Light sensitivity usually isn't a cause for concern, but there are cases where it could point to a serious condition, as our post explains.

Tsung-lin Wu | Dreamstime

Light sensitivity or photophobia is eye discomfort in bright light. Bothersome light sources may include sunlight and harsh indoor lighting such as fluorescent or incandescent light from old-fashioned bulbs.

Light sensitivity is a common symptom that may be accompanied by headache. In most cases, it’s not due to disease. However, occasionally it’s a warning sign of a serious condition that requires urgent attention.

Medline Plus, published by the U.S. National Library of Medicine, explains that light sensitivity can be caused by eye conditions, disorders of the brain, or medication reactions. According to the post “MD Roundtable: Solving the Photophobia Puzzle” at the American Academy of Ophthalmology’s website, the color of your iris can be a factor, as darker pigment offers some protection against harsh light. People with blue irises are more sensitive to light, and the condition tends to worsen with age.

Causes of Light Sensitivity

There are several eye conditions that cause light sensitivity, including:

• Acute iritis or uveitis—Inflammation inside the eye.
• Detached retina—The lifting or tearing of the retina, the layer of tissue in the back of your eye that senses light and sends images to your brain.
• Dry eye—When he quantity and/or quality of tears fails to keep the surface of the eye adequately lubricated.
• Burns to the eye.
• Corneal abrasion—A wound to cornea, the transparent tissue that covers the front of the eye.
• Corneal ulcer—An open sore in the cornea, often caused by infection.
• Contact lens irritation due to excessive wearing or ill-fitting lenses.
• Blepharospasm—Abnormal, involuntary blinking or spasm of the eyelids.
• A stye or chalazion—A small bump in the eyelid caused by a blocked gland.
• Episcleritis—Irritation of the white of the eye (sclera), not usually due to infection.
• Glaucoma—increased pressure in the eye.
• Eye dilation during an eye examination.
• Recovery from eye surgery, including LASIK surgery.

Light sensitivity also can be a side effect of some medications, among them tetracycline and doxycycline, belladonna, furosemide, and quinine.

Light Sensitivity: Connection to Serious Condition

Several brain and psychiatric disorders also can cause light sensitivity. They include:

• Mental health disorders—Depression, anxiety, agoraphobia, bipolar disorder, and panic disorders can sometimes cause light sensitivity.
• Meningitis—An infection of the membranes covering the brain and spinal cord. If you or your child experience a sudden onset of light sensitivity with fever and headache, see your doctor right away.
• Migraines, tension headaches, and cluster headaches.
• Serious brain injury.
• Pituitary tumors.
• Mercury poisoning.
• Botulism.
• Rabies.

Clinical Assessment of Light Sensitivity

If you’re suffering from a sudden onset of light sensitivity, if it’s accompanied by other symptoms, or if it’s chronic and interferes with your life, see your doctor or an opthalmologist.

Light sensitivity is extremely subjective and there is no definitive test to measure severity. Your clinician may ask you to complete a “photophobia questionnaire.” A clinical examination may include:

• Visual Acuity Test—Snellen Chart.
• Funduscopy—Examination of the back of your eye.
• Ocular pressure.
• Pupil reaction to light.
• Blink reflex.
• Contraction of your eye muscles.

Your physician also may perform a slit lamp examination, where he drops a dye called fuorescein into your eye, making the blood vessels easier to see.

Or, if your provider is concerned there may be an underlying medical cause, he or she may order a neurological examination. An MRI scan may be requested if the doctor wants to exclude a neurological problem.

Light Sensitivity Treatment

Treatment begins with identifying and treating the underlying condition, if there is one. This usually reduces or eliminates the problem. If medications are implicated, ask your doctor about switching or stopping the drug.

Self-care treatment revolves around reducing exposure to harsh light. If possible, avoid going outside in the middle of the day and dim lights in your home. If you go outside in bright sunlight, wear wide-brimmed hats and ultraviolet-protection (UV) sunglasses. See your optician to discuss which sunglasses are best; he may recommend UVA and UVB protection and polarized or colored lenses.

If you have lights that bother you at home or at work, ask your optician about yellow lenses or FL-41 lenses, which cut out harmful blue light. You may also want to consider changing your light bulbs at home to “natural” bulbs that mimic dim outside light.

Prosthetic contact lenses are an option in severe, chronic light sensitivity. They reduce the amount of light that enters the eye.

Originally published in 2017, this post is regularly updated.