Experimental Scleral Perforation by Cultured Bacteria in the Needle Used during Strabismus Surgery

Lee, Se Youp; Suh, Seong Il

Abstract

PURPOSE: In order to investigate endophthalmitis and these causative organisms after accidental scleral perforation during strabismus surgery, the used needles after strabismus surgery were cultured and then the cultured bacteria were introduced into rabbit vitreous after perforating the sclera.
METHODS
We cultured the needles of sixty strabismus patients, and the identified bacteria were introduced into rabbit vitreous after perforation of the sclera, by dilution at different concentrations, using either sterile syringe or staining on the needles.
RESULTS
Positive cultures were found in 10 patients. Of these 10, 7 were identified with Staphylococcus epidermidis and 3 with Staphylococcus aureus. After culturing these two strains and diluting them to different concentrations, they were injected into rabbit vitreous using sterile syringe. It was found that S. aureusat the concentration of 10(3)colonies/ml produced endophthalmitis while at 10(5)~10(7)colonies/ml endophthalmitis was found to be present in all eyes. Although S. epidermidis at concentrations between 10(3) and 10(7) colonies/ml also produced endophthalmitis, the degree of inflammation was weaker than that induced by S. aureus, and some rabbits did not even develop endophthalmitis. After S. aureus was diluted to different concentrations, stained on needles and perforated into rabbits vitreous, endophthalmitis developed at the concentration of 10(7)colonies/ml.
CONCLUSION
The two strains isolated after strabismus surgery were the same as the normal bacterial flora found in the lid and conjunctiva. Three days after introduction of both strains, endophthalmitis developed at the relatively high concentration of colonies. In order to prevent endophthalmitis after scleral perforation, the surgeon should decrease the concentration of normal flora in the lid and conjunctiva before strabismus surgery.