Design: Ophthalmic technology assessment (structured literature review), 11 studies
Population: Patients having trabeculectomy with mitomycin C, mostly primary open-angle glaucoma
Primary outcome: Pressure control, surgical success and complications
Effect: Complete success 40.3% to 90.9% (injection) vs 17.7% to 86.5% (sponge); no difference in complications

An American Academy of Ophthalmology technology assessment in Ophthalmology (7 October) reviewed 11 studies comparing mitomycin C (MMC) given by sub-Tenon's or subconjunctival injection with application on sponges during trabeculectomy. Six studies were rated level I evidence.

Complete success in pressure control ranged from 40% to 91% with injection and 18% to 87% with sponges, and pressure reductions were similar, with the wide ranges reflecting different definitions and follow-up. Complication rates, including bleb leak, hypotony and choroidal effusion or haemorrhage, did not differ. Some studies reported fewer 5-fluorouracil injections and more diffuse, less vascular blebs with injection.

Injected MMC has gained popularity because it is quicker, gives a controlled dose and avoids retained sponges. This assessment supports either technique, so surgeons can use the one they are practised in. The bleb morphology advantage of injection is suggestive but not proven to improve long-term outcomes.

Use either injected or sponge-applied mitomycin C at trabeculectomy, according to surgeon experience.
Count sponges carefully if using the sponge technique to avoid retained material.
Document MMC concentration and exposure, which varied widely across studies.
Monitor bleb morphology and pressure closely in the early postoperative period with either method.

Why it matters

It removes uncertainty for surgeons switching to injection, which many find simpler.

The statistics, in plain English

This is a structured literature assessment, not a pooled meta-analysis, so it reports ranges rather than a single combined effect. The overlap of ranges indicates no consistent difference.