Pain in or around one eye usually comes from one of a handful of common, treatable causes, but in rare cases it signals something that needs urgent attention. The eye and the tissues surrounding it are packed with sensory nerve endings, most of which feed into the trigeminal nerve, the same nerve that carries sensation from much of the face and head. That wiring means the list of possible triggers is long: the pain could originate on the eye’s surface, inside the eyeball, in the muscles behind it, or even from structures that have nothing to do with the eye at all, like your sinuses or your neck.
How the Eye Senses Pain
The cornea, conjunctiva, sclera, iris, and deeper structures of the eye are all supplied by sensory neurons from the trigeminal ganglion. These neurons include ones that respond to harmful mechanical pressure, irritant chemicals, and heat, as well as specialized cold-sensitive fibers on the cornea that can trigger discomfort in dry or windy environments.1Progress in Retinal and Eye Research. Neurobiology of ocular pain Signals from those nerve endings travel through the trigeminal ganglion into the brainstem, where they undergo initial processing before reaching higher brain centers.2Frontiers in Pharmacology. Mechanisms of Peripheral and Central Pain Sensitization: Focus on Ocular Pain This is worth knowing because it explains two things about eye pain: first, even minor surface irritation can feel disproportionately intense because the cornea is one of the most densely innervated tissues in the body; second, pain that seems to come from the eye can actually originate elsewhere along this shared nerve pathway.
Digital Eye Strain and Fatigue
If your right eye aches after hours at a screen, the most likely explanation is digital eye strain, formally called asthenopia. Researchers have described two overlapping symptom clusters: an external set involving burning, irritation, tearing, and dryness, closely linked to reduced blinking and dry eye; and an internal set involving a deep ache, strain, and headache behind the eyes, linked to the focusing and convergence effort your eyes make to keep a near target sharp.3BMJ Open Ophthalmology. Digital eye strain: prevalence, measurement and amelioration These two mechanisms often overlap, meaning you can have both a gritty, burning surface and a deeper ache behind the eye at the same time.
Eyestrain-related headaches can be traced to muscle spasms around the orbit, difficulty maintaining accommodation (the eye’s auto-focus), and convergence problems, all of which worsen with prolonged near work.4PubMed Central. Computer vision syndrome: a comprehensive literature review Three main mechanisms drive computer vision syndrome: extraocular muscle fatigue, accommodative stress, and changes to the tear film when blink rate drops.5PubMed Central. Understanding and preventing computer vision syndrome The classic self-help advice (the “20-20-20” rule, where you look at something 20 feet away for 20 seconds every 20 minutes) targets accommodative strain specifically, but if your symptoms lean more toward dryness and burning, deliberate blinking and a humidifier may matter more than looking into the distance.
One detail people miss: if the discomfort is consistently worse in one eye, it could point to an uncorrected or unevenly corrected refractive error. When one eye does more focusing work than the other, the muscles around that orbit fatigue first. An up-to-date refraction from an optometrist is worth getting before you assume the problem is just screen time.
Dry Eye and Corneal Surface Problems
Dry eye disease is one of the most common reasons for ongoing eye discomfort, and it can present asymmetrically, affecting one eye more than the other. Diagnostic criteria typically include tear-film stability measures, surface staining, and osmolarity in both eyes, because inter-eye differences can be clinically meaningful.6PubMed. Capability of the Inter-Eye Differences in Osmolarity, Break-Up Time and Corneal Staining on the Diagnostic of Dry Eye In other words, your right eye could score differently from your left on objective dry-eye tests, which explains why you might feel pain on one side only.
In some people, chronic dry eye evolves beyond a simple tear-film problem. Research suggests that a subset of dry eye may function more like a chronic nerve-pain disorder, with features such as spontaneous burning, heightened sensitivity to stimuli that shouldn’t hurt, and pain out of proportion to what doctors see on examination.7Pain Medicine. Burning Eye Syndrome: Do Neuropathic Pain Mechanisms Underlie Chronic Dry Eye? A related condition, corneal neuropathic pain, is characterized by stinging, burning, photophobia, and deep aching even when the eye’s surface looks normal under a microscope.8PubMed Central. Corneal Neuropathic Pain: A Patient and Physician Perspective If your eye pain has persisted for weeks or months and artificial tears provide only brief relief, these nerve-driven mechanisms are worth discussing with an eye care provider. Standard dry-eye treatments aimed at improving the tear film may not be enough on their own.
Contact Lens Complications
If you wear contact lenses and your right eye hurts, take the lens out. Contact lens wear is a well-recognized risk factor for corneal ulcers, particularly when lenses are worn overnight, for extended continuous periods, or with poor hygiene. Symptoms of a contact-lens-related corneal ulcer start with discomfort and a foreign-body sensation and can escalate to severe pain, redness concentrated around the corneal margin, light sensitivity, discharge, and blurred vision.9PubMed Central. Contact lens related corneal ulcer A corneal ulcer is an infection, and it can scar the cornea permanently if treatment is delayed. Any lens wearer with increasing pain, a red ring around the cornea, or worsening vision should see an eye doctor the same day rather than waiting to see if it improves.
