- Home
- Knowledge centre
- Eye glossary A–Z
- Subconjunctival Hemorrhage and the Conjunctiva: Parts, Function and Conditions
Subconjunctival Hemorrhage and the Conjunctiva: Parts, Function and Conditions
Medically reviewed by {{surgeon}}, {{surgeon's title and specialty}}, on {{review date}}. Last updated {{date}}.
Conjunctiva (noun, plural conjunctivae or conjunctivas): the conjunctiva is the thin, transparent, moist membrane that lines the inside of the eyelids and covers the white of the eye (the sclera) up to the edge of the cornea. It protects the eye, makes part of the tear film and lets the eye move and blink smoothly. It contains many small blood vessels, which is why the white of the eye looks pink or red when it is irritated, infected or bleeding.
Conjunctiva: key facts
- Where it is
- Lines the inner surface of the upper and lower eyelids, then folds back to cover the front of the white of the eye, stopping at the edge of the cornea (the limbus)
- What it is
- A thin mucous membrane: a non-keratinised (soft, moist) layered epithelium about five cell layers deep, on a loose, blood-vessel-rich connective tissue
- Main parts
- Palpebral (eyelid) conjunctiva, forniceal conjunctiva (the fold between lid and eye) and bulbar (eyeball) conjunctiva
- Main jobs
- Barrier against germs and dust, mucus for the tear film, immune defence, smooth movement of the eye under the lids
- Blood supply
- Rich. Unlike the cornea, which has none
- Most common problems
- Conjunctivitis ("pink eye"), subconjunctival hemorrhage, dry or allergic eye, pinguecula and pterygium
- Specialist
- Ophthalmologist; at Laser Istanbul Clinic, Prof. Dr. Ahmet Satıcı, Doç. Dr. Muhammet Derda Özer and Op. Dr. Aysan Bayram
What is a subconjunctival hemorrhage?
A subconjunctival hemorrhage (written subconjunctival haemorrhage in UK English) is bleeding from a tiny vessel into the space between the conjunctiva and the sclera. Because the conjunctiva is clear, the blood shows through as a flat, bright red patch on the white of the eye, anywhere from a pinpoint spot to a patch covering much of the white. According to the American Academy of Ophthalmology (AAO), most people only notice it when they look in a mirror, and it may cause at most mild irritation.
Think of it as a bruise on the surface of the eye. The blood cannot drain quickly, so it stays visible until the body absorbs it. It looks alarming, but in most people it is harmless.
How common is it? EyeWiki (the AAO's clinical wiki) reports that subconjunctival hemorrhage accounts for around 3% of patients seen in outpatient departments and emergency rooms, and that it affects about 10.1% of people over 65.
Subconjunctival hemorrhage causes: why does the white of the eye bleed?
Subconjunctival hemorrhage causes fall into three groups.
1. Sudden pressure rises (the most common trigger). Coughing, sneezing, straining or vigorous eye rubbing temporarily raise pressure in the veins, and a fragile vessel gives way. The AAO lists these as the common causes. Often there is no obvious trigger at all: EyeWiki notes that around 40% of cases in older patients have no identified cause.
2. Injury. A knock to the eye, a scratch, a foreign body or contact lens problems can break vessels. EyeWiki reports minor eye injury as the cause in 83% of children's cases (surgery excluded) and notes more contact-lens-related cases in recent years.
3. Medical conditions and medicines. Risk factors include:
- high blood pressure, the main systemic factor in people over 50
- diabetes, which damages small blood vessels
- blood-thinning medicines such as aspirin, warfarin (Coumadin), clopidogrel (Plavix), apixaban (Eliquis) and rivaroxaban (Xarelto), all listed by the AAO
- long-term steroid eye drops
- eye surgery: a 2010 study cited by EyeWiki found about 10% more patients had a hemorrhage after cataract surgery if they stayed on warfarin or aspirin than if they stopped it a week beforehand. Never stop a blood thinner yourself; your prescriber and surgeon decide that together.
