Abstract
Purpose:
To evaluate for evidence of inflammatory changes and toxicity in the suprachoroidal space (SCS) after direct application of mitomycin-C (MMC) in rabbits.
Methods:
After surgical exposure to the SCS, twenty New Zealand White male rabbits were injected with 0.10 cc of Balanced Salt Solution (BSS) or MMC. Four groups were assigned: Group 1 (5 rabbits, Control, BSS), Group 2 (5 rabbits, MMC at 0.25 mg/ml), Group 3 (5 rabbits, MMC at 0.40 mg/ml, Group 4 (5 rabbits, MMC at 1.0 mg/ml). The MMC exposure time in the SCS was 1 minute for Groups 2-4, followed by irrigation with BSS. Post-op examinations by a masked examiner, including measurement of intraocular pressure (IOP) using a Tonometer, were performed for 4 weeks. The eyes were then enucleated, fixed, processed and sectioned for a blinded histologic evaluation.
Results:
In 6/20 rabbits no significant findings were noted. In the remaining 14/20 rabbits, the only lesions identified were in the area of the injections, but were considered of minimal severity consisting of a small collection of mononuclear inflammatory cells occasionally associated with minimal fibrosis. The lesions appeared to be consistent with injection site reactions and were static in nature. There was no observed difference between the control group and the treatment groups, nor was there an associated dose-response relationship in the three treatment groups. There was also no significant difference in IOP between the 4 groups: Group 1 (BL: 16.2 ± 1.6mm Hg; 4 weeks 13.6 ± 1.3); Group 2 (BL: 14.2 ± 2.5; 4 weeks 13.8 ± 2.2); Group 3 (BL: 15.6 ± 2.2; 4 weeks 12.8 ± 2.0); Group 4 (BL: 14.8 ± 3.7; 4 weeks 14.0 ± 2.6).
Conclusions:
In this rabbit study, apart from mild injection site reactions, the treatment with MMC at 3 different concentrations had minimal influence in the SCS or surrounding tissues, including the ciliary body and retina. IOP also remained largely unchanged across the 4 groups during the study. The direct application of mitomycin-C in the suprachoroidal space in a rabbit model therefore was well tolerated and did not result in any significant toxicity. Additional investigation in human subjects in conjunction with novel glaucoma drainage devices is warranted.
Keywords: 568 intraocular pressure