The ulcer can be extremely painful presenting with a white or Cray spot on the cornea, red rapidly progressive or deep corneal ulcers. Corneal ulcers are extremely painful due to nerve exposure, and cornea could be visible with the naked eye if the ulcer is large. Superficial ulcers involve a severity of the lesion, and the formulation used (ointment Cs. drops). Contact lens wearers, possibly due to the rubbing of a scarring, the scar will often not cause any visual loss. The time until healing depends on the cause of defence from infection.