Among the five senses, the largest area of cerebral cortex is allocated to vision which is probably the most important means of communication with the outside world for human beings. In order to correctly perceive images, health of the visual system and its receptors, namely eyes, is necessary. Like other systems, eye problems and diseases present themselves with some signs to inform the person. Like fever which is a warning sign in many diseases, eye redness is the sign of a disease or problem in eyes. However, it should be noticed that eye redness is not always a sign of eye disease; in many cases, it is a normal phenomenon in situations such as in the morning after waking up, after prolonged wakefulness and heavy work, while having a cold or after crying.
On the other hand, eye redness can be a sign for some diseases, which we will discuss here.
Eye Infections
Generally, eye infections (conjunctivitis) are accompanied by purulent discharges, stickiness of eyelids, watery and burning eyes in addition to eye redness. In some cases, especially in viral infections of eyes (viral conjunctivitis), fever, sore throat and cold symptoms may also be added to these symptoms. In these cases, the same virus causing cold has infected eyes. Eye infections are usually treated by topical antibiotic ointments and drops such as chloramphenicol drop and erythromycin ointment. Washing eyes with cold tea is also beneficial for relieving symptoms and decreasing discharges.
It should be noted that cleanliness is highly important in cases of conjunctivitis because these infections are contagious and are easily transmitted from the infected person to healthy ones. Hand shaking, kissing the infected person and using common towels are among the transmission routes. It is noteworthy that treatment with antibiotic ointment or drop does not immediately improve the infection and healing is gradually achieved by going through its course. In some cases like eye infections with some bacteria like hemophilus or gonorrhea in children under five years old, treatment with oral or intravenous antibiotics must accompany topical treatment.
Eye Allergies
In eye allergies, itching and watery eyes are usually observed along with eye redness but itching is an evident symptom. In some cases, it is easy to find the allergen like make-up, pollen in spring or even pillow feather, but in most cases, finding the allergen is difficult. Considering that there are thousands of allergens in the air, especially in big cities, it is sometimes impossible to find the allergen. Eye allergies are usually temporary and are healed in a couple of days with no treatment; however, in some cases like spring allergic conjunctivitis or atopic types, irritation continues for a couple of months or years and treatment needs prolonged consumption of medication. Usual allergies are treated with topical drops such as anaprydin, flucort and cromolyn as well as cold compress. Cooling the eyes and cold compress considerably relieve the pain.
Corneal Ulcers and Abrasions
It should be noted that corneal surface is the richest organ in terms of pain nerves and surface abrasions which may not cause any symptoms in other organs show themselves with various symptoms like redness, burning and watery eyes as well as foreign body sensation inside eyelid. Therefore, foreign body sensation does not necessarily mean the presence of foreign bodies in the eye since it can sometimes be due to corneal abrasions. Regarding corneal abrasions, after eye examination and assuring the absence of any foreign body, the symptoms are improved by applying eye patches and using a topical antibiotic to avoid infection. Dressing is applied externally or as a lens dressing which is usually removed within two days.
Superficial Ocular Foreign Bodies
Eye foreign bodies also cause symptoms similar to those of corneal abrasions; i.e. redness, burning, watery eyes and foreign body sensation. In such cases, first, the eye should be rinsed with water and, if the foreign body is not removed, no more attempts should be made to remove it because it may result in more damage. It is necessary to visit an ophthalmologist in such a case. The ophthalmologist examines the eye using a slit lamp and removes the foreign body; afterward, the eye is dressed and topical ointment is prescribed.
Eye Redness Following Welding- Ultraviolet Keratitis
This condition usually appears a few hours after welding without goggles or after working in UV-ray rich places or after skiing without sunglasses in snow which has high UV reflection. The symptoms include burning, redness, pain, severe watery eyes and photophobia. The complication is caused by the damage of corneal cells due to UV ray. Treatment includes eye dressing after applying antibiotic and pupil dilating drop. The dressing should usually remain for 24 h so that the damaged cells are repaired and symptoms are improved. Continuous use of topical anesthetic drops or some home remedies like placing potatoes are useless and even dangerous.
Increased Intraocular Pressure- Acute Angle-closure Glaucoma
Acute increased intraocular pressure (acute angle-closure glaucoma) leads to pain and redness in eyes besides blurred vision and sometimes headache, nausea and vomiting. This condition is usually observed in middle aged women at sunset. In this disease which is called acute glaucoma, due to the closure of vitreous fluid outflow in the eye and its accumulation, intraocular pressure suddenly increases and leads to pain, eye redness, blurred vision and seeing halos around objects as well as headache, nausea and vomiting. In this disease, intraocular pressure should be reduced by topical, oral and intravenous medicines followed by laser therapy for both eyes (YAG Laser PI) to avoid recurrence. Prolonged high intraocular pressure results in damage to the optic nerve and the eye itself, decreased vision and permanent blindness. However, it should be noticed that in most cases, headache is caused by neurological problems rather than eye problems. This is also true about cluster headache, a unilateral headache beside eye redness and watery eyes on the same side. This headache should not be confused with eye problems. Meanwhile, it should be noted that glaucoma is not always accompanied by headache. Its chronic type has no symptoms at initial phases and accompanies visual field disorder and decreased vision only at advanced phases. In chronic glaucoma which is the most common type, only examination by an ophthalmologist can help diagnose it. Treating glaucoma with medicines which reduce intraocular pressure at earlier phases can avoid extra damage to the eye and optic nerve so that the individual can enjoy normal life and vision. It should be reminded that increasing intraocular pressure in chronic glaucoma has no symptoms at initial stages and the patient has no headache, redness or other eye symptoms.
