Eye Pain / Redness
Symptoms, Causes & Treatment
Understanding eye pain and redness: when it is a vision-threatening emergency, the common causes, and how each type of red or painful eye is treated.
What Causes Eye Pain and Redness?
A red or painful eye is one of the most common presentations to GPs and emergency departments. Most cases are benign — viral conjunctivitis, dry eye, or subconjunctival haemorrhage — but a significant minority are sight-threatening emergencies requiring immediate specialist intervention.
The critical question is always: is vision affected? A painful red eye with reduced vision, photophobia, or a fixed mid-dilated pupil is an ophthalmic emergency. A red eye with normal vision and a discharge is usually infective conjunctivitis.
Never assume a painful red eye is conjunctivitis without clinical assessment. Contact lens wearers with a painful red eye must attend A&E immediately — corneal infection can cause permanent blindness within 24 hours.
What Are the Symptoms of Eye Pain?
The pattern of redness and pain provides critical clues to the underlying diagnosis. A systematic approach prevents missing sight-threatening conditions.
Eye pain · Redness and injection of conjunctiva · Photophobia · Watering or discharge · Reduced vision · Sensation of foreign body · Circumcorneal redness (red ring around cornea)
Sudden severe eye pain with nausea and visual halos (acute angle-closure glaucoma — emergency) · Penetrating eye injury · Chemical splash to eye · Eye pain with headache and double vision (posterior communicating aneurysm) · Sudden vision loss
Attend A&E immediately for: severe eye pain with nausea and halos; chemical splash; penetrating injury; contact lens wearer with painful red eye; painful eye with restricted eye movement or proptosis. These are all ophthalmic emergencies.
What Causes Eye Pain and Redness?
Eye pain and redness have multiple causes ranging from minor irritation to serious sight-threatening emergencies. Identifying the pattern determines urgency.
Acute angle-closure glaucoma causes sudden severe eye pain, nausea, red eye, and halos around lights. It is caused by sudden blockage of aqueous drainage. This is an ocular emergency requiring immediate ophthalmology treatment.
Uveitis is inflammation of the uveal tract (iris, ciliary body, choroid). It presents with eye pain, photophobia, and circumcorneal injection. It is associated with HLA-B27 conditions including ankylosing spondylitis.
Cataracts cause gradual clouding of the lens, producing progressive blurring, glare, and halos. Cataract extraction is the most commonly performed surgical procedure in the UK and is highly effective.
Age-related macular degeneration (AMD) affects central vision. Wet AMD causes rapid central vision loss from neovascularisation and requires emergency anti-VEGF injection. Dry AMD progresses slowly.
Dry eye disease affects 5–15% of adults and occurs when tears evaporate too quickly (evaporative dry eye from meibomian gland dysfunction) or are produced in insufficient quantity (aqueous deficiency). Both cause ocular surface damage.
Posterior vitreous detachment (PVD) occurs when the vitreous gel separates from the retina. This causes floaters and flashes. In most cases it is benign, but it can cause retinal tears in 10–15% of cases requiring urgent assessment.
Key Risk Factors
How Is Eye Pain Investigated?
Assessment includes visual acuity, pattern of redness, pupil reactions, intraocular pressure, slit-lamp examination, and fluorescein staining. Conjunctival swab identifies infection.
How Is Eye Pain Treated?
Treatment is cause-specific. Bacterial conjunctivitis: chloramphenicol drops. Uveitis: steroid drops. Acute glaucoma: pilocarpine, IV acetazolamide, emergency laser. Keratitis: intensive topical antibiotics. Viral conjunctivitis: supportive only.
Supportive Measures
For mild non-urgent red eyes: use preservative-free artificial tears, avoid rubbing, remove contact lenses, apply cool compresses. If eye is painful with vision change — attend A&E immediately. Do not apply topical steroids without ophthalmology advice.
