Abstract
Purpose: :
Polydioxanone (PDO) is a biocompatible polymer largely used in biodegradable sutures. It received FDA approval in cardiology for valvular surgery. Drugs such as mitomycin C (MMC) can be included in the core of the polymer during the synthesis process resulting in a sustained release drug delivery system as the PDO is biodegraded by hydrolysis. The duration of the hydrolysis can be modulated by adapting the synthesis parameters of the PDO. In this way, MMC or other drugs could be released progressively for up to several weeks. The aim of this preliminary study was to evaluate the clinical and histological tolerance of a PDO membrane in the subconjunctival space of the rabbit eye.
Methods: :
Six New Zealand White rabbits (12 eyes) were operated on under general anaesthesia: after fornix based flap and tenon dissection in all eyes, a membrane of PDO was inserted in 6 eyes whereas the subconjunctival space was left empty in the contralateral 6 eyes which served as a control. A limbal suture closed the conjunctiva in all eyes. Corticoantibiotic drops were applied twice daily until euthanasia. The conjunctivas were clinically evaluated daily and 2 animals were euthanised at day 7, day 15 and day 45. After Hematoxylin-Eosin staining a histological study was completed.
Results: :
Clinically, the PDO membrane remained visible under the conjunctiva for 2 weeks, associated with a moderate and transient hypervascularity of the conjunctiva. No difference was noted between the 2 groups at day 45. Histologically, the PDO membrane and the surrounding conjunctiva were infiltrated with a few inflammatory cells compared to control at days 7 and 15. By the 45th postoperative day, the PDO membrane had degraded and the cellularity returned to control level.
Conclusions: :
Polydioxanone is well tolerated in the subconjunctival space of the rabbit eye without significant inflammatory response during its biodegradation. This could yield to a new drug delivery system in ophthalmology, particularly in glaucoma filtering surgery while using MMC.
Keywords: ocular irritancy/toxicity testing • conjunctiva • wound healing