# Sudden Red Eye: Causes, Symptoms and When It Is an Emergency URL: https://mohamedmohyudin.co.uk/eye-health/red-eye-when-to-seek-help/ Last updated: 2026-09-08 Original clinical review: 2026-08-13; later editorial additions are source-based. ## Quick answer A red eye is most often benign, caused by a burst blood vessel (subconjunctival haemorrhage), conjunctivitis, allergy or dry eye. It becomes an emergency when redness is combined with significant pain, reduced vision, light sensitivity, halos around lights, or follows an eye injury. These warning signs need same-day or emergency ophthalmic assessment. ## Key facts - Most red eyes are benign and resolve without treatment - Subconjunctival haemorrhage clears in 1 to 3 weeks - Red eye with pain, reduced vision or halos needs urgent care - Acute angle-closure glaucoma can cause permanent damage within hours - Contact lens wearers with pain and blur need urgent assessment - West Yorkshire eye casualty: Huddersfield Royal Infirmary ## Introduction A red or bloodshot eye is one of the most common reasons people present to an eye clinic or A&E. The vast majority of cases are benign — a burst blood vessel, a minor infection, or dryness. But a small number represent genuine emergencies where delayed treatment can cause permanent vision loss. The key is knowing which is which. ## Common, non-urgent causes - Subconjunctival haemorrhage — a bright red patch caused by a tiny burst blood vessel on the surface of the eye. Looks alarming but is almost always harmless and resolves in 1–3 weeks without treatment. Often occurs after coughing, sneezing, or straining. - Conjunctivitis (bacterial or viral) — pink or red eye with discharge and mild discomfort. Usually resolves on its own; bacterial conjunctivitis responds to antibiotic drops. - Allergic conjunctivitis — redness, itching and watering, usually both eyes, triggered by pollen, dust mites or pet dander. Antihistamine drops help. - Dry eye disease — chronic low-grade redness, grittiness and fluctuating blur. Very common, especially in older patients and screen users. - Contact lens-related redness — wear time or lens fit issues. Always remove lenses before attending any eye appointment. ## Red eye signs that need urgent assessment today The following combinations require same-day or emergency ophthalmic assessment. Do not wait for a routine GP appointment. - Red eye + significant pain or ache around the eye — could indicate acute angle-closure glaucoma or uveitis (iritis). - Red eye + reduced vision — any measurable drop in clarity is a red flag. - Red eye + sensitivity to light (photophobia) — typical of uveitis, keratitis, or acute glaucoma. - Red eye + seeing halos around lights — a classic symptom of elevated intraocular pressure in acute glaucoma. - Red eye after an injury or foreign body — especially if there is any chance of a penetrating injury. Do not rub the eye. - Red eye in a contact lens wearer with pain and blur — urgent: could be microbial keratitis (corneal ulcer), which can scar rapidly. ## Acute angle-closure glaucoma — the eye emergency most people miss Acute angle-closure glaucoma is the condition that catches people out most often, because it can mimic a headache or even a migraine. The intraocular pressure rises suddenly and dramatically, causing a red, hazy-looking eye, severe pain, nausea, vomiting, and halos around lights. It is a true ophthalmic emergency. Without treatment within hours, permanent optic nerve damage occurs. If you or someone you know has this combination of symptoms, call 999 or go directly to A&E. ## Uveitis (iritis) — the silent inflammatory red eye Uveitis is inflammation inside the eye. It typically presents as a painful, red eye with a small or irregular pupil, blurred vision and photophobia. Unlike conjunctivitis, there is usually minimal discharge. It can be associated with systemic conditions such as ankylosing spondylitis, sarcoidosis, or inflammatory bowel disease, but is often idiopathic. Treatment involves steroid eye drops to reduce inflammation and dilating drops to prevent the iris sticking to the lens. Early treatment prevents complications including raised pressure, cataract, and macular oedema. ## What to do - No pain, normal vision, no recent injury: see your GP or optician within a day or two. - Mild discomfort but vision is normal: call an