Conjunctival hyperaemia is the medical term for what is commonly known as “bloodshot eyes” or “red eyes.” This condition describes the visible reddening of the conjunctiva, the clear membrane covering the white part of the eye and lining the inner eyelids. It occurs when the small blood vessels within this membrane dilate or become engorged with blood, making them more prominent and altering the eye’s appearance from white to pink or red. Conjunctival hyperaemia is a common symptom rather than a specific disease, often indicating an underlying irritation, infection, or inflammation.
How to Identify Conjunctival Hyperaemia
Conjunctival hyperaemia presents as diffuse redness across the white part of the eye, known as the sclera, often appearing brightest furthest from the cornea, the clear front surface of the eye. The involved blood vessels are typically small in diameter and can be seen to move if the conjunctiva is gently manipulated. This diffuse reddening helps distinguish it from other forms of eye redness.
It is distinct from ciliary injection, where redness is concentrated in a deeper, purplish ring around the cornea, indicating inflammation within the eye itself, such as in conditions affecting the iris or ciliary body. A subconjunctival hemorrhage, for example, appears as a localized, bright red patch of blood under the conjunctiva, often resulting from a broken blood vessel. Conjunctival hyperaemia frequently accompanies other symptoms like itching, burning, or discharge, depending on the underlying cause.
What Causes Red Eyes
The dilation of conjunctival blood vessels can stem from various factors. Environmental irritants such as dust, smoke, air pollution, or chemicals like chlorine in swimming pools can trigger an inflammatory response, causing redness. Eye strain from prolonged activities like reading or screen use, as well as insufficient sleep, can also contribute to this irritation.
Infectious agents are a common cause, with viral conjunctivitis, often called pink eye, and bacterial conjunctivitis often presenting with redness. Allergic reactions to substances like pollen, pet dander, or dust mites can cause allergic conjunctivitis, where the immune system releases histamines, leading to dilated blood vessels and associated itching and watery eyes. Chronic dryness of the eye surface, known as dry eye syndrome, can also lead to persistent irritation and redness due to insufficient tear production or poor tear quality. Additionally, issues related to contact lens wear, such as improper hygiene, extended use, or adverse reactions to lens solutions, can irritate the conjunctiva and cause red eyes.
When to Seek Medical Attention
While many instances of red eyes resolve on their own, certain symptoms accompanying conjunctival hyperaemia warrant prompt medical evaluation. Severe or deep eye pain, particularly if persistent, warrants seeking professional help. Any changes in vision, such as blurred vision, sudden onset of halos around lights, or increased sensitivity to light (photophobia), indicate a more serious underlying condition.
Headaches, nausea, or vomiting that occur alongside eye redness can signal acute angle-closure glaucoma, an ocular emergency. Redness following an injury to the eye or exposure to chemicals also requires immediate medical attention. If the redness persists for more than a few days without improvement, or if there is a pus-like discharge, consult a healthcare provider. Red eyes in infants or young children, especially those less than 28 days old, also necessitate an urgent medical assessment. Individuals with compromised immune systems experiencing eye redness should also seek prompt medical care.
Approaches to Treatment and Management
Treatment for conjunctival hyperaemia depends on identifying and addressing the underlying cause. For mild cases, self-care measures can provide relief. Resting the eyes, avoiding known irritants like smoke or allergens, and applying warm or cool compresses can alleviate discomfort. Over-the-counter artificial tears or lubricating eye drops are effective for managing dryness and can wash away irritants.
When a specific cause is identified by a healthcare professional, medical treatments may be prescribed. For instance, allergic conjunctivitis may be treated with antihistamine eye drops, reducing redness and itching. Bacterial infections require antibiotic eye drops, while some severe viral cases may benefit from antiviral medications, though many viral conjunctivitis cases are self-limiting. Specific treatments for dry eye syndrome, such as prescription eye drops, may also be recommended. Prevention involves practicing good eye hygiene, ensuring proper contact lens care, and avoiding known allergens.