Abstract
Purpose: :
Up to date no therapy exists for the treatment of the central retinal artery occlusion. In order to estimate and to possibly extend the time-window for any future treatment, we investigate the survival-time of the ischemic retina.
Methods: :
Enucleated bovine eyes underwent Pars Plana Vitrectomy (PPV) 100 minutes after the animal's death. The eyes were filled with Dulbecco`s Modified Eagle Medium and an oxygen bubble. Four hours after the start of PPV the retina was analyzed from functional and morphological perspective. The functional cell density and the spontaneous electrical activity of retinal ganglion cells was measured with a 256 multielectrode array. The cellular morphology was investigated by immunohistochemistry (Brn3a- and DAPI staining) on cryo sections and the caspase 3/7 activity of the whole retina was evaluated. Furthermore the Thy-1 mRNA expression was measured 24 hours after the beginning of the PPV. The operated eyes were compared to eyes which underwent sham operation and to eyes which suffered from 10-, 100- or 340 minutes of ischemia.
Results: :
The eyes which underwent PPV showed a significantly better survival of retinal ganglions cell compared to eyes which were left untreated for 340 minutes or which received sham operation. Nevertheless, compared to the enucleated eyes which were analyzed 10- and 100 minutes after the animal's death the PPV treated eyes showed a slightly reduced number of functional retinal ganglion cells.
Conclusions: :
Performation of PPV and filling up the globe with Dulbecco`s Modified Eagle Medium and an oxygen bubble can extend the retinal tolerance time against ischemic injury significantly. Further studies are needed to find the optimal composition of the used irrigation solution and to evaluate how long the retinal ganglion cells tolerate ischemia under these conditions.
Keywords: ischemia • neuroprotection • vitreoretinal surgery