Photophobia or Light Sensitivity
Although our eyes are designed to respond to light, there are several conditions that can make them overly sensitive to light. Light sensitivity, or photophobia, is an intolerance of light. Some only feel discomfort from bright lights, while others cannot stand any type of light, whether it is sunlight, fluorescent light, incandescent light, or candle flames. Some light-sensitive people tend to squint or close their eyes when exposed to light. There are many different causes of photophobia, but it is typically a symptom of another condition or disease.
Photophobia happens to people of all ages and both sexes. It can be temporary or constant. A common temporary occurrence is leaving a movie theatre after a matinee showing. After being in darkness for so long, your eyes adjust to the dim lighting. Once the movie is over and you leave the theater, however, sunlight can be almost unbearable. Typically this increased sensitivity to light is temporary. Constant photophobia is usually an indicator of another problem, for which medical attention should be sought.
Why is this? It all has to do with the way light enters the eye. The eyes have a love-hate relationship with light. The eyes love light and need it to see, but too much of it can cause damage and discomfort. During routine eye examinations an eye doctor determines the refraction of light by the eye—that is, how the eyes bend light in order to focus it. When light enters the eye it goes through the cornea and lens before reaching the retina and striking the optic nerve. The optic nerve is the transmitter, the communicator between the eyes and the brain. If light does not reach the retina, or if it reaches the retina abnormally, the brain cannot respond properly and poor sight is the result, regardless of the lighting conditions. This is why it is difficult to see clearly in the dark.
Symptoms of Photophobia
There are a few obvious symptoms of photophobia:
In some cases, the only symptom may be the light sensitivity itself. People have reported light-sensitivity that comes on suddenly, without warning—the eyes are normal one day, and sensitive the next. Each individual is unique and experiences different symptoms. Again, the nature and severity of the symptoms depends on the underlying cause. Some people will suffer other symptoms, depending on the condition or disease that is causing the light sensitivity.
Causes of Photophobia
There are many reasons why someone might suffer from sensitivity to light. Photophobia is not a disease or disorder per se; rather, it is a symptom of many different diseases, disorders, and conditions. For example, an infection or inflammation that irritates the eyes can cause photophobia. It can be a symptom of an underlying disease such as a viral illness, or it can be caused by a severe headache or migraine. When the cornea is compromised or stressed for any reason, it naturally responds by inflaming. Just as a bee sting causes pain, swelling, and tenderness, a similar inflammation response occurs when stress is placed on the cornea. During this response, fluid builds up within the cornea, causing light to scatter abnormally, which leads to extreme photophobia. Light sensitivity caused by infections or inflammation usually subsides once the underlying problem is treated.
A person’s eye color can also influence their sensitivity to light. People with lighter colored eyes experience greater light sensitivity than people with darker colored eyes. The extra pigment in darker colored eyes is thought to protect against harsh lighting and bright sunlight.
Some people are born with large pupils. The pupil is the black center of each eye that allows light to enter. In reality, the pupil is the window of the eye. A kitchen with large windows will let in more natural light than a kitchen with small windows. The same goes for pupil sizes. Each person’s pupil is a different size. Some people experience more sensitivity than others due to larger pupils.
Sometimes photophobia accompanies problems and conditions like color vision defects, conjunctivitis, keratitis, iritis, botulism, etc. Common causes include:
- Corneal abrasions
- Dry eyes
- Contact lens irritations
- Detached retina
- Refractive surgery
There are several common medications that list photophobia as a possible side effect, including:
- Eye drops used to purposely dilate the eyes
If you feel you are experiencing photophobia more often than you should be, you should seek medical attention from an eye care specialist. To diagnose you, your eye doctor will ask you several questions about the light sensitivity and additional symptoms you may be experiencing. You will also undergo a routine eye exam to check the refraction of light by the eye, or how the eyes bend to focus light to produce vision. An eye exam has seven major components:
- Visual acuity exam
- Refraction exam
- Visual field exam
- External exam
- Slit lamp exam
- Ophthalmoscopic exam
Each of these tests can help your eye doctor determine what is causing the photophobia. For some of these examinations, your eye doctor may use eye drops that dilate your pupils, which will increase or worsen the photophobia for a short time. Once a correct diagnosis is made, your eye doctor will create an appropriate treatment plan to reduce your light sensitivity and any other symptoms you may be experiencing.
Treatment for Photophobia
The best way to treat photophobia is to address the underlying cause. In most cases, if you treat the underlying cause, the sensitivity levels decrease and the photophobia disappears. If the photophobia is due to medications, talking with your prescribing doctor about changing medications could help. Another solution is to reduce the amount of light that enters the eyes. Dimming or turning off indoor lights, closing window curtains, and wearing sunglasses with polarized lenses are all things you can do at home to help your situation. A prosthetic contact lens that mimics the color of your eye can also be used. In some cases, avoiding bright light situations altogether could be the only solution. Inform your eye doctor about any issues you may have, including sensitivity to light, even if you believe your case is mild.
As mentioned above, in some cases—such as when a person is born with larger pupils—photophobia cannot be prevented. Even in these types of situations, however, there are steps you can take to reduce your light sensitivity. Here are some prevention tips for photophobia:
- Wear sunglasses with polarized lenses when outdoors, even in the shade.
- Take vitamins and eat foods that contain antioxidants; learn more about eye vitamins; light sensitivity is sometimes a sign of a vitamin A deficiency
- Let as much natural light as possible into indoor settings.
- Dim or turn off indoor lights; close curtains in windows if too much light enters.
- Get treatment for any underlying condition you may have, such as dry eyes or conjunctivitis.
- Wear wide-brimmed hats when outdoors.
- Close your eyes for a while.
Talking to Your Eye Doctor
Here are some questions to ask your eye doctor about photophobia:
- How often should I be experiencing light sensitivity?
- What is causing my increased light sensitivity?
- What can I do to prevent photophobia from occurring?
- Based on my overall eye health, which type of lenses should I use to protect my eyes against bright lights?
- Are there any over-the-counter products that could help reduce my symptoms?
- If my sensitivity remains high, how long should I wait to contact you again?
- Which other treatment options will we explore if the initial treatment fails?
Did you know…according to one study, taking 10 mg of Lutein and 2 mg of zeaxanthin per day can reduce light sensitivity.
- R. Abel, Jr., MD “The Eye Care Revolution” (Kensington Books, 2004) 41-48
- J. DiGirolamo, MD “The Big Book of Family Eye Care” (Basic Health Publications, Inc. 2011) 71-73