Corneal disorders include the following: Bullous keratopathy Cogan syndrome Corneal ulcer Herpes simplex keratitis Herpes zoster ophthalmicus Interstitial keratitis Keratoconjunctivitis sicca Keratoconus Keratomalacia Peripheral ulcerative keratitis Phlyctenular keratoconjunctivitis Superficial punctate keratitis Corneal transplantation (a treatment) Evaluation of the cornea requires fluorescein staining and, when available, slit lamp examination, and sometimes microbial studies.