- rarely, blood-clotting disorders and other blood diseases
Symptoms: what a subconjunctival hemorrhage looks and feels like
| Typical | Not typical (needs checking) |
|---|---|
| A flat, bright red patch on the white of the eye | Pain, or significant discomfort |
| No pain, or mild scratchy irritation | Blurred vision, flashing lights, wavy lines or loss of vision |
| Normal vision | Pain when looking at light, or a severe headache with nausea |
| The pupil, iris and cornea look normal | One pupil bigger than the other |
| No discharge | The whole eye very dark red, or an injury, chemical splash or foreign body |
The NHS lists a "burst blood vessel" as one cause of a red eye and says to get emergency help if a red eye comes with any change in sight, pain when looking at light, a severe headache with nausea, a very dark red eye, an eye injury or chemical splash, or one pupil bigger than the other.
How long does a subconjunctival hemorrhage last, and what is the treatment?
It usually clears in one to four weeks, and no treatment is needed. EyeWiki says the hemorrhage is self-limiting and resolves over 1–4 weeks depending on its size and extent, and that no treatment is known to speed up healing. The AAO gives the same advice: it heals by itself in a few days to a few weeks, and artificial tears can ease any irritation.
What helps, in practice (subconjunctival hemorrhage treatment):
- Wait. The body absorbs the blood slowly; larger patches take longer.
- Use lubricating eye drops (artificial tears) if the eye feels scratchy.
- Try not to rub the eye. Rubbing is one of the triggers.
- Do not start or stop blood thinners on your own. Change prescribed medicines only on a doctor's advice.
- Get your blood pressure checked if you have not had it measured recently, especially if you are over 50.
Subconjunctival hemorrhage treatments by a doctor are only needed when there is an underlying cause to manage: an injury, high blood pressure, a bleeding problem or a medicine review.
Is a subconjunctival hemorrhage serious?
Usually not. On its own it does not threaten vision. It becomes a concern when it follows significant injury, when it comes with pain or vision changes, or when it keeps coming back.
When to see a doctor about a subconjunctival hemorrhage
Seek same-day care (emergency eye service, A&E or an eye doctor) if
- it follows a blow, a sharp or fast-moving object, or a chemical splash. EyeWiki warns that blood around the whole circumference of the eye after trauma may mean a more serious injury
- you have pain, pain when looking at light, a headache with nausea, or any change in vision
- one pupil looks larger than the other, or the eye is very dark red
- it appears in a baby or young child with no clear reason
Book a routine appointment if
- you get repeated hemorrhages. The AAO advises seeing an ophthalmologist if they occur frequently, and EyeWiki notes that recurrent cases deserve investigation for bleeding disorders and other causes
- you take blood thinners, have diabetes or have high blood pressure and notice a hemorrhage for the first time
- it is not clearly fading after about four weeks
Conjunctiva meaning and structure: the parts of the conjunctiva
The word comes from the Latin for "joining": the conjunctiva joins the eyelid to the eyeball. Anatomists divide it into continuous zones.
| Part | Where it is | Notes |
|---|---|---|
| Palpebral conjunctiva | Lines the back surface of the upper and lower eyelids | The tarsal conjunctiva is the portion lying on the firm plate (tarsus) that gives the lid its shape. It is closely attached to the lid and becomes visible when the eyelid is flipped. The palpebral conjunctiva also contains immune cells and lymphoid follicles |
| Forniceal conjunctiva | The loose fold where lid and eyeball meet, above and below the eye | Gives the eye room to move; forms the pocket known as the conjunctival sac |
| Bulbar conjunctiva | Covers the front of the white of the eye (sclera) up to the limbus | Thin, clear and loosely attached to the tissue beneath, so it can slide over the eye. This is where a subconjunctival hemorrhage appears and where a pterygium starts |
At the inner corner of the eye, a small crescent-shaped fold called the plica semilunaris is also part of the conjunctiva.
What is the conjunctiva made of?
It has two layers: a non-keratinised stratified epithelium about five cell layers deep, containing mucus-making goblet cells and immune cells, on top of a loose, richly vascularised connective tissue called the substantia propria. Tiny accessory tear glands (the glands of Wolfring and Krause) sit in this layer, and lymphoid tissue (conjunctiva-associated lymphoid tissue, or CALT) gives it an immune role. A 2025 anatomy review also describes a stable, low-level community of microbes on the conjunctival surface (such as Corynebacterium, Staphylococcus and Cutibacterium).
Conjunctiva function: what does the conjunctiva do?
The conjunctiva has four jobs.
1. Protection. It is a mucous barrier between the outside world and the eye. Immune cells and lymphoid tissue in it help defend the eye against germs.
