Conjunctivitis, also known as acute or subacute conjunctivitis, and keratitis are among the most common diseases of the ocular surface, but they are different. Firstly, the locations of the cornea and conjunctiva are different. The cornea is a transparent, avascular tissue through which light enters the eye, allowing people to see. The conjunctiva is divided into the bulbar conjunctiva and the palpebral conjunctiva. Inflammation occurring on the cornea is called keratitis, while inflammation on the conjunctiva is referred to as conjunctivitis. Symptoms of conjunctivitis include congestion, foreign body sensation, photophobia, and tearing, among others. The symptoms of keratitis include a significant foreign body sensation, distinct pain, often affecting vision, and accompanied by photophobia.