Scleral injection is the medical term for red or bloodshot eyes. This occurs when tiny blood vessels on the sclera, the white outer layer of the eyeball, become dilated and engorged with blood. In this medical context, “injection” refers to this engorgement of vessels, not to administering a substance with a needle. The redness signals irritation or an underlying issue affecting the eye.
Common Causes of Eye Redness
Environmental irritants, such as smoke, dust, pollen, and pet dander, can directly irritate the conjunctiva, the clear membrane covering the white of the eye, causing vessels to dilate. Exposure to harsh weather conditions like strong winds or dry air can also contribute to ocular discomfort and redness.
Lifestyle habits frequently play a role in bloodshot eyes. Insufficient sleep can prevent the eyes from receiving adequate rest and lubrication, leading to a tired and red appearance. Prolonged use of digital screens, often called digital eye strain, reduces the blink rate, which can result in the eyes drying out and becoming irritated.
Dry eye syndrome is another common cause, occurring when the eyes do not produce enough tears or when tears evaporate too quickly, leading to irritation and inflammation. This lack of proper lubrication causes the eye surface to become dry, prompting blood vessels to enlarge. Contact lens wear can also induce redness due to overwear, improper cleaning, or an allergic reaction to solutions.
Differentiating Scleral Injection from Subconjunctival Hemorrhage
Individuals often confuse general eye redness, or scleral injection, with a subconjunctival hemorrhage, though their appearances are distinct. Scleral injection manifests as fine, squiggly red or pink lines across the white of the eye, indicating that tiny blood vessels are swollen and more visible. This pattern often appears diffuse or localized.
In contrast, a subconjunctival hemorrhage presents as a distinct, solid, bright red patch of blood on the sclera. This is caused by a small blood vessel breaking beneath the conjunctiva, allowing blood to pool. While the appearance can be alarming, a subconjunctival hemorrhage is usually harmless and resolves on its own within one to two weeks, similar to a bruise. Scleral injection, however, can point to a wider range of issues, some requiring medical attention.
Associated Symptoms Requiring Medical Attention
While many instances of red eyes are benign, certain accompanying symptoms signal a need for prompt medical evaluation. Significant eye pain, especially if sudden, severe, or throbbing, indicates a potentially serious underlying problem. This pain often suggests inflammation or increased pressure within the eye.
Changes in vision, such as blurriness, double vision, or halos around lights, are concerning signs that warrant immediate attention. These visual disturbances can suggest issues with the cornea, lens, or deeper eye structures. Extreme sensitivity to light (photophobia), when combined with redness, can point to conditions like inflammation of the iris or cornea.
Any thick, yellowish, or greenish pus-like discharge from the eye is a strong indicator of an infection. While clear, watery discharge can accompany allergies or viral irritation, purulent discharge suggests a bacterial infection requiring specific treatment. Recognizing these symptoms empowers individuals to seek timely professional care.
Medical Evaluation and Treatment Options
When persistent or concerning eye redness prompts a visit to a healthcare provider, evaluation typically begins with a detailed history of symptoms and a visual examination. The doctor will inquire about the onset, duration, and any associated discomfort or changes in vision. A specialized instrument called a slit lamp may be used to examine the eye’s surface and internal structures in magnified detail, allowing for precise assessment of blood vessels, cornea, and other tissues.
Treatment options for scleral injection depend on the identified underlying cause. For common issues like dry eye, lubricating eye drops (artificial tears) are frequently recommended to supplement natural tear production and soothe the ocular surface. For redness caused by allergies, antihistamine eye drops or oral medications can help reduce the body’s histamine response, which causes itching and vessel dilation.
If an infection, such as bacterial or viral conjunctivitis, is diagnosed, antibiotic eye drops or oral antiviral medications may be prescribed. For more severe inflammation, like uveitis or scleritis, corticosteroid eye drops or oral steroids might be used to reduce swelling and redness, though their use is carefully monitored due to potential side effects.