What Causes Bloodshot Eyes?

Noticing more prominent than usual red veins across the white part of your eye can feel unsettling. If you are wondering what bloodshot eyes mean, it indicates that the tiny blood vessels on the surface of your eye have become dilated with blood. The answer usually comes down to how your eyes respond to irritation, allergy, infection, reduced oxygen, tiredness, or physical strain.

Everyday Triggers and Broader Causes

Daily life can expose your eyes to many irritants that may leave them looking red or inflamed, even without the added impact of vision aids, like contact lenses. Environmental elements often play a primary role, with exposure to dry central heating, air-conditioning, harsh wind, or tobacco smoke rapidly stripping moisture from the eye. Seasonal allergies such as hayfever compound this by triggering a release of histamines, which cause the delicate surface blood vessels to dilate and swell. Modern screen habits exacerbate the problem further: staring at digital devices drastically reduces your natural blink rate, allowing the protective tear film to evaporate and leaving the cornea dry and vulnerable. 

Beyond these daily environmental stressors, common conditions such as conjunctivitis (viral or bacterial infection or allergic reaction) and blepharitis (inflammation of the eyelid margins) frequently produce widespread redness, swelling, and a persistent gritty sensation usually accompanied by discharge or itching.

Contact Lenses: Wear Them Correctly to Avoid Persistent Redness

While these everyday factors are widespread, not wearing or looking after your contact lenses correctly, as advised by your optician, remains one of the most common reasons people suffer from ocular discomfort. 

Overwearing your contact lenses, skipping proper cleaning routines, sleeping in non-extended-wear lenses, or developing a sensitivity to the chemical preservatives in cleaning solutions can create chronic surface stress. In some patients, dry eyes can also contribute to contact lens intolerance. If your eyes are red after wearing contacts, continuing to wear them increases the risk of painful corneal micro-abrasions, bacterial infections including sight-threatening infections, and permanent contact lens intolerance.

Mr Amir Hamid, Chief Medical Officer and Consultant Ophthalmic Surgeon at Optegra, notes that contact lenses may naturally alter the delicate tear film designed to protect the eye. 

What Causes Bloodshot in One Eye?

Eye redness does not always affect both eyes simultaneously. If an infection, it may start in one eye and gradually spread to the next; if in one eye it can also be caused by an abrasion or trapped foreign bodies. A single bloodshot eye also frequently stems from a subconjunctival haemorrhage, where a tiny blood vessel ruptures just beneath the clear surface of the eye following a heavy cough, a sneeze, or rubbing the eye too firmly or potentially raised blood pressure (if this is your first occurrence, you should visit a pharmacist or GP to get your blood pressure checked.

Recognising Warning Signs and Knowing What to Do

If you experience a bloodshot eye and are unsure of the cause, visit your eye health care practitioner for an assessment. If redness is accompanied by severe eye pain, extreme light sensitivity, discharge, or changes in your vision, you should seek a more urgent assessment from an eye care professional, as these signs indicate a more serious infection or injury. 

Long-Term Freedom Through Laser Eye Surgery

Laser eye surgery provides a permanent, transformative alternative that can provide freedom from contact lens wear,  as well as reduce the long-term costs. Modern procedures such as LASIK and SMILE gently reshape the surface of the eye, and procedures such as SMILE are suitable for patients with mild to moderate dry eye. Book your free consultation with our experts to discuss your laser eye surgery options today.