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Delivery from episcleral exoplants.
Ricardo A Pontes de Carvalho1, Melissa L Krausse, A Linn Murphree
1Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287-9277, USA.
Investigative Ophthalmology & Visual Science
|September 28, 2006
Summary
Episcleral exoplants significantly enhance fluorescein delivery to the retina and posterior vitreous compared to periocular injections. This method also reduces systemic absorption, offering a safer approach for ocular drug delivery.
Area of Science:
- Ophthalmology
- Drug Delivery Systems
- Biomaterials Science
Background:
- Transscleral drug delivery is crucial for treating posterior segment eye diseases.
- Current methods like periocular injections have limitations in achieving therapeutic concentrations in the retina and vitreous.
- Developing efficient and targeted delivery systems is essential to overcome these challenges.
Purpose of the Study:
- To evaluate the efficacy of an episcleral exoplant in facilitating transscleral delivery of fluorescein.
- To compare the ocular and systemic distribution of fluorescein delivered via exoplant versus periocular injection.
- To assess the impact of exoplant design on drug delivery and tissue interaction.
Main Methods:
- New Zealand White rabbits were used to test fluorescein delivery via periocular injection or episcleral exoplants.
- Two exoplant types were evaluated: rigid polyethylene and flexible silicone, with varying implantation methods (apposition and indentation).
- Ocular and plasma fluorophotometry were performed, along with histological analysis.
Main Results:
- Episcleral exoplants resulted in significantly higher fluorescein concentrations in the retina and posterior vitreous compared to periocular injection.
- The polyethylene device in the indentation group showed peak fluorescence in the retina and posterior vitreous.
- Peak plasma fluorescein levels were substantially lower with exoplant delivery, indicating reduced systemic absorption.
Conclusions:
- Episcleral exoplants effectively enhance transscleral diffusion of fluorescein to the retina and posterior vitreous.
- This delivery method achieves higher ocular concentrations and lower systemic absorption than periocular injections.
- The use of episcleral exoplants represents a promising strategy for optimizing drug delivery to the posterior eye while minimizing systemic toxicity.
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