How Your Eyes Process Light
Light sensitivity (also known as photophobia) is a common condition that can cause discomfort or even pain when your eyes are exposed to light. While light is essential for vision, the visual system relies on a precise and coordinated process to interpret it. When something interferes with that process, even normal indoor lighting or sunlight can become overwhelming.
Before exploring what causes photophobia and how it’s treated, it helps to understand how your eyes normally process light and why disruptions can lead to sensitivity.
How Your Eyes Handle Light (Step by Step)
Every time you step into the bright sun, your eyes complete this process in milliseconds:
- Light reflects off objects and enters the front of the eye
- It passes through a thin tear film that protects and nourishes the eye
- The cornea begins focusing the light
- Light moves through the aqueous humor and enters the pupil, which adjusts to control light intake
- The lens fine-tunes focus for near or distant objects
- Light travels through the vitreous humor, a clear gel filling the eye
- The retina converts light into electrical signals
- These signals travel through the optic nerve to the brain
- The brain processes them into the images you see
Many structures are involved; light sensitivity can stem from problems anywhere along this pathway or from conditions outside the eye altogether.
What Causes Photophobia?
According to Medline Plus from the National Library of Medicine, some causes of sensitivity to light include:
- Eye inflammation
- Corneal abrasion or ulcer
- Wearing contact lenses for too long or lenses that fit poorly
- Eye infection, diseases, injury, or recovering from eye surgery
- Meningitis
- Migraine headaches
- Medications
Light Sensitivity, Migraines, and Brain-Related Conditions
Up to 80 percent of people who have photophobia experience a migraine along with the sensitivity to light. According to the American Migraine Foundation, light sensitivity is a symptom of migraines. Not all headaches that cause light sensitivity are migraines; individuals with tension and cluster headaches can also be sensitive to bright light.
If you experience chronic headaches due to light sensitivity, discuss your symptoms with a doctor as these may indicate a serious condition, including a brain injury or disease.
Tumors of the pituitary gland can also cause eye pain and headaches. In some cases, the tumor produces hormones that can cause a variety of symptoms, including headache. In other cases, tumors can grow and begin putting pressure on the surrounding areas in the brain and nerves, which can result in headaches and vision loss. Treatment depends on the symptoms; your doctor may suggest surgery or medicines to counteract excess hormones.
Medications and the Sun: Why Some Drugs Heighten Light Sensitivity
Some medications and supplements contain ingredients that may increase sensitivity to light, according to the Wisconsin Department of Health Services. In addition to photophobia, these drugs may induce a change in the skin that can cause exaggerated sunburn, itching, scaling, rash, or swelling with exposure to ultraviolet light.
Some photosensitizing medications include:
- Antihistamines
- Furosemide
- Non-steroidal, anti-Inflammatory drugs (NSAIDs)
- Oral and estrogen-based contraceptives
- Quinine
- Sulfonamides
- Tetracycline
- Tricyclic anti-depressants
If you’re taking these medications and experiencing eye discomfort in sunlight, Barnet Dulaney Perkins eye doctors can help determine whether photophobia is medication-related or due to an eye condition.
Eye Conditions That Commonly Cause Light Sensitivity
The American Academy of Ophthalmology photophobia may be associated with:
- Cataracts
- Corneal abrasion
- Conjunctivitis or pink eye
- Dry eye disease (very common in Arizona)
- Eye allergies
- Keratitis, which is also caused by corneal inflammation
- Uveitis, an inflammation of the eye
Because increased sensitivity to light is a symptom of many eye conditions, you should schedule an eye exam with your eye doctor as soon as you notice a marked increase in photophobia.
Coping with Light Sensitivity
If you’re dealing with photophobia, these strategies may help reduce discomfort:
- Wait a moment before transitioning between areas with different levels of light. This helps the eyes adjust to the change and could lessen discomfort.
- Shielding your eyes from the sun while outdoors
- Wear polarized sunglasses to help cut down the sun’s glare
- All sunglass lenses should be UV-protected to protect eyes from harmful UV light, OR choose light-activated tinted glasses to help reduce sunlight’s impact
- Wrap-around sunglasses may also prevent light from getting in through the sides
- If your doctor has diagnosed photophobia due to dry eyes, try to keep eye drops on hand to minimize discomfort. However, if there are other underlying causes, such as cataracts or inflammation, your eye doctor may have other lifestyle recommendations.
Managing Photophobia: From Diagnosis to Long-Term Relief
The most effective way to manage light sensitivity is by identifying and treating what’s causing it. Whether photophobia is related to dry eye, cataracts, migraines, or medication use, a comprehensive eye exam can provide answers and relief.
If Arizona sunlight is making everyday activities uncomfortable, the experienced eye doctors at Barnet Dulaney Perkins Eye Center can help determine the cause and guide your treatment.
Schedule an eye exam today and take the next step toward clearer, more comfortable vision.