Injected conjunctivae refers to the appearance of redness in the white part of the eye, the sclera, caused by dilated blood vessels on the conjunctiva. The conjunctiva is a thin, transparent membrane covering the front surface of the eye and lining the inside of the eyelids. While often temporary, recognizing the underlying causes is helpful for maintaining eye health.
Understanding What Causes Red Eyes
The conjunctiva becomes red when its tiny blood vessels dilate. This vasodilation is a physiological response to factors like irritation, inflammation, or infection. The expansion of these vessels increases blood flow, leading to the characteristic reddish appearance.
This process involves the release of vasoactive amines, such as histamine, which further widens blood vessels. Increased blood flow can also lead to leakage of proteins and fluid from capillaries, causing swelling. The location, color intensity, and degree of redness can provide clues about the underlying issue.
Common Conditions Behind Red Eyes
Allergic conjunctivitis is a common cause, triggered by irritants like pollen, dust, or pet dander. This leads to histamine release, causing itching, irritation, and excessive tearing. Allergic conjunctivitis is not contagious and often presents with clear discharge.
Dry eye syndrome also causes redness. This condition occurs when the eyes do not produce enough tears or when tears evaporate too quickly, leading to insufficient lubrication. Symptoms can include a gritty or burning sensation, pain, and blurry vision.
Infections are another cause. Viral conjunctivitis, often called pink eye, is highly contagious and can spread through direct contact, sometimes associated with an upper respiratory infection. Bacterial conjunctivitis, less common, involves a white, yellow, or green pus-like discharge.
Minor irritants like smoke, wind, or dust particles can also cause temporary redness and discomfort. Additionally, issues with contact lenses, including improper cleaning or prolonged wear, can lead to conjunctival irritation and inflammation.
Signs That Red Eyes Need Medical Care
Prompt medical attention is warranted for certain signs of red eyes. A sudden change in vision, such as blurriness or halos around lights, is a warning sign. Severe eye pain or tenderness, especially if accompanied by a headache, nausea, or vomiting, suggests a potentially serious condition like glaucoma.
Pus-like discharge from the eye, particularly if thick, green, or yellow, can indicate a bacterial infection. Redness that does not improve within a few days or worsens, along with increased sensitivity to light, suggests professional evaluation. Any red eye resulting from trauma, injury, or chemical exposure should be immediately assessed.
Approaches to Relieve and Treat Red Eyes
For mild cases, several approaches can provide relief. Applying cool compresses over closed eyes reduces discomfort and redness. Using over-the-counter artificial tears lubricates the eyes and alleviates dryness and irritation. Practicing proper contact lens hygiene, such as cleaning lenses as recommended and not wearing them longer than advised, prevents irritation.
When medical treatment is necessary, it depends on the underlying cause. For allergic conjunctivitis, a doctor might prescribe antihistamine eye drops to counteract histamine. Bacterial infections require antibiotic eye drops or ointments. Severe viral cases might involve antiviral medication, while foreign bodies may need professional removal.
Decongestant eye drops, while reducing redness, should be used sparingly and for short durations. This helps avoid rebound redness, where the eyes become redder once the drops wear off.