Abstract:

Objective To investigate the effect of corneal neovascularization on nerve regeneration in the injured cornea. Design Experimental study. Participants Sprague Dawley (SD) rats. Methods Eighteen SD rats were randomly allocated into 3 groups. Suture method inducing angiogenesis, cornea injury and subconjunctival injection of bevacizumab ware performed in Group A; Suture method inducing angiogenesis and cornea injury ware performed in Group B; Subconjunctival injection of bevacizumab was performed in Group C. At postoperative 1-day, 1-, 2-, 4-weeks, the slit lamp photographic method was used to observe surface area of corneal neovascularization; and confocal microscope was used to investigate corneal stromal nerve length. Corneal subepithelial nerves were stained with β tubulin antibody and pictures of subepithelial nerve plexus were taken at postoperative 4 weeks. The corneal sensation of suture zone was examined using the Cochet - Bonnet perception instrument. The Schirmer test 's tears line was used to measure the tear secretion in the right eye. Main Outcome Measures Corneal neovascularization surface area, corneal stromal nerve length, subepithelial nerve plexus density，corneal sensitivity, tear secretion. Results Corneal neovascularization grew in group A and B at 1-and 2-weeks and regressed at 4-weeks, and the cornea of group C was normal. There were significant difference of the corneal neovascularization area ratio between 1- and 2-weeks of group A and 1- and 2-weeks of group B[(10.86±1.57)% versus(25.42±2.65)%,(1.87±0.69)% versus(6.48±1.10)%, all P=0.000]. The length of injured cornea nerve decreased after experimental surgery in group A and B, and was normal in group C. There was no significant difference between group A and group B at 1-day after surgery[(151.02±4.74)μm versus(149.69±4.32)μm, P=0.306]，and there was significant difference among 1-,2-,4-weeks of group A and 1-,2-,4-weeks of group B[(193.84±2.25)μm versus(155.73±2.98)μm，(217.15±2.08)μm versus(166.21±2.41)μm，(220.70±1.41)μm versus(203.76±1.74)μm， all P=0.000]. The subepithelial nerve of injured cornea in the group C was normal and the subepithelial nerve plexus density was significantly higher in the group A than that in the group B[22.60±2.02)% versus(9.41±2.01)%，P=0.000]. The corneal sensitivity and tear secretion decreased after experimental surgery in group A and B, and were normal in group C, and there were no significant difference among 1-,2-,4-weeks of group A and 1-,2-,4-weeks of group B（all P＞0.05）. Conclusions Corneal neovascularization may retard nerve regeneration of damaged cornea, and inhibition of corneal neovascularization is helpful for nerve regeneration. (Ophthalmol CHN, 2017, 26: 106-111)

Key words: corneal nerves, nerve regeneration, corneal neovascularization