Red eyes are caused by enlarged, dilated blood vessels, leading to the appearance of redness on the surface of the eye.
Bloodshot eyes appear red because the vessels in the surface of the white portion of the eye (sclera) become enlarged and irritated. This may result from extremely dry air, sun exposure, dust, foreign body, an allergic reaction, infection, trauma, or other conditions.One common cause of a red eye is straining or coughing. This can lead to a bright red, uniformly dense bloody area on the sclera. This is called a subconjunctival hemorrhage. Although this bloody area may appear alarming, it is a fairly common occurrence and of little significance. If you notice a bloody blotch in one eye that doesn’t hurt, but just looks bad, don’t worry. It generally clears up on its own within a week or two.Eye infections or inflammation can occur in different locations. They cause redness as well as possible itching, discharge, pain, or vision problems:
- Blepharitis — inflammation of the eyelash follicles along the eyelid. It is caused by skin bacteria. Itching is common, and your eyelids may appear greasy or crusty.
- Conjunctivitis — inflammation or infection of the membrane that lines the eyelids and coats the surface of the eye (the conjunctiva). This condition is often referred to as "pink eye." It may be caused by a virus, bacteria, allergy, or irritation. If caused by an organism, this is highly contagious.
- Corneal ulcers — often caused by a bacterial or viral infection. (The cornea is the outer covering of the eye.)
- Uveitis — inflammation of the uvea, which includes the iris, ciliary body, and choroid. This is often related to an autoimmune disorder, infection, or exposure to toxins. Often, only the iris is inflamed, which is called iritis.
Other potential causes include:
- Cold or allergies.
- Foreign objects in the eye that cut or damage the eye. (See eye emergencies.)
- Acute glaucoma — a sudden increase in eye pressure that is extremely painful and causes serious visual disturbances. This is a medical emergency. Most times, glaucoma is chronic and gradual.
- Corneal scratches caused by sand, dust, or overuse of contacts.
- Bleeding problems (for example, from excess use of blood thinning drugs).
An accurate diagnosis may be difficult without the diagnostic equipment commonly used by ophthalmologists (eye specialists).
Most importantly, there are symptoms and signs which, if present, should prompt you to seek an eye specialistís opinion. Special investigations such as blood tests may also be necessary before treatment is started
Most of the time, a case of red eye is short-lived and disappears on its own. Sometimes, however, red eyes can be caused by a more serious condition. The following danger symptoms in a red eye should be evaluated by a medical professional.
- Blurry Vision:
Blurry vision is often associated with serious ocular disease. When your doctor checks your vision, even during a routine eye exam, it is a simple, quick way to determine the health of the eye. If a patient can read the 20/20 line on the eye chart with ease, that at least tells the doctor that light is being focused on the retina fairly accurately and the retina is processing the information correctly. However, if your eye is red and your vision is blurry, something significant is going on. If the source of the redness is making your vision blurry, than something is interfering significantly with your visual system. On the other hand, if your vision is blurry without associate redness, then one can determine fairly quickly that the vision may be blurry because your prescription may not be up to date.
- Severe Pain:
Conjunctivitis may produce mild irritation or scratchiness, but not extreme pain. Severe pain is a symptom of keratitis, a corneal ulcer, iridocyclitis, or acute open-angle glaucoma. Severe pain should always be evaluated as soon as possible.
Photophobia, or extreme sensitivity to light, is usually a symptom of iritis. Iritis is an inflammatory disorder of the eye in which the ciliary muscle becomes inflamed and begins to spasm, causing the eye to feel sensitive to light.
- Colored Halos:
Colored halos are a symptom of corneal edema and acute open-angle glaucoma. Usually halos seen around lights are caused by a disruption in the optical system of the eye. The cornea, the clear dome light structure on the front part of the eye, becomes thicker, due to the swelling, or edema. As it thickens, it also becomes cloudy. When this occurs, light scatters and we see halos.
If you think you may have one of the warning symptoms with red eye, it is important to see a medical professional.
For fatigue or eyestrain, try to rest your eyes. No treatment is necessary.
If you have conjunctivitis:
- Avoid touching the infected eye and then rubbing the other eye — the infection can spread from one eye to the other.
- Apply cool or warm compresses throughout the day.
- Over-the-counter homeopathic eye drops may provide relief.
- Do not use eye makeup or wear contact lenses until the infection has cleared. Throw away items like these that you used in your infected eye.
- Wash your hands frequently.
If you have blepharitis:
- Apply warm compresses to your eyes for 5 minutes. Do this at least two times per day.
- Using a cotton swab, gently rub a solution of warm water and no-tears baby shampoo along your eyelid, where the lash meets the lid. Do this in the morning and before you go to bed.