This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of Cornea, Subject name: Ophthalmology
Corneal sensations are diminished in: 
Select and explain. 
A. Herpes simplex, B. Conjunctivitis, C. Fungal infections, D. Marginal keratitis
A: Herpes simplex
Answer: A: Herpes simplex 
Explanation: Herpes simplex infection is a common cause of corneal sensory loss, although less severe than in keratitis caused by reactivation of varicella-zoster virus. Some patients with active HSV keratitis present with sensations of spontaneous pain, discomfo, and dryness.