Conjunctivitis, or pink eye, is an infection or inflammation in the eye. The conjunctiva is a layer of tissue that overlays the eye and inner eyelids. It can be caused by a bacterial or viral infection, in which case it is highly contagious. These infections are common in children. Allergic reactions and irritants can also cause conjunctivitis.
General symptoms of conjunctivitis include:
- Pink or red color of the white of the eye
- Swelling of the eyelid
- Tearing of the eye
- Urge to scratch or rub the eye
- Discharge of mucus
- Sensitivity to light
Symptoms can vary based on the cause of the conjunctivitis.
Viral conjunctivitis is caused by a viral infection, usually adenovirus. Its most typical symptoms are irritation, photophobia, and watery discharge from the affected eye. It can occur with symptoms of an upper respiratory infection like a runny nose or a headache. It can also occur with flu-like symptoms. Initial symptoms usually begin in one eye and spread to the other. The preauricular lymph nodes (near the ear) may be enlarged and painful. Photophobia, blurred vision, and foreign body sensation may indicate corneal involvement.
Bacterial conjunctivitis typically begins in one eye, and may spread to the other. There are several species of bacteria that can cause conjunctivitis including Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus species, or, rarely, Chlamydia trachomatis. Typical symptoms include redness, tearing, irritation, and discharge--often with green or yellow pus. Bacterial conjunctivitis is sometimes accompanied by an ear infection. Complications can occur such as corneal ulcers, abscess, and blindness.
Allergic conjunctivitis is typically very itchy with tearing and swelling of the eyes. Other allergy symptoms like a runny nose, sneezing, or asthma may also be present. Within allergic conjunctivitis are several additional categories: seasonal allergic conjunctivitis, perennial allergic conjunctivitis, and vernal keratoconjunctivitis. The seasonal form is caused by allergens like tree pollen, mold spores, and weeds. Perennial allergic conjunctivitis (also atopic conjunctivitis or atopic keratoconjunctivitis) is caused by allergens that have no particular season, like dust mites and animal dander. Vernal keratoconjunctivitis appears in spring and goes away in the fall and winter. It typically affects boys and men between the ages of 5 and 20 who also have seasonal allergies, eczema, or asthma.
Conjunctivitis can be caused by irritants. It typically produces watery eyes and mucus. Irritant conjunctivitis is not contagious and is caused by a mechanical or chemical irritant. Some common irritants are dry eye, acid or alkali solutions, foreign bodies, and abrasions to the eye.
Giant Papillary Conjunctivitis
Giant papillary conjunctivitis is common in contact lens wearers and is also known as contact lens-induced papillary conjunctivitis. The main symptoms are itching, mucus discharge, swelling of the conjunctiva, and formation of large papillae (greater than 0.3 mm) on the inside of the upper eyelid. As the condition progresses, blurring of vision may occur even when wearing contact lenses, and in the advanced stages, patients with giant papillary conjunctivitis experience foreign body sensation and pain on wearing contact lenses. Abnormal deposits form on the lenses, and sheets or strings of mucus are present in the eye. Papillae can grow to greater than 1 mm in size.