Evaluation of Toluidine Blue-Mediated Photodynamic Therapy for Experimental Bacterial Keratitis in Rabbits

Abstract

The objective of this study was to evaluate the effect of toluidine bluemediated photodynamic therapy on experimental bacterial keratitis in rabbits. Methods: Bacterial keratitis was induced in rabbits by the injection of 200 μl Staphylococcus aureus (S. aureus) solution into the anterior stroma of the right cornea. Rabbits were randomly divided into four groups: toluidine blue O and red light (TBOR), levofloxacin eye drops (LEV), the combination of TBOR and LEV (TBOR + LEV), and a control group. Clinical manifestations, histopathology, and transmission electron microscopy were analyzed at various time points. Results: Conjunctival injection and surface area of the corneal ulcer in the TBOR group and the TBOR + LEV group showed significant improvement from baseline after 7 days of treatment. Compared to baseline, the depth of corneal infiltration was decreased at day 14 in the TBOR and TBOR + LEV groups. Microscopic analysis of the TBOR and TBOR + LEV groups showed that the structure of each layer was intact, and there were no inflammatory cells in the corneal stroma. Additionally, IL-1β and TNF-α were highly expressed in the LEV and control groups but were lower in the TBOR and TBOR + LEV groups. Under transmission electron microscopy, the corneas in the TBOR and TBOR + LEV groups were intact, whereas in the LEV and control groups, double-walled structures corresponding to S. aureus were found in the superficial stromal layer. Conclusions: TBOR demonstrated in vivo antibacterial efficacy against S. aureus. Translational Relevance: This study found in vivo antibacterial efficacy of toluidine blue-mediated photodynamic therapy on rabbit experimental bacterial keratitis, thus providing an additional new option for clinical treatment of bacterial keratitis.

Photoactivated Chromophore for Keratitis-Corneal Cross-linking (PACK-CXL)—A Scoping Review Based on Preclinical Studies

“…It was successful in 100% of the animals used in four studies 49 – 52 and in 85.7% and 87.5% in two other studies, respectively. 53 , 54 The success rate of inducing infectious keratitis in the animal model was not provided in the remaining 28 records. The duration between infection and treatment in both fungal and bacterial keratitis animal models ranged from 12 hours to seven days, with the majority of PACK-CXL interventions applied 72 hours after infection (n = 7).…”

Surface Self-Assembly Construction of Therapeutic Contact Lens with Bacterial “Kill-Releasing” and Drug-Reloading Capabilities for Efficient Bacterial Keratitis Treatment

“…aureus suspension (1 × 10 6 CFU/mL) was injected into the corneal basal layer through the limbus with a 1 mL insulin syringe. With the diffusion of the bacterial suspension, the interlamellar swelling of the cornea with a diameter of 3–4 mm was observed . The surface-modified CLs were sterilized by UV irradiation for 30 min before use.…”

“…With the diffusion of the bacterial suspension, the interlamellar swelling of the cornea with a diameter of 3−4 mm was observed. 51 The surface-modified CLs were sterilized by UV irradiation for 30 min before use. After the injection of bacterial suspension into the corneal stroma, the L@(PAcA/PEI) 5 -modified CLs were worn on the rabbit corneal surface and fixed with 5−0 nylon surgical sutures.…”

Fluorescent Nanosystems for Drug Tracking and Theranostics: Recent Applications in the Ocular Field

“…In the Su et al study, in vivo antibacterial efficacy of TB-mediated photodynamic therapy on bacterial keratitis by Staphylococcus aureus in a rabbit was demonstrated. This provides a new option for the clinical treatment of bacterial keratitis [ 96 ].…”