Pain in one eyeball usually comes from something minor like a scratch on the surface, dry eye, or strain, but it can also signal conditions that need prompt attention. The fact that it’s your right eye specifically doesn’t point to a different set of causes than left eye pain. What matters more is the type of pain you feel, whether your vision has changed, and what other symptoms came along with it.
Surface Injuries: Scratches and Foreign Bodies
The most common reason for sudden pain in one eye is a corneal abrasion, a tiny scratch on the clear front surface of the eye. This typically causes a sharp, stinging pain that gets worse when you blink, along with tearing, redness, and a persistent feeling that something is stuck in your eye. You may not remember anything touching your eye. Fingernails, makeup brushes, paper edges, and even dust particles carried by wind can scratch the cornea without you noticing the moment it happens.
A foreign body, like a metal shaving, grain of sand, or eyelash, can lodge on the surface of your eye or get trapped under your upper eyelid. The symptoms feel almost identical to an abrasion: pain, watering, redness, and light sensitivity. Doctors use a fluorescent dye drop that glows under special lighting to reveal scratches invisible to the naked eye, and they’ll flip the upper eyelid (painless, though it sounds uncomfortable) to check for hidden debris. Most corneal abrasions heal within 24 to 72 hours on their own, though antibiotic drops are sometimes prescribed to prevent infection while the surface repairs itself.
Dry Eye in Just One Eye
Dry eye can absolutely affect one eye more than the other. Environmental factors like sitting near an air vent, sleeping on one side with that eye pressed into the pillow, or wind hitting one side of your face can dry out a single eye. Previous eye surgery, including LASIK, can reduce tear production in the operated eye. Eyelid problems where the lid turns slightly inward or outward also disrupt the tear film on one side only.
Dry eye pain tends to feel gritty or burning rather than sharp. It often worsens later in the day, after long stretches of screen time, or in low-humidity environments. If the pain comes and goes and worsens with reading or computer work, dry eye is a strong possibility.
Inflammation Inside the Eye
Deeper, aching pain points to inflammation of structures within or around the eyeball itself. Several conditions fall into this category, and they feel quite different from surface injuries.
Uveitis
Uveitis is inflammation of the middle layer of the eye wall. It causes a dull ache, sensitivity to light, redness concentrated in a ring around the colored part of the eye, and sometimes blurry vision. It can be triggered by autoimmune conditions, infections, or eye trauma, and it often affects one eye at a time.
Scleritis and Episcleritis
The white of the eye has layers, and inflammation can settle in different ones. Episcleritis affects the outermost layer and causes mild discomfort with a bright red or pink patch. It’s usually more annoying than painful and resolves on its own. Scleritis goes deeper, producing severe boring pain that can wake you at night, along with a darker, violet-tinted redness. Scleritis requires treatment because it can damage the eye permanently.
Acute Angle-Closure Glaucoma
This is one of the more serious causes of sudden, intense pain in one eye. It happens when the drainage system inside the eye becomes blocked, causing pressure to spike rapidly. The pain is severe and often comes with a headache, nausea or vomiting, halos around lights, and a hazy or cloudy appearance to the cornea. Vision drops noticeably. This is a medical emergency. Without treatment within hours, permanent vision loss can occur. It’s more common in people over 60, those who are farsighted, and women.
Optic Neuritis
If the pain is a dull ache behind your eye that gets worse when you move it side to side or up and down, optic neuritis is a possibility. This is inflammation of the nerve that connects the eye to the brain. Along with pain during eye movement, it typically causes some degree of vision loss, ranging from a small blind spot to significant blurring, often developing over a few days. Colors may look washed out in the affected eye.
Optic neuritis is significant because about half of people who experience an episode eventually develop multiple sclerosis over their lifetime. It can also occur with other autoimmune conditions like lupus. A single episode often improves on its own over several weeks, but it warrants a thorough neurological workup.
Headache Disorders That Target One Eye
Cluster headaches are one of the most painful conditions in medicine, and they center directly in or behind one eye. The pain is sharp, stabbing, and extreme, typically lasting 15 minutes to 3 hours. The affected side of the face may flush, the eye waters, the nostril runs or becomes congested, and the eyelid may droop or swell. These attacks tend to happen in bouts (clusters) over weeks or months, often at the same time each day, frequently waking people from sleep. Researchers believe the hypothalamus, the brain’s internal clock center, plays a role, which may explain the clocklike timing.
Migraines can also cause pain around one eye, though the pain is usually pulsating rather than stabbing. Nausea, light sensitivity, and sometimes visual disturbances (aura) distinguish migraines from other causes of eye pain.
Orbital Cellulitis
If your eye pain comes with fever, significant swelling of the eyelid or surrounding area, a bulging appearance of the eyeball, or difficulty moving the eye, orbital cellulitis is a concern. This is a bacterial infection of the tissues behind the eye. It often develops after a sinus infection spreads into the eye socket. The swelling can compress the optic nerve and restrict blood flow, so this condition requires emergency treatment, typically with IV antibiotics in a hospital. It’s more common in children but occurs in adults too.
How to Read Your Symptoms
The character of your pain narrows the possibilities considerably. A gritty, scratchy feeling points to the surface: abrasion, foreign body, or dry eye. A deep ache suggests inflammation inside the eye or along the optic nerve. Severe, boring pain with a violet-red eye points to scleritis. Stabbing pain with tearing and nasal congestion on the same side suggests a cluster headache. Pain that worsens specifically when you move the eye is characteristic of optic neuritis.
Certain combinations of symptoms signal an emergency. Seek immediate care if your eye pain is severe and accompanied by a headache, fever, or nausea. A sudden change in vision, halos around lights, swelling in or around the eye, inability to move the eye, or blood or pus coming from the eye all warrant urgent evaluation. If you wear contact lenses and develop eye pain, that also deserves prompt attention because of the risk of corneal ulcers, which start as a grayish spot on the cornea and can progress to a visible crater.
For milder, gritty discomfort without vision changes, try resting from screens, using preservative-free artificial tears, and avoiding rubbing the eye. If the pain hasn’t improved after two to three days, or if it’s getting worse rather than better, get it checked.