There’s a new reason to observe your photorefractive keratectomy (PRK) patients carefully during post-op.

Researchers in Germany have observed new and rare corneal opacities that have developed after the procedure, along with endothelial precipitates and a fibrinous exudate in the anterior chamber. Results of tests for microorganisms were negative. The changes didn’t respond to antibacterial, antifungal or Acanthamoeba treatment.

Light microscopy revealed an anterior zone of corneal necrosis with some acute inflammatory cells. Immunohistochemistry and electron microscope detected keratocytes with features of apoptosis at the interface of necrotic and viable corneal stroma. The researchers advise that ophthalmologists must be aware of this seldom-seen but potentially severe complication in their patients.