Impact of Different Oxygen Supply Methods on the Healing of Corneal Epithelial Wound and the Level of Acetylcholine

Abstract

Purpose: To investigate the impact of different oxygen supply methods on corneal epithelial wound healing and acetylcholine level during wound healing.

Methods: We randomly divided 75 rabbits into three groups: A, B, and C, with 25 rabbits in each group. The central corneal epithelium was removed from all eyes of the rabbits using a 5 mm trephine. Group A rabbits were given low flow oxygen (3 L/min; concentration: 33%) for 2 h per day through goggles. Group B rabbits were given low flow oxygen (3 L/min; concentration: 33%) for 2 h per day via oxygen masks for inhalation. Group C rabbits healed naturally. The area of healed corneal epithelium and acetylcholine content in corneal epithelium were determined at 12 h, 24 h, and 36 h after injury.

Results: At 12 h, 24 h, and 36 h after injury, the healing area of corneal epithelium in the three groups was in the order group A > group B > group C (P < 0.05). At all timepoints, the acetylcholine level in corneal epithelium was in the order of group A > group B > group C (P < 0.05). In all three groups, the acetylcholine content in corneal epithelium showed the order 12 h > 24 h > 36 h (P < 0.05). There was a correlation between acetylcholine expression and the area of unhealed corneal epithelium, and the correlation coefficients of groups A, B, and C were 0.80, 0.83, and 0.85 respectively.

Conclusion: Increasing oxygen concentration through inhalation or via goggles can promote corneal epithelial wound healing, but increasing local oxygen concentration of the eye showed a better effect. Acetylcholine may play an important role in the early process of corneal epithelial wound healing.

Figure 1

The fluorescence staining of corneal epithelium in each group at different time points shows that in groups A, B, and C, the area of fluorescence staining on the cornea was the same at 0 h, when the experiment was initiated, but at 12 h and 24 h after intervention, the area of fluorescence staining in group A was significantly smaller than that of group B and group C. At 36 h, filamentous fluorescence staining was only seen in the center of the cornea, and the surrounding cornea tissue was transparent. At 48 h, no corneal fluorescence staining was found, indicating that the corneal epithelium was completely healed. In group B, the area of corneal fluorescence staining was larger than that of group A but smaller than that of group C at all time points except at 0 h. In group C, the area of fluorescent staining was the largest among all three groups at all time points. After 72 h of intervention, filamentous fluorescence staining still could be seen, indicating that corneal epithelium was rough and not completely healed.