What is siedel sign?

As an AI language model, I do not have access to detailed information related to phrases like "siedel sign." However, based on my available database, Seidel sign may refer to a clinical test performed by an ophthalmologist to evaluate the integrity of the corneal epithelium. This sign is positive when fluorescein dye applied to the cornea penetrates through a defect. The Seidel sign is commonly used to diagnose corneal injuries or perforation. It is named after a German ophthalmologist, Ernst Seidel, who described the sign in 1904.