Safety Evaluation of the Plasma on Ocular Surface Tissue: an Animal Study and Histopathological Findings

Purpose The plasma soft surgery is as an alternative to invasive surgical cosmetic procedures that can reduce the recovery time and possible complications after surgery. Due to the sensitivity of ocular surface tissue and the potential of the plasma, it can be evaluated to treat some ocular surface disorders. Accordingly, we evaluated the safety of the cold plasma on the ocular surface tissue in three areas located in the cornea, limbus, and conjunctiva. Methods Nine adult male New Zealand albino rabbits which divided into three groups were used for experiments. The left eye of each rabbit was chosen for test and the right eye was as the control. Experiments were performed on three ocular surface areas under the influence of the plasma. For this purpose, the plasma was created by Plexr device in continues mode and low power level (white handpiece; 0.7 W) was utilized at 0.7 s intervals using a 22-gauge needle. For evaluation of plasma safety, ocular surface integrity and histopathological changes were assessed after 24 h (A), one week (B), and one month (C) exposure to plasma. Results According to the external and slit-lamp examinations, after 24 h (A) only epithelial defect was visible while ocular surface in other groups (B & C) was healthy had completely recovered. OCT imaging and histologic examination also confirmed these results. After 24 h conjunctival and corneal sections showed a localized area of epithelial loss together with infiltration of inflammatory cells in the subepithelial stroma, but during the one-month period, recovery was evident. Generally, after the first week, the loss of integrity of corneal epithelium has not been completely improved yet, while it was recovered nearly to be normal in group C. It was noteworthy that in all groups the loss of endothelium cells was not apparent which confirming the lack of damage to the deep layers of the eye. Conclusion According to the plasma safety results, it seems that plasma soft surgery has the potential to be used as an alternative method for treatment of some of the ocular surface disorders without needing to conventional surgical procedures.

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