Objective: To study the effects of ultraviolet light combined with
riboflavin treatment (corneal
collagen-crosslinking, CXL) on infectious control and stromal reconstruction of bacterial
keratitis. Methods: Experimental Study. A Staphylococcus aureus rabbit
keratitis model was established by injecting Staphylococcus aureus broth into the shallow stromal layer of the right eye cornea of New Zealand white rabbits. Forty-four rabbits that successfully established the model were randomly divided into four groups:
corneal collagen cross-linking (CXL) group,
antibiotic group, CXL+
antibiotic group and untreated group, with 11 rabbits in each group. Before the treatment and at 3, 7, 14 and 28 days
after treatment,
slit lamp corneal examination, AS-OCT and in vivo confocal microscopy (IVCM) were performed. Clinical efficacy of different treatments were evaluated at different time points. Parameters including conjunctival
hyperemia,
corneal ulcer, infiltration,
edema, and neovascular. Histopathological examinations of corneal lesions were performed in order to detect the infiltration, inflammatory cells and repair in corneal tissue. Normal data were compared with paired t-test and non-normal data were compared with paired rank sum test before and
after treatment. Kruskal-Wallis rank sum test was used to compare 4 groups of data and the generalized estimation equation is used to compare the repeated measurement data at each time point and the comparison between the groups of the treatment groups. Results:
After treatment, different time points and specimens for pathological observation, we obtained the following results:Conjunctival
hyperemia: in CXL and CXL+
antibiotic groups
after treatment for 3 days from treatment before 3 (2, -4) and 3 (2, -3),The reduction was 2 (1, -3) and 2 (1, -2), the difference was statistically significant (Z=-3.91, -5.50; P<0.008); 14 days, the
antibiotic group changed from 3 (3, -4) to 2 (1, -2)
after treatment, the difference was statistically significant (Z=-5.11, P<0.008); the untreated group had no statistical significance before and
after treatment. After 14 days of treatment, the area of
corneal ulcer (0.08±0.11) cm(2), (0.07±0.05) cm(2) in CXL group and CXL+
antibiotic group was significantly lower than that before treatment (0.40±0.18) cm(2), (0.49±0.24) cm(2). The difference was statistically significant. Significance (Z=-3.29, -3.64; P<0.008); after 14 days of treatment, after 14 days of treatment, neovascularization in the CXL and CXL+
antibiotic groups began to resolve, 1 (1, -2) and 1 (0, -2) at 7 days of treatment. decreased to 1 (1, -1) and 0 (0, -1), the difference was statistically significant (Z=4.57, 3.80; P<0.012 5); The degree of
corneal edema was significantly reduced in the CXL group and the CXL+
antibiotic group at 14 days
after treatment, which was reduced from (650±154) μm and (785±255) μm before the treatment to (432±95) μm and (455±109) μm, the difference was statistically significant (t=4.50, 4.92; P=0.00); The density of corneal stromal cells was also reduced from (446±257)/mm(2), (321±145)/mm(2) to (107±66)/mm(2), (114±94)/mm(2), the difference was statistically significant (t=4.15, 4.76; P<0.05). Histopathological observation under light microscope showed that most of the corneal
ulcers healed in the CXL group and the CXL+
antibiotic group at 7 days of treatment. The epithelial cells were clearly visible and misaligned, and a small amount of neutrophils in the stromal layer. The upper epithelial layer was treated for 14 days. The cells are arranged neatly, the structure is clear, and the inflammatory cells are significantly reduced. Conclusion: Ultraviolet light combined with
riboflavin corneal collagen cross-linking has a certain
therapeutic effect on rabbit bacterial
keratitis infection control and
ulcer repair, and can be used as an auxiliary treatment for
antibiotics. (Chin J Ophthalmol, 2018, 54:902-910).