Use of topical mitomycin C in myoplasty of the medial rectus muscle of rabbits.

The study examines the use of mitomycin C to decrease post-surgical adhesions in the repair of rabbit eye muscles and observes the limited reinforcement benefits of using an equine renal capsule.

Study Design and Methodology

• The researchers conducted a study on 24 rabbits, which were divided into two groups of 12 each. One group served as the control, receiving no additional treatment, and the other group was treated with mitomycin C.
• The medial rectus muscle (one of the eye muscles) of one eye in each rabbit was surgically ruptured and repaired 24 hours later using sutures and an equine renal capsule. This is a surgical model used to mimic the process of eye muscle repair in actual clinical scenarios.
• Following the surgery, all rabbits received eye drops containing a mix of neomycin, polymyxin B and dexamethasone, which are antibiotics and anti-inflammatory drugs, for eight days. Their eyes were also rinsed daily with physiological saline.
• The group of rabbits receiving mitomycin C treatment were given a topical application of 0.04% mitomycin C every 6 hours for 14 consecutive days.

Observations and Results

• Initial observations revealed that the rabbits treated with mitomycin C had a greater irritation of the ocular surface in the early postoperative days.
• There were adhesions (tissues sticking together) observed in both groups at 15 and 30 days of assessment, but these were more extensive in the untreated (control) rabbits at 60 days.
• There was an inflammatory exudation (leakage of fluid due to inflammation) seen in both groups, but this was greater in the mitomycin C-treated animals.
• In spite of the initial irritation, the regular application of mitomycin C reduced the occurrence of fibrosis (formation of excess fibrous connective tissue) in the repaired eye muscle areas.
• However, the use of equine renal capsule, intended to reinforce the repaired tissues, was found to have negligible benefits in the process of myoplasty (muscle repair).

Implications

• The researchers suggest that the use of mitomycin C can be beneficial in reducing unwanted tissue adhesion and fibrotic reaction that often occur after ocular surgeries. The drug’s initial side-effect of surface irritation appears to be outweighed by its long-term benefits.
• The study also highlights the ineffectiveness of the equine renal capsule as a reinforcement material in eye muscle repairs, contrary to what might be expected or practiced. These findings might have implications for future surgical practices and materials used in ocular surgeries for better patient outcomes.