If your eyes feel painful, uncomfortable, or overly reactive to light — indoors, outdoors, or in front of screens — you have photophobia. Understanding why your eyes are sensitive to light requires identifying which part of the visual or nervous system is involved, because photophobia is a symptom with dozens of possible causes.

How Light Normally Reaches Your Brain

To understand why eyes become sensitive to light, it helps to trace the normal pathway: Light → cornea → lens → retina → optic nerve → visual cortex (for vision) AND a separate pathway through intrinsically photosensitive retinal ganglion cells (ipRGCs) → trigeminal nucleus (pain processing). In normal light sensitivity, this second pathway is activated only at extreme intensities. In photophobia, it becomes activated at ordinary light levels.

The Most Common Reasons Eyes Are Sensitive to Light

Anatomical illustration of the eye-to-brain photophobia pathway: ipRGC cells in retina sending signals via optic nerve to thalamus and trigeminal nucleus, pain signal shown in red — Photophobia happens when the ipRGC–trigeminal pathway fires at ordinary light levels — identifying which part of this pathway is sensitized determines the correct diagnosis and treatment.

1. Migraine — the #1 cause

Migraine is the most common cause of photophobia. During an attack, the trigeminal pain system becomes intensely sensitized, making any light — even dim indoor light — feel agonizing. Between attacks (interictally), many migraine sufferers have persistent, lower-grade light sensitivity that never fully resolves. If your light sensitivity comes with headache, nausea, and/or visual disturbances, migraine is the most likely cause.

2. Dry Eye Disease — the most common eye cause

Dry eye is the most common ocular cause of light sensitivity. When the tear film is inadequate (from meibomian gland dysfunction, Sjögren’s syndrome, environmental factors), the corneal surface becomes irregular and partially exposed. The dense network of corneal nerve endings — the most densely innervated tissue in the body — becomes hyperactivated, producing chronic photophobia. Dry eye photophobia typically worsens in dry or windy environments, with screen use, and toward the end of the day.

Medical illustration grid showing the top 6 causes of eye light sensitivity: migraine brain, dry eye cornea, concussion, uveitis inflamed iris, cataracts, and MS optic nerve — The top causes of light-sensitive eyes span neurology and ophthalmology — accurate identification is critical since migraine, dry eye, and concussion each require fundamentally different treatments.

3. Concussion and Brain Injury

Even mild concussion can cause persistent photophobia. The injury disrupts the normal filtering and processing of visual information, causing the brain to be overwhelmed by light input that would normally be processed without symptoms. Post-concussion photophobia can last months to years and often co-occurs with cognitive fatigue, headache, and sleep disruption.

4. Corneal Conditions

The cornea has more pain-sensing nerve endings per square millimeter than any other tissue. Anything that irritates or damages the cornea causes intense photophobia:

Corneal abrasion — scratch on the corneal surface; acute intense photophobia
Corneal ulcer — infected or inflamed cornea; requires urgent treatment
Keratitis — corneal inflammation from infection, UV exposure (snow blindness, welder’s flash), or contact lens complications

5. Uveitis

Uveitis is inflammation inside the eye (iris, ciliary body, choroid). When the iris and ciliary body are inflamed, they go into spasm — causing deep aching pain and photophobia. Uveitis requires prompt ophthalmology evaluation and treatment to prevent complications.

6. Medications

Many common medications cause light sensitivity as a side effect: doxycycline, tetracycline, fluoroquinolones, hydrochlorothiazide, amiodarone, and others. If you recently started a new medication and your eyes became sensitive to light, this may be the cause.

7. Other Conditions

Multiple sclerosis — optic neuritis (MS eye inflammation) causes acute photophobia
Meningitis/encephalitis — fever + photophobia + headache = emergency
Fibromyalgia/chronic pain syndromes — central sensitization amplifies all sensory inputs
Anxiety disorders — sensory hypersensitivity including photophobia
Thyroid eye disease — proptosis and corneal exposure

What the Pattern of Your Light Sensitivity Tells You

Pattern	Most likely cause
Comes with headache and nausea	Migraine
Worse on screens, improves with rest	Dry eye, digital eye strain
Sudden onset with fever	Meningitis (emergency)
Eye pain + redness + tearing	Corneal problem or uveitis
Started with a new medication	Drug-induced
After head trauma	Concussion
Lifelong since birth	Albinism, congenital disorder

When to See a Doctor

Sudden new photophobia with fever, severe headache, or stiff neck → emergency evaluation
Eye pain with redness → same-day ophthalmology
Persistent photophobia lasting more than 2 weeks → ophthalmologist or neurologist
Photophobia affecting daily functioning → specialist evaluation

Sources

Digre KB, Brennan KC. “Shedding light on photophobia.” J Neuro-Ophthalmol. 2012;32(1):68-81.
Noseda R, et al. “A neural mechanism for exacerbation of headache by light.” Nat Neurosci. 2010;13(2):239-245.
Katz BJ, Digre KB. “Diagnosis, pathophysiology, and treatment of photophobia.” Survey of Ophthalmology. 2016;61(4):466-477.

Why are my eyes sensitive to light: Complete Guide