Diagnosing conjunctivitis can include the doctor’s consideration of the patient’s personal history, report of the symptoms, examination of the eye, and diagnostic testing. There are different types of conjunctivitis. Many types of conjunctivitis have similar symptoms. By having complete information, the physician has an easier time of diagnosing conjunctivitis.

Personal history can be important in cases of allergic conjunctivitis and types of conjunctivitis that can be caused by wearing contact lenses. A personal or familial history of allergies, eczema, or asthma increases the individual’s risk of allergic conjunctivitis. A personal history of dry eye or recurrent conjunctivitis could point to an underlying problem or condition. For example, an infant with recurrent conjunctivitis could indicate a blocked tear duct. Personal history may provide obvious information impacting the diagnosis such as if the person sustained an eye injury or if the eye was splashed with chemicals.

The symptoms that the patient experiences can provide the doctor with crucial clues as to what kind of conjunctivitis the patient has. For example, bacterial conjunctivitis typically has thick, yellow-green discharge which is most apparent in the mornings. This is vastly different from the tearing and lack of discharge that is typical of allergic conjunctivitis. The length of time that the person has been experiencing symptoms can provide some clues to which type of conjunctivitis the person has since some types of conjunctivitis like viral conjunctivitis are generally short in duration.

The doctor is likely to examine the eye while diagnosing conjunctivitis. The doctor may use a small light and check the eye. In some cases, the doctor may need to closely examine the eyelid to diagnose conjunctivitis. Some types of pink eye can cause irritation or surface changes in the conjunctiva underneath the eyelid.

One method for checking for keratitis in severe cases of conjunctivitis is to add a yellow dye to the surface of the eye and use a slit lamp. Keratitis is irritation of the cornea. Keratitis conjunctivitis can cause permanent damage to the cornea which can permanently impair vision and even cause blindness.

The doctor may take samples of infectious tissue or eye secretions for diagnostic testing to diagnose conjunctivitis. Testing may be used to identify the bacteria or infectious agent that is causing the conjunctivitis. Analysis of a sample by a laboratory can confirm the physician’s diagnosis and let the doctor know how best to treat the conjunctivitis. Another type of testing that may be done in relation to conjunctivitis is allergy testing in cases of allergic conjunctivitis.