Light Sensitivity Cause
The Cause of sensitivity to light can be from a number of things. The eye controls the amount of illumination reaching inside by varying the size of the pupil. The iris, or colored part of the eye acts like camera diaphragm and enlarges or reduces the pupil size. At night we typically need more light to see and the pupil becomes larger. The brightness used in car headlights is abnormal in the naturally low light levels at night and before the pupil can compensate for this sudden shift in illumination there is an overwhelming stimulus with the resultant eye pain and light sensitivity. If this response of the pupil of the eye is disrupted, an inappropriate amount of light will reach the inside of the eyes.
Eye Pain With Light
Eyes sensitive to light can be painful. There are numerous nerves that end on the the front tissues of the eye and the internal parts of the eye towards the front. These nerves feed into the ophthalmic division of the Trigeminal Nerve. hey carry pain stimulus to parts of the brain. Anything that scratches the cornea on the front of the eye, damages or inflames the other tissues (conjunctivitis or eye infections, iritis or infections of the colored part of the eye) will cause this to be stimulated and heighten the response to light. There is another pathway that presumably transmits light from the back of the eye to the thalamus, a relay like structure in the brain. Light probably stimulates theses cells and they in turn stimulate a region in the thalamus that is interpreted as pain with light exposure. There are no cells known to transmit pain signals directly from the retina, or the tissue on the inside back of the eyes. The blood vessels around the optic nerve exiting the eye do have pain receptors and indirect stimulation of these cells from other parts of the eye activated by light might also be causes of light sensitivity. People who have had traumatic brain injuries frequently have vision symptoms in bright light. People with a history of migraines are very similar in this respect. People who have migraines also have another problem-
Light Sensitivity Headache
Migraine sufferers are more light sensitive, even between migraine episodes when they are headache free. They are also often more sensitive to fluorescent lights in stores. Some research has indicated there may be a defect in the visual pathway that transmits information about vision over time versus what we normally think of in the eye doctors office when reading the eye chart. This system helps us know where over visual information is located over a changing time frame. The eyes move and we move throughout the day but our world stays together like a great movie. Things get a little disjointed if the magnocellular pathway is disrupted. Some people may be able to perceive a higher flicker rate of lights from alterations in this pathway, rendering them more prone to eye pain with light from fluorescent light fixtures.
Light Sensitivity Cause in Colorado
In Fort Collins we average 300 days of sunshine per year. Northern Colorado is at a higher altitude and due to less filtering of light by the air (and less clouds & air particles to scatter light) we have a higher amount of light that is shifted towards blue and UV. People that are more sensitive to light generally benefit some by wearing the brown blue blocking lenses or reddish/pink type of tints. Sunglasses that have more wrap (more closely aligned to the shape of the face) and offer more goggle shaped protection on the sides can lead to a dramatic improvement in comfort. Adding a partial mirror on the front or utilizing transition brown lenses can be useful in reducing eye pain with light. Due to the high amount of light reflected off of water and snow, polarized lenses are also called fort if you spend significant times outdoors in Colorado.
One last tip: Don’t wear tinted lenses indoors! There are actually some long term changes that occur in the eyes when you do this and they take months to wear off. By wearing sunglasses indoors, you reduce the effect they have on light sensitivity.
OK One really last tip: Dry eyes are the most common cause of eyes sensitivity to light. In the Fort Collins area, we live in a very low humidity climate and mild dry eye syndrome effects a lot of people. See you optometrist for an evaluation and you may be helping a lot more than just symptoms of dry eyes!