The right eyes of 84 rabbits, divided into 3 groups of 28 rabbits each, underwent standard 3-port pars plana
vitrectomy with
silicone oil (SO group),
silicone oil and intravitreal
dexamethasone implant (SO/DEX group), or
silicone oil and
triamcinolone acetonide (SO/TA group). The retina from the left eye of each rabbit served as a control. The animals were killed at 4 weeks after surgery. Qualitative and quantitative histopathologic analyses were performed 4 weeks after surgery, and investigation for apoptosis was performed using the Tunel assay.
RESULTS: Intravitreal
triamcinolone acetonide and
dexamethasone implant were associated with increased
retinal neuronal survival, primarily in the outer nuclear layer, inner nuclear layer, and
ganglion cell layer. In the SO group, the cell density in eyes that underwent PPV/SO was 31% lower in the outer nuclear layer, 33% lower in the inner nuclear layer, and 45% lower in the
ganglion cell layer compared to control eyes (p < 0.05 for all PPV/SO versus control comparisons). Compared to eyes that underwent PPV/SO, the cell density in eyes treated with
triamcinolone was 27% higher in the outer nuclear layer, 66% higher in the inner nuclear layer, and 100% higher in the
ganglion cell layer (p < 0.05 for all
triamcinolone versus PPV/SO comparisons). Compared to eyes that underwent PPV/SO, the cell density in eyes treated with
dexamethasone was 46% higher in the outer nuclear layer, 62% higher in the inner nuclear layer, and 77% higher in the
ganglion cell layer (p < 0.05 for all
dexamethasone versus PPV/SO comparisons). Analyses using the Tunnel assay demonstrated apoptotic bodies in all eyes in the SO group, compared with none of the eyes in the SO/TA and SO/DEX groups. The presence of cell nuclei stained with 49,6-diamidino-2-phenylindole (
DAPI) was demonstrated in all groups.
CONCLUSION: In this experimental model of neuroprotection, increased
retinal neuronal survival was seen in the
steroid-treated groups compared with the controls.