Аннотация:Background
Perioperative corneal abrasion (CO) is an ophthalmological complication commonly found in patients undergoing general anesthesia. Etiology of perioperative CO was hypothesized to involve changes in quantity and quality of the precorneal tear film. To develop a paradigm for prevention of the anesthesia-induced CO, its time-response characteristics were evaluated together with associated alterations in biomechanical and biochemical properties of the tear film. Considering the obtained data, a new approach to prevention of perioperative CO based on antioxidant premedication was tested.
Materials & Methods
The corneal abrasions were induced in experimental animals (rabbits) by their exposure to general anesthesia for 1-6 h with or without antioxidant premedication. The development of CO was clinically monitored by means of fluorescein test and verified by histopathological examination of the corneas. Secretion and stability of the tear film was evaluated using standardized Schirmer’s test and BUT test, respectively. Tear proteins content was measured by BCA assay, the proteins were separated using SDS-PAGE and identified by mass-spectroscopy. Tear antioxidant activity was validated using the hemoglobin-hydrogen peroxide-luminol chemiluminescence assay. The content of antioxidant enzymes and inflammatory cytokines in tear samples was evaluated using specific colorimetric kits.
Results
Fluorescein stained point lesions in cornea were occasionally detected 1 hour post injection of anesthetic whereas six-hour anesthesia resulted in corneal injury in all experimental animals. The lesions were histologically diagnosed as corneal abrasions restricted to the corneal epithelium and involved cell deaths in its mid- and deep layers. The corneal damage was associated with dramatically reduced tear secretion and stability of the tear film. Analysis of the tear proteome pointed to depression of lacrimal glands function, and suggested serotransferrin, serum albumin and annexin A1 as potential tear markers of the complication. The tear film alterations included fast drop of total antioxidant activity and activity of antioxidant defense enzymes, and delayed increase in proinflammatory cytokines. Premedication using antioxidants considerably restored biochemical properties of the tear film and recovered clinical and morphological sings of the disease.
Conclusions
Our data suggests antioxidant premedication as prospective approach for prevention of perioperative CO. In addition our data should be considered in any ophthalmological study employing anesthetized animals as results of such a study might be affected by general anesthesia.
Acknowledgements
This work was supported by the Russian Science Foundation (grant # 16-15-00255).