Diagnosing light sensitivity (photophobia) means identifying its underlying cause — there is no single “photophobia test.” Because photophobia is a symptom shared by dozens of conditions spanning neurology, ophthalmology, and internal medicine, the diagnostic workup is guided by the clinical context: when the photophobia started, what accompanies it, and what makes it better or worse.

Who Diagnoses Light Sensitivity?

The appropriate specialist depends on the suspected cause:

Ophthalmologist — for ocular causes (dry eye, uveitis, corneal disease, glaucoma, cataract)
Neurologist / headache specialist — for migraine, TBI, MS, meningitis, IIH
Primary care physician — initial evaluation; referral coordination
Rheumatologist — if systemic autoimmune disease (lupus, Sjögren’s, JIA) is suspected
Dermatologist — for cutaneous photosensitivity (drug reactions, porphyria, lupus)

For most patients without clear ocular symptoms, the workup begins with the primary care physician or neurologist, since migraine is by far the most common cause.

The Diagnostic History: Key Questions

The history is the most important diagnostic tool. Clinicians evaluate:

Onset:

Sudden (hours to days) vs. gradual (weeks to months) vs. lifelong
Sudden photophobia + fever → meningitis until proven otherwise
After head trauma → concussion/TBI
After starting a new medication → drug-induced

Character:

Pain in the eyes vs. headache triggered by light vs. skin reaction in sun
Continuous vs. episodic (during headaches only)
Unilateral vs. bilateral

Associated symptoms:

Headache, nausea, aura → migraine
Fever, neck stiffness → meningitis (emergency)
Eye redness, pain with eye movement → ocular cause
Visual loss, color desaturation → optic neuritis
Skin rash after sun exposure → cutaneous photosensitivity

Triggers:

Fluorescent lights specifically → migraine, TBI
Sunlight / UV only → cutaneous photosensitivity
All light equally → severe photophobia, uveitis

What helps:

Lying in dark room → migraine
Sunglasses outdoors only → mild photophobia
Closing eyes doesn’t help → central (brain) origin

Ophthalmological Examination

For suspected ocular causes:

Slit-lamp biomicroscopy (anterior segment):

Evaluates cornea (abrasion, ulcer, keratoconus, dry eye staining)
Anterior chamber (cells and flare in uveitis)
Iris and lens (signs of inflammation, cataract)

Dilated fundus examination (posterior segment):

Retinal pathology, optic nerve appearance, vitreous

Tonometry: Intraocular pressure measurement (elevated in glaucoma)

Tear film assessment: Tear break-up time (TBUT), Schirmer test, corneal staining — for dry eye

Corneal topography: For keratoconus, irregular astigmatism

Neurological Evaluation

For suspected central (neurological) photophobia:

Medical history and headache diary: Migraine diagnosis is clinical — based on ICHD-3 criteria (5+ attacks, 4–72 hours, unilateral, pulsating, moderate-severe, with nausea and/or photophobia/phonophobia)

Neurological examination: Visual fields, pupillary responses, extraocular movements, fundoscopy for papilledema

MRI brain with and without contrast: For atypical headache, suspected MS (white matter lesions), IIH, intracranial mass

Lumbar puncture (CSF analysis): For suspected meningitis, SAH (xanthochromia), IIH (elevated opening pressure)

Visual evoked potentials (VEPs): For suspected optic neuritis / MS

Laboratory Testing

Directed by clinical suspicion:

Suspected condition	Key tests
Lupus photosensitivity	ANA, anti-dsDNA, complement C3/C4
Porphyria	Urine porphyrins, plasma porphyrins
Lyme disease	ELISA + Western blot
Sarcoidosis	ACE level, chest X-ray
Sjögren’s (dry eye)	Anti-SSA/SSB, Schirmer test
Drug-induced	Medication review — no specific test

Measuring Photophobia Severity

Research uses validated questionnaires to quantify photophobia severity:

Photosensitivity Assessment Questionnaire (PAQ) — assesses sensitivity to various light sources
Photophobia Impact Questionnaire — assesses functional impact
Migraine-Specific Quality of Life (MSQ) — includes photophobia items in migraine assessment

In clinical practice, simple 0–10 scales or visual analogue scales are commonly used.

Sources

Katz BJ, Digre KB. “Diagnosis, pathophysiology, and treatment of photophobia.” Survey of Ophthalmology. 2016;61(4):466-477.
Digre KB, Brennan KC. “Shedding light on photophobia.” J Neuro-Ophthalmol. 2012;32(1):68-81.
Headache Classification Committee. “ICHD-3.” Cephalalgia. 2018;38(1):1-211.

Light sensitivity diagnosis: What It Means & When to Seek Help