Ciliary body toxicity of cyclosporin A and octreotide acetate in rabbit eyes: a comparison with mitomycin C and 5-fluorouracil

Sustained subconjunctival delivery of cyclosporine A using thermogelling polymers for glaucoma filtration surgery

We successfully developed a subconjunctival delivery system of CsA using an injectable thermogel to inhibit post-surgical scar formation after glaucoma filtration surgery.

Development of a novel CsA-PLGA drug delivery system based on a glaucoma drainage device for the prevention of postoperative fibrosis

The formation of a scar after glaucoma surgery often leads to unsuccessful control of intraocular pressure, and should be prevented by using a variety of methods. We designed and developed a novel drug delivery system (DDS) comprising cyclosporine A (CsA) and poly(lactic-co-glycolic acid) (PLGA) based on a glaucoma drainage device (GDD) that can continuously release CsA to prevent postoperative fibrosis following glaucoma surgery. The CsA@PLGA@GDD DDS was observed by field emission scanning electron microscopy and revealed an asymmetric pore structure. Thermogravimetric analysis was performed to measure the weight loss and evaluate the thermal stability of the CsA@PLGA@GDD DDS. The in vitro drug release profile of the DDS was studied using high performance liquid chromatography, which confirmed that the DDS released CsA at a stable rate and maintained adequate CsA concentrations for a relatively long time. The biocompatibility of the DDS and the inhibitory effects on the postoperative fibrosis were investigated in vitro using rabbit Tenon's fibroblasts. The in vivo safety and efficacy of the DDS were examined by implanting the DDS into Tenon's capsules in New Zealand rabbits. Bleb morphology, intraocular pressure, anterior chamber reactions, and anterior chamber angiography were studied at a series of set times. The DDS kept the filtration pathway unblocked for a longer time compared with the control GDD. The results indicate that the CsA@PLGA@GDD DDS represents a safe and effective strategy for preventing scar formation after glaucoma surgery.

Modulation of postoperative scarring with tacrolimus and octreotide in experimental glaucoma filtration surgery

PURPOSE

The purposes of this study were to investigate the effects of topically administrated Tacrolimus and Octreotide on modulation of postoperative scarring in experimental glaucoma filtration surgery and to compare the antifibrotic properties of these agents with mitomycin-C (MMC).

MATERIAL AND METHODS

A total of 28 New Zealand rabbits weighing 2.5-3 kg were randomly divided into a surgical control (SC) group and three experimental groups. Standard filtration surgeries were performed on the right eyes of all the rabbits. The rabbits in the SC group received only vehicle after the surgeries, whereas the rabbits in the three experimental groups were treated either with 0.4 mg/mL MMC during the surgery (MMC group) or with 0.3 mg/mL Tacrolimus drop four times a day (TT group) or with 10 µg/mL Octreotide drop three times a day (OT group) for 14 days. The animals were killed on day 14, eyes were enucleated and histologically and immunohistochemically analyzed.

RESULTS

In SC group mean fibroblast, mononuclear cell number and fibroblast growth factor-β (FGF-β), transforming growth factor-β (TGF-β) immunostaining intensity was higher than all treatment groups. In OT group mean fibroblast number was lesser than MMC (p < 0.01) and TT (p < 0.05) group. In TT group mean fibroblast number was lesser than MMC group (p < 0.05). Mean mononuclear cell number was similar between MMC, OT and TT groups (p > 0.05). In MMC, OT and TT groups mean TGF-β and FGF-β immunostaining intensity was similar (p > 0.05).

CONCLUSIONS

Topically administration of Tacrolimus and Octreotide effectively reduced the subconjuntival scarring response 2 weeks after experimental glaucoma filtration surgery.

The effect of paclitaxel on conjunctival wound healing: a pilot study

PURPOSE

To compare the effects of mitomycin C (MMC) and paclitaxel entrapped within Carbopol 980 hydrogel (CH) on conjunctival wound healing.

METHODS

Twenty rabbits were randomized into 2 groups. In group 1, limbal-based conjunctival flaps were created in both eyes. In this stage, eyes were randomized for 4 different processes. In process 1, a dry cellulose sponge soaked with 0.2 mg/mL of MMC was applied to the scleral surface. A cellulose sponge soaked with balanced saline solution was applied in the same manner in process 2. In process 3, paclitaxel 1 mg/mL entrapped within CH was placed between the conjunctiva and sclera. In process 4, CH without paclitaxel was applied in the same manner. The conjunctiva was then sutured. All procedures were applied in the same manner in both eyes of animals in group 2. Eyes from group 1 were sampled at the seventh day, and the sampling was also carried out in group 2 on day 14. The inflammatory response and fibrosis were evaluated with light microscopy.

RESULTS

Among 4 different processes, lower cell counts and fibrosis scores were found in eyes treated with MMC and paclitaxel compared with balanced saline solution and CH groups (P<0.05). There was no difference between eyes treated with MMC and paclitaxel in terms of these histopathologic parameters (P>0.05).

CONCLUSIONS

Paclitaxel was shown to provide MMC-like antifibrotic effects during conjunctival wound healing, particularly when delivered with CH and might be a promising alternative as an adjunctive antimetabolite in glaucoma filtration surgery.