Common diseases of the cornea are keratitis, ocular herpes, herpes zoster and keratoconus. These conditions can damage the cornea, resulting in scars that interfere with vision by distorting light as it enters the eye, says WebMD.
Keratitis causes inflammation, infection and ulceration of the cornea, and its symptoms include redness, blurred vision, discharge, severe pain, tearing and extreme sensitivity to light. Herpes zoster is an infection caused by the chickenpox virus. It can cause lesions on the cornea, and it is common in individuals over 80 years, especially those whose immune systems are weak, according to WebMD.
Ocular herpes is a viral infection caused mainly by the herpes simplex virus, which causes sores on the cornea and is not curable. Keratoconus causes scarring, swelling and changes the shape of the cornea, creating distortions such as nearsightedness, notes WebMD.