# A Case Series: Methylene-Blue-Related Toxic Anterior Segment Syndrome

## TL;DR

Methylene blue used during cataract surgery can cause severe eye damage, leading to corneal swelling and vision loss.

## Contribution

This case series highlights methylene blue's cytotoxic effects on intraocular tissues and emphasizes the need for strict dye verification protocols.

## Key findings

- Three patients experienced corneal edema and inflammation after methylene blue exposure during cataract surgery.
- Two patients required DSEK due to irreversible endothelial decompensation, while one showed partial recovery with treatment.
- No intraocular pressure spikes or retinal toxicity were observed in the cases studied.

## Abstract

An intracameral injection of methylene blue 1% during cataract surgery induces extreme cytotoxicity, primarily affecting the corneal endothelium and iris epithelium. This case series illustrates the clinical presentation, management, and outcomes of three patients who underwent cataract surgery, with unintended exposure to methylene blue.

All patients demonstrated early-onset corneal edema and anterior segment inflammation shortly after surgery. Two patients developed severe, irreversible endothelial decompensation, leading to persistent corneal edema, decreased visual acuity, and eventual need for Descemet’s stripping endothelial keratoplasty (DSEK). In contrast, the third patient experienced transient corneal edema, which gradually resolved with medical therapy, resulting in significant, though incomplete, visual recovery. No intraocular pressure spikes or retinal toxicity were noted.

In conclusion, methylene blue is highly cytotoxic to intraocular structures, particularly the corneal endothelium and iris epithelium. Accidental administration can cause serious and irreversible visual impairment. Vigilant dye verification protocols, enhanced labeling systems, and multidisciplinary checks are critical in preventing such adverse events. Surgeons must remain cautious and ensure that only approved agents are utilized for anterior capsule staining during cataract surgery.