2. Making the tear film. Goblet cells in the conjunctiva produce mucin, the inner layer of the three-layer tear film (the middle watery layer comes from the lacrimal glands, the outer oily layer from the meibomian glands). Mucin helps tears spread evenly over the eye. This is why conjunctival damage is linked to dry eye.
3. Lubrication and movement. The smooth, moist lining lets the eyelids glide over the eye with every blink, and the loose bulbar conjunctiva lets the eyeball turn freely.
4. Blood supply and repair. Its many small blood vessels supply the conjunctiva itself. It is also the reason the white of the eye turns red when the conjunctiva is inflamed or when a vessel breaks.
Conjunctiva vs cornea: what is the difference?
They sit side by side but are different tissues. The conjunctiva covers the white of the eye and has blood vessels; the cornea is the clear dome in front of the iris and pupil and has none.
| Conjunctiva | Cornea | |
|---|---|---|
| Where | Covers the white of the eye and lines the eyelids | The clear dome over the iris and pupil |
| Blood vessels | Many (so it can redden or bleed) | None (so it stays clear) |
| Main job | Protection, mucus, immune defence | Protection and most of the eye's focusing power |
| Typical problems | Conjunctivitis, subconjunctival hemorrhage, pinguecula, pterygium | Keratoconus, ulcers, dystrophies, scars |
| Relevant surgery | Pterygium removal | Corneal transplant, cross-linking, laser vision correction |
Read more in our entries on the iris and the pupil: Glossary: Iris → and Glossary: Pupil →.
Common conjunctival conditions
Conjunctivitis, and the "conjunctiva virus"
Conjunctivitis ("pink eye") is inflammation of the conjunctiva, and it is what most people mean by a "conjunctiva virus." The AAO describes three types: viral (the most common and contagious), bacterial (less common, but very contagious) and allergic (not contagious). EyeWiki reports that 65% to 90% of viral cases are caused by adenoviruses. Typical signs are redness, a gritty or burning feeling, watering or discharge, itching (strongest in allergic types) and puffy eyelids.
How it differs from a hemorrhage: conjunctivitis makes the eye pink and gritty, often with discharge, and can spread between people. A subconjunctival hemorrhage is a flat red patch with little or no discomfort and no discharge.
The AAO says conjunctivitis usually goes away on its own within one to two weeks; EyeWiki notes that adenoviral infections can stay contagious for about 10–14 days. Viral and allergic types do not respond to antibiotics, while bacterial cases may be given antibiotic drops. The NHS advises seeing a GP if symptoms last more than 7 days, and calling 111 for eye pain, light sensitivity, vision changes or very red eyes. The AAO advises not wearing contact lenses until the infection has cleared.
Pinguecula
A pinguecula is a harmless, raised yellow-white patch on the bulbar conjunctiva. EyeWiki links it to ultraviolet light, wind and dust, and notes it is more common on the side nearest the nose. It does not involve the cornea. Many people have no symptoms; artificial tears help if it is irritated, and removal is considered only if it is cosmetically bothersome or chronically inflamed.
Pterygium
A pterygium (Greek for "wing") is a growth that starts on the conjunctiva and progressively involves the cornea. EyeWiki gives ultraviolet exposure as the main risk factor, with higher rates near the equator, in dry climates and in people who work outdoors. Many people have no symptoms; others have irritation, and as it grows it can cause astigmatism or block vision. Lubricating drops ease mild irritation. Removal with a conjunctival autograft is described as the standard surgery, with recurrence of about 5–10%.
Dry eye and allergic eye disease
Because the conjunctiva makes mucin, dry eye and allergic eye disease are closely tied to it. A 2025 review links disturbed conjunctival microbes to allergic conjunctivitis, dry eye disease and ocular rosacea.
How is the conjunctiva examined?
An eye specialist examines the conjunctiva as part of an ordinary eye examination, and it takes minutes.
- History and vision check. Questions about injury, contact lenses, blood thinners, blood pressure and previous episodes, plus a vision test.
- Slit-lamp examination. A microscope with a bright beam of light shows the conjunctiva in detail, including the inside of the eyelids, which the doctor turns up to check. It shows the exact site and size of a hemorrhage, any discharge, follicles or growths.
- Checks for the cause. For a recurrent or unexplained hemorrhage, EyeWiki notes that blood tests and a medicine review are warranted, and a blood pressure check is a sensible first step.