Dry Eye
Dry eye and lack of adequate tears may occur alone as an eye disease or be accompanied by other complications in other parts of body. For instance, in Sjogren syndrome, eye dryness is along with dryness of mouth and other mucous membranes. It is also a symptom of some rheumatic diseases. Eye dryness and lack of tear cause symptoms like foreign body sensation, burning, dryness and watery eyes. These symptoms are exacerbated in dry and hot seasons as well as dry regions and polluted air. Contrary to its name, watery eye and tearing due to irritated eye is a symptom of eye dryness. Treatment of eye dryness in slight to medium cases includes tear substitute drops and lubricators like artificial tear and lubricating substances. In severe cases, sometimes other treatments such as closure of tear duct openings are required to prevent tear outflow.
Eyelid Problems
Eyelid problems like blepharitis (infection and inflammation of eyelid margins) can result in burning, eye redness and foreign body sensation. Inflammation and infection of eyelid margins are observed in belpharitis. In some cases, small flakes stick to eyelids and base of eyelashes. In severe cases, inflammation of the eyelid appears as red and thick eyelid margins and thin eyelashes which can be observed by naked eye, as well. Eye redness is also observed in such cases. Most belpharitis cases (infection and inflammation of eyelid margin) are treated by routine hygiene, which includes washing eyelid margins and eyelash bases with baby shampoo, eyelid massage and warm towel (eyelid warm compress).
In severe cases, topical and oral treatments are required. In some cases, eye redness is due to problems in eyelash growth site such as ectopic cilia or inward growth of eyelashes (Trichiasis) or inward folding of eyelid margins (Entropion). Sometimes, irregular eyelid margins due to previous diseases like trachoma also cause problems. In these cases, if symptoms do not improve with treatments like artificial tear and lubricating ointment, surgery is usually mandated for treating the abnormal condition.
External Eye Diseases
Some external eye disease such as keratoconus, pterygium, and loose conjunctival tissue can lead to eye redness and eye discomfort which can be treated by drops, topical lubricating ointments, artificial and steroidal tear and surgery in more severe cases.
Eye Redness Caused by Medicine
Some medicines especially hormones in neurology and psychiatry medications can result in redness and dilation of superficial blood vessels of the eyes which are usually improved when the medicine is stopped. Even some foods can cause eye redness, especially those rich in caffeine such as coffee. In cases that the patient is forced to take the medicine, no measures should be taken. It is sometimes possible to use naphazoline drop temporarily to reduce redness. This drop should not be used continuously because its prolonged use exacerbates redness symptoms when it is stopped. Some topical eye medicines such as anti-glaucoma, intraocular pressure reducing and anti-virus drugs can result in eye redness.
External Eye Inflammations
In inflammations of the external eye such as scleritis and episcleritis, eye redness is usually accompanied by eye irritation and pain. In mild cases, it is treated using topical corticosteroid drops and, in severe cases, oral corticosteroids are required.
Intraocular Inflammations
Intraocular inflammation such as uveitis causes redness and pain besides photophobia. In some cases, reduced vision is also observed. These inflammations (uveitis) are usually recurrent and, in some cases, are accompanied by a systemic inflammatory disease like rheumatic and autoimmune diseases. As a result, the patient must let the physician know about other symptoms like joint pain, back pain or oral ulcers. Treatment includes topical corticosteroid drops as well as pupil dilating drops and in some cases, oral medicines and injections around the eye. Here, in addition to treating eye problems, other organs should also be checked for the underlying diseases. In intraocular inflammation caused by cat parasite (Toxoplasma), severe intraocular inflammation is observed which is accompanied by vision loss. Antibiotics against cat parasite (Toxoplasma) must be taken; otherwise vision loss will be permanent.
Vascular Diseases
In some vascular diseases in head, face and neck such as ectopic connection of vein with artery (Carotid-cavernous fistula) or Sturge-Weber disease, due to ectopic vascular connections, blood return to veins and blood accumulation in tissues, eye redness is observed which is not accompanied by pain or foreign body sensation. Accordingly, no eye redness treatment is needed in such cases since the underlying disease must be treated by surgery or other medications.
Subconjunctival Hemorrhage
Subconjunctival hemorrhage is a common condition in elderly and people with history of hypertension. Redness (bleeding) usually follows sneezing, coughing, straining or anger and in most cases, it occurs spontaneously. This redness is not associated with any other symptoms such as burning, foreign body sensation, vision loss or pain. It is noticed while looking in the mirror or by another person. This bleeding is not dangerous for the eyes; it will not make any problems in future, either. There is no relationship between this bleeding and intraocular pressure but the patient must be checked for hypertension and the associated diseases. The condition first grows a little and then gradually clears within two weeks, leaving no trace.