Pembrolizumab-Related Enophthalmos.

Pembrolizumab is a highly selective immune checkpoint inhibitor that targets the programmed cell death protein (PD-1) receptor on lymphocytes and has been approved for the treatment of malignant melanoma. A 59-year-old woman had been treated for 1 year with pembrolizumab for melanoma metastatic to lung, spleen, and central nervous system. She noted changes of her facial appearance with temporal wasting and sunken eyes while denying any decrease in body weight. Exophthalmometry was 11 mm for the right eye (OD) and 10 mm for the left eye (OS). (Fig A, B) Axial magnetic resonance imaging (MRI) scans performed 6 months apart (Fig C, D) demonstrated a significant change in globe position with 4.7 mm recession on the right and 4.1 mm on the left. There were no signs of orbital metastasis or inflammation. She had no other medical or iatrogenic factors to explain loss of orbital volume and enophthalmos. (Magnified version of Fig A-D is available online at www.aaojournal.org).