Investigating retinal toxicity of tempol in a model of isolated and perfused bovine retina
PURPOSE To compare the effect of a taurine-containing intraocular irrigation solution (PuriProtect TM) to a standard irrigation solution (BSS TM) we evaluated the retinal function using an electroretinogram (ERG) and analyzed the survival of retinal ganglion cells on isolated whole mount retinas. MATERIALS AND METHODS During ERG recordings, each irrigation solution was superfused for 45 min with the relevant irrigation solution. To investigate the effects on photoreceptor function, 1 m M asparate was added to obtain a-waves.The recovery of the a- and b-wave was monitored after superfusing the retinas with standard medium again. To evaluate the percentage of dead ganglion cells, retinas were stored for 24 h at 4°C in darkness and after staining the retinas with ethidium homodimer-1 the retinas were analyzed using fluorescence microscopy. RESULTS The application of standard medium supplemented with 2 m M taurine resulted in a significant increase of the b-wave amplitude compared to standard medium alone. The a-wave amplitudes showed no significant changes under taurine supplementation. Compared to standard medium BSS showed no significant decrease in b-wave amplitudes, but a significant decrease ina-wave amplitudes. In contrast to BSS there were no significant changes in the a- or b-wave amplitudes detectable after the application of PuriProtect. At the end of the washout period no significant changes in a- or b-wave amplitudes were recorded for any tested irrigation solution. Retinas stored for 24 h in PuriProtect or in standard medium with taurine had a statistically significant smaller amount of dead cells than retinas stored in standard medium without taurine supplementation. CONCLUSIONS BSS does not seem to be an ideal irrigation solution, because it compromises the a-wave in the ERG. In contrast to BSS, PuriProtect showed no significant impact on the ERG and showed a better long-term effect on ganglion cell survival. Taurine supplementation,therefore, seems to be neuroprotective and its supplementation to an intraocular irrigation solution favorable for the retina.