Abstract
Purpose:
To compare effects of microneedle injection of triamcinolone acetonide (TA) into the suprachoroidal space (SCS) versus intravitreal (IVT) TA injection in a model of acute posterior uveitis.
Methods:
Twenty weanling pigs had BSS or lipopolysaccharide (LPS) IVT injection followed 24 hours later with SCS or IVT injection of 0.2 mg or 2.0 mg TA. SCS injections were made using purpose-designed microneedles and 27G needles were used for IVT injections. Clinical ocular inflammatory scores (CIS) and intraocular pressure measurements (IOP) were collected daily, while electroretinography, optical coherence tomography (OCT), and wide-field ocular fundus photography were performed on -1, 0, and 3 days after treatment. Pigs were then euthanized, aqueous and vitreous humor collected for cell counts and protein levels, and the eyes were processed for histopathology.
Results:
SCS TA injection using microneedles was simple, effective, and not associated with adverse effects, elevated IOP, or toxicity. Cumulative mean CIS of eyes receiving 0.2 and 2.0mg SCS TA were not significantly different than either control (non-uveitis induced) eyes or eyes receiving 2.0mg IVT TA at all examination times. Cumulative mean CIS, however, of 0.2mg IVT TA was not significantly less than LPS injected, vehicle treated eyes. OCT vitreal cellular infiltrate was significantly lower after treatment with both 0.2 and 2.0 mg SCS TA than eyes treated with vehicle but were not significantly different than eyes treated with IVT TA. Histologic inflammatory suppression after 0.2 and 2.0mg SCS TA was similar to eyes treated with 2.0mg IVT TA. Mean vitreal cell counts and protein concentrations were not significantly different between eyes injected with 0.2mg SCS TA and 0.2 and 2.0mg IVT TA. Furthermore, 2.0mg SCS TA mean cell counts and protein concentrations were not significantly different than negative control eyes.
Conclusions:
Results from this study suggest that delivery of TA to the SCS provides effective control of acute posterior uveitis in a model that is similar in anatomy, size, and retinal vascular pattern to the human eye. There were no adverse effects, increased IOP, or evidence of procedural or drug toxicity following injection of TA into the SCS using microneedles in porcine eyes. This study supports the further evaluation of the SCS as a site of drug delivery to ocular posterior segment.
Keywords: 746 uveitis-clinical/animal model •
503 drug toxicity/drug effects •
561 injection