Mitomycin C and 5-Fluorouracil in Eye Surgery: Dilution, Application, Timing and Safe Handling
Last updated: November 2026
Mitomycin C (MMC) and 5-fluorouracil (5-FU) are antimetabolites that reduce scarring. They are used in trabeculectomy, bleb needling, pterygium and refractive surgery, and as topical chemotherapy. The dose depends on the concentration and the time the tissue is exposed, so small preparation errors matter. This page shows how to make the common dilutions, how to apply them and how to handle them safely.
Strengths at a glance
| Drug | Usual stock | Common working strength | Equivalent |
|---|---|---|---|
| Mitomycin C | 2 mg vial (powder) | 0.02% and 0.04% | 0.02% = 0.2 mg/mL; 0.04% = 0.4 mg/mL |
| 5-Fluorouracil | 50 mg/mL solution | 50 mg/mL (sponge) or 5 mg in 0.1 mL (injection) | Usually used undiluted |
Making MMC dilutions from a 2 mg vial
| Add to the 2 mg vial | Concentration | Common use |
|---|---|---|
| 5 mL diluent | 0.4 mg/mL (0.04%) | Trabeculectomy (sponge or injection) |
| 10 mL diluent | 0.2 mg/mL (0.02%) | Pterygium, trabeculectomy, PRK, needling |
| Then 1 mL of 0.4 mg/mL + 1 mL diluent | 0.2 mg/mL | Making a second strength from the first |
Use sterile water for injection or saline as the label allows. Swirl until fully dissolved (the solution is violet-blue). Label the syringe clearly with the drug, strength and "CYTOTOXIC". Many hospital pharmacies prepare MMC in a safety cabinet and supply ready-made syringes; use that service if you have it.
How MMC is used
| Procedure | Typical regimen | Notes |
|---|---|---|
| Trabeculectomy | 0.2–0.4 mg/mL on sponges under the conjunctiva/Tenon for 1–3 minutes; or 0.1 mL of 0.2–0.4 mg/mL injected subconjunctivally before dissection | Wider, posterior treatment gives diffuse blebs; keep MMC away from the conjunctival edge |
| Pterygium (with or without graft) | 0.02% on a sponge to the bare sclera or under conjunctiva for 1–3 minutes | Lowest effective dose; avoid on bare sclera with poor healing (scleral melt risk) |
| PRK / surface ablation | 0.02% on a sponge to the ablated stroma for about 12–60 seconds | To prevent haze in deeper ablations |
| Bleb needling | Small subconjunctival injection (e.g. 0.1 mL of 0.2 mg/mL) away from the needling site | Some units use 5-FU instead |
| Ocular surface squamous neoplasia | Topical 0.02–0.04% drops in cycles, with breaks | Punctal plugs reduce drainage toxicity |
Sponge technique
- Cut small sponges (cellulose or PVA) and soak them in MMC; squeeze off excess so it does not drip.
- Place under the conjunctiva/Tenon or on the bed; keep the cut conjunctival edge and cornea away.
- Start the timer when the sponge touches tissue.
- Remove and count every sponge: a retained sponge causes ongoing toxicity.
- Irrigate the area with at least 20–30 mL of balanced salt solution.
- Discard sponges, syringes and gloves in the cytotoxic waste bin.
5-FU
- Intraoperative: sponges soaked in 50 mg/mL 5-FU for about 5 minutes, then irrigate. Weaker antiscarring effect than MMC.
- Postoperative or needling: subconjunctival injection of 5 mg (0.1 mL of 50 mg/mL), placed away from the bleb, sometimes repeated over days.
- Side effects: corneal epithelial toxicity (punctate keratopathy, epithelial defects), wound leak, conjunctival toxicity. Do not inject into the bleb or let it reach the cornea.
Complications of antimetabolites
- Thin, avascular, leaking blebs; late bleb leak and blebitis or endophthalmitis.
- Hypotony and hypotony maculopathy, especially in young myopes.
- Scleral thinning or melt (especially bare sclera in pterygium).
- Corneal epithelial toxicity and limbal stem cell damage.
Safe handling
Both drugs are cytotoxic. Wear gloves (and a mask and eye protection when preparing), avoid aerosol and spills, label everything, keep the drug off the instrument trolley except when in use, and dispose of all contaminated items in cytotoxic waste. Pregnant staff should not prepare it.
Pearls
- A 2 mg vial in 10 mL gives 0.02% (0.2 mg/mL); in 5 mL it gives 0.04%.
- Count sponges in and out; a forgotten MMC sponge is a disaster.
- Irrigate generously after MMC before closing.
Common mistakes
- Confusing 0.2 mg/mL with 0.2% (ten times stronger).
- Letting MMC touch the conjunctival wound edge, causing leaks.
- Using MMC on bare sclera in a high-risk pterygium without considering melt.
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Related: Pterygium for Residents: Grading, Surgery and Preventing Recurrence, Glaucoma Notes for Residents: Topics and Syllabus, Fibrin Glue for Pterygium Autograft: Reliseal, Fibroseal and Tisseel Compared, Preparation and Technique, Ocular Surface Squamous Neoplasia (OSSN): Diagnosis and Topical Chemotherapy, Sutures, Needles and Sterilisation in the Eye Theatre.
Key sources
- Wilkins M, Indar A, Wormald R. Intra-operative mitomycin C for glaucoma surgery. Cochrane Database Syst Rev. 2005;4:CD002897
- Kaufman SC, Jacobs DS, Lee WB, et al. Options and adjuvants in surgery for pterygium: a report by the American Academy of Ophthalmology. Ophthalmology. 2013;120:201-208
- Majmudar PA, et al. Mitomycin-C in corneal surface excimer laser ablation techniques: a report by the American Academy of Ophthalmology. Ophthalmology. 2015;122:1085-1095
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