4. Viral infections.
Viral infections can cause infectious keratitis. There are dozens of viruses that can enter the eye, but the most common viral infection that can lead to infectious keratitis is the herpes simplex virus or HSV. There are two main types of HSV: Type 1 is the most prevalent; it affects the face and is responsible for causing the common cold sore or fever blister; Type 2 is the sexually transmitted form of the herpes virus.
While Type 2 is less common than Type 1, it’s still prevalent, and though it primarily affects the genitals, it can also spread to the eye. Transmission of either type HSV to the eye can occur when an active lesion is touched, and then the eye is touched. If you have been diagnosed with either type of HSV and you are experiencing off-putting symptoms in your eye, you may have infectious keratitis.