Inflammation of the Eye Wall
The white of the eye (sclera) and the thin tissue over it (episclera) can become inflamed on their own. Episcleritis tends to cause a localized patch of redness with mild discomfort and is generally benign, often recurring but rarely progressing to anything more serious. The main complication is an occasional mild inflammation of the corneal margin.10British Journal of Ophthalmology. Scleritis and episcleritis Scleritis, by contrast, involves deeper inflammation and tends to produce a boring, intense pain that can radiate to the forehead, cheek, or jaw. It sometimes signals an underlying autoimmune condition and needs a more thorough workup. If the redness is localized, the pain is mild, and it comes and goes without vision changes, episcleritis is more likely. If the pain is severe and you notice a violet hue to the sclera or any vision changes, scleritis is the concern.
Acute Angle-Closure Glaucoma
This is the eye emergency people most commonly miss because it doesn’t always look like an eye problem. Acute closed-angle glaucoma occurs when the drainage pathway for fluid inside the eye is suddenly blocked, and pressure spikes rapidly. Symptoms include eye redness, worsening vision, visual disturbances like halos around lights, headache, and nausea.11PubMed Central. Acute Closed-Angle Glaucoma-an Ophthalmological Emergency The nausea and headache can dominate the picture so much that people end up in emergency departments being evaluated for migraine or gastrointestinal problems before anyone checks eye pressure.
This condition develops because the physical pathway between the front and back chambers of the eye becomes obstructed, causing intraocular pressure to surge and threatening the optic nerve.12PubMed. Acute angle closure glaucoma It is uncommon in the general population but tends to affect people with certain anatomical risk factors: farsightedness, older age, shallow anterior chambers, and East Asian descent. If you develop sudden severe eye pain with blurred vision, a rock-hard feeling in the eye, and nausea, get to an emergency department and specifically ask them to check your intraocular pressure. Permanent vision loss can occur within hours if the pressure is not brought down.
Optic Neuritis
Optic neuritis is inflammation of the optic nerve itself. The classic presentation is mild pain around the eye that worsens with eye movement, often appearing two to three days before vision starts to deteriorate.13Frontiers in Pain Research. Pain Symptoms in Optic Neuritis The pain typically resolves on its own over several days, but the visual loss (often described as dimming, color desaturation, or a central blind spot) can persist longer. Optic neuritis is sometimes an early sign of multiple sclerosis, which is why your doctor will likely recommend an MRI of the brain and optic nerves if this diagnosis is suspected. It most commonly affects one eye at a time, so unilateral pain with eye-movement sensitivity and vision changes in a younger adult is a pattern that warrants prompt evaluation.
Herpes Zoster Ophthalmicus
Shingles can reactivate in the ophthalmic branch of the trigeminal nerve, producing a condition called herpes zoster ophthalmicus (HZO). This branch further divides into smaller nerves that supply the forehead, eyelids, nose tip, conjunctiva, sclera, cornea, iris, and deeper eye structures.14Ophthalmology. Herpes Zoster Ophthalmicus: Natural History, Risk Factors, Clinical Presentation, and Morbidity About half of patients with HZO develop actual eye disease, and up to a quarter of those develop chronic or recurrent problems. Common manifestations include conjunctivitis, corneal inflammation, and inflammation inside the eye, while optic nerve damage and retinal infection are uncommon but possible.15PubMed Central. Herpes Zoster Ophthalmicus: Presentation, Complications, Treatment, and Prevention
The hallmark is a painful, blistering rash on the forehead and upper eyelid that respects the midline of the face, affecting only one side. If the rash involves the tip of your nose (Hutchinson sign), the risk of eye involvement goes up because the same nerve branch supplies both the nose tip and the eye’s interior structures. Early antiviral treatment reduces the risk of complications, and ocular involvement needs urgent evaluation by an ophthalmologist.
Cluster Headache and Other Headache Disorders
Not all pain felt in the eye actually originates there. Cluster headache produces excruciating, strictly one-sided pain centered around or behind the eye, lasting anywhere from 15 minutes to three hours per attack. It comes with unmistakable autonomic signs on the same side: tearing, nasal congestion, drooping eyelid, constricted pupil, lid swelling, and redness of the eye.16PubMed Central. Cluster headache17Nature Reviews Disease Primers. Cluster headache The attacks tend to cluster in bouts lasting weeks or months, often at the same time of day, and people with cluster headache typically pace or rock rather than lying still (which distinguishes it from migraine).
Migraine can also produce unilateral periorbital pain, though it tends to be more of a pulsating ache accompanied by nausea, light sensitivity, and sometimes visual aura. The key distinction is the autonomic features: cluster headache almost always causes a visibly red, tearing eye on the painful side, while migraine usually does not. If your eye pain recurs in predictable, short, devastating episodes with a watery red eye, you are dealing with something in the cluster headache family and should see a neurologist rather than an ophthalmologist.