optician for a same-day appointment. - Pain, reduced vision, photophobia, or halos: go to your local eye casualty or A&E today. In West Yorkshire: Huddersfield Royal Infirmary Eye Casualty. - Suspected penetrating injury: call 999. ## Where should West Yorkshire patients go after hours? Huddersfield Royal Infirmary runs the local eye-casualty pathway (01484 342000). If you cannot get there, A&E will still see a painful red eye. Do not start leftover steroid drops from an old prescription. Do not sleep in contact lenses ‘just tonight’. Private clinics, including Spire Elland, are not an emergency department. ## Why are contact-lens red eyes a special case? Microbial keratitis can look like ‘just conjunctivitis’ for a few hours and then scar the cornea. Remove the lens, keep it for culture if asked, and do not put a new lens in. Pain, light sensitivity, or a white spot on the cornea is same-day care. Cheap online lenses and tap-water rinsing are how this story often starts. ## When is a painless red eye still worth a booked clinic? When it has lasted weeks, when you have blepharitis or dry eye that is not responding to lid hygiene, or when redness is only on one sector of the sclera and you have autoimmune disease — episcleritis and scleritis live in that gap. That is a prompt outpatient, not 999. ## What information helps a clinician triage a red eye? Describe whether one or both eyes are affected, when redness began and whether there is pain, light sensitivity or a change in sight. Mention contact-lens use, recent eye surgery, injury, chemical exposure and any drops already used. These details can change the urgency of the assessment. A photograph may show redness but cannot rule out problems inside the eye or establish that the cornea is healthy. If you wear contact lenses, remove them and seek urgent advice for a red or painful eye. Avoid using another person’s drops or leftover steroid drops. Sudden changes in vision, severe pain or marked light sensitivity warrant urgent assessment rather than a routine callback. For a mild problem already assessed by a professional, ask what improvement to expect and exactly which change should trigger another examination. A treatment plan should include a way to get help if the first diagnosis no longer fits the symptoms. ## Questions to take to your appointment - Does this need assessment today? - Should I stop contact-lens wear until reviewed? - What worsening symptoms should prompt urgent reassessment? ## Sources - [NHS: red eye — when to seek urgent help](https://www.nhs.uk/symptoms/red-eye/) ## FAQs ### Is a completely red eye (subconjunctival haemorrhage) dangerous? A bright red patch on the white of the eye — a subconjunctival haemorrhage — looks alarming but is almost always harmless. It is caused by a tiny blood vessel bursting on the surface (not inside) the eye. Vision is unaffected and it resolves over 1–3 weeks. If it recurs frequently, a blood pressure check is worthwhile. If it is associated with pain or reduced vision, seek urgent review. ### Can pink eye (conjunctivitis) cause permanent damage? Simple viral or bacterial conjunctivitis very rarely causes lasting damage. However, certain types of infective keratitis (corneal infection) — which can superficially resemble conjunctivitis — can scar the cornea if untreated. Any red eye with significant pain or reduced vision in a contact lens wearer needs urgent assessment. ### My eye has been red for weeks with no other symptoms. Should I worry? Chronic, low-grade redness without pain or vision change is most commonly dry eye disease, blepharitis (lid margin inflammation), or mild allergic conjunctivitis. It is worth seeing an optician or GP to confirm. If artificial tears and basic lid hygiene do not help within a month, a consultant ophthalmology opinion is appropriate. ### Should I use over-the-counter ‘get the red out’ drops? Whitening drops shrink surface vessels and can rebound. They also hide the sign we use to judge inflammation. Lubricant is safer while you wait for a proper look. They are not treatment for glaucoma, uveitis, or an ulcer. ### Can Mr Mohyudin see a red eye privately the same week? A non-emergency red eye can often be seen within 1–2 weeks at Spire Elland (01422 324000). A painful, photophobic, or contact-lens red eye should not wait for that diary — use eye casualty.