Abstract
Purpose :
Endophthalmitis is a rare but significant vision threatening emergency. The time from symptom onset to treatment is a significant factor in final visual outcome. Standard of care is treatment with fortified broad-spectrum antibiotics that require specialist pharmacy preparation creating a delay in care. Aqueous chlorhexidine gluconate is a readily available, stable antiseptic with broad-spectrum antimicrobial, anti-viral, and anti-fungal action. The purpose of this study is to determine the feasibility of intravitreal injection of aqueous chlorhexidine in terms of retinal toxicity and antimicrobial efficacy in an animal endophthalmitis model.
Methods :
Intravitreal injections of aqueous chlorhexidine (0.1%, 0.01%, and 0.001%) were administered to 3-month-old brown Norway rats (n=3 per group). Each group received either 2µL of 0.1%, 0.01% or 0.001% chlorhexidine in one eye (n=3 eyes per group) with the contralateral eye receiving a sham injection of 2µL saline to serve as the control (n=3 eyes per group). The animals were assessed using fundus imaging, optical coherence tomography (OCT), and electroretinography (ERG) at 6h, 24h, 72h, and 1-week post injection. Animals were sacrificed at 1 week and eyes were fixed in 4% paraformaldehyde for histochemical analysis.
Results :
0.1% Chlorhexidine vs. sham: All 3 eyes in the treatment group developed visually significant cataracts by one week. ERG analysis demonstrated severely impaired B-wave in the treatment group at 24h. ERG was normal in the sham group. 0.01% Chlorhexidine vs. Sham: 2 of 3 treatment eyes developed mild cataract by 1 week. Fundus imaging revealed normal retinal morphology in both groups. ERG analysis demonstrated a mild reduction in B-wave amplitude in the 3 treatment eyes compared to the sham eyes. 0.001% chlorhexidine vs. Sham: There were no significant lenticular changes in treatment or sham injected eyes. Fundus imaging demonstrated normal retinal morphological in both groups. ERG amplitudes were similar vs sham eyes.
Conclusions :
These data demonstrate concentrations of chlorhexidine above 0.01% injected into the vitreous may have toxic effects on the retina and predispose to cataract formation. This suggests concentrations below 0.01% may be the safe upper limit for intravitreal aqueous chlorhexidine. These data support that aqueous chlorhexidine may be safe for intravitreal use.
This is a 2021 ARVO Annual Meeting abstract.