Effect of amniotic membrane transplantation on the healing of bacterial keratitis

To study, with the use of an animal model, the efficacy of amniotic membrane (AM) transplantation as adjunctive treatment in corneal healing after bacterial keratitis.

Staphylococcus aureus keratitis was induced in 47 rats by injection of bacteria into the corneal stroma. Treatment was started 48 hours later with one of three randomly assigned protocols: cefazolin drops (50 mg/mL) and AM transplantation (n = 16); nonpreserved 0.9% saline drops and AM transplantation (n = 15); or cefazolin without AM transplantation (n = 16). Cefazolin and saline drops were administered every 30 minutes for 6 hours, then hourly for 6 hours. AM was transplanted 24 hours after termination of cefazolin or saline treatment. Results were clinically assessed 7 days after AM transplantation or at the corresponding time in the nontransplanted animals. The rats were then killed, and their corneas were removed for bacterial counts or histopathologic examination.

The best clinical results were observed in the group treated with cefazolin and AM transplantation, manifested by the least corneal haze and neovascularization (P = 0.007 and P = 0.014, respectively) and minimal bacterial counts (28 colony-forming units [CFU]/mL compared with 160 CFU/mL and 240 CFU/mL, respectively). Histopathologic examination showed that the central corneal vessels from rats treated with cefazolin and AM were smaller and less congested than those from the other two groups.

AM transplantation is a useful adjunctive treatment after bacterial keratitis in this rat model. The transplanted AM improved the healing process, resulting in decreased corneal haze and less neovascularization.