Unilateral conjunctivitis is an inflammation of the conjunctiva, the transparent membrane lining the eyelid and covering the white part of the eyeball, affecting only one eye. This condition irritates the small blood vessels in the conjunctiva, making them more visible and giving the eye a reddish or pink appearance. While bothersome, unilateral conjunctivitis rarely impacts vision.
What Makes It Unilateral?
Conjunctivitis can begin in one eye and may or may not spread to the other. This initial unilateral presentation often results from direct contact with an infectious agent, like touching an infected surface and then rubbing one eye. For instance, bacterial and viral infections are transmissible through eye-hand contact, frequently presenting in one eye before potentially involving the second eye. A foreign body or chemical irritant in the eye can also cause a localized inflammatory response in a single eye.
The localized nature of the irritation or infection typically prevents immediate spread to the other eye, maintaining its unilateral characteristic. While some cases might be early stages of an infection that later becomes bilateral, effects from foreign bodies or chemical splashes are usually confined to the directly exposed eye. This one-sided involvement is a key diagnostic clue for healthcare providers.
Common Causes
Unilateral conjunctivitis can stem from infectious agents or environmental irritants. Viral infections are the most frequent cause, with adenovirus accounting for 65% to 90% of cases. Herpes simplex virus (HSV) also commonly causes unilateral conjunctivitis and requires specific management due to potential complications. These viral forms are highly contagious.
Bacterial infections, often caused by Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae, also contribute. Chlamydia trachomatis can cause chronic unilateral follicular conjunctivitis, while Neisseria gonorrhoeae may lead to a severe, hyperacute form demanding immediate medical attention due to its vision-threatening potential. Both viral and bacterial infections can spread through direct contact.
Non-infectious causes include foreign bodies like dust, sand, or wood, which can lodge in one eye and cause localized irritation. Chemical irritants such as chlorine, household cleaning products, or cosmetics can also provoke a unilateral inflammatory response upon direct exposure. While allergic conjunctivitis usually affects both eyes, a localized allergic reaction is possible with asymmetric allergen exposure.
Identifying the Symptoms
Symptoms of unilateral conjunctivitis include redness, making the white of the eye appear pink or reddish. Patients often report a gritty feeling, mild pain or discomfort, and increased tearing.
Discharge from the affected eye varies by cause. Viral conjunctivitis typically produces a watery discharge. Bacterial infections often result in a thicker, purulent (pus-like) or mucopurulent (mucus and pus) discharge that may cause eyelashes to stick together, especially upon waking. Allergic reactions, though less commonly unilateral, may present with stringy or ropy discharge and significant itching. Other symptoms can include mild sensitivity to light and eyelid swelling.
Seeking Care and Treatment
Seek medical attention for unilateral conjunctivitis if you experience severe eye pain, vision changes like blurred vision, extreme sensitivity to light, or if symptoms worsen or do not improve within several days. Contact lens wearers should stop wearing lenses immediately and seek professional advice, as related infections can be serious. Any signs of conjunctivitis in a baby, especially those less than 30 days old, require urgent medical evaluation.
Home care measures can help alleviate discomfort and prevent spread. Apply warm or cool compresses to the affected eye for relief. Maintain good hygiene by frequent handwashing, avoiding touching the eye, and not sharing towels, pillowcases, or eye cosmetics. Over-the-counter artificial tears can also help lubricate the eye and wash away irritants.
Treatment varies based on the specific cause identified by a healthcare professional. For viral conjunctivitis, which often resolves on its own, treatment typically focuses on symptom relief; antiviral medications may be prescribed for herpes simplex virus. Bacterial conjunctivitis may be treated with antibiotic eye drops or ointments to shorten symptom duration and reduce spread.
A foreign body requires careful removal. Chemical exposure requires immediate and thorough eye flushing with water. For allergic reactions, treatment involves avoiding the allergen and may include antihistamine eye drops or mast cell stabilizers. Avoid self-diagnosing or sharing eye drops, as this can delay proper treatment or worsen the condition.