Recurrent Eye Pain or Redness
Recurrent uveitis requires ophthalmology follow-up and investigation for underlying systemic cause (HLA-B27, sarcoidosis, inflammatory bowel disease). Recurrent episcleritis may be associated with autoimmune disease. Recurrent bacterial conjunctivitis in a contact lens wearer requires lens hygiene review and possible lens type change.
When Should You Seek Medical Advice for Eye Pain?
Sudden severe eye pain with nausea, vomiting, and halos (acute angle-closure glaucoma) · Chemical splash to the eye · Penetrating eye injury · Painful eye with proptosis and restricted eye movement · Contact lens wearer with painful red eye. All require immediate A&E assessment.
Red eye without vision loss that has not improved after 5 days of antibiotic drops · Contact lens wearer with any degree of eye redness or pain · Red eye with photophobia or floaters.
How Can You Prevent Eye Pain?
Many causes of eye pain and redness are preventable with appropriate eye care practices.
Follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds. Use artificial tears for screen-related dry eye. Increase screen font size to reduce eye strain.
All diabetics should attend annual NHS diabetic eye screening (dilated fundal photography) to detect diabetic retinopathy before it causes irreversible vision loss. This is free and highly effective.
Never sleep in contact lenses. Clean lenses strictly as directed. Replace on schedule. Use sterile solution, not tap water. Contact lens keratitis can cause permanent vision loss within 24 hours.
Warm compresses applied to closed eyelids for 2 minutes twice daily improve meibomian gland function, reduce dry eye symptoms, and prevent blepharitis flares. This should become a daily habit.
Attend regular NHS sight tests (free every 2 years on the NHS, more frequently if you are diabetic, over 60, or have glaucoma in the family). Eye tests detect glaucoma, retinal disease, and AMD before symptoms appear.
Wear UV400-protective sunglasses outdoors. UV exposure increases the risk of cataracts and AMD. Polarised lenses do not provide additional UV protection unless UV400-rated.
Speak to a Clinician About Eye Pain or Redness
Through The GP Service, a clinician can assess eye symptoms, identify the likely cause, and arrange same-day ophthalmology referral for urgent presentations.
Expert clinical advice, when you need it.
Eye Pain / Redness FAQs
A sudden red, painful eye requires same-day urgent assessment. It may indicate acute angle-closure glaucoma (with halos and nausea), uveitis, corneal ulcer, or scleritis. Never dismiss a painful red eye as conjunctivitis without clinical assessment.
Yes. Contact lens wearers are at high risk of bacterial keratitis (corneal infection), which can cause permanent vision loss within 24 hours. Remove lenses immediately if your eye is painful or red. Do not sleep in lenses. Attend A&E or an eye emergency clinic urgently.
Uveitis is inflammation of the uveal tract (iris, ciliary body, choroid). It presents with eye pain, photophobia, and a red eye. It is associated with HLA-B27 conditions including ankylosing spondylitis. It requires urgent ophthalmology assessment and treatment with steroid eye drops.
Eye pain with severe headache, nausea, halos around lights, and a fixed mid-dilated pupil indicates acute angle-closure glaucoma — an ophthalmic emergency. Attend A&E immediately. Without treatment, permanent vision loss can occur within hours.
Chemical splashes to the eye require immediate first aid: irrigate with large volumes of water for at least 15–20 minutes. Do not rub the eye. Call 999 or attend A&E. Alkaline chemicals (bleach, cement) cause more serious injuries than acidic chemicals.
Episcleritis causes a sectoral red, mildly uncomfortable eye without visual loss. It is usually self-limiting and treated with anti-inflammatory eye drops. Scleritis causes severe boring eye pain often with systemic autoimmune disease and requires urgent ophthalmology management.
Eye pain after trauma with reduced vision, irregular pupil, or protruding eye requires emergency assessment to exclude globe rupture, orbital fracture, or traumatic retinal detachment.
Viral conjunctivitis is self-limiting and needs no treatment. Bacterial conjunctivitis responds to antibiotic eye drops. Allergic conjunctivitis is treated with antihistamine eye drops. All three types cause redness and discharge but have different features — a clinician can advise on the appropriate treatment.