Background: Corneal staining with fluorescein resulting from a cause distinct from that of general epithelial barrier disturbance.
Case: A 66-year-old woman saw her doctor complaining of blurred vision and foreign-body sensation in her left eye. Superficial punctate keratopathy (SPK) was detected on her left cornea. Following instillation of some eye drops, the patient developed corneal staining with fluorescein. Assuming that the staining was due to drug toxicity, eye-drop instillation was discontinued but the staining did not improve and her doctor then referred her to us. Although we tried glucocorticosteroid and artificial tear eye drops, the staining spread until it covered the patient's cornea almost completely. On a following day, we attempted to observe the patient's cornea by confocal microscopy, yet her corneal epithelium could only partially be seen due to what can best be described as a "black-cloud-like" formation on her cornea. However, immediately following that observation the corneal staining diminished without epithelial disturbance and the patient's symptoms were improved. Suspecting that some foreign materials may be stuck to her cornea, we performed impression cytology and detected the existence of MUC16.
Conclusion: The patient's corneal staining may have resulted from her cornea being covered by materials related to MUC16.