- Checking the rest of the eye. The cornea, pupil and inner eye are looked at too, to be sure there is no deeper injury.
Our approach at Laser Istanbul Clinic
Prof. Dr. Ahmet Satıcı, Doç. Dr. Muhammet Derda Özer and Op. Dr. Aysan Bayram examine the front of the eye as part of every pre-operative assessment, and surgery takes place in a fully equipped, Ministry of Health–licensed operating theatre in Istanbul. Doç. Dr. Özer leads cornea and ocular surface care.
If you are planning cataract, laser or other eye surgery in Istanbul and notice a red patch on your eye beforehand, tell your coordinator. It is usually harmless, but your surgeon will want to look at the eye and review your medicines first. If you already have a report from another doctor, you can send it for review before you travel.
Frequently asked questions
It is a bleed from a tiny blood vessel under the clear surface of the eye (the conjunctiva). It shows as a bright red patch on the white of the eye and is usually painless and harmless.
Most often, sudden pressure from coughing, sneezing, straining or rubbing the eye. Injuries, contact lens problems, high blood pressure, diabetes, blood thinners and eye surgery are other causes. In many older adults no cause is found.
Typically one to four weeks, depending on its size. No treatment is known to speed it up.
Usually none. Artificial tears can relieve irritation. A doctor looks for and treats any underlying cause such as high blood pressure, and reviews blood-thinning medicines if you take them.
The NHS lists a burst blood vessel as a cause of a red eye and says to seek emergency help if a red eye comes with changes in sight, pain on looking at light, severe headache and nausea, a very dark red eye, an injury or chemical splash, or one pupil bigger than the other.
On its own it rarely is. It needs urgent assessment after an injury, with pain or vision changes, or in a baby or child with no clear reason. Repeated episodes call for a check of blood pressure and bleeding tendency.
The thin, clear, moist membrane covering the white of the eye and lining the inside of the eyelids. It protects the eye, makes the mucus layer of the tear film and contains small blood vessels.
The palpebral conjunctiva lines the eyelids; the tarsal conjunctiva is the part over the lid's firm plate; the bulbar conjunctiva covers the white of the eye. The forniceal conjunctiva is the fold that joins them.
Yes. It is usually viral conjunctivitis, most often caused by adenoviruses, and it is contagious. According to the AAO it usually clears within one to two weeks.
Sources for the facts on this page
- American Academy of Ophthalmology. What Is Subconjunctival Hemorrhage? https://www.aao.org/eye-health/diseases/what-is-subconjunctival-hemorrhage
- EyeWiki (AAO). Subconjunctival Hemorrhage. https://eyewiki.org/Subconjunctival_Hemorrhage
- NHS. Red eye (symptoms and when to get help). https://www.nhs.uk/symptoms/red-eye/
- NHS. Conjunctivitis. https://www.nhs.uk/conditions/conjunctivitis/
- American Academy of Ophthalmology. What Is Pink Eye (Conjunctivitis)? https://www.aao.org/eye-health/diseases/pink-eye-conjunctivitis
- EyeWiki (AAO). Conjunctivitis. https://eyewiki.org/Conjunctivitis
- American Academy of Ophthalmology. Conjunctiva. https://www.aao.org/eye-health/anatomy/conjunctiva-list
- EyeWiki (AAO). Basic Histology of the Eye and Accessory Structures. https://eyewiki.org/Basic_Histology_of_the_Eye_and_Accessory_Structures
- Clinical anatomy: cornea and ocular surface. Med Hypothesis Discov Innov Ophthalmol 2025. PMC12528774: https://pmc.ncbi.nlm.nih.gov/articles/PMC12528774/
- EyeWiki (AAO). Pinguecula. https://eyewiki.org/Pinguecula
- EyeWiki (AAO). Pterygium. https://eyewiki.org/Pterygium
Red patch on your eye, or a diagnosis you want checked?
Send us your eye report, photos or scans. One of our surgeons will review them and tell you what is likely to be going on and whether you need to be seen, with no obligation.
3 eye surgeons
Your case is reviewed by a named surgeon, not a salesperson. Reply within {{response time}}.
Prof. Dr. Ahmet Satıcı
Doç. Dr. Muhammet Derda Özer
Op. Dr. Aysan Bayram