Sinus and Neck Pain Referred to the Eye
The trigeminal nerve’s wide territory creates opportunities for pain to be felt in the eye when the real problem is elsewhere. Sinus inflammation is a classic example. Pain in or around the eye is a frequent symptom of sinus disease, and it can appear even when there are no obvious nasal symptoms directing attention to the nose.18SAGE Journals / PubMed Central. Referred Pain of Nasal Sinus Inflammation The frontal and ethmoid sinuses sit directly above and beside the orbit, so inflammation there naturally radiates to the eye region. If your right eye pain worsens when you bend forward or is accompanied by congestion, facial pressure, or thick nasal discharge, a sinus problem is worth considering.
Less obviously, pain originating from the upper cervical spine can also be referred to the orbit. Anatomical and clinical evidence shows that pain from cervical spine structures can travel to the forehead and even to the eye area because sensory input from the upper neck converges on the same brainstem neurons that process trigeminal input from the face.19PubMed. Cervicogenic headache: evidence that the neck is a pain generator A series of patients with eye or periorbital pain were found to have cervical region dysfunction, with marked tenderness in the suboccipital region on the same side as their eye pain. When this area was treated with local injections, the eye pain resolved.20PubMed. Referred ocular pain relieved by suboccipital injection If your eye pain is accompanied by neck stiffness, worsens with neck movement, or doesn’t respond to any eye-directed treatment, cervicogenic referral is a possibility that often goes unrecognized.
Orbital Cellulitis
An infection of the soft tissues behind the eye is an emergency, especially in children. Orbital cellulitis typically follows a sinus infection that spreads into the orbit. Key signs include reduced vision, pain deep in the orbit, significant lid swelling, chemosis (swollen conjunctiva), the eye being pushed forward, pain on eye movements, and sometimes double vision.21Paediatrics and Child Health. Management of periorbital and orbital cellulitis Preseptal cellulitis, a more superficial infection of the eyelid skin, looks similar but does not restrict eye movement or affect vision. The distinction matters because orbital cellulitis can spread to the brain and requires intravenous antibiotics and sometimes surgery, while preseptal cellulitis is usually managed with oral antibiotics. If your eye is swollen, red, painful, and you have trouble moving it or see double, go to an emergency department.
When to Seek Urgent Care
A useful clinical framework groups eye-pain red flags by what they point to. Exam findings such as optic disc swelling, cranial nerve problems, specific patterns of redness, and elevated intraocular pressure all guide how urgently you need to be seen and by whom.22PubMed. Approach to Eye Pain: Differential Diagnosis and Work Up for the Neurologist As a general guide, you should seek same-day evaluation if you have any of the following:
- Vision loss: any sudden decrease in vision, new blind spots, or sudden onset of floaters with flashes of light.
- Severe pain with nausea: suggests acute angle-closure glaucoma, particularly if the eye feels hard and vision is blurry.
- Pain with eye movement plus vision change: raises concern for optic neuritis or orbital inflammation.
- Rash on the forehead or eyelid: suggests herpes zoster ophthalmicus, which benefits from early antiviral treatment.
- Proptosis or restricted eye movement: the eye being pushed forward or unable to move freely suggests orbital cellulitis, abscess, or a vascular abnormality.
- Recent eye surgery or trauma: any new pain after eye surgery or a penetrating injury warrants emergency evaluation.
On the other hand, mild aching that follows a long day of screen work, improves with rest, and comes with no redness or vision changes is almost certainly eye strain or dry eye and can be managed with breaks, lubricating drops, and an updated glasses prescription.
What Your Doctor Will Check
An eye-pain evaluation typically starts with a history and visual acuity check, then progresses through pupil examination, external inspection, eye-movement testing, visual-field screening, and sometimes color vision. A slit lamp is used to examine the cornea, anterior chamber, and lens under magnification. After that, the optic nerve and retina are examined, and intraocular pressure is measured. Additional imaging or referral for ultrasound and dilated examination may follow depending on what the initial evaluation reveals.23The Journal of Emergency Medicine. Ocular examination techniques for the emergency department Knowing this sequence can be reassuring if you’re anxious about the visit: most of it is painless and quick, and the slit lamp examination in particular is the single most informative step for identifying corneal abrasions, inflammatory cells inside the eye, and signs of elevated pressure.
Rare Vascular Causes
Very rarely, pain in one eye results from abnormal blood-vessel connections involving the cavernous sinus, the venous channel that sits just behind the eye. A carotid cavernous fistula, an abnormal connection between an artery and this venous channel, can cause the eye to bulge, the conjunctiva to become engorged, and vision to blur. In a systematic review of patients with these fistulas, the most frequently reported sign was proptosis, followed by conjunctival congestion and diplopia, while eye pain itself was reported in a small minority of cases.24PubMed Central. Neuro-Ophthalmic Manifestations of Carotid Cavernous Fistulas: A Systematic Review and Meta-Analysis These conditions are rare enough that they are unlikely to be the cause of garden-variety eye pain, but they enter the conversation when a bulging, red eye is accompanied by a pulsating sound (bruit) that the patient can hear, or when standard treatments fail to resolve symptoms. A CT angiogram or MR angiogram can confirm or rule out vascular abnormalities when clinical suspicion is raised.