Evaluation of the effect of subconjunctival botulinum toxin-a application on corneal nerve plexuses and corneal stroma cells in rabbit experimental model

Purpose: The objective of this study was to investigate the histopathological and molecular based changes induced by subconjunctival application of botulinum toxin-A (BoNT-A) on corneal nerve plexuses and corneal stromal cells in a rabbit experimental model. Methods: Six adult New Zealand white rabbits were included in the study. The rabbits were divided into two groups: the toxin group (n=6 eye) and the control group (n=6 eye). The toxin group received subconjunctival injections of BoNT-A, while the control group received saline injections. After a designated period (2 weeks), corneal specimens were collected from both groups. Histopathological and protein isolation studies were performed to evaluate the alterations in corneal nerve plexuses and corneal stromal cells. Results: The histopathological analysis revealed significant changes in the corneal nerve plexuses or corneal dendritic cells in the toxin group compared to the control group. In the corneal nerve plexuses, there were findings indicating a decrease in nerve fiber score. The nerve cell score in the toxin (subject) and control groups was statistically significant (p=0.016), but there was no significant difference in the fibroblast score (p=0.63). The mean and median values for nerve cells in the control group were 8923.0, 7477.0; 4112.7, 3786.5 in the toxin (subject) group, respectively; the mean and median values for fibroblasts in the control group were 5725.0, 5830.0; 5381.7, 5045.0 in the toxin (subject) group, respectively. Conclusion: Subconjunctival application of botulinum toxin-A in the rabbit experimental model resulted in histopathological changes in corneal nerve plexuses. These findings suggest that BoNT-A administration can potentially affect to corneal nerve plexuses. Further studies are warranted to elucidate the functional implications of these histopathological alterations and their potential clinical relevance in ophthalmology. Keywords: Botulinum toxin-A, corneal nerve plexuses, corneal stromal cells, histopathological examination, rabbit experimental model.