What is the cause of red eyes?

The eyes turn red because the blood vessels in the sclera become inflamed or dilated. Red eyes can be combined with other symptoms of diseases: pain, itching, watery eyes, swollen eyelids, or loss of vision.

Eye diseases

1. Conjunctivitis is an infectious eye disease. If the virus enters the conjunctiva (a thin, transparent film between the sclera and eyelid), irritation begins. Because of it, the blood vessels become inflamed, and the eyes turn red. There are several types of conjunctivitis that require different treatments, so be sure to see your doctor for an accurate diagnosis.
2. Dry eye syndrome occurs when the lacrimal glands do not produce enough tear fluid to keep the eyes moist. Constant dryness leads to irritation and inflammation of the blood vessels. Moisturizing eye drops are prescribed as a treatment.
3. Computer vision syndrome occurs when you stare at a screen for several hours. When working at a computer, we blink less often, so the tear fluid dries quickly. So that your eyes do not hurt after work, take breaks, look into the distance. You can also use moisturizing drops to relieve and soothe redness of the eyes.
4. Injury to the eye from a blow or a fall can lead to reddening of the eye or even hemorrhage. The body responds immediately by directing blood to the injured area so that it heals faster. This causes the blood vessels to dilate or rupture. Eye injuries range from microscopic scratches to puncture wounds or chemical burns. They all require immediate medical attention.
5. A corneal ulcer is an infectious disease that can lead to blindness. Requires immediate treatment. It is accompanied by pain, decreased vision and discharge from the eye. Occurs as a result of untreated injury or infection.
6. Herpes is a viral infection that is accompanied by swelling of the eyelids, pain, lacrimation, and increased photosensitivity. If the herpes on the eye is not cured, it can lead to the appearance of scarring on the retina, and then the operation to replace the retina will have to be performed.
7. Uveitis is an inflammation of the choroid of the eyes. It is accompanied by pain, photosensitivity and the appearance of flies in the eyes. The cause could be trauma, infection, or autoimmune disease. If you do not see a doctor in time, retinal detachment, cataracts, or high eye pressure may occur, leading to loss of vision. 
8. In the early stages, glaucoma is asymptomatic. Then it is sharply manifested by redness and pain in the eyes, decreased vision and dizziness. Urgent medical attention and treatment is required.  

Other causes of eye redness

• Allergy. If the body reacts with hostility to any substance (pollen, animal hair, dust or cosmetics), an inflammatory process begins. During it, histamine is produced, which fights against allergens. It dilates the blood vessels, making the eyes look red and puffy. Treatment is primarily directed at stopping contact with the allergen or treating symptoms.
• Contact lenses. If you exceed the wearing period of your lenses or do not clean them properly, bacteria on the lenses can cause inflammation of the surface of the eye. Such inflammations are dangerous because they can lead to fungal diseases or keratitis. If your eyes turn red while wearing your lenses, remove them immediately and see an ophthalmologist. In addition, improperly fitted lenses can cause dry eye by blocking oxygen access.
• Vasoconstrictor drops. Drops that are designed to reduce eye redness can be harmful. If you use them too often, the body gets used to them, and more and more drops are required. As soon as their effect wears off, the eyes turn red with a vengeance. So do not overdo it, use drops only as directed by your doctor.
• Influenza and colds – the eyes turn red from a sinus infection. After the cure of a cold, the redness disappears.
• Pregnancy – hormonal changes can change the shape and size of the cornea, lead to intolerance to contact lenses, and cause severe photosensitivity. These inconveniences are temporary and will go away on their own within a few weeks after giving birth.
• Smoking – tobacco increases the likelihood of developing macular degeneration, cataracts, secondary cataract discs, and uveitis. In addition, tobacco smoke can act as an allergen and cause redness and swelling of the eyes.  
• Excessive alcohol consumption – alcohol reduces the flow of oxygen to the eye, so the vessels become inflamed and look reddened. Stopping smoking and drinking alcohol will immediately improve your eyes.
• Overwork and lack of sleep. Overvoltage causes the blood vessels to burst or become inflamed. Please note that you cannot rub your eyes after sleep – this will make them even more inflamed.

If you don’t know why you have red eyes, make an appointment with your ophthalmologist. They will help you remove an unpleasant symptom and restore eye health.