Red Eyes

Eye redness, whether diffuse or appearing as a spot, is a symptom of various ocular conditions of varying severity.

Symptoms and causes

The term "red eyes" refers to redness of the sclera, which is the white part of the eye. This redness occurs when the blood vessels on the surface of the eye dilate or become inflamed, making them much more visible than normal.

Although it may be alarming, red eye is usually a very common symptom that resolves within a short period without complications. In most cases, it is due to a mild, often transient cause; however, it may occasionally be the consequence of a serious condition requiring urgent medical attention.

Symptoms

The characteristic symptom is a change in the colour of the eyeball, which loses its characteristic white appearance. It may present in different ways:

Diffuse redness.
Red spot in the eye, which usually appears suddenly.
Red dot, smaller than the previous lesion and similar in appearance to a freckle.

Red eyes are often not accompanied by other symptoms; however, depending on the underlying disease, other pathological signs may be present, such as:

Itching.
Tearing.
Discharge, which may be clear, whitish, or greenish.
Nasal congestion.
Sneezing.

When eye redness is accompanied by any of the following symptoms, it constitutes a medical emergency:

Severe and sudden eye pain.
Visual changes (blurred vision, double vision).
Vision loss.
Halos around lights.
Nausea.
Vomiting.
Severe headache.
Photophobia (light sensitivity).
Sensation of a foreign body in the eye.
Eyelid inflammation (blepharitis).

Causes

The eyes may become red due to a wide range of conditions. Among the milder causes are:

Conjunctivitis: the most common cause. It is inflammation of the conjunctiva, the transparent membrane that lines the inside of the eyelid and the sclera (the white part of the eye). It may be infectious, viral, bacterial, or irritative in origin.
Allergies: common in patients who are sensitive to pollen, dust mites, animal hair, or mould.
Dry eye: inadequate lubrication of the ocular surface causes irritation and the sensation of grit in the eye. It is often a consequence of excessive screen use or air conditioning. Nocturnal dry eye can cause red eyes upon waking.
Ocular hemorrhage or subconjunctival hemorrhage: caused by the rupture of a blood vessel. Although alarming in appearance, it does not cause pain or affect vision. It usually resolves spontaneously within one to two weeks.
Stye and chalazion: bacterial infection causing a painful lump on the lower eyelid.
Herpes zoster ophthalmicus: reactivation of the varicella-zoster virus within the tissues of the eye.
Improper contact lens use: sleeping with contact lenses, poor hygiene, or excessive wear reduces oxygen supply to the cornea and causes eye irritation.
Eye strain resulting from lack of sleep or accumulated fatigue.
Stress: intraocular pressure increases and blinking frequency decreases, increasing the likelihood of capillary rupture or dry eye.
Environmental irritants: smoke, pollution, excessive sun exposure, cosmetics, pool chlorine, or high salt concentrations in seawater can adversely affect the eyes.

Serious conditions that may present with eye redness and require medical attention as soon as possible include:

Glaucoma: damage to the optic nerve leading to progressive vision loss. It is currently the second leading cause of blindness worldwide.
Uveitis: inflammation of the uvea, the middle layer of the eye.
Keratitis: inflammation of the cornea due to infection or injury.
Eye trauma or the presence of foreign bodies in the eye.
Corneal ulcer: a wound on the surface of the eye.

Red eyes in babies are usually the result of nasolacrimal duct obstruction. In children, the most common causes are conjunctivitis, allergies, and irritation caused by swimming pool chlorine.

Risk Factors

Factors that increase the risk of developing red eyes include:

Excessive screen exposure.
Exposure to allergens.
Spending prolonged periods in dry environments.
Improper contact lens use.
Exposure to irritating agents.

Complications

Although uncommon, red-eye conditions may lead to the following complications:

Keratoconus: thinning of the cornea, causing it to bulge outward into a cone shape as a result of excessive rubbing.
Corneal scarring affecting ocular refraction.
Orbital cellulitis: infection of the soft tissues surrounding the eye.
Conjunctival lacerations.
Macular edema: accumulation of fluid in the retina.
Bleeding.
Retinal detachment.
Cataracts: clouding of the crystalline lens.
Chronic dry eye disease.
Permanent vision impairment.
Blindness.

Which doctor treats red eyes?

Red eyes are treated within the specialty of Ophthalmology and, in some cases, in Emergency department. In milder cases, ocular redness may be managed in Paediatrics or Family and community medicine.

Diagnosis

Diagnosis of the cause of red eyes begins with a medical history (anamnesis) in which information is gathered regarding the patient’s medical background, lifestyle, contact lens use, trauma, and associated symptoms. This is followed by a comprehensive examination:

General physical examination: assessment of the eyes, head, and neck.
Eye examination: evaluation of the following aspects:
- Visual acuity: measures the eye’s ability to perceive objects and details at both near and far distances.
- Pupillary reactivity: assesses pupil size, symmetry, and response to light. This provides information about the autonomic nervous system.
- Ocular motility: determines whether the extraocular muscles move normally.
- Intraocular pressure: measured using tonometry. The procedure involves applying force to the cornea (usually by means of a gentle puff of air). According to the Imbert-Fick principle, this force is equal to the pressure inside the eyeball.
- Detection of foreign bodies.

Treatment

Red eyes do not require specific treatment. Even subconjunctival hemorrhages usually resolve spontaneously after a few days. When necessary, itching can be relieved using artificial tears or saline solution to cleanse and lubricate the eye.

Conditions causing eye redness require appropriate treatment to prevent complications:

Conjunctivitis: antibiotic eye drops are effective when the infection is bacterial. If the condition is related to environmental allergens, antihistamines are used.
Allergies: in addition to limiting exposure to the triggering allergen, corticosteroids may be administered.
Dry eye: in most cases, artificial tears or tear production stimulants are sufficient. If the condition persists:
- Intense Pulsed Light (IPL) therapy to reduce eyelid inflammation and promote tear production.
- Surgical intervention to repair damage to the tear ducts. This is only necessary in the most severe cases.
Stye and chalazion: antibiotic ointments or eye drops help combat the infection. If persistent, surgical drainage is performed to remove accumulated pus.
Herpes zoster ophthalmicus: oral antivirals and topical corticosteroids are the recommended treatment.
Glaucoma: initial treatment consists of eye drops containing medications that increase aqueous humour drainage or reduce aqueous humour production. If the expected results are not achieved:
- Trabeculoplasty to improve aqueous humour drainage.
- Trabeculectomy to create a new drainage opening.
Uveitis: anti-inflammatory eye drops are usually sufficient to achieve resolution. If not, a vitrectomy is performed to surgically remove the vitreous humour.
Keratitis: depending on the type of infection, antibiotic, antiviral, or antifungal medications are used.
Corneal ulcer: in addition to treating the infection, eye drops are commonly administered to dilate the pupil and relieve pain. If complications arise, a corneal transplant may be necessary.