Purpose: The authors conducted in vivo assessment of corneal endothelial toxicity of air and SF6 in the feline model. This research was motivated by the increased use of air in anterior segment surgery in human subjects.
Methods: This was a prospective masked study. The eyes of 16 healthy adult cats were randomly assigned for the injection of 0.7 mL air into the anterior chamber of one eye and SF6 in the contralateral eye. Daily examination included slit lamp photographs, pachymetry, and tonometry. Specular microscopy was performed before, 7 days after, and 10 days after injection. The animals were euthanatized, and the corneas were processed for alizarin red-trypan blue staining and for light and electron microscopy.
Results: SF6 remained in the anterior chamber significantly longer than air. Both groups showed postinjection inflammation, which on average was maximal at day 2 and more severe with SF6. No difference in IOP was observed between the two groups. Specular microscopy showed significant endothelial cell loss in the SF6 group (mean postinjection cell loss, 132 ± 50 cells/mm(2)) but not in the group injected with air. Alizarin red staining revealed significant regional differences in cell density only in the SF6 group and more pronounced endothelial cell loss in the superior area.
Conclusions: These results indicate that both air and SF6 injected into the anterior chamber of the eye can induce intraocular reaction in the feline model and that SF6 is more toxic than air in terms of endothelial cell loss and anterior chamber inflammation.