
D000818:Animals; D002386:Cataract / Q000517:prevention & control*; D002455:Cell Division / Q000187:drug effects; D003315:Cornea / Q000473:pathology; D004728:Endothelium, Corneal / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology; D007903:Lens Capsule, Crystalline / Q000187:drug effects* / Q000473:pathology; D010778:Photochemotherapy; D011166:Porphyrins / Q000627:therapeutic use*; D011817:Rabbits
D011166:Porphyrins; C065423:bacteriochlorin a