Severe toxic effect of methylene blue 1% on iris epithelium and corneal endothelium.

Purpose: To report a case of comeal endothelial decompensation and iris pigment dispersion following the inadvertent use of methylene blue 1% for capsular staining during cataract surgery. Design: Case report. Methods: During an otherwise routine phacoemulsification cataract surgery, inadvertent anterior capsule staining with methylene blue 1% instead oftrypan blue 0.025% was performed. Copious irrigation of the anterior chamber with balanced salt solution was initiated upon identification of the wrong dye. The operation was completed with minimal ultrasound energy without complications. Results: Iris discoloration and severe comeal edema developed in the early postoperative period, resulting in severe visual loss. The patient developed bullous keratopathy and underwent penetrating keratoplasty 16 months later. Conclusions: In vivo intracameral injection of methylene blue 1% induces extreme cytotoxicity, primarily on the comeal endothelium and iris epithelium.