To present a case of corneal endothelial damage caused by inflow of 5-FU after subconjunctival 5-FU injection in a patient undergoing trabeculectomy.

A 65-year-old female patient diagnosed with chronic angle-closure glaucoma underwent trabeculectomy using mitomycin C. Three weeks after the surgery, her intraocular pressure (IOP) elevated, and the follicles had disappeared by trabeculectomy. Subsequently, subconjunctival 5-FU injection was performed. Following the fourth injection, visual acuity abruptly decreased, and corneal edema was observed. Upon presumption of inflow of 5-FU into the anterior chamber, anterior chamber irrigation was performed within 40 minutes. On postoperative day 1, visual acuity decreased from 0.8 to counting fingers, and diffuse corneal edema and anterior capsular opacity of the lens were noted. Three months after the irrigation, visual acuity improved to 0.8. Corneal edema and capsular opacity also improved, however the density of the corneal endothelial count decreased.

Inflow of 5-FU into the anterior chamber can cause corneal and lenticular toxicity. Anterior chamber irrigation is considered necessary to prevent 5-FU toxicity.