An ocular twist to cancer therapy: Pseudomicrocysts and myopic shift linked to trastuzumab emtansine

A 49-year-old woman with a diagnosis of HER-2 positive breast cancer on trastuzumab emtansine (Kadcyla) therapy developed symptoms of dry eye, and blurry vision bilaterally. Subjective myopic shift was noted and slit lamp examination revealed bilateral corneal epithelial pseudomicrocysts. These ocular symptoms emerged within weeks of Kadcyla initiation, improved with drug cessation and recurred on reintroduction, suggestive of keratopathy secondary to antibody-drug conjugate (ADC) toxicity. Management included intensive ocular lubrication, close follow-up, and reassurance of the temporality of symptoms with ADC use. Antibody-drug conjugate therapy was continued as tolerated. This case highlights the potential for reversible keratopathy, including pseudomicrocysts and myopic shift associated with trastuzumab emtansine.