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Sonya Bamba, Jean T. Jacob, Jeffery Hobden, Brett Gudden, Sara Reggie, Tamika Y. Edwards, Jewel Germany; Treatment of Severe Bacterial Keratitis with Corneal Collagen Crosslinking. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1075.
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To characterize the antibiotic effect and induced histologic alterations of corneal collagen crosslinking in severe bacterial keratitis.
The corneas of both eyes of 16 New Zealand white rabbits were infected with Pseudomonas aeruginosa intrastromally. One eye of each animal served as the control and the randomly chosen contralateral eye served as the experimental crosslinked eye. Infection was allowed to progress for 36 hr to induce severe keratitis. At 36 hr, both eyes were treated with 1 drop of fortified tobramycin (14 mg/ml), and the experimental eye treated additionally with corneal collagen crosslinking. Crosslinking entailed removal of the corneal epithelium by scraping and dropping the eye with 1 drop of 0.1% riboflavin every 2 min for 60 min. During the latter 30 min of riboflavin administration, the eyes were exposed continuously to UVA light. The rabbits were sacrificed 30 min, 4 hr, or 8 hr after crosslinking. Corneas were harvested for plating and colony counting as well as for histologic examination. A separate infected non-treated control rabbit was sacrificed at 36 hr after infection to characterize the extent of the infection alone.
Thirty minutes after crosslinking, the experimental cornea was significantly less edematous than the antibiotic-treated cornea. Histologic examination of the crosslinked eye showed more tightly packed and coherent lamellae of the stromal collagen fibers in the anterior stroma compared to the antibiotic-treated eye, which has a disorganized, irregular pattern of the collagen fibers. Four hours after crosslinking, there was a paradoxical increase in the amount of corneal edema in the crosslinked eye compared to the antibiotic-treated eye, likely secondary to temporary stromal edema from keratocyte apoptosis induced by crosslinking. By 8 hr after crosslinking, the structural integrity of both the crosslinked and antibiotic-treated corneas was improved, but the anterior stroma of crosslinked cornea had a near-normal histologic appearance. Colony counts showed a statistically significant difference between the crosslinked eyes and antibiotic-treated eyes only at the 30 min time period.
Corneal collagen crosslinking is a useful adjuvant tool to treat infection and to maintain the structural integrity of the cornea in severe bacterial keratitis.
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